CN106290794B - The analysis method of oncolite origin mechanism - Google Patents

Abstract

The invention discloses a kind of analysis methods of oncolite origin mechanism, belong to geology field.This method comprises: determining the gross feature and microscopic feature of multiple oncolite samples；Determine the content of stable isotope and the content of microelement in multiple oncolite samples；The content of the content of the stable isotope of the seawater of objective area and microelement, analyzes the origin mechanism of the oncolite of objective area when being formed according to the content of stable isotope and the content of microelement in the gross feature of multiple oncolite samples, microscopic feature, multiple oncolite samples and the oncolite in objective area.The embodiment of the present invention carries out quantitative-sxemiquantitative by the stable isotope and microelement of gross feature, microscopic feature and multiple oncolite samples to the multiple oncolite samples in objective area and tests, the palaeoenvironment when origin mechanism and oncolite formation of the oncolite of objective area is analyzed, the accuracy to objective area oncolite Genetic Mechanism is improved.

Description

The analysis method of oncolite origin mechanism

Technical field

The present invention relates to geology field, in particular to a kind of analysis method of oncolite origin mechanism.

Background technique

Microbialites are to capture and bond detrital sediment by Di Qi microbiologic population or using them as mineral precipitation center And a kind of biogenic deposit rock formed.Stromatolite, grumeleuse stone, karyomorphism can be classified as according to the macroscopic view group structure of Microbialites Stone, six major class of texture stone, tree-like stone and uniform stone.As a kind of important grain structure type of Microbialites, oncolite can be made The reference lamina for dividing and comparing for regional stratum, while being also the important indicator of recovery System Domain, therefore for a long time by ground The extensive concern of matter scholar.When carrying out regional stratum using oncolite to divide and compare, and restoring the work such as System Domain, The origin mechanism of oncolite is therefore how one of the key factor for determining that can these work go on smoothly analyzes oncolite The method of origin mechanism becomes urgent problem to be solved.

The method of prior art research oncolite origin mechanism mainly passes through the means such as field investigation and microscopic observation, from The form of oncolite, internal structure etc., infer oncolite origin mechanism.

However, oncolite origin mechanism can only be inferred using field investigation and with means such as microscopic observations, without Oncolite origin mechanism can accurately be analyzed, to reduce the accuracy rate of analysis.

Summary of the invention

In order to solve problems in the prior art, the embodiment of the invention provides a kind of analysis sides of oncolite origin mechanism Method.The technical solution is as follows:

The embodiment of the invention provides a kind of analysis methods of oncolite origin mechanism, which comprises

Determine the gross feature and microscopic feature of multiple oncolite samples, the multiple oncolite sample is in objective area It collects, the objective area is the area of oncolite origin mechanism to be analyzed；

Determine the content of stable isotope and the content of microelement in the multiple oncolite sample；

It is same according to stablizing in the gross feature of the multiple oncolite sample, microscopic feature, the multiple oncolite sample The seawater of the content of position element and the content of microelement and the oncolite in the objective area objective area when being formed Stable isotope content and microelement content, analyze the origin mechanism of the oncolite of the objective area.

Optionally, the gross feature of the multiple oncolite samples of the determination, comprising:

Determine size, shape and the abundance of the multiple oncolite sample；

Based on size, shape and the abundance of the multiple oncolite sample, the core of the objective area different location is determined The distribution characteristics of shape stone sample in machine and transverse direction.

Optionally, the microscopic feature of the multiple oncolite sample of the determination, comprising:

For each oncolite sample in the multiple oncolite sample, is tested using thin slice and determine the oncolite sample The constituent of the component structure of product and the component structure, the component structure include core and lamina, the group of the core It include bioclast, spherolite and the body of crystal structure containing algal gel at ingredient；

The color relationship between the core and lamina that determine the oncolite sample is tested using cathodoluminescence；

The mineral classification and the mineral classification of the oncolite sample are determined by X ray test and electron probe test Percentage composition in the oncolite sample.

Optionally, the multiple oncolite sample includes oncolite whole-rock sample and oncolite lamina sample, the karyomorphism Stone whole-rock sample includes the oncolite sample and same interval oncolite sample of different sizes of different intervals, the karyomorphism stone pattern Layer sample includes the oncolite sample of same oncolite difference lamina type；

Correspondingly, the content of stable isotope and the content of microelement in the multiple oncolite sample of the determination, Include:

The content of the content of stable isotope Sr, the content of C and O in the oncolite whole-rock sample is tested, In the determination oncolite whole-rock sample⁸⁷Sr isotopic content with⁸⁶The ratio of Sr isotopic content⁸⁷Sr/⁸⁶Sr, C isotope Content δ¹³C and O isotopic content δ¹⁸O；

The content of microelement Fe, Mn and Sr in the oncolite whole-rock sample are tested, with the determination karyomorphism Microelement Fe content, Mn content and Sr content in stone whole-rock sample；

The analysis of microcell laser C-O isotopes is carried out to the oncolite sample of the same oncolite difference lamina type, With the C isotopic content δ in the oncolite sample of the determination same oncolite difference lamina type¹³C and O isotopic content δ¹⁸O。

Optionally, the oncolite whole-rock sample is without the fresh sample by burying metharmosis, the core Shape stone whole-rock sample does not include impurity and jelly, the core in the oncolite whole-rock sample using microcell sampling gained Shape stone pattern layer sample be as under microscope light tone lamina and dark laminae used obtained by laser sampling respectively.

Optionally, described according to the gross feature of the multiple oncolite sample, microscopic feature, the multiple oncolite sample The content of stable isotope and the content of microelement and the target in the oncolite formation of the objective area in product The content of the stable isotope of the seawater in area and the content of microelement, analyze the origin cause of formation machine of the oncolite of the objective area System, comprising:

According to the gross feature and microscopic feature of the multiple oncolite sample, the oncolite for analyzing the objective area exists Development of microorganisms environment in forming process, turbulent water effect, the stability of depositional environment and forming process duration length It is short；

According to the content of stable isotope in the microscopic feature of the multiple oncolite sample, the multiple oncolite sample With the content of microelement, and in the oncolite formation of the objective area seawater of the objective area the same position of stabilization Whether the content of element and the content of microelement, analyze the oncolite of the objective area in forming process by metrical water Whether environment of the oncolite of effect and the objective area in forming process is inorganic environment.

Optionally, the gross feature and microscopic feature according to the multiple oncolite sample, with analyzing the target The oncolite in area in forming process development of microorganisms environment, turbulent water effect, depositional environment stability and forming process The length of duration, comprising:

If the shape of mature, the multiple oncolite sample of development of microorganisms is in the lamina of the multiple oncolite sample The partial size of round, the multiple oncolite sample is all larger than partial size threshold value, the abundance of the multiple oncolite sample be all larger than it is rich Coral rock dust agensis is covered on degree threshold value or the multiple oncolite sample, it is determined that the oncolite of the objective area Environment in forming process be suitble to the environment of development of microorganisms, in forming process by the effect of strong turbulent water, deposition ring The duration is long in border stabilization, forming process；

If the shape of immature, the multiple oncolite sample of development of microorganisms in the lamina of the multiple oncolite sample For there are the oncolite samples that partial size is less than or equal to the partial size threshold value in ellipsoid or hat shape, the multiple oncolite sample There are abundance to be less than or equal to the oncolite sample of the abundance threshold value or described more in product, the multiple oncolite sample The development of coral rock dust is covered on a oncolite sample, it is determined that environment of the oncolite of the objective area in forming process be Be not suitable for the environment of development of microorganisms, in forming process by strong turbulent water acts on, depositional environment is unstable, was formed The duration is short in journey.

Optionally, the microscopic feature according to the multiple oncolite sample, stablize in the multiple oncolite sample The content of isotope and the content of microelement, and in the oncolite formation of the objective area objective area sea The content of the stable isotope of water and the content of microelement, analyze the oncolite of the objective area in forming process whether It whether is inorganic environment by environment of the oncolite of metrical water effect and the objective area in forming process, packet It includes:

If in the multiple oncolite sample there are Fe content, Mn content and⁸⁷Sr/⁸⁶The core of Sr presentation positive offset characteristic Shape stone sample, there are Sr contents, δ¹⁸O、δ¹³The oncolite sample of C presentation negative offset characteristic, there are core colors and lamina color The oncolite sample of Chinese red is presented or there are terrigenous clastic contents to be greater than content threshold value and lamina type for light tone lamina Oncolite sample, it is determined that the oncolite of the objective area is acted in forming process by strong metrical water；

If the Fe content of the multiple oncolite sample, Mn content and⁸⁷Sr/⁸⁶Sr is without being presented positive offset characteristic, institute State Sr content, the δ of multiple oncolite samples¹⁸O、δ¹³Core of the C that negative offset characteristic, the multiple oncolite sample is not presented Heart color and lamina color do not give out light deeply or the multiple oncolite sample lamina in be less than there are terrigenous clastic content or Equal to the content threshold value and lamina type is the oncolite sample of dark laminae, it is determined that the oncolite of the objective area exists It is not acted on by strong metrical water in forming process；

If the multiple oncolite sample is free of microorganism and δ¹³C and δ¹⁸Negative offset characteristic is presented in O, it is determined that described Environment when the oncolite formation of objective area is inorganic environment；

If the multiple oncolite sample is rich in microorganism and δ¹³C and δ¹⁸Negative offset characteristic is presented in O, it is determined that target Environment when the oncolite formation in area is organic and inorganic dual environment.

Optionally, the method also includes:

Determine the content of the C isotope in the multiple oncolite sample and the content of O isotope；

According to the C isotopic content and O isotopic content of the multiple oncolite sample, the multiple oncolite sample is determined The salinity of product；

According to the oncolite sample of the salinity of the multiple oncolite sample and the objective area different location vertical To the rule changed relatively with the distribution characteristics in transverse direction, analysis sea level；

Based on the rule of the opposite variation in the sea level, the multiple oncolite sample is simulated in the sea of different developmental phases Plane is with respect to variation diagram；

Based on the multiple oncolite sample on the sea level of different developmental phases with respect to variation diagram and the multiple karyomorphism Global sea variation diagram when the formation of stone sample determines the palaeoenvironment when oncolite formation of objective area, the target Land construction lifting activity and sea when palaeoenvironment when the oncolite formation in area includes the oncolite formation of the objective area Plane lifting activity.

Technical solution provided in an embodiment of the present invention has the benefit that the embodiment of the present invention passes through to objective area The gross features of multiple oncolite samples, microscopic feature and stable isotope in multiple oncolite samples and microelement into Quantitative-sxemiquantitative of going is tested, and is determined in gross feature, microscopic feature and the multiple oncolite samples of multiple oncolite samples Stable isotope content and micro content, gross feature, microscopic feature and multiple oncolite samples based on multiple oncolite samples Stable isotope content and micro content in product, analyze the origin mechanism of the oncolite of objective area, that is to say, by multiple The design parameter of oncolite sample analyzes the origin mechanism of the oncolite of objective area, rather than simply by field investigation Inferred with modes such as microscopic observations, therefore improves the accuracy to objective area oncolite Genetic Mechanism.

Detailed description of the invention

To describe the technical solutions in the embodiments of the present invention more clearly, make required in being described below to embodiment Attached drawing is briefly described, it should be apparent that, drawings in the following description are only some embodiments of the invention, for For those of ordinary skill in the art, without creative efforts, it can also be obtained according to these attached drawings other Attached drawing.

Fig. 1 is a kind of analysis method flow chart of oncolite origin mechanism provided in an embodiment of the present invention；

Fig. 2A is the analysis method flow chart of another oncolite origin mechanism provided in an embodiment of the present invention；

Fig. 2 B is a kind of C- and O-isotopes point of multiple oncolite samples of objective area provided in an embodiment of the present invention Cloth schematic diagram；

Fig. 2 C is a kind of schematic diagram of the different lamina types of objective area oncolite sample provided in an embodiment of the present invention；

Fig. 2 D is that a kind of strontium isotope distribution of multiple oncolite samples of objective area provided in an embodiment of the present invention is shown It is intended to；

Fig. 2 E is a kind of distribution of the oncolite sample of objective area provided in an embodiment of the present invention in machine and transverse direction Feature schematic diagram；

Fig. 2 F is that karyomorphism rock layers are comprehensive at the top of a kind of objective area Middle Devonian series treasure stone group provided in an embodiment of the present invention Feature schematic diagram.

Specific embodiment

To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with attached drawing to embodiment party of the present invention Formula is described in further detail.

Before carrying out detailed explanation to the embodiment of the present invention, first the research object of the embodiment of the present invention is given It introduces.The objective area of the embodiment of the present invention is Longmenshan Beichuan area, and research object is the objective area Middle Devonian series karyomorphism Stone.Objective area is located at one band of the Beichuan County township Gui Xi Yuanwang Cave, and the oncolite developing stratum of the objective area is Middle Devonian series gold At the top of jewel group upper section, this section of depositional environment belongs to shore bank-marine shelf environments.

The prior art is mainly to the result of study of the oncolite of the objective area: bottom surpasses residual in the ancient karst that underlies on Return of spring fluvial sandbody on lamination, in, lower part be shallow-sea continental shelf phase sand, mud stone alternating layers combination, upward transition be mud stone with The mixed long-pending continental shelf of raw bits limestone alternating layers, top are the shelf-edge organic reef environment of coral rock development, and top is mud shale development Low energy environment contain a small amount of siltstone and argillaceous rocks in mud shale based on micrite calcite, horizontal lamination development, in it is raw Materialization stone is abundant, comprehensive including intact mussel-shrimp, foraminifer etc. and sea lily, peduncle, abdominal foot, bryozoan fragment etc. Conjunction thinks that the mud shale section is that backreef lagoon mutually deposits.

The origin mechanism of oncolite can only be inferred by means, the prior art such as field investigation and microscopic observation, And oncolite origin mechanism cannot accurately be analyzed.Therefore, the embodiment of the invention provides a kind of oncolite origin mechanisms Analysis method, pass through the gross feature of multiple oncolite samples to objective area, microscopic feature and multiple oncolite samples In stable isotope and microelement carry out quantitative-sxemiquantitative test, analyze the oncolite of objective area origin mechanism and Palaeoenvironment when the oncolite formation of objective area, improves the accuracy to objective area oncolite Genetic Mechanism.

Fig. 1 is a kind of analysis method flow chart of oncolite origin mechanism provided in an embodiment of the present invention, as shown in Figure 1, The analysis method of the oncolite origin mechanism, includes the following steps.

Step 101: determining the gross feature and microscopic feature of multiple oncolite samples, multiple oncolite sample is in mesh Mark area collects, and objective area is the area of oncolite origin mechanism to be analyzed.

Step 102: determining the content of stable isotope and the content of microelement in multiple oncolite samples.

Step 103: same according to stablizing in the gross feature of multiple oncolite samples, microscopic feature, multiple oncolite samples The stabilization of the seawater of objective area is same when the content of position element and the content of microelement and the oncolite in objective area are formed The content of position element and the content of microelement, analyze the origin mechanism of the oncolite of objective area.

Gross feature, microscopic feature and the multiple cores that the embodiment of the present invention passes through multiple oncolite samples to objective area Stable isotope and microelement in shape stone sample carry out quantitative-sxemiquantitative test, determine the macroscopic view of multiple oncolite samples Feature, microscopic feature and stable isotope content and micro content in multiple oncolite samples are based on multiple oncolite samples Gross feature, microscopic feature and stable isotope content and micro content in multiple oncolite samples, analyze objective area Oncolite origin mechanism, that is to say, the oncolite of objective area is analyzed by the design parameter of multiple oncolite samples Origin mechanism, rather than modes are inferred simply by field investigation and under the microscope etc., therefore improve to target The accuracy of regional oncolite Genetic Mechanism.

Optionally it is determined that the gross feature of multiple oncolite samples, comprising:

Determine size, shape and the abundance of multiple oncolite samples；

Based on size, shape and the abundance of multiple oncolite samples, the oncolite sample of objective area different location is determined Distribution characteristics in machine and transverse direction.

Optionally, the microscopic feature of multiple oncolite samples is determined, comprising:

For each oncolite sample in multiple oncolite samples, the component for determining oncolite sample is tested using thin slice The constituent of structure and component structure, the component structure include core and lamina, the constituent of core include bioclast, Spherolite and the body of crystal structure containing algal gel；

The color relationship between the core and lamina that determine oncolite sample is tested using cathodoluminescence；

The mineral classification and mineral classification for determining oncolite sample by X ray test and electron probe test are in oncolite Percentage composition in sample.

Optionally, multiple oncolite samples include oncolite whole-rock sample and oncolite lamina sample, oncolite total rock sample Product include the oncolite sample and same interval oncolite sample of different sizes of different intervals, and oncolite lamina sample includes same The oncolite sample of one oncolite difference lamina type；

Correspondingly, the content of stable isotope and the content of microelement in multiple oncolite samples are determined, comprising:

The content of the content of stable isotope Sr, the content of C and O in oncolite whole-rock sample is tested, with true In the fixed oncolite whole-rock sample⁸⁷Sr isotopic content with⁸⁶The ratio of Sr isotopic content⁸⁷Sr/⁸⁶Sr, C isotopic content δ¹³C and O isotopic content δ¹⁸O；

The content of microelement Fe, Mn and Sr in the oncolite whole-rock sample are tested, to determine that the oncolite is complete Microelement Fe content, Mn content and Sr content in rock sample product；

The analysis of microcell laser C-O isotopes is carried out to the oncolite sample of same oncolite difference lamina type, with true C isotopic content δ in the oncolite sample of fixed same oncolite difference lamina type¹³C and O isotopic content δ¹⁸O。

Optionally, oncolite whole-rock sample is without the fresh sample by burying metharmosis, oncolite total rock Sample does not include impurity and jelly in oncolite whole-rock sample using microcell sampling gained, and oncolite lamina sample is logical Cross under microscope light tone lamina and dark laminae used obtained by laser sampling respectively.

Optionally, stablize same position according in the gross feature of multiple oncolite samples, microscopic feature, multiple oncolite samples The stabilization same position of the seawater of objective area when the content of element and the content of microelement and the oncolite in objective area are formed The content of element and the content of microelement, analyze the origin mechanism of the oncolite of objective area, comprising:

According to the gross feature and microscopic feature of multiple oncolite samples, the oncolite of objective area is analyzed in forming process Middle development of microorganisms environment, turbulent water effect, the stability of depositional environment and forming process duration length；

According to the content and micro member of stable isotope in the microscopic feature of multiple oncolite samples, multiple oncolite samples Element content, and objective area oncolite formation when objective area seawater stable isotope content and micro member Whether the content of element analyzes the oncolite of objective area in forming process by metrical water effect and objective area Whether environment of the oncolite in forming process is inorganic environment.

Optionally, according to the gross feature and microscopic feature of multiple oncolite samples, the oncolite for analyzing objective area exists Development of microorganisms environment in forming process, turbulent water effect, the stability of depositional environment and forming process duration length It is short, comprising:

If the shape of mature, the multiple oncolite sample of development of microorganisms is round, more in the lamina of multiple oncolite samples The partial size of a oncolite sample is all larger than partial size threshold value, the abundance of multiple oncolite samples is all larger than abundance threshold value or multiple Coral rock dust agensis is covered on oncolite sample, it is determined that environment of the oncolite of objective area in forming process is suitable In the environment of development of microorganisms, forming process by the effect of strong turbulent water, depositional environment is stable, the duration in forming process It is long；

If the shape of immature, the multiple oncolite sample of development of microorganisms is in the lamina of multiple oncolite samples with ellipsoid With hat shape based on, in multiple oncolite samples there are partial size be less than or equal to partial size threshold value oncolite sample, multiple oncolites It is less than or equal on the oncolite sample or multiple oncolite samples of abundance threshold value in sample there are abundance and covers coral rock dust Development, it is determined that environment of the oncolite of objective area in forming process is the environment for being not suitable for development of microorganisms, was formed It is not acted on by strong turbulent water in journey, depositional environment is unstable, the duration is short in forming process.

Optionally, according to the content of stable isotope in the microscopic feature of multiple oncolite samples, multiple oncolite samples With the content of microelement, and objective area oncolite formation when objective area seawater stable isotope content With the content of microelement, whether the oncolite for analyzing objective area is acted on by metrical water in forming process and mesh Mark whether environment of the oncolite in area in forming process is inorganic environment, comprising:

If in multiple oncolite samples there are Fe content, Mn content and⁸⁷Sr/⁸⁶The oncolite sample of Sr presentation positive offset characteristic Product, there are Sr contents, δ¹⁸O、δ¹³The oncolite sample of C presentation negative offset characteristic, there are core colors and lamina color, and tangerine is presented Red oncolite sample or it is greater than content threshold value there are terrigenous clastic content and lamina type is the oncolite of light tone lamina Sample, it is determined that the oncolite of objective area is acted in forming process by strong metrical water；

If the Fe content of multiple oncolite samples, Mn content and⁸⁷Sr/⁸⁶Sr is without being presented positive offset characteristic, Duo Gehe The Sr content of shape stone sample, δ¹⁸O、δ¹³C is without being presented negative offset characteristic, the core color and lamina of multiple oncolite samples Color deeply do not give out light or multiple oncolite sample laminas in there are terrigenous clastic content be less than or equal to content threshold value and line Channel type is the oncolite sample of dark laminae, it is determined that the oncolite of objective area is in forming process not by powerful gas Fresh water effect；

If multiple oncolite samples are free of microorganism and δ¹³C and δ¹⁸Negative offset characteristic is presented in O, it is determined that objective area Oncolite formation when environment be inorganic environment；

If multiple oncolite samples are rich in microorganism and δ¹³C and δ¹⁸Negative offset characteristic is presented in O, it is determined that objective area Oncolite formation when environment be organic and inorganic dual environment.

Optionally, this method further include:

Determine the content of the C isotope in multiple oncolite samples and the content of O isotope；

According to the C isotopic content and O isotopic content of multiple oncolite samples, the salt of multiple oncolite samples is determined Degree；

According to the oncolite sample of the salinity of multiple oncolite samples and objective area different location in vertical and horizontal On distribution characteristics, the rule of the opposite variation in analysis sea level；

Based on the rule of the opposite variation in the sea level, multiple oncolite samples are simulated in the sea level phase of different developmental phases To variation diagram；

Based on multiple oncolite sample on the sea level of different developmental phases with respect to variation diagram and multiple oncolite sample Global sea variation diagram when product formation determines the palaeoenvironment when oncolite formation of objective area, the karyomorphism of objective area Land construction lifting activity and eustasy activity when palaeoenvironment when stone formation includes the oncolite formation of objective area.

All the above alternatives, can form alternative embodiment of the invention according to any combination, and the present invention is real It applies example and this is no longer repeated one by one.

Fig. 2A is the flow chart of the analysis method of another oncolite origin mechanism provided in an embodiment of the present invention, such as Fig. 2A Shown, the analysis method of the oncolite origin mechanism includes the following steps.

Step 201: acquiring the oncolite sample of objective area, and prepare multiple oncolite samples of objective area.

Multiple oncolite samples of objective area include oncolite whole-rock sample and oncolite lamina sample, oncolite total rock Sample includes the oncolite sample and same interval oncolite of different sizes of different intervals, and oncolite lamina sample includes same The sample of oncolite difference lamina type.

It should be noted that oncolite whole-rock sample is without the fresh sample by burying metharmosis, the core Shape stone whole-rock sample should be avoided impurity and jelly, be guaranteed the pure of oncolite whole-rock sample using microcell sampling gained, the microcell Degree, reliability and representativeness.Oncolite lamina sample be by under microscope light tone lamina and dark laminae use respectively Obtained by laser sampling.

Step 202: determining the gross feature and microscopic feature of multiple oncolite samples.

The gross feature of oncolite sample includes size, shape and the abundance and objective area difference of oncolite sample The distribution characteristics of the oncolite sample of position in machine and transverse direction.The oncolite sample of the objective area different location is in longitudinal direction With oncolite sample size in machine and transverse direction that the distribution characteristics in transverse direction is objective area different location, shape and rich Spend distribution characteristics.

According to the size, shape and abundance of oncolite sample, oncolite sample can be divided into four major class: big spherical, small Spherical, hat shape and irregular.

Fig. 2 B is a kind of C- and O-isotopes point of multiple oncolite samples of objective area provided in an embodiment of the present invention Cloth schematic diagram is as shown in Figure 2 B, big by partial size in multiple oncolite samples according to the difference of the shapes and sizes of oncolite sample In the spherical oncolite of 1cm be classified as the big spherical oncolite of spherical oncolite, size between 0.1-1cm be classified as it is coccoid Oncolite, shape is hat shape or hemispherical oncolite sample group is hat shape oncolite.

The microstructure characteristic of oncolite sample is used to describe the inner structural features of oncolite sample.Oncolite sample Microstructure characteristic can be determined by means such as thin slice test, cathodoluminescence test, X ray test and electron probe tests. Specifically, for each oncolite sample in multiple oncolite samples, the component for determining oncolite sample is tested using thin slice The constituent of structure and component structure, component structure include core and lamina, and the constituent of core includes bioclast, ball Grain and the body of crystal structure containing algal gel；The color relationship between the core and lamina that determine oncolite sample is tested using cathodoluminescence； The mineral classification and mineral classification for determining oncolite sample by X ray test and electron probe test are in oncolite sample Percentage composition.

In the embodiment of the present invention, for multiple oncolite samples of objective area, surveyed using thin slice test, cathodoluminescence Examination, X ray test and electron probe test test the microstructure characteristic of multiple oncolite sample.Wherein, thin slice Test is tested using high magnification microscope, and cathodoluminescence test is tested using cathode-ray luminescence test macro, and X is penetrated Line test is tested using X-ray diffractometer, and electron probe test is tested using zone X ray detecting spectroanalysis instrument.It surveys Test result is shown:

Thin slice test display oncolite sample is made of core and involucrum, and core can be divided into 3 classes: bioclast, spherolite or The orbicule and the body of crystal structure containing algal gel of early stage oncolite composition, mainly by biologies such as lamellibranch, shell, bryozoan, foraminifers Clast composition；Lamina includes 2 major class of light tone lamina and dark laminae, under high-power microscope, it may be clearly seen that mud-powder crystal structure Light tone lamina in contain a large amount of ten thousand algae of Pueraria lobota, be about 100 μm, it is 10 μm wide, be especially enriched in the lamina close to core.Thin slice is surveyed Examination and X ray test analysis shows that, oncolite sample lamina mineral are based on calcite, and electron probe display part is containing a small amount of The Lu Yuan quartz sand of 0.05-0.1mm size, quartz particles sorting, rounding are good, are randomly distributed in ring layer, content 1% or so. Under cathode-ray irradiation, for the core of oncolite sample in dead color, lamina is in Chinese red, indicates that the lamina of the oncolite sample exists It is acted in diagenetic process by stronger metrical water.

Step 203: determining the content of stable isotope and the content of microelement in multiple oncolite samples.

Isotope refers to that the chemical element of the same race that proton number is identical and neutron population is different, stable isotope refer to natural same position Element or non radioactive isotope, i.e. nonradiative decay, in the chemical conversion of earth evolution, the quality holding of stable isotope is eternal not Become.In geochemistry, microelement is an opposite concept, and content in natural system is usually lower than to 0.1% element Referred to as microelement.Microelement cannot independently be known as mineral, need to be contained in the mineral solid solution being made of other components, molten In body or stream phase body.

Specifically, it is determined that the content of stable isotope and the content of microelement in multiple oncolite samples, including it is following Step:

(1), it determines in oncolite whole-rock sample⁸⁷Sr isotopic content with⁸⁶The ratio of Sr isotopic content⁸⁷Sr/⁸⁶Sr、C Isotopic content δ¹³C and O isotopic content δ¹⁸O。

The method analyzed C- and O-isotopes has two major classes, respectively phosphoric acid method and microcell laser method.Phosphoric acid method It is that oncolite sample and phosphatizing are generated into CO₂Gas, using gas mass spectrograph is to the CO₂Gas is analyzed, it is measured C-O isotopes value, as the C-O isotopes value of the oncolite sample.Microcell laser method is by the focusing laser of high-energy Beam carries out high-temperature heating to oncolite sample and generates CO₂Gas, to the CO₂Gas using gas mass spectrograph measures the same position of its carbon, oxygen Element value, as the C-O isotopes value of the oncolite sample.The embodiment of the present invention is to C- and O-isotopes analysis side in oncolite Method is not specifically limited.

Preferably, for the oncolite whole-rock sample, C- and O-isotopes value therein is tested using phosphoric acid method.

In the embodiment of the present invention, the stable isotope test condition of oncolite whole-rock sample are as follows: Sr isotope is tested by south The analysis of capital university modern analysis center isotope mass spectrometry room is completed, and test equipment is Britain VG354 isotope mass spectrometer (TIMS), Experiment condition is 22 DEG C of temperature, and humidity 50%, detection is according to education sector standard: JY/T004-1996 surface heat ionised isotopes Mass spectrometry method general rule,⁸⁷Sr/⁸⁶Sr ratio measurement error is less than 0.02%；δ¹³C and δ¹⁸O value is by geographical science institute of Southwest University Geochemistry and isotopic laboratory analysis are completed, and carry out C-O isotopes analysis, analysis instrument Delta using phosphoric acid method V Plus+Kiel IV Carbonate Device, δ¹³The analytical error range of C is between 0.006-0.042, δ¹⁸The analysis of O Error range is between 0.009-0.043.

Table 1 is the stable isotope regularity of distribution of multiple oncolite whole-rock samples of objective area, as shown in table 1, target The regularity of distribution of the multiple oncolite samples in area in terms of stable isotope is as follows:

In terms of carbon isotope, δ in different-grain diameter oncolite sample spherical greatly¹³C value changes greatly, wherein big greater than 2cm The δ of spherical oncolite sample¹³C value is most light, and -1.52 ‰~-0.46 ‰, average -0.99 ‰, the big spherical oncolite less than 2cm The δ of sample¹³C value is between 0.8 ‰~0.92 ‰, and average 0.86 ‰；The δ of coccoid oncolite sample¹³C value is 0.02 ‰； Hat shape oncolite δ¹³C value is 0.05 ‰.

In terms of oxygen isotope, the δ of the big spherical oncolite sample greater than 2cm¹⁸O value is most light, and -8.77 ‰~-7.72 ‰, it puts down - 8.25 ‰；The δ of big spherical oncolite sample less than 2cm¹⁸O value between -7.52 ‰~-6.85 ‰, it is average - 7.19‰；The δ of coccoid oncolite sample¹⁸O value is -7.22 ‰；The δ of hat shape oncolite sample¹⁸O value is -6.79 ‰.

In terms of strontium isotope, big spherical oncolite sample⁸⁷Sr/⁸⁶Sr ratio be distributed in 0.708552~0.708703 it Between, average 0.708647；Coccoid oncolite sample⁸⁷Sr/⁸⁶Sr ratio is 0.708586；Hat shape oncolite sample⁸⁷Sr /⁸⁶Sr ratio is 0.708625.

The stable isotope regularity of distribution of the multiple shape stone whole-rock samples of the core of 1 objective area of table

On the whole, big spherical oncolite sample has minimum δ¹³C value, δ¹⁸O value and highest⁸⁷Sr/⁸⁶Sr ratio is small Spherical oncolite sample is similar with the Geochemical Characteristics of hat shape oncolite sample, has higher δ¹³C value, δ¹⁸O value and lower 's⁸⁷Sr/⁸⁶Sr ratio.

(2), microelement Fe content, Mn content and the Sr content in oncolite whole-rock sample are determined.

To the test of the microelement of inorganic matter generally use high-resolution inductive coupling plasma mass spectrometry analyzer into Row test, the instrument have many advantages, such as high-resolution, high sensitivity, high precision, high stability and the wide range of linearity, Ke Yitong When in inorganic matter various trace elements carry out fast quantification test.

In the embodiment of the present invention, to the test condition of the content of the microelement in multiple oncolite samples of objective area Are as follows: the content of microelement Fe, Mn and Sr are analyzed by Institute of Analysis of Institute of Multipurpose Utilization of Mineral Resources, Chinese Academy of G, Test equipment is 2000DV, and detection divides according to being JY/T015-1996 " inductively coupled plasma atomic emission spectrum method general rule " Analysis result indicates that detection limits 0.001%, error 0.002% with single element content.

As shown in table 1, microelement Mn, Fe, Sr distribution of content of the oncolite sample of objective area is as follows: Fe member Plain aspect, big spherical oncolite sample F e content 1.32~2.21%, average 1.67%；Coccoid oncolite sample F e content is most Height is 2.22%；Hat shape oncolite sample F e Content is minimum, is 1.37%；In terms of Mn element, big spherical oncolite sample Mn content 0.26~0.37%, average 0.3%；Coccoid oncolite sample Mn content 0.28%；Hat shape oncolite sample Mn contains Measure it is minimum, be 0.22%；In terms of Sr element, big spherical oncolite sample Sr content 0.03~0.063%, average 0.046%；It is small Spherical oncolite sample Sr content 0.052%；Hat shape oncolite sample Sr content is minimum, is 0.043%.

On the whole, big spherical oncolite sample has highest Mn content value, and coccoid oncolite sample has highest Fe, Sr content value, hat shape oncolite sample have minimum Fe, Mn and Sr content value.

(3), the C isotopic content δ in oncolite lamina sample is determined¹³C and O isotopic content δ¹⁸O。

Laser method has the advantage that required sample size is less relative to phosphoric acid method, may be implemented to sample fine structure Isotope analysis, spatial resolution with higher.It is not limited in the embodiment of the present invention.

Preferably for the test of the C- and O-isotopes content in the oncolite lamina sample of objective area, the present invention Embodiment is using the C- and O-isotopes content in the oncolite lamina sample in laser method test target area.Fig. 2 C is the present invention A kind of schematic diagram of the different lamina types for objective area oncolite sample that embodiment provides, as shown in Figure 2 C, objective area Oncolite sample lamina type it is complicated, the surface a variety of lamina intertexture superimposition different in the depth will according to unit lamina feature It is divided into 2 major class of light tone lamina and dark laminae, and wherein light tone lamina can be divided into mud-powder crystal lamina and powder crystal lamina, dark-coloured Lamina can be divided into micrite lamina, containing biological lamina, microorganism lamina and grumeleuse shape lamina.Pass through microcell laser carbon, the same position of oxygen The analysis of the C-O isotopes of the different laminas to objective area oncolite sample may be implemented in element analysis.

It is separately sampled to the different type lamina of objective area oncolite sample, and use microcell laser testing such as Fig. 2 C institute The C- and O-isotopes content of the different lamina types of the sample shown.Table 2 is the different laminas of the oncolite sample of objective area C- and O-isotopes value.As shown in table 2, which is, in light tone lamina Powder crystal lamina δ¹³C value is most light, is -1.06 ‰, and mud-powder crystal lamina is secondly, be -0.69 ‰, and dark laminae is most heavy, is distributed in Between 0.01 ‰~0.61 ‰, average 0.27 ‰, light tone lamina has most obvious Negative CIE spy relative to dark laminae Sign；The regularity of distribution in terms of oxygen isotope is the powder crystal calcite lamina δ in light tone lamina¹⁸O value is most light, is -11.52 ‰, Mud-powder crystal calcite lamina is -9.65 ‰, and dark laminae is distributed between -10.79 ‰~-8.93 ‰, average -9.866 ‰, The light tone lamina δ of powder crystal structure¹⁸O value is obviously defeated by mud-light tone lamina of powder crystal structure and the δ of dark laminae partially¹⁸O value.

The C- and O-isotopes value of the different laminas of the oncolite sample of 2 objective area of table.

Step 204: same according to stablizing in the gross feature of multiple oncolite samples, microscopic feature, multiple oncolite samples The stabilization of the seawater of objective area is same when the content of position element and the content of microelement and the oncolite in objective area are formed The content of position element and the content of microelement, analyze the origin mechanism of the oncolite of objective area.

Specifically, the origin mechanism of the oncolite sample of objective area is analyzed, comprising the following steps:

(1), according to the gross feature and microscopic feature of multiple oncolite samples, the oncolite for analyzing objective area is being formed Development of microorganisms environment, turbulent water effect, the stability of depositional environment and forming process duration in the process.

During oncolite formation, the size and abundance of oncolite are held by the stability and forming process of depositional environment The influence of continuous time, specifically, depositional environment is more stable, and the forming process duration is longer, and the oncolite partial size of formation is bigger, Abundance is higher, therefore can be according to the stabilization of depositional environment when the formation of the size and enrichment analysis oncolite of objective area oncolite The stability of property and forming process duration.

Meanwhile during oncolite formation, if will affect the shape of oncolite by turbulent water effect, specifically Ground, during oncolite formation, if being acted on by strong turbulent water, water energy is very strong at this time, the oncolite of formation Shape is circle, if not acted on by strong turbulent water, water energy is weaker at this time, core during oncolite formation The depositional environment of shape stone is quieter, and the shape of the oncolite of formation is ellipsoid or hat shape.It therefore can be according to oncolite Whether the shape analysis oncolite of sample is acted in forming process by strong turbulent water.

Correspondingly, according to the gross feature and microscopic feature of oncolite sample, the oncolite for analyzing objective area is being formed In the process development of microorganisms environment, turbulent water effect, the stability of depositional environment and forming process duration, may include In terms of following two:

First aspect: if development of microorganisms maturation, the shape of multiple oncolite samples in the lamina of multiple oncolite samples For round, multiple oncolite samples partial size be all larger than partial size threshold value, the abundance of multiple oncolite samples is all larger than abundance threshold value, Or coral rock dust agensis is covered on multiple oncolite samples, it is determined that ring of the oncolite of objective area in forming process Border be suitble to the environment of development of microorganisms, in forming process by the effect of strong turbulent water, depositional environment is stable, in forming process Duration is long.

Second aspect: if development of microorganisms is immature in the lamina of multiple oncolite samples, multiple oncolite samples obtain shape Shape is that there are the oncolite samples, more that partial size is less than or equal to partial size threshold value in ellipsoid or hat shape, multiple oncolite samples It is less than or equal on the oncolite sample or multiple oncolite samples of abundance threshold value in a oncolite sample there are abundance and covers reef Limestone dust development, it is determined that environment of the oncolite of objective area in forming process is the ring for being not suitable for development of microorganisms It is not acted on by strong turbulent water in border, forming process, depositional environment is unstable, the duration is short in forming process.

As shown in Figure 2 B, the oncolite of objective area according to its gross feature can be divided into big spherical, coccoid, hat shape and Irregular 4 class oncolite, big spherical oncolite depositional environment is stable and algae reaches maturity, and it is heavy that coccoid oncolite is formed in Product environment moderate stable and algae develop slightly immature, the depositional environment shakiness of hat shape oncolite and irregular oncolite Fixed, algae development degree depends on the size of oncolite sample particle diameter.

For the oncolite sample of objective area, wherein hat shape oncolite sample and irregular oncolite sample are being formed During do not acted on by turbulent water, be formed in low energy environment, the shape of such oncolite sample is irregular and lamina It is not concentric lamina.

Microscopic feature analysis to multiple oncolite samples of objective area, the results showed that the oncolite sample of objective area Product are made of core and lamina two parts, wherein core include bioclast, spherolite or early stage oncolite composition orbicule with And 3 classes such as body of crystal structure containing algal gel, lamina include mud-powder crystal, the light tone lamina of powder crystal structure and micrite, containing biology, microorganism With 2 major class of dark laminae of solidifying block structure, research thinks that dark laminae is mainly rich algae lamina, the more deeper richer algae of color, powder The light tone lamina of crystal structure is the product in poor algae stage, and mud-powder crystal structure light tone lamina is still the product in rich algae stage, generation The product that algae bonding mud-powder crystal calcite is formed under table high-energy environment.

(2), according to the content of stable isotope in the microscopic feature of multiple oncolite samples, multiple oncolite samples and micro- The content of secondary element, and the content of stable isotope of the seawater of objective area and micro- in the oncolite formation of objective area Whether by metrical water effect and target the content of secondary element analyzes the oncolite of objective area in forming process Whether environment of the oncolite in area in forming process is inorganic environment.

In the diagenetic process of oncolite, the geochemical difference of locating earthly environment, is led when due to oncolite formation Cause the element in oncolite, the especially combination of microelement and stable isotope and content difference.It therefore, can be according to karyomorphism The Geochemical Record retained in stone sample, such as the content of microelement and stable isotope in oncolite sample, inverting Environmental change when the oncolite formation of objective area.

Relative to metrical water, seawater is imbued with¹³C isotope and microelement Sr, it is poor in¹⁸O isotope and microelement Fe,Mn.Therefore can according to the content of microelement Fe, Mn, Sr in oncolite sample and¹³C、¹⁸The content and mesh of O isotope Mark area oncolite formation when seawater in microelement Fe, Mn, Sr content and¹³C、¹⁸The pass of the content of O isotope System, analyzes the origin mechanism of the oncolite of objective area.

It should be noted that nature has inorganic carbon and two kinds of organic carbon, wherein organic carbon is rich¹²C, inorganic carbon are rich¹³C has The generation and consumption of machine carbon are influenced by eustasy.During sea level rise, the reserve of biological organic carbon increases, and Ancient land aoxidizes area and reduces, and the organic carbon amounts for bringing ocean into because degrading substantially reduces, and is dissolved in CO in seawater in this way₂It is rich¹³C, this When the oncolite that balances each other with seawater it is rich¹³C, i.e. δ¹³C value increases.During Sea-level drop, continent area increases, due to oxygen Change the quantity increase degraded into the organic carbon of seawater；In addition, the biological effect in ocean weakens, promote the δ in seawater¹³C value It reduces.

Specifically, whether the oncolite for analyzing objective area is acted on by metrical water in forming process and target Whether environment of the oncolite in area in forming process is inorganic environment, in terms of may include following four:

In a first aspect, if in multiple oncolite samples, there are Fe content, Mn content and⁸⁷Sr/⁸⁶It is special that positive offset is presented in Sr The oncolite sample of property, there are Sr contents, δ¹⁸O、δ¹³The oncolite sample of negative offset characteristic, cathodoluminescence test result is presented in C Show that there are core colors and lamina color, and Lu Yuan in the oncolite sample or multiple oncolite sample laminas of Chinese red is presented Clast content is high and light tone lamina is developed, it is determined that the oncolite of objective area is made in forming process by strong metrical water With；

Second aspect, if the Fe content of multiple oncolite samples, Mn content and⁸⁷Sr/⁸⁶Sr is special that positive offset is not presented Property, the Sr content of multiple oncolite samples, δ¹⁸O、δ¹³C shows without presentation negative offset characteristic, cathodoluminescence test result more The core color of a oncolite sample and lamina color do not give out light deeply or multiple oncolite sample laminas in terrigenous clastic contain It measures low and dark laminae to develop, it is determined that the oncolite of objective area is not acted on by strong metrical water in forming process；

The third aspect, if multiple oncolite samples are free of microorganism, δ¹³C and δ¹⁸Negative offset characteristic is presented in O, it is determined that Environment when the oncolite formation of objective area is inorganic environment；

Fourth aspect, if multiple oncolite samples are rich in microorganism, δ¹³C and δ¹⁸Negative offset characteristic is presented in O, it is determined that Oncolite sample is influenced in forming process by organic and inorganic dual environment.

Fig. 2 D is that a kind of strontium isotope distribution of multiple oncolite samples of objective area provided in an embodiment of the present invention is shown It is intended to, as shown in Fig. 2 B, Fig. 2 D and table 2, for the content of the isotope in multiple oncolite samples of objective area, and at that time Carbon, oxygen, the strontium isotope background value of seawater are compared, and all oncolite samples all have oxygen isotope negative offset and strontium isotope positively biased Feature is moved, the big spherical oncolite sample and dark laminae carbon isotope of hat shape, coccoid, partial size between 1-2cm are normal, light tone The carbon isotope of lamina and the more big spherical oncolite sample greater than 2cm of lamina containing light tone is partially negative.Multiple oncolite samples In micronutrient levels and the oncolite in distribution characteristics displaying target area of oxygen and carbon isotopes content passed through in forming process Metrical water effect is gone through, the light tone lamina of powder crystal structure is influenced the most serious, mud-powder crystal structure light tone line by metrical water Level it, dark laminae is influenced weaker by metrical water.

Step 205: determining the content of the C isotope in multiple oncolite samples and the content of O isotope, and according to multiple The C isotopic content and O isotopic content of oncolite sample, determine the salinity of multiple oncolite samples.

Isotope δ¹⁸O、δ¹³The variation tendency of C value is all, especially δ related with salinity¹³The value of C is mainly by water body saliferous The restriction of degree, and be inversely proportional with water depth.Keity and Weber are δ¹⁸O and δ¹³Both C combine, to indicate ancient salt Degree, formula are as follows:

Z=2.048 × (δ¹³C+50)+0.498(δ¹⁸O+50)

Wherein Z value is to indicate the parameter of paleosalinity, and salinity is high, and water is shallow, and Z value is big, on the contrary then small.Using Z=120 as salt water And fresh water boundary, the fluid salinity of the higher reflection of Z value are higher.

Step 205 can occur before the step 204, can also occur after step 204, or both side by side into Row, that is, determining the content of the C isotope in multiple oncolite samples and the content of O isotope, and according to multiple oncolite samples The C isotopic content and O isotopic content of product determine that the salinity of multiple oncolite samples can be in analysis objective area oncolite Origin mechanism before occur, can analysis objective area oncolite origin mechanism after occur, or both simultaneously into Row.The embodiment of the present invention is not specifically limited in this embodiment.

Specifically, the embodiment of the present invention is by taking step 205 occurs after step 204 as an example, namely determines multiple oncolites The content of C isotope in sample and the content of O isotope, and according to the C isotopic content of multiple oncolite samples and the same position O Cellulose content determines that the salinity of multiple oncolite samples occurs after the origin mechanism of analysis objective area oncolite.

The embodiment of the present invention carries out the oncolite lamina sample of objective area using above-mentioned salinity formula to its salinity It calculates, the results are shown in Table 2.As shown in table 2, the salinity of 4 different dark laminaes is respectively 123.8,122.0,122.2 and 123.4, and the salinity of 2 light tone laminas is respectively 199.4 and 121.1, the salt of the salinity average specific dark laminae of light tone lamina It spends low.

The distribution characteristics of oncolite sample in machine and transverse direction refers to the oncolite sample of same profile in the longitudinal direction The gross feature of oncolite sample horizontally in gross feature, and different sections.

Fig. 2 E is a kind of distribution of the oncolite sample of objective area provided in an embodiment of the present invention in machine and transverse direction Feature schematic diagram, as shown in Figure 2 E, the distribution characteristics of the oncolite sample of objective area in machine and transverse direction are as follows.

Show as that lower part partial size is small, content is few on longitudinal direction, top partial size is big, the feature more than content, can be further divided into 4 Cycle, each cycle are made of upper and lower two parts, and wherein lower part oncolite is less relative to top content.Oncolite in transverse direction Population of samples feature is similar, can compare substantially, and certain otherness is locally present, and comparability shows that oncolite is developed Interval, mineralogical composition and feature of fabric etc..Otherness is mainly manifested in 3 aspects: (1) place of mud shale thickness, karyomorphism rock layers Duan Houdu is relatively large, as thickness 5.5m, 4.1m, 5.6m and 4.8m, oncolite interval are thick respectively respectively for section 1-4 mud shale 2.6m, 1.6m, 2.7m and 2.55m；(2) regional area oncolite partial size cross directional variations are larger, as in mud shale slumping block and reef Breccia underlies region relative to around it, and oncolite partial size is smaller；(3) regional area oncolite Plantago fengdouensis is larger, dust The region oncolite abundance of rock agensis is bigger, and the local oncolite content as the 5th layer of lower part reef breccia is developed in section 1 is 10%, and it is being laterally extended the place less than 1m, oncolite content can achieve 60% in mud shale.

Step 206: according to the oncolite sample of the salinity of multiple oncolite samples and objective area different location vertical To with the distribution characteristics in transverse direction, the rule of the opposite variation in sea level is analyzed, and based on the opposite rule changed in the sea level, mould Intend multiple oncolite samples on the sea level of different developmental phases with respect to variation diagram.

The distribution characteristics of the oncolite sample of objective area different location in machine and transverse direction reflects to a certain extent The specific features of the ancient stratigraphic procedures of objective area.And the rule of the opposite variation in sea level plays the development of ancient stratigraphic sequence The rule of the effect of deciding factor, the opposite variation in sea level has substantial control of the formation and transformation of sedimentary facies and facies tract, Determine the specific features of bed succession development.Therefore the specific features inverting sea level at that time that can be developed according to bed succession The rule of opposite variation.That is, the distribution characteristics according to the oncolite sample of objective area different location in machine and transverse direction The rule of the inverting opposite variation in sea level at that time.

Sea level variability refers to the variation up and down occurred with the relatively a certain datum level in time-shift sea level, and sea level becomes Change may be that eustasy causes, it is also possible to be that land construction lifting activity causes.Analyze the common skill of sea level variability Art is Meter-scale Cyclic Sequences technology.

Meter-scale Cyclic Sequences refer to that this different origin cause of formation machine is shaken on the high frequency sea level as caused by Milankovitch astronomical events From cycle sedimentation products under system control.The technology can identify the stratigraphic unit of objective area, and in this, as in Sequence Analysis Most basic working cell.The stratigraphic sequence of high level has been marked off according to its summation rule on vertical sequences.

Fig. 2 F is that karyomorphism rock layers are comprehensive at the top of a kind of objective area Middle Devonian series treasure stone group provided in an embodiment of the present invention Feature schematic diagram, the embodiment of the present invention are analyzed as follows the meter-scale cycle of the oncolite interval of objective area:

Combining target area oncolite interval longitudinal direction upper particle size, abundance, go out 6 for the karyomorphism rock layers further division The cycle of secondary level-one Sea-level drop, the 1st cycle are the environment that shoals upwards from hiatus surface beach to lagoon transition, 2-5 Cycle show as oncolite development interval in 4 oncolite cycles, the 6th cycle show as oncolite development mud shale interval to The mud shale interval transition of bryozoan development.

Step 207: based on multiple oncolite samples on the sea level of different developmental phases with respect to variation diagram, with multiple karyomorphisms Global sea variation when the formation of stone sample compares, and determines the palaeoenvironment when oncolite formation of objective area.

Land construction lift when palaeoenvironment when the oncolite formation of objective area includes the oncolite formation of objective area Rise activity and eustasy activity.

Since sea level variability may be that eustasy causes, it is also possible to be that land construction lifting activity causes.Cause This sea level for needing to be inferred according to the rock characteristic of objective area is with respect to variation diagram, when being formed with the oncolite of objective area Global sea variation compare, so that it is determined that still having land at that time when sea level variability caused by eustasy Caused by ground constructs lifting activity.That is, determining the palaeoenvironment when oncolite formation of objective area.

As shown in Figure 2 F, the oncolite sample Z value of objective area is 119.8~125.5.The oncolite in combining target area The meter-scale cycle of interval is analyzed, the results showed that objective area treasure stone group latter stage paleostructure be lifted not be pugil and, answer For pulsating lifting, it can at least be divided into the 6 phases sub-first grade structure lifting phase, tectonism is gradually reinforced, and water body gradually becomes shallower as, directly To being completely exposed to earth's surface by weathering and erosion.

It is special by the macroscopic view to multiple oncolite samples in the Middle Devonian series oncolite of objective area Longmenshan Beichuan area Sign, microstructure characteristic and stable isotope in multiple oncolite samples and microelement carry out quantitative-sxemiquantitative test, The palaeoenvironment when oncolite of the origin mechanism and objective area of analyzing the oncolite of objective area is formed.Make a concrete analysis of result such as Under:

(1), the oncolite of objective area is developed in backreef lagoon environment, is made of core and lamina two parts, wherein Core includes that 3 classes, the laminas such as bioclast, the orbicule of spherolite or early stage oncolite composition and the body of crystal structure containing algal gel include Mud-powder crystal, the light tone lamina of powder crystal structure and micrite, 2 major class of dark laminae containing biology, microorganism and solidifying block structure, grind Study carefully and think that dark laminae is mainly rich algae lamina, more deeper richer algae, the light tone lamina of powder crystal structure are the production in poor algae stage to color Object, and mud-powder crystal structure light tone lamina is still the product in rich algae stage, represents algae bonding mud-powder crystal side's solution under high-energy environment The product that stone is formed.

(2), the oncolite of objective area can be divided into big spherical, coccoid, hat shape and irregular 4 class oncolite, big ball Shape oncolite is formed in high-energy environment, and coccoid oncolite is formed in medium energy environment, and hat shape oncolite is formed in low energy ring Border, irregular oncolite is that terrigenous clastic corrosion function is formed in diagenetic process, research shows that the formation of hat shape oncolite Environment is consistent with depositional environment, but the formation environment of big spherical oncolite and the different cause of depositional environment, is initially formed in height Can shoal environment, after be transported to low energy lagoon ambient deposition, and the possibility of coccoid oncolite is consistent, it is also possible to inconsistent.

(3), compared with the carbon of seawater at that time, oxygen and strontium isotope background value, it is same that all samples of objective area all have oxygen The plain negative offset in position and strontium isotope positive offset feature, the big spherical oncolite and dead color of hat shape, coccoid, partial size between 1-2cm Lamina carbon isotope is normal, and light tone lamina and the more big spherical oncolite carbon isotope greater than 2cm of lamina containing light tone are partially negative. According to the microscopic feature of multiple oncolite samples, isotopic content feature and micronutrient levels feature, objective area is analyzed Oncolite experienced metrical water effect in forming process, and the light tone lamina of powder crystal structure is influenced the tightest by metrical water Weight, mud-powder crystal structure light tone lamina take second place, and dark laminae is most heavy.

(4), the oncolite of objective area is Pueraria lobota in the environment of Ge Wanzao development, turbulent water and metrical water participate in The outer rim that ten thousand algaes are coated on raw bits forms, and core substance component, algae development degree, water energy size and duration are control An important factor for oncolite formation, size and abundance.

(5), according to the oncolite interval of objective area, longitudinally above the synthesis of partial size, abundance and geochemistry etc. is ground Study carefully, the oncolite development interval for analyzing objective area is that Longmen Mountain Area construction is lifted the production for causing the RELATIVE SEA LEVEL decline stage Object can at least separate the 6 phases sub-first grade structure lifting phase, until exposure earth's surface, by weathering and erosion.

Gross feature, microscopic feature and the multiple cores that the embodiment of the present invention passes through multiple oncolite samples to objective area Stable isotope and microelement in shape stone sample carry out quantitative-sxemiquantitative test, determine the macroscopic view of multiple oncolite samples Feature, microscopic feature and stable isotope content and micro content in multiple oncolite samples are based on multiple oncolite samples Gross feature, microscopic feature and stable isotope content and micro content in multiple oncolite samples, analyze objective area Oncolite origin mechanism and objective area oncolite formation when palaeoenvironment, improve to the objective area oncolite origin cause of formation The accuracy of mechanism analysis.

The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.

Claims (8)

1. a kind of analysis method of oncolite origin mechanism, which is characterized in that the described method includes:

Determine the gross feature and microscopic feature of multiple oncolite samples, the multiple oncolite sample is acquired in objective area It obtains, the objective area is the area of oncolite origin mechanism to be analyzed；

Determine the content of stable isotope and the content of microelement in the multiple oncolite sample；

According to stable isotope in the gross feature of the multiple oncolite sample, microscopic feature, the multiple oncolite sample Content and microelement content and in the oncolite formation of the objective area seawater of the objective area it is steady Determine the content of isotope and the content of microelement, analyzes the origin mechanism of the oncolite of the objective area；

It is described same according to stablizing in the gross feature of the multiple oncolite sample, microscopic feature, the multiple oncolite sample The seawater of the content of position element and the content of microelement and the oncolite in the objective area objective area when being formed Stable isotope content and microelement content, analyze the origin mechanism of the oncolite of the objective area, comprising:

According to the gross feature and microscopic feature of the multiple oncolite sample, the oncolite for analyzing the objective area is being formed In the process development of microorganisms environment, turbulent water effect, the stability of depositional environment and forming process duration length；

According to the content of stable isotope in the microscopic feature of the multiple oncolite sample, the multiple oncolite sample and micro- The content of secondary element, and the stable isotope of the seawater of the objective area in the oncolite formation of the objective area Whether the content of content and microelement, the oncolite for analyzing the objective area are made in forming process by metrical water With and environment of the oncolite in forming process of the objective area whether be inorganic environment.

2. the method as described in claim 1, which is characterized in that the gross feature of the multiple oncolite samples of determination, comprising:

Determine size, shape and the abundance of the multiple oncolite sample；

Based on size, shape and the abundance of the multiple oncolite sample, the oncolite of the objective area different location is determined The distribution characteristics of sample in machine and transverse direction.

3. the method as described in claim 1, which is characterized in that the microscopic feature of the multiple oncolite sample of determination, Include:

For each oncolite sample in the multiple oncolite sample, is tested using thin slice and determine the oncolite sample The constituent of component structure and the component structure, the component structure include core and lamina, the composition of the core at Divide includes bioclast, spherolite and the body of crystal structure containing algal gel；

The color relationship between the core and lamina that determine the oncolite sample is tested using cathodoluminescence；

The mineral classification and the mineral classification for determining the oncolite sample by X ray test and electron probe test are in institute State the percentage composition in oncolite sample.

4. the method as described in claim 1, which is characterized in that the multiple oncolite sample include oncolite whole-rock sample and Oncolite lamina sample, the oncolite whole-rock sample include different intervals oncolite sample and same interval it is of different sizes Oncolite sample, the oncolite lamina sample include the oncolite sample of same oncolite difference lamina type；

Correspondingly, the content of stable isotope and the content of microelement in the multiple oncolite sample of the determination, comprising:

The content of the content of stable isotope Sr, the content of C and O in the oncolite whole-rock sample is tested, with true In the fixed oncolite whole-rock sample⁸⁷Sr isotopic content with⁸⁶The ratio of Sr isotopic content⁸⁷Sr/⁸⁶Sr, C isotopic content δ¹³C and O isotopic content δ¹⁸O；

The content of microelement Fe, Mn and Sr in the oncolite whole-rock sample are tested, it is complete with the determination oncolite Microelement Fe content, Mn content and Sr content in rock sample product；

The analysis of microcell laser C-O isotopes is carried out to the oncolite sample of the same oncolite difference lamina type, with true C isotopic content δ in the oncolite sample of the fixed same oncolite difference lamina type¹³C and O isotopic content δ¹⁸O。

5. method as claimed in claim 4, which is characterized in that the oncolite whole-rock sample be without through burying the later period at The fresh sample of rock effect, the oncolite whole-rock sample sample gained using microcell, and in the oncolite whole-rock sample not Including impurity and jelly, the oncolite lamina sample be by under microscope light tone lamina and dark laminae make respectively Obtained by laser sampling.

6. the method as described in claim 1, which is characterized in that the gross feature according to the multiple oncolite sample and Microscopic feature analyzes the oncolite of the objective area development of microorganisms environment, turbulent water effect, deposition in forming process The stability and the length of forming process duration of environment, comprising:

If the shape of mature, the multiple oncolite sample of development of microorganisms is circle in the lamina of the multiple oncolite sample Shape, the multiple oncolite sample partial size be all larger than partial size threshold value, the abundance of the multiple oncolite sample is all larger than abundance Coral rock dust agensis is covered on threshold value or the multiple oncolite sample, it is determined that the oncolite of the objective area exists Environment in forming process be suitble to the environment of development of microorganisms, in forming process by the effect of strong turbulent water, depositional environment Stablize, the duration is long in forming process；

If the shape of immature, the multiple oncolite sample of development of microorganisms is ellipse in the lamina of the multiple oncolite sample In spherical or hat shape, the multiple oncolite sample there are partial size be less than or equal to the partial size threshold value oncolite sample, There are oncolite samples or the multiple core that abundance is less than or equal to the abundance threshold value in the multiple oncolite sample The development of coral rock dust is covered on shape stone sample, it is determined that environment of the oncolite of the objective area in forming process is discomfort Close the environment of development of microorganisms, do not acted on by strong turbulent water in forming process, depositional environment is unstable, in forming process Duration is short.

7. the method as described in claim 1, which is characterized in that the microscopic feature according to the multiple oncolite sample, The content of stable isotope and the content of microelement in the multiple oncolite sample, and the karyomorphism in the objective area The content of the content of the stable isotope of the seawater of the objective area and microelement, analyzes the objective area when stone formation Oncolite in forming process whether by metrical water effect and the objective area oncolite in forming process Environment whether be inorganic environment, comprising:

If in the multiple oncolite sample there are Fe content, Mn content and⁸⁷Sr/⁸⁶The oncolite of Sr presentation positive offset characteristic Sample, there are Sr contents, δ¹⁸O、δ¹³The oncolite sample of C presentation negative offset characteristic, there are core colors and lamina color to present The oncolite sample of Chinese red or there are terrigenous clastic contents to be greater than the karyomorphism that content threshold value and lamina type are light tone lamina Stone sample, it is determined that the oncolite of the objective area is acted in forming process by strong metrical water；

If the Fe content of the multiple oncolite sample, Mn content and⁸⁷Sr/⁸⁶Sr is without being presented positive offset characteristic, the multiple The Sr content of oncolite sample, δ¹⁸O、δ¹³C is without being presented negative offset characteristic, the core color of the multiple oncolite sample With lamina color do not give out light deeply or the multiple oncolite sample lamina in there are terrigenous clastic contents to be less than or equal to institute It states content threshold value and lamina type is the oncolite sample of dark laminae, it is determined that the oncolite of the objective area was being formed It is not acted on by strong metrical water in journey；

If the multiple oncolite sample is free of microorganism and δ¹³C and δ¹⁸Negative offset characteristic is presented in O, it is determined that the target Environment when the oncolite formation in area is inorganic environment；

If the multiple oncolite sample is rich in microorganism and δ¹³C and δ¹⁸Negative offset characteristic is presented in O, it is determined that objective area Environment when oncolite formation is organic and inorganic dual environment.

8. the method as described in claim 1, which is characterized in that the method also includes:

Determine the content of the C isotope in the multiple oncolite sample and the content of O isotope；

According to the C isotopic content and O isotopic content of the multiple oncolite sample, the multiple oncolite sample is determined Salinity；

According to the oncolite sample of the salinity of the multiple oncolite sample and the objective area different location longitudinal and Distribution characteristics in transverse direction, the rule of the opposite variation in analysis sea level；

Based on the rule of the opposite variation in the sea level, the multiple oncolite sample is simulated on the sea level of different developmental phases Opposite variation diagram；

Based on the multiple oncolite sample on the sea level of different developmental phases with respect to variation diagram and the multiple oncolite sample Global sea variation diagram when product formation determines the palaeoenvironment when oncolite formation of objective area, the objective area Land construction lifting activity and sea level when palaeoenvironment when oncolite formation includes the oncolite formation of the objective area Lifting activity.