Study of an Early Silurian–Early Permian paleo-weathering profile in Zunyi, north Guizhou Province, China  

作　　者：Xiao-hui Xiong Jia-fei Xiao Rui-zhong Hu Yi Wang Jian Wang Xiu-gen Fu 

机构地区：[1]State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences [2]Chinese Academy of Geological Sciences [3]Chengdu Institute of Geology and Mineral Resources [4]Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences

出　　处：《Chinese Journal Of Geochemistry》2015年第4期558-578,共21页中国地球化学学报

基　　金：supported by the 12th FiveYear Plan Project of State Key Laboratory of Ore Deposit Geochemistry, Chinese Academy of Sciences (SKLODG-ZY125-08);funds from the State Key Laboratory of Palaeobiology and Stratigraphy, Chinese Academy of Sciences;the National Basic Research Program of China (2007CB411408)

摘　　要：To understand and help settle the controversy around the living time of Pinnatiramosus qianensis Geng, a paleo-weathering profile situated in the town of Yongle near the city of Zunyi, north Guizhou Province, China, was analyzed. The profile formed during a break in sedimentation between the Early Silurian and the Early Permian.Paleosol developed with a depth of several meters. The fossil plant P. qianensis Geng is present, but only in the lower portions(Layer 2) of the paleosol. Another plant with an irregularly branching system is found in Layers 2and 3. The distinct geochemical characteristics of the lower and upper portions of the Gaojiayan paleosol indicate a compound genesis. Its lower portions(Layers 1 and 2)resulted from in situ weathering of silty mudstone of the lower Silurian Hanjiadian Formation. The upper portions(Layer 3) are allochthonous. Transgression brought substantial concentrations K and Na, and led to K- and Naenrichment in the profile. Pumping of vascular plants and downward leaching enhanced the K enrichment in the middle portions. A superior preservation of P. qianensis Geng was observed in an exposure of Layer 2. Mass balance calculation indicates a great K enrichment related to bioaccumulation in the top of Layer 2 and a K loss in Layer3. Fossil plants(e.g., P. qianensis Geng) preserved in the paleosol are Permian rooting systems growing down into the lower Silurian rocks.To understand and help settle the controversy around the living time of Pinnatiramosus qianensis Geng, a paleo-weathering profile situated in the town of Yongle near the city of Zunyi, north Guizhou Province, China, was analyzed. The profile formed during a break in sedimentation between the Early Silurian and the Early Permian.Paleosol developed with a depth of several meters. The fossil plant P. qianensis Geng is present, but only in the lower portions（Layer 2） of the paleosol. Another plant with an irregularly branching system is found in Layers 2and 3. The distinct geochemical characteristics of the lower and upper portions of the Gaojiayan paleosol indicate a compound genesis. Its lower portions（Layers 1 and 2）resulted from in situ weathering of silty mudstone of the lower Silurian Hanjiadian Formation. The upper portions（Layer 3） are allochthonous. Transgression brought substantial concentrations K and Na, and led to K- and Naenrichment in the profile. Pumping of vascular plants and downward leaching enhanced the K enrichment in the middle portions. A superior preservation of P. qianensis Geng was observed in an exposure of Layer 2. Mass balance calculation indicates a great K enrichment related to bioaccumulation in the top of Layer 2 and a K loss in Layer3. Fossil plants（e.g., P. qianensis Geng） preserved in the paleosol are Permian rooting systems growing down into the lower Silurian rocks.

关 键 词：风化剖面 早二叠世 早志留世 中国北方 贵州省 遵义市 化石植物 地球化学特征 

分 类 号：P534.4[天文地球—古生物学与地层学]