二叠系-三叠系研究的进展

介绍了近年来二叠系、三叠来年代地层学的研究趋势及最新的年代地层表与磁性地层表。在二叠系、三叠系界线方面报道了新的底界方案及四个层型候选剖面，以及与之有关的生物地层学进展。界线事件地层学的总趋势是球外事件研究趋于沉静而缺氧事件、海侵事件及火山事件的综合作用导致生物大绝灭的观点已占主导地位，其中界线缺氧事件的确立以及海侵始于二叠纪末的新观点是引人注目的发展。在层序地层学方面对于二叠系的全球海平面变化一般趋向于分四个旋回，但对于三叠纪则尚未统一。早二叠世的全球冰期—海平面升降旋回及三叠纪的米兰柯维奇旋回在我国均有可能发现和研究。文章最后提出了层序地层界线与年代地层界线不一致所产生的理论问题并探讨了解决方法。     

陆相二叠系-三叠系界线研究进展

着重介绍了几个目前陆相二叠系—三叠系界线（TPTB）研究的重点剖面及其生物地层学研究进展；分析了陆相二叠系—三叠系界线综合地层学研究现状，包括生物地层学、事件地层学、同位素年代学、磁性地层学和层序地层学等；剖析了陆相二叠系-三叠系界线地层学研究中存在的问题及进一步的研究方向。生物地层方面，陆相二叠系-三叠系界线附近存在晚二叠世与早三叠世生物混生的层位，其中不同类别生物的时间界线常不一致，又由于陆相界线地层中含脊椎动物化石的层位一般较少，以脊椎动物化石（Lystrosaurus）为标准的精确界线常不确定，因而需重新寻找并确定陆相三叠系底界的标准化石。事件地层标志可能会成为连结海、陆相二叠系-三叠系界线地层高精度对比的纽带。     

浙江长兴二叠系—三叠系界线剖面层序地层研究

本文是在详细研究了国际二叠系—三叠系界线展型侯选剖面——中国长兴煤山剖面生物事件面、生态地层事件、高分辨率异旋回驱动机制事件、微相及沉积体系的基础上,将晚二叠世长兴期和早三叠世Griesbachian期划分出三个三级层序及百余个高频旋回层或米兰科维奇旋回层,建立了以煤山剖面为主干的,下扬子区跨越不同相区沉积体系、在等时地层格架内的空间配置和层序地层格架。本文还应用生物群生境型,进行了古水深半定量测定和相对海平面变化研究。     

碳酸盐缓坡区的露头层序地层研究

碳酸盐缓坡区沉积相带宽, 缺乏直观的物理层序界面标志, 但区域上受气候海平面控制的多级岩性旋回发育, 可对比性强, 生物丰富, 因而可借助于旋回地层学和生态地层学方法进行区域露头层序地层研究.通过岩性旋回叠加型式和生境型迁移过程研究, 较好地进行了下扬子区下三叠统露头层序划分, 建立了层序地层格架, 并提出以海侵面为界进行层序划分对于碳酸盐缓坡区露头层序地层研究更有可操作性和实用性.      

唐古拉地区拉卜查日组牙形石的发现、锶同位素组成及地层学意义

首次在唐古拉地区晚二叠世—早三叠世拉卜查日组中获得牙形石化石,其分子为Hindeodus typicalis、H.eurypyge和H.praeparvus。根据其地层意义并结合层序地层学及海平面变化研究,最终将研究区二叠系与三叠系界线的可能位置定在实测剖面的29层顶、30层底。基于此,作者系统测试了拉卜查日组中的碳酸盐岩87Sr/86Sr比值,结果表明,二叠系/三叠系界线附近87Sr/86Sr比值为0.707017~0.707032,显著小于国内外其他地区二叠系/三叠系界线附近87Sr/86Sr比值。造成这种差异的主要原因,可能是由于唐古拉地区二叠系/三叠系界线附近存在广泛的火山活动以及上扬子地区二叠纪广泛的玄武岩喷发等地方性事件。此外,剖面上锶同位素演化曲线与海平面变化曲线对比显示,87Sr/86Sr比值的最小值与初始海泛面基本一致,锶同位素演化曲线与海平面变化曲线有着很好的一致性,说明全球海平面变化是其最主要的控制因素。     

黔南桂中二叠系Cisuralian统和Guadalupian统层序地层及其与牙形石演化的关系

通过对黔南罗甸纳水剖面和桂中来宾铁桥剖面２个斜坡相剖面详细的层序地层研究,将华南二叠系Ｃｉｓｕｒａｌｉａｎ统和Ｇｕａｄａｌｕｐｉａｎ统划分为１个二级层序,即阳新层序,及其９个三级层序,并建立了相应的海平面变化曲线．结合原有和最新的生物地层资料,将这２个剖面的层序地层实现了精确划分对比,从而将原有地层对比精度提高了一倍．阐明了层序与海侵海退旋回的区别与联系．将二叠纪牙形石演化划分为５个阶段、４个演替事件,并阐明了它们与层序地层及海平面变化事件之间的相互关系．同时,提出了二叠纪牙形石分带及其全球对比表．发现栖霞亚统的氧碳同位素在下部偏轻、上部偏重,具全球对比意义     

四川龙门山马角坝地区石炭纪层序地层及海平面变化研究

在沉积学、生物地层学研究之基础上，结合沉积地球化学资料，对龙门山马角坝地区石炭系进行了露头层序地层学研究。首次识别出９个三级层序和若干个四至五级高频层序。在三级层序中，岩关组２个、大塘组３个、威宁组２个、马平组２个，它们均可作区域性对比。其中，四个层序分别与冈瓦纳大陆晚古生代五次冰川事件中四次间冰期－冰期旋回相对应，表明其成因与冰川型全球海平面变化有关。显然，研究区石炭纪层序主要受控于全球海平面升降旋回，具有全球对比意义。     

层序界面及其附近的地质特征与地质过程的表现

本文探讨了层序界面及其附近的地质特征及其构型,建立了三型(Ⅰ,Ⅱ,Ⅲ型)八类层序界面分类方案;Ⅰ型界面包括暴露侵蚀削截面、古土壤面、古喀斯特面和暴露侵蚀界面;Ⅱ型界面包括海平面下降结构转换面和海侵上超界面;Ⅲ型界面包括海底侵蚀成岩间断面和事件界面。运用岩石地层学、生物地层学、磁性地层学及碳氧同位素等多学科,对二叠纪和三叠纪中,二叠与前二叠系之间、二叠与三叠系之间和中下三叠统之间3个主要层序界面进行了探讨,这3个界面分别属于Ⅰ型、Ⅲ型和Ⅰ型界面。提出了层序界面及其附近的地质特征及其地质过程的表现。     

湖南桃源瓦尔岗剖面层序地层框架下的寒武系第10阶旋回地层学研究

很多地层学与沉积学特征,如显生宙较高的海平面位置以及最高的大气圈二氧化碳含量、全球性温暖的气候(温室效应条件)、后生动物骨骼生物礁的贫乏、三叶虫的主导性、典型的方解石海、SPICE碳同位素事件所代表的大洋缺氧事件和大气圈增氧事件,将寒武纪芙蓉世特征化。经过多年的努力,一个全新的芙蓉统年代地层格架已经得到了系统的确立,芙蓉统可以进一步划分为排碧阶、江山阶和没有得到最后定义的第10阶。湖南桃源县瓦尔岗剖面,以丰富的斜坡相三叶虫的发育著称,是全球寒武系芙蓉统第10阶底界GSSP的候选剖面。为了配合第10阶层型剖面的年代地层学研究,在层序地层学框架内,对该剖面第10期地层为主的地层序列进行了较为系统的旋回地层学研究。基于基本的岩相和沉积相的观察与研究,将该剖面沈家湾组中主要归为第10期的大部分地层归为一个三级沉积层序,并进一步划分为两个四级海平面变化层序;该三级沉积层序大致包含48个准层序级别的六级米级旋回,这些米级旋回常常4个一组构成五级旋回(准层序组)而表现出明显的沉积旋回的1∶4的叠加样式,成为较为典型的米兰柯维奇旋回属性而可以作为代表性的"定时器"。结果表明,第10期地层的形成时限大致为4.80Myr(百万年),稍大于地球化学测年得出的4.10Myr(~495.0-489.5Ma);而且层序界面代表的沉积环境变化要超前于阶的界面代表的生物变化。因此,层序地层学框架内的旋回地层学研究,丰富了瓦尔岗剖面的地层学内容。     

鲁西陆表海盆地高分辨率层序划分与海侵过程成煤特点

晚石炭世至早二叠世华北陆表海盆地的高频海平面变化,是盆地充填和聚煤作用的主要控制因素,因而形成了旋回结构十分清楚的含煤层序。本文运用高分辨率层序地层学的思路、分析技术,研究了鲁西陆表海盆地含煤地层的高分辨率层序地层学特征,识别和划分了中长期和中、短期基准面旋回。研究表明,突发性的海侵事件对陆表海盆地聚煤作用具有重要影响,海侵过程成煤为鲁西煤聚积的显著特点。     

Sequence Stratigraphy of the Permian--Triassia Boundary Section of Changxing, Zhejiang, Southern China

Three third-order sequences and about one hundred high-frequency cycles or Milankovitchcycles within the Late Permian Changxingian to Early Triassic Griesbachian are identified in theMeishan Section of Changxing, Zhejiang Province, southern China, the candidate stratotype sec-tion of the global Permo-Triassic boundary, based on a detailed study of the biological,ecological and high-resolution allochthonous cyclic events, microfacies and depositional systems.Furthermore, the stacking pattern of the depositional systems across various Changxingian andGriesbachian sedimentary facies of the Lower Yangtze and the sequence stratigraphic frameworkare outlined with the Meishan section as the principal section. In this paper the habitat types offossil biota are applied to semiquantitative palaeobathymetry and the study of relative sea levelchanges.     

中国南部二叠、三叠纪“混生生物群”及二叠、三叠系界线

本文系统描述了中国南部二叠、三叠纪“混生生物群”。根据笔者的统计,目前巳经发现有“二叠纪型”分子36属53种与三叠纪菊石、双壳类、牙形剌共生。 笔者认为中国南部可以以牙形剌Anchignathodus parvus 的出现作为三叠系的底界,双壳类Pteria ussurica variabilis,菊石 Hypophiceras的出现可以作为三叠系开始的辅助标志。文中还将这一界线与世界上其它地区的二叠、三叠系界线进行了对比。     

Organic carbon content and carbon isotope variations across the Permo-Triassic boundary in the Gartnerkofel-1 borehole,Carnic Alps,Austria

The Gartnerkofel borehole is one of the most thoroughly studied and described Permo-Triassic sections in the world. Detailed bulk organic carbon isotope studies show a negative base shift from ? 24‰ to ? 28‰ in the Latest Permian which latter value persists into the Earliest Triassic after which it decreases slightly to ? 26‰. Two strongly negative peaks of > ? 38‰ in the Latest Permian and a lesser peak of ? 31‰ in the Early Triassic are too negative to be due to a greater proportion of more negative organic matter and must be due to very negative methane effects. The overall change to more negative values across the Bulla/Tesero boundary fits the relative rise in sea level for this transition based on the facies changes. A positive shift in organic carbon isotope values at the Late Permian Event Horizon may be due to an increase in land-derived organic detritus at this level—a feature shown by all Tethyan Permo-Triassic boundary sections though these other sections do not have the same values. Carbonate carbon isotope trends are similar in all sections dropping by 2–3 units across the Permo-Triassic boundary. Gartnerkofel carbonate oxygen values are surprisingly, considering the ubiquitous dolomitization, compatible with values elsewhere and indicate reasonable tropical temperatures of 60 °C in the Latest Permian sabkhas to 20–40 °C in the overlying marine transition beds. Increased land-derived input at the Late Permian Event Horizon may be due to offshore transport by tsunamis whose deposits have been recognized in India at this level.     

湖南桑植县仁村坪上二叠统—下三叠统底部菊石动物群序列及其区域对比

湖南桑植县仁村坪剖面二叠-三叠系界线地层连续,菊石动物化石丰富.根据该剖面上二叠统大隆组至下三叠统大冶组底部菊石动物群的分布,自下而上划分为4个菊石带:Araxoceras-Konglingites-Sanyangites带、Sinoceltites带、Pseudotirolites-Rotodiscoceras带和Hypophiceras-Ophiceras-Lytophiceras带.通过对该剖面菊石和牙形石生物地层及其与华南其他剖面的对比可知,Araxoceras-Konglingites-Sanyangites带与牙形石Neospathodus orientalis带同期,为吴家坪期晚期;Sinoceltites带与牙形石N.subcarinata-N.wangi带同期,为长兴期晚期;Pseudotirolites-Rotodiscoceras带与牙形石N.postwangi-N.changxingensis带和N.xiangsiensis-N.changxingensis带同期,为长兴期晚期;Hypophiceras-Ophiceras-Lytophiceras带与H.parvus、I.isarcica-I.staesche和N.planata 3个牙形石带同期,相当于印度期早期.根据仁村坪剖面菊石Hypophiceras-Ophiceras-Lytophiceras带底界的出现位置,将该剖面的二叠-三叠系界线确定在第27a层的中部.     

Magnetostratigraphic Study of Meishan Permian-Triassic Section, Changxing, Zhejiang Province, China

INTRODUCTIONBecause many P/ T boundary sections around the worldare stratigraphically unconformed,som e possible exceptionsdeveloped in Greenland,Iran,Russia and South China are ofcourse of international importance.Especially successive sedi-ments from the L ate Paleozoic to Early Mesozoic widely ap-peared in South China,for example,the Meishan Section inChangxing County,Zhejiang Province,and som e analogies inGuangyuan,Wulong and Shangsi counties,Sichuan Province.Some geologists…     

陆相二叠一三叠系界线划分和事件

我国陆相二叠—三叠系界线的划分主要依据古脊椎动物,孢粉,双壳类、介形虫和古植物等.这些化石组合特征在界线附近都有明显的变化.这种变化不仅可以用来划分界线,而且结合在界线附近其它非生物（沉积物的粒度和颜色等）的异常变化,可以看出在二叠—三叠纪之交曾发生过某种事件.     

The terminal Permian in European Russia: Vyaznikovian Horizon,Nedubrovo Member,and Permian–Triassic boundary

The comprehensive analysis of the data obtained on terrestrial vertebrata, ostracods, entomologic fauna, megaflora, and microflora in deposits of the Vyaznikovian Horizon and Nedubrovo Member, as well as the paleomagnetic data measured in enclosing rocks, confirms heterogeneity of these deposits. Accordingly, it is necessary to distinguish these two stratons in the terminal Permian of the East European Platform. The combined sequence of Triassic–Permian boundary deposits in the Moscow Syneclise, which is considered to be the most complete sequence in the East European Platform, is as follows (from bottom upward): Vyatkian deposits; Vyaznikovian Horizon, including Sokovka and Zhukovo members; Nedubrovo Member (Upper Permian); Astashikha and Ryabi members of the Vokhmian Horizon (Lower Triassic). None of the sequences of Permian–Triassic boundary deposits known in the area of study characterizes this sequence in full volume. In the north, the Triassic deposits are underlain by the Nedubrovo Member; in the south (the Klyazma River basin), the sections are underlain by the Vyaznikovian Horizon. The Permian–Triassic boundary adopted in the General Stratigraphic Scale of Russia for continental deposits of the East European platform (the lower boundary of the Astashikha Member) is more ancient than the one adopted in the International Stratigraphic Chart. The same geological situation is observed in the German Basin and other localities where Triassic continental deposits are developed. The ways of solving this problem are discussed in this article.     

准噶尔盆地滴南凸起二叠系、三叠系层序地层格架的建立

通过区域地质背景分析、地震反射特征等识别出准噶尔盆地滴南凸起二叠系底面、三叠系顶面以及两系之间的分界面均为层序界面,且这3个界面均是区域性的岩性突变面.受其启示,对三叠系克拉玛依组和白碱滩组的分界面进行了分析,发现该界面同样为区域性的岩性界面,同时还是地层缺失面、地震强反射界面,判断其亦为层序界面.因此,本区二叠系、三叠系共划分为3个层序,在每个层序内部又进行了体系域的划分.     

Permo-Triassic high-pressure metamorphism in the central western Korean Peninsula,and its link to Paleo-Tethyan Ocean closure: Key issues revisited

Permo-Triassic high-pressure(HP) mafic granulites, together with the Bibong retrogressed eclogite,preserved along the central western Korean Peninsula provide important insights into the Late Permian to Triassic collisional orogeny in northeast Asia. The metamorphic pressureetemperatureetime(P-T-t)paths of these rocks, however, remain poorly constrained and even overestimated, owing to outdated geothermobarometers and inaccurate isopleth techniques. Here we evaluate the metamorphic Pe T conditions of Triassic HP mafic granulites including those in Baekdong, Sinri and Daepan and the Bibong Triassic retrogressed eclogite in the Hongseong area, and the Permo-Triassic Samgot mafic granulite in the Imjingang Belt of the central western Korean Peninsula through the application of modern phase equilibria techniques. The Baekdong and Samgot mafic granulites and the Bibong retrogressed eclogite yield a range of 12.0 -16.0 kbar and 800 -900℃, representing HP granulite facies conditions. The Sinri and Daepan granulites from the Hongseong area show relatively lower grade metamorphic conditions between HP granulite and normal granulite facies, and are characterized by sub-isothermal decompression during exhumation. The similarities in the metamorphic ages and the post-collisional igneous activity from the central western Korean Peninsula indicate that the Triassic ages represent the retrograde stage of the metamorphic Pe T paths. In contrast, the Late Permian metamorphic ages, which are older than protolith ages of the post-collisional igneous rocks, correspond to the possible prograde stage of metamorphism. The P-T-t paths presented in this paper, together with the metamorphic ages and post-orogenic igneous events reported from these areas suggest trace of the subduction, accretion and exhumation history, and indicate a tectonic linkage among the northeast Asian continents during the Paleo-Tethyan Ocean closure.