The Best Natural Boundary:a New Concept Developed by Combining the Sequence Boundary with the GSSP

Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme has been proposed. By combining organically the concept of sequence boundaries with the GSSP, it is suggested that the GSSP should be chosen in a conformale portion of a related sequence boundary, and the boundary established in light of this concept is defined as the Best Natural Boundary (BNB). The definition of the BNB points out the working area and stratigraphic level for the GSSP. By referring to a case study of the Permian Guadalupian/Lopingian boundary, the concept of the BNB has been elaborated in detail, and it is proposed that the BNB of the Guadalupian and the Lopingian lies between the Mesogondolella granti Zone and the Ctarkina postbitteri Zone, which is also the sequence chronostratigraphic boundary between th     

A Study on Sequence Stratigraphy of Mesoproterozoic and Neoproterozoic in Southern North China Platform

INTRODUCTIONThestrataofMesoprotCrozoicandNeoproterozoicaredevelopedcompletelyinthesouthpartoftheNorthetnaplatformandconsistofthreesystems,inasCendingorder,Jixiaulan,QingbaikouanandSlman.BasedonadetailedinvestigationontheolltcropandthecomprehenSiveanalysis,wediscussthecharaCterofsequencestratigraphyandthecorrelationoftheMemo--Neoproterozoicinthearea.FnThRrsor~unCrsANDPARA~unCrsMeSO--NooprotffezoicRadonalfortigraphyThesouthernpartofNorthChinaplatformherereferstotheareasincluding…     

Early Ordovician Sea Level Changes in South China and Their Worldwide Correlation

INTRODUCTIONTheoaf~ansed~arewidelydistributedinSouthetna,fromtheYanalCratondPborminnorthtocontinentalmarginofsoutheastern~insouth.ThePreSentpaperdiscussesmainlytheEarlyOrdovidan(thehoeofHirmtodontussimplex~tothebaseofNemopagngraciliszone,Wangatal.,1992)sealeVelchangeSandtheirworldwidecorrelationbasedonasyntheticalstudyofseqUenCe,bioshatiglaphyandaretratigl'aphy.Thisapproachwillfillinthe~instudyoftheOrdovidanofChina,andimprovethesu~ionandCO~ionofbio--,litho--andcbronostheigraphy.Mea…     

赣北修水观音阁砾岩特征及其构造意义

有关赣北地区双桥山群内角度不整合和地壳运动存在与否问题,一直争论不休。论文以较丰富的详细野外调查资料为基础,并结合前人研究成果和室内各类样品测试结果,围绕这个赣北地区重要的基础地质问题进行了讨论。作者认为“修水运动”不能成立,并提出了砾岩的沉积模式。     

鄂西娄山关组顶部古岩溶不整合面的发现及层序地层学意义

鄂西娄山关组顶部存在古岩溶不整合面，有众多陆上暴露和溶蚀标志，表明其产生受寒武纪末海平面下降事件的控制。它不仅形成了碳酸盐台地上典型的Ⅱ型层序界面，而且恰与寒武—奥陶纪年代地层界线相重合，体现了层序界面、年代界线和事件界线三位一体的有机结合     

湖北省随枣地区推覆构造格局的研究

研究区构造格局的基本特征是上地壳多层次自北而南的逆冲—拆离，柳林、洪清、大洪山３条逆掩断层与深部拆离面一起组成了尖端指向南的楔形薄皮构造。逆冲系统以背驮式扩展演化。多层次推覆构造格局因后期高角度断裂的切割破坏而复杂化，构造格局定型时代为燕山期     

鄂尔多斯地区南部与东秦岭早古生代的关系和演化——以中层序(mesosequence)观点述之

鄂尔多斯地区南部和东秦岭北部是华北稳定陆块与秦岭海槽之间的过渡带．早古生代可划分为５个中层序（ｍｅｓｏｓｅｑｕｅｎｃｅ）．ＭＳ－１．包括下寒武统及中寒武统徐庄组，为混水台地沉积体系，时间跨度在３５Ｍａ；ＭＳ－２．包括下寒武统张夏组、上寒武统和下奥陶统冶里—亮甲山组，为清水台地沉积体系，时间跨度近３７．９Ｍａ；ＭＳ－３．包括下奥陶统马家沟组和峰峰组，为蒸发型台地沉积体系，时间跨度近３１Ｍａ．三者组成显生宙第一大层序（ｍｅｇａｓｅｑｕｅｎｃｅ），形成一巨大沉积旋回，为地壳动力伸张所成；ＭＳ－４．包括赵老峪组，为弧后盆地形成的斜坡沉积体系和盆地沉积体系，时间跨度１７Ｍａ；ＭＳ－５．系上奥陶统，包括背锅山组、上店组、两岔口组等，为残留海台地型沉积体系．这两个中层序形成显生宙第二大层序的主体，形成一巨大沉积旋回，为地壳动力挤压所成．     

萨拉乌苏组沉积时代的重新厘定

重新认识我国北方地区晚更新世河湖相标准地层--萨拉乌苏组的形成时代，对于萨拉乌苏组与马兰黄土的关系，与冰期气候对比等具有重要意义。笔者近年来根据野外层位对比和地层沉积相的划分，采用绝对年代控制，并结合黄土－古土壤序列研究的最新成果，初步建立了可以与黄土、深海沉积记录和冰期气候波动对比的萨拉乌苏组地层序列。认为河湖相沉积的萨拉乌苏组形成于约１４００００～７００００ａ.Ｂ.Ｐ.的末次间冰期，大致与深海氧同位素第５阶段对应，与黄土高原古土壤Ｓ１发育同期。城川组风成细砂形成于约７００００～１００００ａ.Ｂ.Ｐ的末次冰期，与黄土高原的马兰黄土是同期异相地质体.     

辽河盆地下第三系层序分析

根据岩性、岩相、地震反射、测井响应、古生物、构造旋回、接触关系及同位素年龄测定等，将辽河盆地下第三系划分为４个层序和１２个亚层序。根据地层层序综合分析，辽河盆地早第三纪具有如下沉积演化特征：①构造运动的控制性；②沉积格架的不均衡性；③沉积演化的阶段性；④沉积中心的迁移性。     

从综合地层学观点论华南浅海相泥盆系—石炭系的分界

生物地层学、事件地层学和层地层学综合研究表明，华南浅海相区与Ｓｉｐｈｏｎｏｄｅｌｌａｐｒａｅｓｕｌｃａｔａ带和Ｓ．ｓｕｌｃａｔａ带之间的界线相当的泥盆系－石炭系的界线不仅高于Ｃｙｓｔｏｐｈｒｅｎｔｉｓ带楔界，而且还应高于引起Ｃｙｓｔｏｐｈｒｅｎｔｉｓ绝灭的海退事件层的顶界。