柴北缘西段早石炭世构造—沉积格局——来自下石炭统怀头他拉组稀土元素的证据  

Early Carboniferous Tectono-sedimentary Pattern in the Western North Margin of Qaidam Basin:Evidence from the rare earth elements of the Lower Carboniferous Huaitoutala Formation

作　　者：施辉 王波 胡俊杰 吴志雄 马立成 SHI Hui;WANG Bo;HU JunJie;WU ZhiXiong;MA LiCheng(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Paleomagnetism and Tectonic Reconstruction,Ministry of Natural Resources,Beijing 100081,China;Key Laboratory of Petroleum Geomechanics,China Geological Survey,Beijing 100081,China;Qinhai Oilfield Company,PetroChina,Duhuang,Gansu 736200,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]自然资源部古地磁与古构造重建重点实验室,北京100081 [3]中国地质调查局油气地质力学重点实验室,北京100081 [4]中国石油青海油田分公司,甘肃敦煌736200

出　　处：《沉积学报》2025年第2期408-422,共15页Acta Sedimentologica Sinica

基　　金：中国地质调查局地质调查项目(DD20230260,DD20230313)。

摘　　要：【目的】柴北缘构造带石炭系沉积地层记录了原特提斯洋向古特提斯洋转换历史,但石炭系变质程度高,制约了对区域构造—沉积格局的认知。泥质岩稀土元素化学性质稳定,是重建构造背景、物质来源与沉积环境的有效途径。【方法】采用电感耦合等离子质谱法(ICP-MS)分析小赛什腾山下石炭统怀头他拉组(C1h)泥质岩的稀土元素地化特征。【结果】早石炭世小赛什腾山地区是受南昆仑洋壳向北俯冲弧陆体系影响的弧后盆地,处在柴达木地块及北缘俯冲碰撞带所组成局部高地和宗务隆大陆裂谷之间,呈“南高北低,由陆向海”的整体古地貌格局;东南方向的碰撞带是重要物源区,早期供给花岗岩—碱性玄武岩—沉积岩的风化碎屑,随区域构造活动变弱顶部碳酸盐岩段泥质岩夹层的碎屑可能来源于先存沉积物的再搬运。沉积古水体表现为由浅变深复变浅的趋势,碎屑岩段泥页岩形成于相对缺氧环境,而碳酸盐岩段泥岩夹层则为氧化环境,发育“台地边缘浅滩—台地前斜坡—陆棚边缘—台地前斜坡—台地边缘生物礁”的相序。【结论】以上研究结果及认识为理解区域性古地理格局和原特提斯洋—古特提斯洋时空演化及能源矿产效应提供了依据。[Objective]The Carboniferous deposits developed in the north margin of Qaidam Basin,which records the history of the transition from Proto-Tethyan to Paleo-Tethyan Ocean.However,the high metamorphism of the Carboniferous system restricts our understanding of the regional tectono-sedimentary pattern.The rare earth element(REE)properties of argillaceous rocks are stable;therefore,analysing their geochemical characteristics is an efficient path for reconstructing the tectonic setting,material source,and sedimentary environment.[Methods]Inductively coupled plasma mass spectrometry(ICP-MS)has been applied to investigate REE geochemistry in the Lower Carboniferous Huaitoutala Formation(C1h)in Xiaosaishenteng Shan.[Results]The results indicate that the Xiaosaishenteng Shan area was likely a back-arc basin influenced by the northern subduction of the South Kunlun oceanic crust,located between the local highland composed of the Qaidam block and the subduction collision zone in the northern margin and the western extension zone of the Zongwulong continental rift.Thus,it exhibits an overall palaeogeomorphic pattern of"high in the south and low in the north,from land to sea".The orogenic belt extending west from the subduction collision zone in the north margin of Qaidam to the southeast of Xiaosaishenteng Shan was the important provenance area,providing the weathered detrital materials of parent rocks composed of granite,alkaline basalt,and sedimentary rock to the study area since the early deposition of the C1h.With the weakening of regional tectonic intensity,the clastic materials of argillaceous interlayers in the top C1h carbonates may come from the re-transport of the preexisting sediments.Overall,the sedimentary paleo-water of C1h showed a trend of shallow to deep and to shallow again.The clastic shale was formed in a relatively anoxic environment,while the mudstone interlayers in carbonate rocks occurred in an oxidized environment.The phase sequence of“platform edge shoal-platform front slope-shelf edge-platform fr

关 键 词：构造背景 物源 沉积环境 早石炭世 小赛什腾山 

分 类 号：P512.2[天文地球—地质学]