岩相特征对海平面升降的响应——以山东苍山寒武系为例  

Response of Lithofacies Characteristics to Sea-level Fluctuations:A case study from the Cambrian Cangshan profile,Shandong province

作　　者：樊爱萍 李诚 杨仁超 韩作振 吴祥生 FAN AiPing;LI Cheng;YANG RenChao;HAN ZuoZhen;WU XiangSheng(College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao,Shandong 266590,China)

机构地区：[1]山东科技大学地球科学与工程学院,山东青岛266590

出　　处：《沉积学报》2023年第4期1040-1053,共14页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(40972043);教育部科学技术研究重点项目(211097)。

摘　　要：对于陆表海浅水沉积而言,小幅度的海平面升降即可造成沉积环境和岩相的快速变化。为了研究岩相特征对海平面升降的响应,以出露条件好、岩相变化频繁的山东苍山寒武系为例,通过野外观察、剖面实测,并结合室内薄片鉴定,对研究区寒武系的岩性特征进行了详细分析。将其划分为鲕粒灰岩相、生屑灰岩相、泥灰岩相、灰质砂岩相、微生物灰岩相、页岩相和砂岩相等7种岩相。研究认为,该区馒头组主要发育潮坪—障壁岛—潟湖沉积;张夏组发育局限台地和开阔台地沉积;与馒头组相比,张夏组水动力条件更强;水体能量、深度、光照、清澈程度的旋回性变化,影响微生物的生长以及微生物岩的发育特征。山东苍山剖面寒武系岩相的频繁变化反映了海平面升降和沉积环境的垂向变化,海平面上升晚期或高海平面时期,开阔台地占据主导地位,其高能相带有利于发育鲕粒灰岩、生屑灰岩沉积;开阔台地潮下低能带有利于微生物灰岩丘、疙瘩状灰岩的发育。海平面上升初期或下降期,局限台地、潮坪等主导浅水区沉积,多发育泥晶灰岩、泥质灰岩;潮坪环境水动力条件变化频繁,可发育生屑灰岩、泥晶灰岩、页岩和砂岩等多种类型的沉积岩相。For epeiric-sea shallow water deposition,small-scale fluctuations of sea level cause rapid changes of sedimentary environment and lithofacies.The example of the response of lithofacies characteristics to sea-level fluctuations in this study is the Cambrian Cangshan profile(Shandong province),which has good outcrop conditions and frequent lithofacies changes.The lithological characteristics were analyzed in detail using field observation,section measurement and thin section identification.The area contains seven lithofacies:oolitic limestone,bioclastic limestone,marl,gray sandstone,microbial limestone,shale and sandstone.It is considered that the Mantou Formation in this area mainly developed intertidal zone-barrier island-lagoon deposition.The Zhangxia Formation developed from restricted-and open-platform deposition;and experienced stronger hydrodynamic conditions than the Mantou Formation,with cyclical changes of water energy,depth,light and clarity affecting the growth of microorganisms and the characteristics of microbial rocks.The frequent changes of lithofacies reflect the vertical sea-level fluctuation and sedimentary environment.The open platform dominated in the late period of rising or high sea level,with a high-energy facies zone conducive to the development of oolitic limestone and bioclastic limestone deposits and a low-energy zone below the tide level of the open platform that was conducive to the development of microbial limestone hills and keloid limestone.In the early or descending period of sea-level rise,platform and tidal flat sediments dominated shallowwater deposits,developing more mud limestone and argillaceous limestone.The frequent changes in hydrodynamic conditions on the tidal-flat environment resulted in the development of many sedimentary facies types,including bioclastic limestone,mud limestone,shale and sandstone.

关 键 词：海平面升降 碳酸盐岩 岩相 寒武系 馒头组 张夏组 沉积环境 

分 类 号：P581[天文地球—岩石学]