豫淮盆地太原组顶部斯威特刺(Sweetognathus)种的分类修正及其地层意义

作者通过对豫淮盆地太原组顶部灰岩中牙形刺的研究,发现Sweetognathus动物群较为丰富,计4属10种,含一个新种:Sweetognathuspraeiranicussp.nov.。其中以Sweetognathus最为繁盛,并对其种的分类进行了修正,将原定的Sweetognathusinornatus的大部分标本归入Sweetognathusmerrilli。根据新的分类,建立了两个组合带,即Sweetognathusmerrilli带和Sweetognathuswhitei-Xuzhougnathusmonoridgosus带。通过与国内外相当牙形刺组合带(带)的对比,初步认为该动物群属中、晚萨克马尔到早亚丁斯克期。

Early Permian Conodonts from the Baoshan Block, Western Yunnan, China

The Rabeignathus bucaramangus fauna was recently found from the limestone beds of the top part of the elastics-dominated Dingjiazhai Formation in the Aluotian section, southern Baoshan Block, western Yunnan. With Rabeignathus bucaramangus as the dominant species, this fauna includes Rabeignathus bucaramangus (Rabe), Homeoiranognathus huecoensis (Ritter), Sweetognathus inomatus Ritter, Sweetognathus whitei (Rhodes), Mesogondolella cf. bisselli (Clark and Behnken) and a few of ramiform elements. The characteristies of the fauna suggest that it can be correlated with the upper part of the Sweetognathus whitei Zone and assigned to the Middle Artinskian.

滇黔桂盆地早二叠世亚丁斯克期的沉积环境分异与䗴有孔虫响应

亚丁斯克期华南滇黔桂地区沉积环境分异明显,主要发育局限或半局限海台地沉积区、开阔海台地沉积区和台地边缘沉积区,不同沉积区䗴有孔虫动物群面貌也有所区别。本文详细研究了黔南地区的猴场打望剖面和惠水竹子冲剖面阿瑟尔期—亚丁斯克期的地层,在打望剖面识别出4个䗴类化石带,由老至新为Pseudoschwagerina beedei-Sphaeroschwagerina constans共存延限带、Staffella xiushuiensis-Eoparafusulina contracta富集带、Pseudofusulina ellipsoidalis富集带和Misellina subcycloidea间隔带。竹子冲剖面识别出3个化石带,由老至新为Pseudoschwagerina uddeni-Sphaeroschwagerina sphaerica组合带、Eoparafusulina certa富集带和Staffella discoides延限带。对滇黔桂地区不同沉积相区剖面䗴类动物群以及沉积相特征的综合研究显示:开阔台地或台地边缘环境的䗴动物群以Pamirina为特征分子,同时还产出丰富的希瓦格䗴亚科(Schwagerininae)分子;局限或半局限台地环境䗴类以史塔夫䗴亚科分子(Staffellininae)为主。沉积环境对䗴有孔虫的影响可能主要来自水动力、光照和氧气含量。个体较大、隔壁褶皱强烈的纺锤形希瓦格䗴亚科分子更适应水动力强、透光性好、氧气充足的水体;小个体、结构简单的史塔夫䗴亚科分子可在透光性差、含氧量较低的水体中生存。

Palaeoenvironmental reconstruction for the Permian(lower Gondwana)succession of the Godavari Valley Coalfield in southern India based on a combined palynofacies,carbon isotope,and biomarker study

The study presents integrated palynofacies,organic carbon isotope,and biomarker data to reconstruct palaeoenviromental setting for the Permian sediments(borehole MGK-6)of the Kachinapalli block of the Godavari Valley Coalfield,southern India.The palynofacies data reveal three distinct palynofacies(A-C)as follows.Palynofacies A is dominated by abundant arborescent vegetation(glossopterids and conifers)along with structured organic matter,suggesting freshwater forest swamps in proximal settings.Palynofacies B is dominated by abundant degraded organic matter and amorphous organic matter,suggesting lakeshore/flooded palaeomires in slightly dismal settings.It has a high water level in the hinterland,which enables bacterial degradation of organic matter and establishes low-oxygenation conditions within the water column.These conditions would have provided grounds for the accumulation of either degraded or amorphous organic matter.Palynofacies C is dominated by the abundance of charcoal/opaque phytoclasts,indicating prolonged transportation or postdepositional alteration,suggesting a highly-oxidizing condition in distal settings.The bulk organic δ^(13)C range(-25.1‰ to-20.9‰)in the borehole MGK-6 is in close agreement with the global Permian records.This study also shows a weak but statistically significant correlation with the major forms of palynofacies A and C.The interlinked behaviour of bulk organic δ^(13)C and palynofacies suggests that the changes in palaeobiogeography/palaeodepositional settings were most likely driven by the change in mean annual precipitation.The biomarker study shows the presence of n-alkane from C_(15) to C_(31) with unimodal and bimodal distribution patterns,revealing the source materials as vascular plants and microbially-altered organic matter.The combined palynofacies,organic carbon isotope,and biomarker data provide vital clue to salient findings for the development of environmental conditions of Godavari Valley Coalfield during lower Gondwana sedimentation.

AGE OF THE LONGYIN FORMATION IN SOUTHWEST GUIZHOU PROVINCE——A DISCUSSION ABOUT THE CORRELATION OF THE LOWER PERMIAN BETWEEN SOUTH CHINA AND THE URAL OF USSR

The Permian Artinskian age of the Longyin Formation is indicated by the appearanceof the ammonoid Popanoceras fauna at its lowermost part. The upper Maping Formationin South China should include all the Sakmarin deposit at least.

昌宁—孟连带沧源糯良—孟来地区深色薄层灰岩层系牙形石生物地层学及沉积学特征

滇西昌宁—孟连带沧源县附近糯良—孟来一带发育一套以深色薄层灰岩为主的石炭纪—二叠纪地层。通过研究糯良、龙洞和孟来三条剖面的牙形石生物地层学和沉积地层学,在糯良剖面建立了Sweetognathus whitei带、Neostreptognathodus prayi带和S.guizhouensis带,在龙洞剖面建立了S.guizhouensis-N.pequopensis带。与北美、乌拉尔山南部、保山、华南和日本等地区牙形石带对比,证明本次研究所测糯良剖面和龙洞剖面的地层均为亚丁斯克阶一空谷阶。所测孟来剖面的牙形石Clarkina longicuspidata和C.transcaucasica指示该段地层为吴家坪阶。三条剖面识别出20种碳酸盐岩微相类型,可归为4个微相组合,分别对应浅潮下带、深潮下带上部、深潮下带下部和盆地四种沉积环境。