四川盐源地区名胜剖面志留系龙马溪组黑色泥页岩地球化学特征及物源构造背景分析  

Analysis of geochemical characteristics, provenance, and tectonic background of black shale in the Silurian Longmaxi Formation of the Mingsheng section in the Yanyuan area, Sichuan Province

作　　者：程锦翔 邓敏 杨贵来 余谦 CHENG Jinxiang;DENG Min;YANG Guilai;YU Qian(Chengdu Center,China Geological Survey(Geosciences Innovation Center of Southwest China),Chengdu 610218,China;Key Laboratory of Sedimentary Basin and Oil and Gas Resources,Ministry of Natural Resources,Chengdu 610218,China;Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural Resources,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]中国地质调查局成都地质调查中心(西南地质科技创新中心),四川成都610218 [2]自然资源部沉积盆地与油气资源重点实验室,四川成都610218 [3]自然资源部深时地理环境重建与应用重点实验室,成都理工大学,四川成都610059

出　　处：《沉积与特提斯地质》2024年第4期840-853,共14页Sedimentary Geology and Tethyan Geology

基　　金：中国地质调查局项目“四川盆地东南缘煤层(系)气调查评价”(DD20242049);“四川盆地及周缘页岩气地质调查与评价”(DD20240046);“四川盆地油气资源潜力评价”(DD20242405);“自然资源部深时地理环境重建与应用重点实验室开放基金”(DGERA20231107)。

摘　　要：盐源地区早志留世沉积了以龙马溪组为代表的笔石页岩。本文选择盐源地区名胜剖面志留系龙马溪组的新鲜露头剖面,系统采样并分析其主、微量元素和稀土元素在剖面垂向上的变化特征,从地球化学特征角度,探讨该时期物源特征及其构造环境。结果表明:盐源地区名胜剖面龙马溪组以硅质页岩相(L1段,L3段和L4段)为主,碳酸盐矿物在L2和L5段含量较高,脆性矿物石英和长石在L2和L5段含量较少,而黏土矿物含量自下而上呈明显增加趋势。名胜剖面龙马溪组沉积物具有镁铁质和长英质双重来源,其中L3段和L4段为镁铁质或超镁铁质物源,而L1段、L2段和L5段更多为长英质或长英质与镁铁质混合物源。源岩形成的构造背景为大陆边缘,沉积物具有活动大陆边缘和被动大陆边缘的双重特征。物源组成的变化表明志留纪早期康滇古陆构成复杂。The graptolitic shales of the Longmaxi Formation were widely deposited during the Silurian transition in the Yanyuan area.This study selected fresh outcrops of the Silurian Longmaxi Formation at the Mingsheng section in the Yanyuan area,systematically sampled them,and analyzed the vertical variation characteristics of major,trace,and rare earth elements in the section.Moreover,this study discussed the perspective of geochemical characteristics,provenance characteristics,and tectonic environment of that period.Research results show that the Longmaxi Formation at the Mingsheng section in the Yanyuan area is predominantly siliciclastic shale facies(sections L1,L3,and L4),with higher carbonate mineral content in sections L2 and L5,and brittle minerals such as quartz and feldspar are less abundant in sections L2 and L5,while clay minerals show a significant increasing trend from bottom to top.The sediments of the Longmaxi Formation at the Mingsheng section have a dual source of mafic and felsic materials:sections L3 and L4 are of mafic or ultramafic provenance,while sections L1,L2,and L5 are more felsic or a mixture of felsic and mafic sources.The tectonic background of the source rock formation is continental margin,and the sediments exhibit dual characteristics of both active and passive continental margins.The variation in provenance indicates that the composition of the Kangdian paleocontinent was complex in the Early Silurian.

关 键 词：名胜剖面 志留系 龙马溪组 泥页岩 物源特征 构造背景 

分 类 号：P595[天文地球—地球化学]