滇西保山和腾冲地区二叠纪珊瑚及其古地理意义  

Permian corals in the Baoshan and Tengchong blocks of western Yunnan and their paleogeographical implications

作　　者：李小铭 王向东 Li Xiaoming;Wang Xiangdong(School of the Earth Sciences and Engineering,Nanjing University,Nanjing,210023,China)

机构地区：[1]南京大学地球科学与工程学院,南京210023

出　　处：《南京大学学报（自然科学版）》2022年第4期720-729,共10页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金(91955201)。

摘　　要：基默里大陆在二叠纪时位于冈瓦纳大陆和欧亚大陆之间,由一系列大陆碎片或地块组成,包含掸泰马地块、腾冲地块、保山地块、拉萨地块、南羌塘、阿富汗南部和伊朗南部等地区.保山和腾冲地块作为基默里大陆的重要组成部分,在早二叠世时从地处冈瓦纳大陆的北缘裂解,并在中二叠世-晚二叠世向北漂移,这种特殊的古纬度变化导致保山和腾冲地块在下、中二叠统分别产出可能指示冷水和暖水的浅水水域环境的Cyathaxonia动物群和大型单体及复体四射珊瑚.中二叠世两个地块暖水型单体和复体珊瑚共有属种少,说明两者在古地理上并不相近.与中二叠世正处于低纬度地区的华南地块中极高的四射珊瑚生物多样性相比,保山和腾冲地块较低的四射珊瑚多样性,反映了两个地块在中二叠世时仍未到达温暖的低纬度地区.The Cimmerian Continent is composed of several allochthonous blocks, including the Shan-Thai, Tengchong,Baoshan,Lhasa,southern Qiangtang,southern Afghanistan,and southern Iran blocks. It was located between the Gondwanan and Eurasian continents during the Permian Period. The Baoshan and Tengchong blocks,as ones of the important parts of the Cimmerian Continent,splitted from the northern margin of Gondwana in the Early Permian,then drifted northward during the Middle Permian-Late Permian. This special latitudinal shift resulted in the occurrence of the cold shallow-water Cyathaxonia assemblage, and warm shallow-water large solitary and compound rugose corals in the Lower and Middle Permian respectively from these two blocks. The Middle Permian yields Iranophyllum sp.,Pavastehphyllum sp.,Thomasiphyllum cf.spongifolium, Wentzelloides sp., Naoticophyllum sp., Wentzellophyllum persicum, in the Baoshan Block, and Lonsdaleiastraea sp. A, Lonsdaleiastraea sp. B, Wentzelellites sp., Thomasiphyllum tengchongense, Waagenophyllum kueichowense in the Tengchong Block. Only a same genus Thomasiphyllum developed in the Middle Permian of these two blocks,which is also widely developed in the Middle Permian of the Cimmerian Continent. Only few co-occurrence of coral taxa between the Baoshan and Tengchong blocks may indicate that the two blocks are not close during the Middle Permian.Compared with the high diversity of rugose corals in the low-latitude South China Block during the Middle Permian,much lower diversity of rugose corals occurred in the Baoshan and Tengchong blocks, which implies that these two blocks could have not reached at warm,low latitude during this time.

关 键 词：四射珊瑚 二叠纪 基默里大陆 古生物地理 

分 类 号：Q911[天文地球—古生物学与地层学]