Spatial and Temporal Distribution of the Cryptospirifer Fauna(Middle Permian Brachiopods) in the Tethyan Realm and Its Paleogeographic Implications

The middle Permian Cryptospirifer fauna （brachiopod） has hitherto been found in more than 30 localities in the Yangtze Platform, South China. Examination of data from various localities shows that it occurs stratigraphically in three intervals in the range from the upper Kungurian to Wordian. In the Baoshan block in western Yunnan the fauna occurs in the basal part of the Daaozi Formation and is of possibly an early Wordian age. Outside China the Cryptospirifer fauna has been reported from central and northwest Iran and central Turkey, where the fauna may have an age around the Wordian／Capitanian boundary. Rapid global warming since the late Early Permian and possession of other suitable environmental factors such as proper substrate, clastic input and water depth enabled the Gondwana-derived Baoshan Block and related tectono-stratigraphic units in Iran and Turkey to host the Cryptospirifer fauna, a fauna evolved in the Yangtze Platform that is a type area of the Cathaysian province.

The Bivalve Yangtzedonta is not the Brachiopod Xianfengella

Abstract The alleged ＂holotype＂of the bivalve Yangtzedonta primitiva Yu.1985 figured by Qian （2001） is a broken and distorted specimen of the brachiopod Xianfengella prima He and Yang, 1982 and not the holotype of Y. primitiva. Qian contends that the oldest recognized monoplacophoran, Maikhanella pristinis （Jiang, 1980）, is neither a monoplacophoran nor the oldest molluscan fossil in the Meishucunian Stage of China. Furthermore, he considers that the oldest bivalve Xianfengoconcha eUiptica Zhang, 1980 is an inarticulate brachiopod, not a mollusc. WatsoneUa yunnanensis （He and Yang, 1982）, is associated with Yangtzedonta primitiva Yu but indicates no evolutionary relationship between the Classes Rostroconchia and Bivalvia in the Lower Cambrian Zhongyicun Member of the Yuhucun Formation. Qian＇s confusion in using non-molluscan fossils to discuss the early evolution of shelled molluscs also confuses the basic concepts of the respective groups.

Coevolution of Brachiopod Paleobiogeography and Tectonopaleogeography during the Early–Middle Permian

A comprehensive compilation and systematic analysis of known early and middle Permian brachiopod faunas shows that the early Permian brachiopod faunas comprise three realms, six regions, and eleven provinces, while those of the middle Permian comprise three realms, four regions, and eight provinces. A comparison and analysis of brachiopod faunal patterns reveal a coevolution between global brachiopod paleobiogeography and tectonopaleogeography during the early-middle Permian. Although temperature/latitude is the main factor controlling the formation of three realms, tectonopaleogeographic factors determine the temperature/latitude in which the continents were located. The ＇continental barrier＇ of Pangea, as a ＇central axis＇ continent, divided the three realms into six regions, which indicates that the formation of biogeographic regions was controlled mainly by the tectonopaleogeographic factors. The evolution of tectonopaleogeography was sometimes a long-term process, so that the biogeographic regions（or provinces） controlled by tectonopaleogeography displayed relative stability. Shifts in the nature of biogeographic provinces（e.g., from cool water to warm water, and vice versa）, extensions or narrowing of geographical ranges, and recombinations of some provinces were all related to regional tectonic evolution. The study of the coevolution between brachiopod paleobiogeography and tectonopaleogeography not only accounts for the formation mechanisms of brachiopod paleobiogeographic patterns during the early-middle Permian, but also provides evidences for the locations and configurations of oceans and plates（blocks） during this period.

Paleocommunity Replacements of Benthic Brachiopod in the Middle-Upper Devonian in the Longmenshan Area,Southwestern China:Responses to Sea Level Fluctuations

Twelve paleocommunities dominated by benthic brachiopod are recognized in the Givetian-Frasnian stages of the Devonian in the Longmenshan area, southwestern China, in which two kinds of brachiopod community replacement are classified. One is the abrupt replacement, represented by abrupt alternation between the Leiorhynchus community and Zhonghuacoelia-Striatopugnax community in the Frasnian Tuqiaozi Formation. The other is the gradual one, developed in the Givetian Guanwushan Formation, which had been completed by the shift of the Independatrypa lemma-Uncinulus heterocostellis-Emanuella takwanensis community via the Sinospongophyllum irregulare-Pseudomicroplasma fongi community to the Clathrocoilona spissa-Hexagonaria composite reef community. According to analyses of the paleocommunities, either the abrupt or gradual paleocommunity replacement of the Middle-Upper Devonian in the Longmenshan area is suggested as a response to the 5th-order sea level fluctuation due to the replacements of the paleocommunities in a tracts-system of depositional sequence. It is supposed that changes of paleocommunity diversity, one of the results of paleocommunity replacement, are depended on the range and magnitude of sea level fluctuation, but there is not a linear relationship between them. Furthermore, a suggestion is proposed that the concept of paleocommunity succession seem to be abandoned in the paleocommunity analysis because it almost never be practiced to recover the information of community succession in the geological record at present.

Jurassic Brachiopods and Paleogeography of North Qinghai-Tibetan Plateau

This paper deals with Jurassic brachiopods from North Tibet and South Qinghai and the stratigraphical subdivision there. Based on faunas and strata,a general outline of the palaeogeographical evolution has been traced out along the line of plate-tectonic movements . In this paper , 10 species of 8 genera are described , among which the species Lacunosella rhombica , Rntithyris vulgaris , Tanyothyris appositus , Apatecosia navicularis and Flabellothyris sp . nov . have been recognized as new .

Biogeographic characteristics of Zhesi brachiopod fauna and reconstruction of tectonopaleogeography of Jiamusi-Mongolia Block

The Kungurian-Capitanian （Permian） Zhesi branchiopod fauna is mainly composed of cold-water typed taxa with high diversity and abundance. This fauna is similar with the coeval brachiopod faunas from Ti- man-Pechora, Svalbard, and Queen Elizabeth Islands of the Boreal Realm, with no real ＂warm-water＂ species. Zhesi brachiopod fauna is a cold-water fauna and should be assigned to the Boreal Realm. Considering the paleogeographic characteristics of this fauna and the basic rationale of paleobiogeographie provinces being controlled by latitude-temperate, and that the above areas were located at 50°N -70°N in the global paleoclimate reconstruction map compiled by Boucot et al. , the paleo-latitude of the southern margin of Jiamusi-Mongolia Block, where developed the Zhesi brachiopod fauna, is suggested ranging from 40°N to 60°N. Zhesi brachiopod fauna is an endemic fauna, containing more than 75% endemic species and self-grouped as a biogeographic province, termed Inner Mongolia Province. These characteristics indicate that this area was closed or semiclosed at that time. On the Jiamusi-Mongolia Block, the Herlen-Jiamusi Old-land as an obvious ＂continental barrier＂ hindered the northward migration of the Zhesi brachiopod fauna and the immigration of brachiopod species from other areas. The Tarim plate has collided with the Kazakhstan plate and the western part of South Tianshan-Beishan-Xar Moron Ocean has been closed. At the same time, the western margin of Jiamusi-Mongolia Block was joined with the Tarim plate. The Xar Moron Ocean in south of Jiamusi-Mongolia Block was wide e- nough and the ocean temperature rose gradually southward, so that it is not suitable for the cold-water brachiopods to survive and thrive on the northern margin of the North China plate. Thus, the ocean with large width and high temperature formed another natural barrier for the southward migration of the cold-water brachiopods.

Mechanism on bipolar distribution of Permian brachiopods

By reasearch on geographic distribution, nine genera in bipolar distribution are selected from Permian brachiopods. These taxa originated from middle-high latitude areas in the boreal realm, of which five genera were derived from Late Carboniferous, and other four genera originated from Permian. They were all in bipolar distribution during some different stages in Permian. Specific diversity for each genus was high in the boreal realm, whereas in the Gondwana realm was very low. Perdurability was long in the boreal realm, and short in the Gondwana realm. It was the time when these nine genera came to their maximum diversity that these genera appeared in the Gondwana and formed bipolar distribution; while they also migrated to the low latitude from high latitude. This shows very close relationship between several main cooling events in Permian and the migration of genera from the boreal realm to the Gondwana reahn through the Tethys. Therefore, the cooling events might be the main drive which caused these cold-water-type brachiopods migrated to the Gondwana realm and being bipolar distribution. In this process, the planula tolerance to warm water would be another important factor.

First Record of Brachiopod Species in Myanmar

The Paleozoic rocks are well exposed in the Taungnyo area and the main purpose of classification is taxonomic status of the invertebrate fossils and describing the systematic paleontology of brachiopod fossils from Taungnyo Formation. Mainly distributed clastic sedimentary rocks of Taungnyo Formation (Early Carboniferous) and carbonate rocks of Moulmein Limestone Group (Permian to Middle Triassic) are well exposed in the Taungnyo area. In this study, mainly, a total of five species are recognized in the clastic sediments of Taungnyo Formation. Most brachiopods are generally found abundant and well preserved in the mudstone unit. Among them, most of the taxa have not been recorded previously. The brachiopods include: Fimbrispirifer venustus, Ovetensispirifer ovetensium, Aullacella sp., Kayserellae emanuelensis, and Chonopectus sp. All of the species are first recorded in Myanmar.

西藏申扎地区晚石炭世—早二叠世冈瓦纳相腕足类动物群再研究

西藏申扎地区德日昂玛-下拉剖面永珠组中上部和昂杰组的腕足类动物群可以与国内、外冈瓦纳相和亲冈瓦纳相地区的腕足类动物群进行对比,但又显示出其独特的一面。将其自下而上划分为4个组合,永珠组中上部为Reedoconcha xizangensis-Spinomartinia xainzaensis组合、Cimmeriella mucronata-Reedoconcha excellens组合和Trigonotreta magnifica-Bandoproductus in-termedia组合,昂杰组为Aulosteges ingens-Punctocyrtella nagmargensis组合。按照国内、外冈瓦纳相、亲冈瓦纳相地区及华夏特提斯地区腕足类的时代意见,永珠组中部腕足类组合的时代为晚石炭世巴斯基尔期,上部2个腕足类组合分别为早二叠世萨克马尔早期—萨克马尔晚期,昂杰组的腕足类组合的时代为早二叠世亚丁斯克期。

长江源各拉丹冬地区晚二叠世乌丽群的腕足类生物组合

在长江源区各拉丹冬-带晚二叠世地层中建立了2个腕足类生物组合,下部为Spinomarginifera cf.kueichowensis-Tschernyschewia cf.sinensis-Tyloplecta cf.yangtzeensis组合,见于乌丽群下部的那益雄组;上部为Leptodus nobilis-Perigeyerellacostellata-Enteletes subequivalis组合,见于乌丽群上部的拉卜查日组。两个组合生物群属于特提斯动物群,均可与华南地区同期地层中的生物群相对比。

石炭纪海相碳酸盐岩的锶同位素演化及其意义

本文从马角坝剖面石炭系海相碳酸盐岩和腕足化石的锶同位素变化出发,讨论了锶同位素地层曲线的地质意义,并且指出海相碳酸盐岩和腕足化石的锶同位素组成可作为了解地球构造演化的工具。

贵州台江早、中寒武世凯里组的腕足动物

描述贵州台江下、中寒武统凯里组的腕足动物化石６属１０种，其中包括１新种，２比较种和２未定种。该腕足动物组合带有波希米亚及哈萨克斯坦的色彩，对于我国寒武纪腕足动物的分类、演化、古生物地理研究及查清凯里动物群的组成、凯里组的时代，均有重要的意义。

川东南兴文地区长兴期腕足动物及其群落结构

通过川东南兴文地区长兴期腕足动物地层的研究 ,总结了腕足动物群的性质 ,指出了本区长兴期腕足动物群不同于灰岩相类群 ,也不同于硅质岩相类群 ,而属于灰岩、砂页岩混合相类群。文章重点研究了本区腕足动物群落结构 ,并提出了生态类群这一新观点 ,指出生态类群是以生态学而不是以纯分类学标准进行分类的 ,这有助于群落生态研究中简化群落内物种间的复杂关系。

华南奥陶、志留纪腕足动物群的更替兼论奥陶纪末冰川活动的影响

地史时期大规模的生物群更替与全球大环境的灾难性变化密切相关 ,尽管这种更替在性质、延续时间及等级上各个时期不尽相同。奥陶、志留纪腕足动物群的更替提供了一个重要的实例。全球广布的晚奥陶世较深水叶月贝动物群 ( Foliomena Fauna)和其后浅、凉水的赫南特贝动物群 ( H irnantia Fauna)的灭绝 ,均受控于当时的冈瓦纳大陆冰川活动及其影响效应。志留纪早期 ,以正形贝目和扭月贝目占主导地位的晚奥陶世动物群被一大批新类型 (如无洞贝目、五房贝亚目和石燕目 )所替代 ,组成典型的志留纪动物群。

泥盆纪海水的碳、氧同位素变化--来自腕足化石的同位素记录

生物壳体中的碳、氧同位素一直被用来反演地质历史时期海水同位素组成。具有较强抵抗成岩后生作用(低镁方解石)的腕足化石,分布广泛,被认为是反演古生代海水同位素的理想样品之一。本文通过对四川龙门山泥盆纪保存完好的腕足化石碳、氧同位素的提取,建立该时期海水同位素变化曲线,并对其控制因素进行探讨。研究显示:碳同位素组成在～2‰～+2‰(PDB下同)之间变化。其间经历3个旋回,其相对高值分别对应龙门山地区其中3个成礁期。同时因海平面变化不同,碳同位素表现出正偏幅度的不同。表明生物生长以及海平面变化共同控制着海水碳同位素组成,且生物生长对其影响较大。氧同位素组成在4‰～～10‰之间变化。在埃姆斯阶对应的甘溪组、谢家湾组以及二台子组时期,氧同位素从～10‰逐渐升高到～6‰。但相对于世界其他地区该时期氧同位素偏低～2‰～～4‰。可能原因是早期处于封闭海洋环境的平驿铺群时期,淡水注入造成海水氧同位素严重偏负。埃姆斯阶全球海平面上升,广海海水同化作用,氧同位素不断上升。从养马坝至小岭坡组时段内,氧同位素在～4‰～～6‰之间变化,同世界其他地区相当。其幅度变化表明:温度可能是其控制因素。

华北地台石炭二叠纪腕足动物群及生物地理研究

通过对华北地台早石炭世晚期至早二叠世腕足动物群的全面系统研究 ,认为全区腕足动物群的发展演化具有一致性和阶段性 ,可清楚地分为 5个阶段 ,即田师傅期 (C13 —C21) [1] 、本溪期 (C22 )、太原期早期 (C23 )、太原期晚期 (P11)和山西期 (P12 )。在此基础上 ,进行了国内外同期腕足动物群的对比和腕足动物生物古地理分析 ,确立了华北地台东北部田师傅期腕足动物的生物地理归属 ,命名为天山—辽吉腕足动物生物地理分区 。

吉林—延吉—朝鲜咸北地区晚古生代沉积特征及其构造演化意义

中国吉林东部与朝鲜半岛北部地区对比研究,无疑对揭示朝鲜半岛的地质属性、中朝板块北缘东延及演化有着重要的贡献。针对中国吉林东部延边地区和朝鲜咸北地区的晚古生代地层进行化石组合、沉积特征、基底性质以及岩浆序列等方面的对比研究认为:朝鲜二叠纪鸡笼山腕足动物群与中国北方二叠纪哲斯腕足动物群有明显差异,与吉林地区范家屯组,尤其是延边地区庙岭组有较强的可对比性;中国吉林—延吉褶皱带和朝鲜咸北地块均以元古宇为基底,没有太古宙岩石出露;在晚古生代期间,中国吉林东部—延边地区和朝鲜咸北地区沉积环境、岩浆活动相似;朝鲜咸北地块和狼林地块的边界断裂——输城川断裂带应与华北地块和吉黑造山带之间缝合线的东端—古洞河断裂相连接,吉黑造山带东部地块和朝鲜咸北地块在晚古生代时期应处于同一个大地构造单元。

相对海平面变化对腕足动物群落取代的影响——以吐哈盆地北缘桃西沟上石炭统祁家沟组—奥尔土组剖面为例

相对海平面的升降变化引起的相对水深及相关生态条件的改变对腕足动物群具有影响。相对海平面变化的速度和幅度是引起腕足动物群面貌变化的重要因素。相对海平面的持续缓慢上升有利于腕足动物丰度的增加和分异度的提高,海平面的大幅度快速变化对腕足动物群落则是一个不利的因素,是造成腕足动物物种丰度下降、新种增加量减少乃至彻底死亡的重要原因。吐哈盆地北缘晚石炭世发育的5个腕足动物群落全部与相对海平面上升期有关。在海平面的持续缓慢上升期,腕足动物的丰度不断增加,分异度迅速提高;而在相对海平面下降期,本区陆源粗碎屑物大量注入,不适合腕足动物的生存。

寒武早期泥质基底腕足动物的生活策略——来自澄江动物群的证据

目的系统分析滇东泥质基底澄江化石库腕足动物的生活方式。方法依据澄江化石库丰富的腕足动物资料,论证寒武纪早期泥质基底腕足动物的生活策略。结果寒武纪早期泥质基底上腕足动物的生活方式主要包括肉茎附着型(pedicle-anchoring or pedicle-attaching)、自由平躺型(free-lying)、假内栖型(qusi-infaunal)和表栖粘附型(cemented epifaunal),肉茎附着型是早寒武世腕足动物生活的最普遍的型式。结论空间生态分析显示,早寒武世滇东海盆中,腕足动物的分布已经具有一定的空间层次性,不同的腕足类型占据了不同的生态位,形成了比较复杂的空间群落结构。

西藏申扎和改则地区早石炭世地层及腕足类研究

西藏申扎和改则地区早石炭世地层发育,腕足类及珊瑚类化石丰富。腕足类化石计有34属45种,共建立3个组合;申扎大塘阶下部巴日阿郎寨组Ovatia-Unispirifer组合;大塘阶上部永珠组Balakhonia-Productus组合;改则大塘阶上部Latiproductus-Striatifera组合。本文系统讨论了各腕足类组合的时代及与国内外同期地层的对比,将西藏境内早石炭世的沉积物及生物群划分为3个类型。根据生物群及沉积物在空间上的分布特点,笔者认为在早石炭世时,班公湖至怒江断裂南北生物群及沉积物具有明显的差异,即南部申扎和珠峰地区生物群及沉积物特征与冈瓦纳大陆相似,而北部改则地区与扬子地台的生物群及沉积物特征相同,其间可能有宽阔的海域隔离。