Age of the peel sandstone group,isle of man

An Early Devonian age for the continental, red‐bed succession of the Peel Sandstone Group can be defined on the basis of: (1) a derived marine fauna of late Wenlock (Homerian) age, (2) a Scoyenia ichnofacies assemblage (including Beaconites and Diplichnites) characteristic of latest Silurian to Early Devonian (Lower Old Red Sandstone magnafacies) sediments in the British Isles, (3) a microflora of late Lochkovian to Pragian age, (4) a detrital palaeomagnetic remanence that pre‐dates local, Acadian palaeomagnetic directions and coincides with a prominent, southerly, Late Silurian to Early Devonian excursion in the local apparent polar wander path, and (5) a mid‐Devonian palaeomagnetic remanence that overprints (?)Acadian, thrust‐related folding. Data presented in this study confirm previous suggestions (Allen and Crowley 1983) that the Peel Sandstone Group represents a rare example of Early Devonian sedimentation preserved on the northern margin of the former Eastern Avalonia microcontinent. Potential correlations and linkages with other Lower Old Red Sandstone successions exposed in the Anglo‐Welsh Basin are developed and discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

四川自贡地区侏罗纪恐龙动物群组合特征

自贡地区涵盖侏罗纪3个不同时期的恐龙动物群组合。早侏罗世是恐龙动物群的萌发阶段,以原蜥脚类和原始蜥脚类恐龙共存为主要特征,属禄丰蜥龙动物群范畴;中侏罗世蜀龙动物群具有过渡性质,代表恐龙动物群的繁荣阶段,特点是原蜥脚类绝迹,原始的蜥脚类和进步的蜥脚类共同成为动物群的主要成员,并开始出现一些特化的蜥脚类,肉食龙类和鸟脚类成为动物群的重要成员,剑龙类开始出现;晚侏罗世马门溪龙动物群代表恐龙动物群发展的鼎盛阶段,特点是成渝龟类被蛇颈龟类所取代,原始的蜥脚类已消亡,特化的长颈型的马门溪龙类为主要成员,肉食龙类、鸟脚类和剑龙类向大型化发展。自贡地区侏罗纪恐龙动物群的兴衰和更替与四川盆地古地理环境和古气候的变迁密切相关。     

Ceno-Tethyan Ammonite Fauna from the Raskoh Arc, Balochistan, Pakistan

The Raskoh arc, which occurs in the western part of Pakistan, is about 250 km long, 40 km wide and trends in ENE direction. This arc is designated as frontal arc of Chagai-Raskoh arc system. Arc is convex towards southeast and is terminated by the Chaman transform fault zone towards east. The Raskoh arc is a fossil oceanic island arc which was formed due to the intra-oceanic convergence in the Ceno-Tethys. The Late Cretaceous Kuchakki Volcanic Group is the most widespread and previously considered the oldest unit of the Raskoh arc followed by sedimentary rock formations including Rakhshani Formation (Paleocene), Kharan Limestone (Early Eocene), Nauroze Formation (Middle Eocene to Oligocene), Dalbandin Formation (Miocene to Pleistocene), and semi-unconsolidated Subrecent and Recent deposits. The Rakhshani Formation is the most widespread and well-exposed unit of the Raskoh arc. During the present field investigation the Rakhshani Forma-tion in the southeastern part of the Raskoh arc is dentified as an accretionary complex, which is designated as Raskoh accretionary complex. The Raskoh accretionary complex is subdivided into three units: (a) Bunap sedi-mentary complex, (b) Charkohan radiolarian chert, and (c) Raskoh ophiolite mélange. The Bunap sedimentary complex is farther divided into three tectonostratigraphic units viz., northern, middle and southern. Each unit is bounded by thrust fault, which is usually marked by sheared serpentinites, except northern unit, which has grada-tional and at places faulted contact with the Kuchakki Volcanic Group. The northern unit mainly comprises al-lochthonous fragments and blocks of limestone, sandstone, mudstone and the volcanics in dark gray, greenish gray and bluish gray siliceous flaky shale. At places the shale is metamorphosed into phyllite. This unit is thrust over the middle unit, which exhibits relatively a coherent stratigraphy represented by greenish gray calcareous flaky shale with intercalation of thin beds and lenticular bodies of mudstone, sandstone and limestone. The middle unit is again thrust over the southern unit, which is mainly composed of large exotic blocks of volcanic rocks, lime-stone, sandstone, mudstone and conglomerate embedded in a dark gray, greenish gray and bluish gray siliceous flaky shale which is generally moderately argillized. The unit is thrust over the Kharan Limestone. During the present field investigation several poorly preserved ammonite fossils were collected from the dark green to black mudstones of the middle unit of the Bunap sedimentary complex. These fossils are identified as Pachysphinctes cf. P. africanus a Lower Kimmeridgian, Torquatisphinctes cf. P alterniplicatus, an Upper Kim-meridgian and Parodontoceras cf. Blandfordiceras wallichi: a Lower Tithonian ammonite. The Bunap sedimentary complex was probably deposited on the ocean floor of the Ceno-Tethys that once occurred between the newly dis-lodged collage of Cimmerian continent (Central Iran, Afghan blocks, Lhasa and West Burma) and the northern passive margin of Gondwana.     

Ceno-Tethyan Jurassic Radiolarian Fauna from the Raskoh Arc, Balochistan, Pakistan

The Raskoh arc is about 250 km long, 40 km wide and trends in ENE direction. The arc is convex towards southeast and terminated by the Chaman transform fault zone towards east. This arc is designated as frontal arc of the Chagai-Raskoh arc system. The Late Cretaceous Kuchakki Volcanic Group is the most widespread and previously considered the oldest unit of the the Raskoh arc followed by sedimentary rock formations including Rakhshani Formation (Paleocene), Kharan Limestone (Early Eocene) and Nauroze Formation (Middle Eocene to Oligocene), Dalbandin Formation (Miocene to Pleistocene), and semi-unconsolidated Subrecent and Recent deposits. The Rakhshani Formation is the most widespread and well-exposed unit of the Raskoh arc. During the present field investigation the Rakhshani forma-tion in the southeastern part of the Raskoh arc, is identified as an accretionary complex, which is designated as Raskoh accretionary complex. The Raskoh accretionary comple is subdivided into three units: (a) Bunap sedimen-tary complex, (b) Charkohan radiolarian chert, and (c) Raskoh ophiolite melange. The Bunap sedimentary complex is farther divided into three tectonostratigraphic units viz., northern, middle and southern. Each unit is bounded by thrust faults, which is usually marked by sheared serpentinites, except northern unit, which has gradational and at places faulted contact with the Kuchakki Volcanic Group. The northern unit is mainly composed of allochthonous fragments and blocks of limestone, sandstone, mudstone and the volcanics in dark gray, greenish gray and bluish gray siliceous flaky shale. At places the shale is metamorphosed into phyllite. This unit is thrust over the middle unit, which exhibits relatively a coherent stratigraphy, represented by greenish gray calcareous flaky shale with intercalation of thin beds and lenticular bodies of mudstone, sandstone and limestone. The middle unit is again thrust over the southern unit, which is mainly composed of large exotic blocks of volcanic rocks, limestone, sand-stone, mudstone and conglomerate embedded in dark gray, greenish gray and bluish gray siliceous flaky shale which is generally moderately argillized. The unit is thrust over the Kharan Limestone. During the present field investigation about 350 meter thick sequence of thin-bedded maroon and green chert intercalated with the siliceous flaky shale of the same colour are discovered within this unit, which is found in the southeastern part of the Ras-koh arc. This chert sequence occurs on the margins of a large exotic block (350m X 3 km) of volcaniclastic rocks of unknown origin, which makes an overturned syncline. This chert sequence is developed on its both limbs and has lower faulted contact with the Bunap sedimentary complex. Two samples collected from this chert sequence yielded radiolarian fauna, which include Parvicingula sp., Laxto-rum sp., Parahsuum cf. simplum, Parahsuum sp., Nassellaria gen. et sp. indet., Hsuum cf. Matsuokai., Archaeo-spongoprunum sp., Nassellaria gen. et sp. indet. and Hagias gen. et sp. indet., Tricolocapsa sp., Hsuum sp., Ris-tola sp., Archaeospongoprunum sp. and Tritrabinate gen. et sp. indet. This radiolarian chert sequence represents the late Early to Middle Jurassic pelagic sediment deposited in Ceno-Tethyan ocean floor; prior to the inception of volcanism in the Raskoh arc and accreted with the arc during Late Cretaceous to Eocene along with the Bunap sedimentary complex of Late Jurassic age.     

周口店地区第四纪哺乳动物群的演化与环境变迁探讨

讨论了Ａｌｉｌｅｐｕｓａｎｎｅｃｔｅｎｓ、ＨｙｐｏｌａｇｕｓｂｒａｃｈｙｐｕｓＬｅｐｕｓｓｐ．、Ｓｃｉｕｒｏｔａｍｉａｓｐｒａｅｃｏｘ、ＡｌｌｏｃｒｉｃｅｔｕｓｔｅｉｌｈａｒｄｉＣｒｉｃｅｔｉｎｕｓｖａｒｉａｎｓ、Ｈｙｐｅｒａｃｒｉｕｓｙｅｎｓｈａｎｅｎｓｉｓ、Ａｌｌｏｐｈａｉｏｍｙｓｃｆ．ｐｌｉｏｃａｅｎｉｃｕｓ、Ｐｒｏｅｄｒｏｍｙｓｃｆ．ｂｅｄｆｏｒｄｉ、Ｃｈａｒｄｉｎｏｍｙｓｎｉｈｅｗａｎｉｃｕｓ、Ｍｕｓｃｆ．ｍｕｓｃｕｌｕｓ和Ａｐｏｄｅｍｕｓｄｏｍｉｎａｎｓ的地史分布。根据哺乳动物群的分析与对比，得出第１８地点为早更新世早期，第１２地点、东洞地点为早更新世中期，第９地点、西洞地点为早更新世晚期，第１３地点为早更新世末期至中更新世初期，第１、２、５、６、１１、１０、２１、２３及上店洞地点为中更新世，新洞为中更新世晚期至晚更新世早期，东岭子洞为晚更新世，山顶洞为晚更新世晚期。还讨论了周口店地区一些主要第四纪哺乳动物群的生态类型特点，第四纪的气候波动及生态环境变迁。     

贵州省六枝县郎岱“法郎组”的牙形石及其时代意义

本文描述了采自贵州省六枝县郎岱剖面“法郎组”的一些牙形石,该牙形石群主要由Paragondolella polygnthiformis,P.maantangensis,P.tadpole,P.navicula navicula,P.foliata foliata,P.foliata inclinata,P.jiangyouensis,P.langdaiensis Yang sp.nov.等组成,自下而上可识别出3个牙形石带,竹杆坡组Pargondolella polynathiformis-Paragondolella maantangensis组合带、Paragondolella polygnathiformis-Paragondolella tadpole组合带,瓦窑组Pragondolella polygnathiformis带,因此,该剖面“法郎组”的时代,不仅上部（当前的瓦窑组）,而且下部（当前的竹杆坡组）,都是晚三叠世卡尼期的。     

内蒙古西乌旗地区早二叠世皱纹珊瑚化石组合及其地质意义

基于生物地层学的研究，详细描述了内蒙古西乌旗地区早二叠世的皱纹珊瑚，建立了7个新种，划分了2个珊瑚组合：Lytvolasma-Cyathocarinia组合和Lytvolasma-Caninophyllum-Pseudopolythecalis组合。前一组合主要为小型单体，无鳞板，隔壁加厚，外壁厚，一些分子具典型中柱的珊瑚类型；后一珊瑚化石组合表现为群体珊瑚和单体珊瑚混生融合。本区珊瑚动物群在早二叠世阿木山期混生类型为超覆型，在早二叠世包特格期混生类型为混合型。这种混生现象与石炭纪末一二叠纪初全球气候变冷事件相吻合，并反映了古气候暖-冷-暖的变化。同时也佐证了古亚洲洋洋壳的性质在稍早的时期已经发生了本质变化。此时海盆性状应该是岛弧浅海，而不是大洋。     

Newly Discovered Fish Faunas from the Early Triassic, Karoo Basin, South Africa, and their Correlative Implications

Recent collecting in exposures of the lowermost Burgersdorp Formation (Beaufort Group), of the Karoo Basin of South Africa, has revealed a previously unknown fish fauna from the Early Triassic (Scythian), lowermost Cynognathus Assemblage Zone (CAZ), which forms an important component of the total vertebrate assemblage. The newly discovered fish material includes lungfish, saurichthyids, and a large microfauna that includes numerous isolated chondrichthyan teeth, two fin spine fragments, and actinopterygian scales and teeth. The latest fish finds, together with the lowermost Cynognathus Assemblage Zone vertebrate faunas, make this Karoo Basin Assemblage Zone one of the most diverse Early Triassic faunal assemblages, comparable in faunal diversity to those from the Czatkowice Formation (Poland) and the Arcadia Formation (Australia). The presence of the lungfish Ptychoceratodus phillipsi in the early Middle Triassic Cynognathus Assemblage Zone (Subzone B), and in the underlying latest Early Triassic Cynognathus Assemblage Zone (Subzone A), indicates that these lungfish could serve as range index fossils within the CAZ, and thus are potentially useful biostratigraphic markers across the Early-Middle Triassic boundary. Furthermore the ‘new’ fish fauna provides a vital marine realm link in particular with the faunas of Madagascar and Australia, that is unavailable using the tetrapod faunal elements of the lower CAZ.     

河南灵宝朱阳下寒武统辛集组软体动物群的发现

河南灵宝朱阳地区下寒武统辛集组中新发现的小壳动物化石包括软体动物群的软舌螺、单板类、双壳类和腹足类以及海绵骨针和齿形类。该动物群可与安徽淮南雨台山组、河南确山、叶县、宝丰及陕西洛南辛集组动物群对比，时代属早寒武世中期，与澳大利亚新南威尔士早寒武世中期软体动物群属同一生物地理区。软体动物有可能在中国云南开始出现，并迅速迁移至扬子浅海各地，后经某种渠道迁移到华北地台南缘，演化成新的动物群。