Weathering Mechanism And Model Of Organic Rich Shale

The study of weathering mechanism has very important theoretical significance for the change of rock properties,the reconstruction of paleoclimate,the prediction of the future evolution trend of weathering,and the prediction of the global climate change trend.Organic-rich shale is susceptible to weathering,and its weathering characteristics are clearly different from those of granite,basalt,dolomite,and loess.Based on the horizon,lithology,marker layer,gamma value and radioactive nuclear elements,the thesis establishes the correspondence between the drilling stratum of Well Yuke 1 and the adjacent Niutitang Formation in the outcrop section of Tongling Village,and discusses the rich organic matter Shale weathering mechanism and mode.Mainly obtained the following research understanding:Based on the horizon,lithology,marker layer,gamma value and radioactive nuclear elements,the correspondence relationship between the outcrop weathering profile and the drilling profile is established,and it is considered that the Niutitang Formation in the outcrop section of Tongling Village corresponds to the cattle hoof in Well Yuke 1 The middle and lower part of the pond group.Clarified the influence of mineral composition on weathering.The comparative study found that the carbonate minerals,pyrite and potash feldspar of the outcrop samples were reduced by 98%,90% and 41% compared to the core samples,respectively,while the contents of plagioclase and quartz in the outcrop samples were compared with the core samples.Increased by 28% and 31% respectively.In the outcrop profile,the weathering resistance of organic-rich shale minerals is ranked as follows: carbonate minerals <sulfide <potassium feldspar <plagioclase <quartz.The response relationship between different types of element changes and weathering is established.The constant element has a clear positive correlation with the corresponding mineral.The changing characteristics of the constant element during the weathering process depend on its existing form in shale.The weathering characteristics of trace elements are related to their own activities and their occurrence minerals.The transition elements in the trace elements show a loss,and most elements with high field strength show an enrichment.The changes of rare earth elements are small,the main change is a small amount of enrichment of light rare earth and a small amount of loss of heavy rare earth,the change trend is basically the same.Affected by weathering,the H/C ratio of organic elements decreased,and the O/C ratio increased.According to the weathering characteristics of the elements,it is pointed out that the Sc-La-Th ternary diagram of shale material sources and the V/Cr and Ni/Co indicators for determining the paleoenvironment are still applicable.Although weathering changes the absolute concentration of trace elements,it does not necessarily significantly change the ratio of trace elements.From the perspective of elements,minerals,organic matter and rock weathering,the weathering stage of organic-rich shale is divided.It is pointed out that the outcrop profile of Tongling Village is in a weak to moderate weathering stage,and the weathering mode of organic-rich shale is established.