中国下、中二叠统界线附近菊石生物群及其生物地层意义  

AMMONOID FAUNAS AROUND THE EARLY AND MIDDLE PERMIAN BOUNDARY IN CHINA AND THEIR BIOSTRATIGRAPHIC IMPLICATIONS

作　　者：牟林[1] 

机构地区：[1]中国科学院南京地质古生物研究所,江苏南京21008

出　　处：《古生物学报》2011年第4期439-449,共11页Acta Palaeontologica Sinica

基　　金：国家自然科学基金(41002005);国家基础科学人才培养基金特殊学科点(J0930006);现代古生物学和地层学国家重点实验室基础性项目(20092101)资助

摘　　要：基于一些业已报道的Kungurian阶与Roadian阶界线附近的菊石材料进行重新研究,认为中国中、下二叠统界线附近的菊石生物群主要分布在华南和中国西部两个地区。通过与俄罗斯地区同时代的菊石动物群比较后认为中国在这一界线附近的菊石群以地方性的分子为主,主要包括:假海罗菊石亚科(Pseudohaloritinae)和寿昌菊石亚科(Shouchangoceratinae)。通过再研究,修订多个菊石动物群的组成,并认为双堡塘组下部的时代为空谷阶,中上部为罗德阶,范家屯组的时代为罗德阶或沃德阶,西藏日喀则的加拉组和堆龙德庆的乌鲁龙组为罗德阶。通过菊石动物群研究认为中国最有潜力解决Kungurian阶和Roadian阶界线的剖面为甘肃的双堡塘剖面和西藏加拉剖面。The Early-Middle Permian（Cisuralian-Guadalupian） boundary is marked globally by tremendous changes in terms of the development of ammonoid faunas.At that time the new Order Ceratitida appeared and their first known representatives are found in the lowest part of the Middle Permian Roadian Stage.The earliest Ceratitida therefore serve as reliable markers for the boundary between the Lower and Middle Permian in the Tethyan region and North America in terms of ammonoids.In other biogeographic regions,how-ever,where Ceratitida have not been found,representatives of the families Pseudogastrioceratidae and Spirolegoceratidae play an important role in biostratigraphical subdivision.The GSSP（Global Stratotype Section and Point） between the Lower and Middle Permian is defined in the Glass Mountains of Texas based on the first appearance of the conodonts species Jinogondolella nanking-ensis.However,the first Middle Permian representatives ammonoids appear slightly below this level in the Texas section.As the Roadian Stage was originally defined by Furnish based on ammonoid data.Many ammonoid experts do not agree with a definition based on conodonts in view of a fact that a typical set of Middle Permian ammonoids existed in the Early Permian based on the conodont definiton.Ammonoid experts therefore strongly suggest that the ceratitid Paraceltites elegans and other ceratitid ammonoids should all be attributed to Middle Permian.In this study,characteristic ammonoid faunas around the boundary between the Lower and Mi-ddle Permian in China are re-identified and reviewed.Based on a number of ammonoid occurrences materials near the Kungurian-Roadian boundary previously reported,I consider that ammonoid faunas near the Lower-Middle Permian boundary mainly occur in South and northwest China.Compared with the coeval ammonoid faunas in Russia,it can be concluded that endemic elements including Pseudohaloritinae and Shou-changoceratinae dominate the ammonoid faunas near the boundary.Based on a new study of a number of the amm

关 键 词：菊石 空谷阶 罗德阶 下二叠统 

分 类 号：Q911.6[天文地球—古生物学与地层学]