The Early Jurassic to Aalenian paleobiogeography of the Arctic realm: Implication of microbenthos (Foraminifers and Ostracodes)

Stages in evolution of the Early Jurassic to Aalenian foraminifers and ostracodes are established based on the analyzed diversity dynamics of respective microfauna associations. Evolution of foraminifers is divided in two, the Hettangian-initial early Toarcian and the late early Toarcian-Aalenian stages, while the identical first stage in evolution of ostracodes has been followed by the late early Toarcian-Callovian stage. During the Jurassic, periodic migrations of foraminiferal and ostracod genera and species, which were interrelated with large transgressions and climatic changes, took place in the initial late and mid-late Pliensbachian, initial early Toarcian, and the late Toarcian-early Aalenian. Being isolated to the maximum extent in the second half of the late Aalenian, the Arctic basin lost connections with seas of northwestern Europe. The Early Jurassic to Aalenian biogeography of the Arctic basin is established based on the results of cluster analysis (group average link method, Jaccard coefficient, presence or absence of foraminifers and ostracodes genera) with due account for preceding and subsequent formation history of microbenthos structure in biochores. The distinguished biochores are ranked as realms and provinces of foraminifers and ostracodes. As is established, contours of the realms and provinces populated by different groups of microbenthos did not coincide and changed with time. Ecotones between the realms (e.g., the North Sea province) changed their localitization to be a part of the Arctic or Boreal Atlantic realms in different epochs. The Early-Middle Jurassic sedimentary successions of the Arctic basins reveal several levels of sharp taxonomic changes in composition of microbenthos under influence of the first-order abiotic factors.     

Devonian shallow marine ostracods from central Japan

Thirteen ostracod species including two new species, Clavofabellina fukujiensis n. sp. and Bythocypris wangi n. sp., are reported from the Middle Shale Member of the Fukuji Formation, Devonian of central Japan. The ostracods demonstrate species‐links with South China, indicating that the Hida‐Gaien Terrane of central Japan shared biogeographical affinities with the shallow marine faunas of the South China paleocontinent during the Early Devonian.     

吉黑造山带二叠纪生物古地理区划及特征

吉黑造山带其实质是天山－兴安造山带的东延部分,夹持于华北板块与西伯利亚板块之间,北部为以佳木斯地块为中心的地块群,南部为古生代陆缘褶皱带,东北部为中生代走滑拼贴的那丹哈达－比金地体。该造山带是由于晚古生代末期华北板块与北部中间地块间的陆－陆碰撞对接和中生代太平洋板块的斜向俯冲挤压形成的。二叠纪是吉黑造山带古地理、古气候和古构造变化最为显著的时期,反映在生物古地理方面的生物混生和交融也非常明显。详细研究该时期生物古地理格局与演化是解决造山带二叠纪古构造格局的关键。     

亚洲东部的志留系

亚洲东部包括西伯利亚,科累马,塔里木—中朝和华南等古板块,以及围绕或穿插其间的活动带.不同古板块基本上被归于不同大区,同一大区中的稳定和活动地带属不同的一级地层区,同一区中的不同岩相和生物相带为不同的二圾地层区.志留纪时期除冈瓦纳古陆之外,其他各板块都分布在赤道两侧的低、中纬度地带,而且以南半球为主.在各古板块内的志留纪古地理面貌上,本文着重剖析华南古板块.志留纪的生物地理区系划分,虽然基于不同门类有不同的认识,但亚洲东部范围内均属北方大区.本文用生态地层学、沉积学,古地理学等方法研究了华南早志留世海平面升降的规律变化.     

Fossil biotas from Pakistan with focus on dinosaur distributions and discussion on paleobiogeographic evolution of Indo-Pak Peninsula

Recent geological and paleontological exploration in the Indus basin of Pakistan allowed the discover-ies of numerous remains of non-marine reptiles (titanosaurian sauropod,abelisaurian and noasaurian theropod dinosaurs),and marine reptiles (crocodiles),flying reptiles (pterosaurs),marine and non-marine mammals, fishes,invertebrates,and plants,especially Pakistan is relatively rich in footprints/trackways in the Mesozoic. These vertebrates of Indo-Pakistan are very significant for paleobiogeographic study due to the present-day con-nection of this continent with Asia in Northern Hemisphere,whereas during past (Jurassic and pre-Jurassic)it was connected to the Gondwana.The Mesozoic vertebrates show close affinities with Gondwanan landmasses. The Cenozoic vertebrates show Eurasian affinity and migrated from Indo-Pak subcontinent to Eurasia or vice ver-sa via Paleo Indus River systems along Western Indus Suture,after long journey of about 6 000 km the first col-lision of Indo-Pak subcontinent with Asia occurred at terminal Cretaceous.     

江汉盆地早寒武世生态地层及生物古地理特征

本文通过对江汉盆地６个地区早寒武世地层剖面古生态研究，建立了２３个化石群落，通过群落生境型的分析，揭示了江汉盆地早寒武世海平面及地理特征的演变，并将研究区早寒武世生态体系的演化划分８个阶段。通过对江汉盆地早寒武世生态地层的研究，本文建立了该盆地生态地层系统，其中包括２３个群落带和１１个群落组的分布，组成，生态环境特征和顶底界线以及各群落组与油气的关系。古生物地理特征分析表明，研究区西南缘石门杨家坪     

秦岭三叠纪古海盆的生态地层、生物古地理特征及其演化

本文在对西秦岭4条剖面进行生态地层研究的基础上,通过生态地层对比揭示了三叠纪秦岭海盆进化的一般模式和海平面变化的细节。古生物地理分析表明:三叠纪时,秦岭北侧属于温带生物区系,秦岭南部属于热带-亚热带生物区系。秦岭各区与邻区之间生物相似性系数研究表明,秦岭三叠纪海盆具有一定的宽度和深度,但不是宽广的大洋。     

First Record of Hoplictis(Carnivora,Mustelidae) in East Asia from the Miocene of the Ulungur River Area,Xinjiang,Northwest China

The first unequivocal remains of medium to large-sized mustelids from the middle Miocene Halamagai and Kekemaideng formations have been found in the Ulungur River area, Xinjiang, northwestern China. These new fossils are referred to the hypercarnivorous mustelid Hoplictis Ginsburg, 1961 and denote the first record of the genus in East Asia.We define Hoplictis baihu n. sp., for the mustelid from Tieersihabahe(Halamagai Fm.), which represents the smallest species of the genus. This primitive form is closer to H. florancei and H. noueli than to H. anatolicus and later, larger and more derived Hoplictis spp., from Europe and North America. A large toothless mandible from Duolebulejin(Kekemaiden Fm.) is assigned to Hoplictis cf. helbingi, and it presumably might represent the first record of H. helbingi outside Western Europe. The systematic position of Hoplicitis in relation to Ischyrictis with which it is similar is clarified. The occurrence in East Asia of two species of Hoplictis greatly expands the known distribution and diversity of the genus, and supports a Palaearctic Neogene dispersal event of carnivorans between Europe and Asia during the late Shanwangian–early Tunggurian equivalent to MN5–6 in Europe, and indication of another dispersal event from Europe to North America,through Northwest China during the late Tunggurian, equivalent to MN7–8 in Europe.     

天山东段“北天山洋”构造涵义及演化模式再认识

准噶尔-吐哈地块与伊犁-中天山地块之间分布着多条时代和类型各不相同的古生代蛇绿混杂岩带,前人一般将这些蛇绿混杂岩统一视为北天山洋盆的纪录,并由此推断该洋盆的时代跨度至少始自寒武纪并一直持续到晚石炭世甚至二叠纪。本文基于近几年在东天山地区地质调查工作的新成果,通过新界定的以康古尔塔格-大草滩蛇绿混杂岩带为代表的北天山洋两侧志留纪—泥盆纪活动大陆边缘物源性质和生物古地理对比,对北天山洋的构造属性和演化过程进行了重新厘定。研究揭示,志留纪—早泥盆世,北天山洋两侧的准噶尔-吐哈地块和伊犁-中天山地块分属于不同的物源体系和生物古地理区系,指示该洋盆具有显著的构造古地理分隔意义。至中泥盆世,北天山洋两侧隶属同一生物大区的珊瑚动物群指示该洋盆已演化至残余洋盆阶段;晚泥盆世晚期—早石炭世,天山地区广泛分布的陆相磨拉石-火山岩建造与下伏岩系之间的区域性角度不整合关系以及南北两侧物源的相互贯通说明东天山段的北天山洋已完全闭合,南北陆块的碰撞缝合应发生在此前的晚泥盆世早期(~370 Ma)。 石炭纪—早二叠世,可能受南部南天山洋北向俯冲及板片后撤作用影响,在前期已经碰撞拼合形成的统一准噶尔- 吐哈-中天山地块之上,沿康古尔-雅山一带重新裂解出具不成熟洋壳的康古尔弧后有限洋盆。该有限洋盆存续至 早二叠世早期(~290 Ma)最终闭合,其与北天山洋盆是两个不同阶段不同性质的洋盆体系。     

根据古生物地理和古地磁资料探讨秦岭二叠纪的海盆重建

根据秦岭及邻区二叠纪古生物地理和古地磁数据分析，以活动论观点为指导，探讨了秦岭的海盆特征。２４组古地磁数据和珊瑚、腕足和类的古生物地理说明二叠纪的秦岭海位于低纬度区并以不同的速度向北不断移动。早二叠世东、西部的海盆定分别是１０００ｋｍ和２０００ｋｍ。