科研之友
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摘要
The Enping Formation is a key target layer for the development of source rocks. Based on ICP-MS analysis, measurements of trace element are conducted by using 18 mudstone samples of Enping formation in WenchangA depression. Research shows that Pb, Th, U are significantly enriched in Enping Formation mudstone, Zn, Ba, Nb, Be, Cu, Sc, Li are slightly enriched, and Co, Ni, Cr, V, Sr, P, Ti are deficient. The correlation coefficient and cluster analysis show that Pb/Mo and Ni/Pb are obviously positively correlated, Cu/Pb, Ti/Cu, Cu/Mo, Cu/Ni, Sc/Cu, P/Cu and Ca/Ti, Al/ Cu has a significant negative correlation, and Pb mainly comes from silicate rock-forming minerals. The combination of trace elements is mostly lithophile elements, derived from silicate minerals, clay minerals and sulfides. The palaeoclimate of the Enping Formation source rock during the deposition period is warm and humid, and the hydrodynamic condition is a weakly reduced freshwater-slightly brackish water environment, which is affected by lake waves and weathering in the basin. The sedimentary environment of the Enping Formation is divided into three sub-segments. In the first sub-segment, peat swamps are not developed, and the water body is under the condition of weak oxidation-weak reduction brackish water. The injection intensity of debris carried by the water body increases slightly, and the oxidation of the water body is enhanced. The content of mudstone in the second sub-segment increases significantly, and the reducibility of water body is enhanced. In the third sub-segment, the lacustrine depositional environment is continuously developed, peat bogs develop in the shallow lacustrine phase, the water column deepens, reducibility increases, and terrestrial-derived detrital material decreases.
