石炭—二叠纪冰川型海平面变化碳酸盐岩地球化学特征及其地质意义:以安徽省宣州区宝丰船山组为例  

Geochemical characteristics and geological significance of Carboniferous-Permian glacier-type sea level change carbonate rocks: An example from the Upper Carboniferous-Lower Permian Chuanshan Formation in Baofeng section, Xuanzhou area, Anhui Province

作　　者：徐锦龙[1] 章诚诚 张晋喆 汪雅菲 张利伟[3] Xu Jinlong;Zhang Chengcheng;Zhang Jinzhe;Wang Yafei;Zhang Liwei(Anhui Institute of Geological Survey,Hefei 230001;Nanjing Center,China Geological Survey,Nanjing 210016;School of Resources and Environment,Henan Polytechnic University,Jiaozuo,Henan 454000)

机构地区：[1]安徽省地质调查院,合肥230001 [2]中国地质调查局南京地质调查中心,南京210016 [3]河南理工大学资源环境学院,河南焦作454000

出　　处：《地质科学》2022年第4期1240-1261,共22页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：安徽省矿山生态修复工程实验室开放课题(编号:KS-2021-002);中国地质调查局地质调查项目(编号:DD20160036,1212011120848)资助。

摘　　要：冈瓦纳冰川的扩张和消融导致了全球石炭纪—二叠纪高频率、大振幅的冰川型海平面变化。北半球冰川活动的直接证据相对较少,但保存有地层、古盐度、古水温和冰川型海平面变化的记录。本文在露头层序地层学和沉积学研究基础上,对宣州区宝丰地区晚石炭世—早二叠世船山组碳酸盐岩的主量、微量、稀土元素和碳、氧同位素的组分含量、特征比值等地球化学指标开展系统分析。研究表明:船山组底部和内部共识别出两次明显的暴露事件,划分为两个三级层序;层序S1相当于Triticites带,时代为晚石炭世晚期,层序S2相当于Pseudoschwagerina带,时代为早二叠世早期,整体经历了两次快速上升和缓慢下降的海平面变化过程,是冰川驱动下的全球性海平面变化事件;碳酸盐岩受陆源物质的影响微弱,能较好地反映古海水的地球化学特征;稀土元素的富集和分馏程度可能与沉积水体和核形石的选择性吸附有关;船山组整体为温暖湿润、富氧的浅水开阔台地—滩相环境,早二叠世早期较晚石炭世晚期沉积水体浅、水体变化频繁、盐度高、水温低,受早二叠世萨克马尔晚期冰期P1冰盖扩张的影响更为明显,至早二叠世中晚期冰盖扩张达到顶峰。本研究为深入了解北半球晚古生代冰期事件,特别是低纬度地区冰川型海平面变化与P1冰期、古气候变化和地质演化提供了层序地层沉积记录和地球化学指标信息。The expansion and melting of Gondwana glacier led to the global CarboniferousPermian high-frequency and large amplitude sea-level changes. Although there is relatively little direct evidence of glacial activities in the northern hemisphere, geological records of the change of strata, paleosalinity, paleotemperature and glacial-related sea-level occur. Base on a sequence stratigraphic and sedimentological study of field outcrops, this paper systematically analyzes the geochemical indicators such as major, trace, rare earth element, carbon and oxygen isotope content and characteristic ratio of the carbonate rocks of the Upper Carboniferous-Lower Permian Chuanshan Formation in Baofeng area, Xuanzhou District. The results show that two exposure events have been identified at the bottom and inside of the Chuanshan Formation, which are divided into two third-order sequences. The sequence S1 is equivalent to Triticites belt, which is determined to the late Late Carboniferous. The sequence S2 is equivalent to Pseudoschwagerina belt, which is determined to the early Early Permian.These two sequences suggest two sea-level change processes of rapid rise and slow decline. It is a global sea-level change event driven by glaciers. Carbonate rocks are weakly affected by terrigenous materials, which can better reflect the geochemical characteristics of ancient seawater;the enrichment and fractionation of rare earth elements may have a strong coupling relationship with the selective adsorption of sedimentary water and nucleate stones;the Chuanshan Formation as a whole is a warm and humid shallow open platform beach facies environment with strong oxidation and oxygen enrichment. The sedimentary water in the Early Permian and Late Carboniferous is shallow and ice free. The injection of molten fresh water has high salinity and low water temperature. It is more affected by the expansion of P1 ice sheet in the Late Sakmarian glacial period of the Early Permian, and the expansion of ice sheet in Liangshan section of Qixia Formation rea

关 键 词：古气候 冰川型海平面变化 石炭—二叠纪 碳酸盐岩 地球化学特征 

分 类 号：P588.245[天文地球—岩石学] P595[天文地球—地质学]