共查询到20条相似文献，搜索用时 437 毫秒
1.
《Earth》2009,96(3-4):119-157
Anomodont synapsids represent the dominant herbivores of Permian and Triassic terrestrial vertebrate ecosystems. Their taxonomic diversity and morphological disparity in combination with their cosmopolitan distribution makes them an ideal study object for macroevolutionary patterns across the most devastating extinction event in earth history. This study provides a thorough review of anomodont-bearing tetrapod faunas to form the basis for a faunal similarity analysis and future studies of anomodont diversity. The stratigraphic correlation and composition of all known anomodont assemblages is revisited, including a discussion of the validity of the globally distributed anomodont species. The similarity analysis of anomodont faunas is performed on the basis of presence–absence data of anomodont taxa, using explorative methods such as cluster analysis (UPGMA) and non-metric multidimensional scaling (NMDS). The recovered faunal groupings indicate a common biostratigraphic age and furthermore reflect biogeographic patterns. Even though endemism and faunal provinciality was a constant element in anomodont faunas of the Permian and Triassic, the available evidence indicates that the end-Permian extinction resulted in a distinct uniformity that was unique to Early Triassic anomodont faunas. This is in particular characterized by the global distribution and overwhelming abundance of the disaster taxon Lystrosaurus. In contrast, cosmopolitan anomodonts also existed in the Late Permian (e.g., Diictodon) and Middle Triassic (e.g., Shansiodon), but those taxa coexisted with endemic faunal elements rather than dominated the fauna as Lystrosaurus did. 相似文献
2.
Tectonic implications of the Nan Suture Zone and its relationship to the Sukhothai Fold Belt, Northern Thailand 总被引：2，自引：0，他引：2
The Nan Suture and the Sukhothai Fold Belt reflect the processes associated with the collision between the Shan-Thai and Indochina Terranes in southeast Asia. The Shan-Thai Terrane rifted from Gondwana in the Early Permian. As it drifted north a subduction complex developed along its northern margin. The Nan serpentinitic melange is a thrust slice within the Pha Som Metamorphic Complex and in total this unit is a Late Permian accretionary complex containing offscraped blocks from subducted oceanic crust of Carboniferous and Permian age. The deformational style within the Pha Som Metamorphic Complex supports a west-dipping subduction zone. The Late Permian to Late Triassic fore-arc basin sediments are preserved in the Sukhothai Fold Belt and include a near continuous sedimentary record, at least locally. The whole sequence was folded and complexly thrust in the Late Triassic as a result of the collision. Late syn- to post-kinematic granites place an upper limit of 200 Ma on the time of collision. Post-orogenic sediments prograded across the suture in the Jurassic. 相似文献
3.
西藏西部狮泉河地区二叠纪和三叠纪牙形石的发现及其意义 总被引：2，自引：3，他引：2
西藏西部阿里狮泉河地区的昂杰组、下拉组和左左组中发现牙形石化石。昂杰组的牙形石组合大致对比于中二叠世空谷期早中期Mesogondolella idahoensis-Vjalovognathus shindyensis组合带。下拉组顶部的牙形石组合大致对比于晚二叠世长兴期晚期Clarkina changxingensis带。左左组中含有早三叠世的Neospathodus sp.和Gladigondolella sp.,左左组和下拉组整合接触,左左组主体时代为三叠纪。狮泉河地区在早二叠世末期就开始由冈瓦纳相碎屑岩沉积转变为特提斯相碳酸盐岩沉积,在晚二叠世长兴期和早三叠世依然维持在海相沉积环境中。冈底斯西部在晚二叠世和三叠纪为古陆的观点有待于重新审视。 相似文献
5.
6.
Palynomorphs extracted from glacigenic sediments in Northern Ethiopia are latest Carboniferous-Early Permian in age. These sediments were hitherto thought to be either of Upper Ordovician or of Late Carboniferous-Early Permian age. The predominantly glaciolacustrine and glaciofluviatile sediments were deposited in glacial troughs and valleys that were eroded into Precambrian basement rocks and into Early Palaeozoic deposits, possibly equivalents of Upper Ordovician sediments in Eritrea. In the latest Carboniferous-Early Permian, glaciated uplands to the north of Ethiopia must have existed in Eritrea and/or in southern or central Saudi Arabia. 相似文献
7.
Paleo‐fires and Atmospheric Oxygen Levels in the Latest Permian: Evidence from Maceral Compositions of Coals in Eastern Yunnan,Southern China 总被引：1，自引：0，他引：1
Inertinite maceral compositions of the Late Permian coals from three sections in the terrestrial and paralic settings of eastern Yunnan are analyzed in order to reveal the paleo-fire events and the atmospheric oxygen levels in the latest Permian. Although the macerals in the studied sections are generally dominated by vitrinite, the inertinite group makes up a considerable proportion. Its content increases upward from the beginning of the Late Permian to the coal seam near the Permian-Triassic boundary. Based on the microscopic features and the prevailing theory that inertinite is largely a by-product of paleo-fires, we suggest that the increasing upward trend of the inertinite abundance in the latest Permian could imply that the Late Permian peatland had suffered from frequent wildfires. Since ignition and burning depend on sufficient oxygen, a model-based calculation suggests that the O2 levels near the Wuchiapingian/Changhsingian boundary and the Permian-Triassic boundary are 27% and 28% respectively. This output adds supports to other discoveries made in the temporal marine and terrestrial sediments, and challenges the theories advocating hypoxia as a mechanism for the Permian-Triassic boundary crisis. 相似文献
8.
华北陆台晚古生代岩相古地理 总被引：1，自引：0，他引：1
位于天山-阴山、昆仑山-秦岭两大纬向构造带之间的华北陆台。在稳定地壳基底上逐渐发展形成晚古生代多旋回克拉通大型含煤盆地。加里东运动使陆台缺失O3-C1沉积，晚石炭世至晚二叠世陆台为海陆交互相滨海、湖泊、三角洲沉积，随着古地理环境演变,陆台各沉积古地理环境在时、表现为由老至新、自北向南迁移。 相似文献
9.
ZHANG Shaohu LIU Chiyang YANG Minghui WANG Jianqiang BAI Jianke Huang Hexin 《《地质学报》英文版》2019,93(4):845-856
Multi-dating on the same detrital grains allows for determining multiple different geo-thermochronological ages simultaneously and thus could provide more details about regional tectonics. In this paper, we carried out detrital zircon fission-track and U-Pb double dating on the Permian-Middle Triassic sediments from the southern Ordos Basin to decipher the tectonic information archived in the sediments of intracratonic basins. The detrital zircon U-Pb ages and fission-track ages, together with lag time analyses, indicate that the Permian-Middle Triassic sediments in the southern Ordos Basin are characterized by multiple provenances. The crystalline basement of the North China Craton (NCC) and recycled materials from pre-Permian sediments that were ultimately sourced from the basement of the NCC are the primary provenance, while the Permian magmatites in the northern margin of NCC and Early Paleozoic crystalline rocks in Qinling Orogenic Collage act as minor provenance. In addition, the detrital zircon fission-track age peaks reveal four major tectonothermal events, including the Late Triassic-Early Jurassic post-depositional tectonothermal event and three other tectonothermal events associated with source terrains. The Late Triassic-Early Jurassic (225–179 Ma) tectonothermal event was closely related to the upwelling of deep material and energy beneath the southwestern Ordos Basin due to the coeval northward subduction of the Yangze Block and the following collision of the Yangze Block and the NCC. The Mid-Late Permian (275–263 Ma) tectonothermal event was associated with coeval denudation in the northern part of the NCC and North Qinling terrane, resulting from the subduction of the Paleo-Asian Ocean and Tethys Ocean toward the NCC. The Late Devonian-early Late Carboniferous (348±33 Ma) tectonothermal event corresponded the long-term denudation in the hinterland and periphery of the NCC because of the arc-continent collisions in the northern and southern margins of the NCC. The Late Neoproterozoic (813–565 Ma) tectonothermal event was associated with formation of the Great Unconformity within the NCC and may be causally related to the Rodinia supercontinent breakup driven by a large-scale mantle upwelling. 相似文献
10.
黔南晚二叠世深水相地层及双壳类动物群 总被引：7，自引：0，他引：7
根据生态环境和沉积环境的差异 ,黔南晚二叠世生物群和地层可分出两种类型 :“浅海台地型”和“次深海裂陷槽型”,后者为深水型。简述了深水相地层的特征 ,据地层内所含化石确证了地层时代 ;据所含菊石、遗迹化石及围岩的沉积特点和类型 ,证实研究区晚二叠世时为深水环境 ;较系统地研究了黔南晚二叠世深水相双壳类动物群 ,它们的特征为薄壳、壳体较小、个体数量多、壳表以光滑和同心饰为主。化石中以 Claraia,H unanopecten最为发育 ,建立了 H u-nanopecten exilis-Claraia primitiva组合 ,并与国内同期的双壳类组合进行了比较。 相似文献
11.
通过对柴达木地块天峻县组合玛地区晚二叠世13个采点的系统古地磁测定,揭示了一组高温特征剩磁分量.实验结果表明,采样剖面获得的晚二叠世古地磁结果具有正、反极性,其特征剩磁方向为:Dg=333.7°,Ig=37.3°,Kg=35.4,N=9,α95 =8.8;Ds=333.9°,Is=41.7°,Ks=69.9,α95 =6.2°,相对应的古地磁极位置为:64.0°N,342.4°E,A95=5.9°,古纬度为24.0°N.这一高温分量通过了倒转检验,我们认为这一高温特征剩磁分量很可能代表了研究区晚二叠世时期的原生特征剩磁.通过对比塔里木地块晚石炭-晚二叠世古地磁结果,发现两块体在晚石炭世存在明显的古纬度差(16.6±9.3°),而在晚二叠世其古纬度差(3.5±5.4°)在古地磁误差范围内并没有明显差别,从构造意义上说,说明柴达木地块在晚二叠世已是塔里木地块的一部分,结合地质资料,认为柴达木地块在晚二叠世时古地理位置处于塔里木地块的南缘或西南缘,这表明柴达木/塔里木地块间的古阿尔金断裂的形成时代不可能早于晚石炭世时,很可能形成于晚二叠世以后. 相似文献
12.
朱儒峰 《吉林大学学报(地球科学版)》1990,(1)
本文通过早二叠世岩相、生物群落、岩石化学、古地磁资料的综合研究分析,认为内蒙—兴安亚区的古地理,早二叠世早期,在乌兰浩特—林东—林西—线存在—火山弧。火山弧对沉积物和生物群落均有一定的控制作用,古地势为东低西高。早二叠世晚期,亚区东部迅速抬升,西部以海盆沉积为主,古地势为东高西低。同时根据海洋底栖、浮游生物的不同时混生现象,确定了板块分隔、对接、碰撞时期。 相似文献
13.
巴颜喀拉残留洋盆的沉积特征 总被引：6，自引：4，他引：6
巴颜喀拉盆地垂向沉积序列表明：盆地于早古生代被动陆缘的浅海基础上裂陷、拉开，泥盆纪贯通，早石炭世洋盆扩展为成熟大洋，晚石炭世洋盆北部开始消减、南部继续扩张，晚二叠世-中三叠世进入残留洋阶段，晚三叠世转化为周缘前陆盆地．三叠纪末完全闭合，盆地自形成到消亡为一个连续的沉积和地质构造演化过程。其主体由早中三叠世深海沉积、典型浊积岩复理石和晚三叠世浅海复理石、风暴岩沉积、海相磨拉石构成，北部零星出露了中二叠世海山型沉积，昆南结合带以北有早中三叠世岛弧沉积。以盆地为中心具有向南北两侧陆块双向相背俯冲的极性特点，东西两端的碰撞造山不迟于晚二叠世。总体反映了古特提斯晚二叠世-中三叠世的残留洋盆性质和主洋域之所在。 相似文献
14.
黑龙江多宝山古生代海盆闭合的岩石学证据 总被引：2，自引：0，他引：2
综合研究黑龙江多宝山地区古生代沉积地层、生物化石,通过分析侵入岩岩石地球化学及其锆石U--Pb 同位素测年资料,表明该地区早奥陶世至晚泥盆世早期为海相沉积地层,晚泥盆世晚期为海陆交互相沉积地层,早石炭世为陆相河湖沉积地层。多宝山海盆东南侧出露一套年龄为( 300 ± 3 ～ 357 ± 4) Ma 的花岗岩,其中正长、二长花岗质糜棱岩为后造山花岗岩,碱长花岗岩为造山后A 型花岗岩。表明多宝山海盆于晚泥盆世开始闭合,至早石炭世为陆相河湖沉积,晚石炭世-早二叠世为抬升剥蚀阶段。表现为多宝山地区于早石炭世开始造山,晚石炭世晚期或延至早二叠世发生造山后伸展作用。 相似文献
15.
16.
辽西兴城地区上古生界沉积环境识别 总被引：2，自引：1，他引：1
以粒度分析结果为依据,结合地层的序列、结构、构造及岩性等方面的特征,在辽西兴城地区的上古生界中识别出四种沉积环境,每种环境均有独特的粒度特征:①曲流河环境:所在层位为本溪组与石盒子组中下部,沉积物平均粒径多集中在3φ附近,分选度较好,频率曲线多为微正偏的正态分布,概率累积曲线存在差异,河道为典型两段式,决口扇为低悬两段式;②三角洲平原环境,所在层位为太原组与山西组,其中平原沼泽沉积物粒度较细,集中在3.2φ之间,但分支河道粒度相对较粗,与曲流河类似,三角洲平原沉积物分选好,频率曲线正偏、负偏均存在,概率累积曲线存在差异,分支河道为低悬两段式而平原沼泽则为一段式,反映垂向加积特征;③辫状河环境,对应石盒子组上部层位,沉积物平均粒度2.5φ左右,分选中等至较好,频率曲线多为微正偏态,概率累积曲线介于典型两段式与高悬两段式之间;④冲积扇环境,所在层位为蛤蟆山组,平均粒径集中在2φ左右,分选中等,频率曲线为正偏态至很正偏态,表明沉积物以粗组分为主,概率累积曲线均为高悬两段式,代表很高的水动力条件。从水动力条件及沉积环境的演化趋势来看,本地区晚石炭世至中二叠世中期处于温暖湿润的濒海盆地环境,中二叠世后期开始,随着地壳抬升,本地区不断向内陆环境变化,至晚二叠世末期,已经进入干旱炎热的内陆盆地环境。 相似文献
17.
详细描述了分别位于桂西的北、中、南部的几个晚古生代地层剖面,据此建立桂西晚古生代深水沉积的地层序列,其岩石地层单位自下而上可归人广西原有的平恩组、罗富组、榴江组、五指山组、鹿寨组、巴平组、南丹组、四大寨组和领薅组.和这些单位的命名剖面比较,桂西腹地的同期地层具有更典型的深水相沉积,并含大量玄武岩,构成从早泥盆世晚期到晚二叠世末的连续深水沉积.桂西晚古生代为广海远洋环境,其中孤立碳酸盐台地上泥盆-石炭系灰岩中出现的二叠纪"化石脉",是古特提斯张裂作用的结果. 相似文献
18.
沉积物源分析是认识盆山演化的重要途径。了解四川盆地西南缘上二叠统宣威组物源,对于重建晚二叠世扬子克拉通周缘演化具有重要意义。本文对峨眉山地区宣威组顶部泥岩、砂岩开展了岩石学和全岩地球化学分析,进行了物源、沉积环境和构造背景的研究。宣威组泥岩主要成分为黏土矿物,SiO2含量(平均49.42%)中等;砂岩成分大部分为火山岩屑,含有少量石英及长石,具中等的SiO2含量(平均44.12%),属于杂砂岩系列。泥岩与砂岩均具有轻稀土元素富集、重稀土元素较右倾的稀土元素配分型式,微量元素相对大陆上地壳富集高场强元素(如Nb、Zr),亏损大离子亲石元素(如Sr、Ba)。根据地球化学分析结果结合已发表的扬子克拉通周缘二叠系沉积岩数据,认为上二叠统宣威组顶部沉积岩物源区经历了强烈的化学风化作用,沉积古环境为富氧的淡水沉积环境;宣威组顶部沉积物物源不仅来自于近源搬运的峨眉山高Ti玄武岩,还接受了扬子克拉通的补给,扬子克拉通西缘晚二叠世时期是活动大陆边缘沉积。 相似文献
19.
20.
班公湖-怒江缝合带洞错混杂岩物质组成、时代及其意义 总被引：3，自引：1，他引：2
班公湖-怒江缝合带中段洞错混杂岩保存了完整的与大洋演化相关的混杂岩系,包括蛇绿岩岩块、洋岛残片,以及复理石岩片、大陆边缘沉积等沉积岩块体,是恢复和反演班公湖-怒江洋演化的理想地区。在综述前人研究的基础上,结合近年来的研究成果,归纳和总结洞错混杂岩的物质组成和时代,初步阐述洞错混杂岩对班公湖-怒江洋演化的指示意义。结果表明,洞错混杂岩中无论是蛇绿岩残块、洋岛残片还是次深海-深海复理石岩片等,均是不同时代多期次构造混杂的混杂体。最早的年龄记录可追溯至晚二叠世末期,最晚可延至早白垩世中晚期,是班公湖-怒江洋晚二叠世末期—早白垩世中晚期连续演化的记录。洞错混杂岩早白垩世中晚期大陆边缘沉积与蛇绿岩等的不整合仅是弧前楔顶盆地沉积的产物,不能约束班公湖-怒江洋的最终消亡。 相似文献