| 浙西下寒武统大陈岭组地震液化脉微量元素特征研究 |
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| 关键词:seismic liquified vein trace element soft-sediment deformation Cambrian western Zhejiang Province |
| 基金项目:国家自然科学基金项目(编号: 41672209) |
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| Trace Element Characteristics of Seismic Liquified Veins from the Lower Cambrian Dachenling Formation in Western Zhejiang Province |
| Seismic liquified vein is one of the most important soft sediment deformation structures induced by seismic events. Previous researches have been crried out on morphology and dynamics of the veins, however, few studies on microscopic geochemical behavior of their genesises has been conducted. In this study, trace element analysis of veins and vein-hosting carbonate rocks was done on twenty-one samples from three beds of seismic veins from deposition of two seismic events along the Peilingjiao section. The experiment result shows that the values of Cs, Ba, Th, Zr, Hf, Cr, Rb and Nb of liquified veins are obviously higher than those of vein-hosting carbonate rocks, suggesting terrigenous origin. In contrast, the values of Sr, Y and Ni are more abundant in vein-hosting carbonate rocks, which indicates the features of marine sediments. Based on the research on enrichment of V, Mo and characteristic parameters of trace elements including Sr/Ba and Th/U ratios, liquified veins are interpreted to be of oxidizing environment, whereas vein-hosting carbonate rocks should imply reducing environment. In addition, the veins and vein-hosting carbonate are characterized by freshwater sedimentation. The result shows that there was complement of terrigenous material from erosion source areas during the deposition process of dolomitic limestone in the Early Cambrian. Under the sudden vibration force of earthquakes, the water-rich soft sedimentary rock layers were liquefied with water-escape. Because of properties differences between chemical and clastic sediments, the plastic carbonate sediments were partially lost with water, leading to the lower content of the carbonate sediments per unit area than the surrounding carbonate rocks and more terrigenous material in veins. Soft sedimentary beds are of supratidal sediments, which were exposed during the period from the late stage of liquefaction draining to diagenesis. The late terrigenous resupply and atmospheric precipitation leaching alteration effects led to abnormal paleoclimate and salinity of the soft sediments, which provided geochemical evidence for shallow water sedimentation of Dachenling Formation in western Zhejiang Province. |
| YAN Zhao-bin,PEI Jun-ling,GUO Fu-sheng,HU Jun-jun,LIU Li-jie.2019.Trace Element Characteristics of Seismic Liquified Veins from the Lower Cambrian Dachenling Formation in Western Zhejiang Province[J].Acta Geoscientica Sinica,40(1):236-248. |
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