摘要
探讨滇西保山地块晚古生代类、有孔虫、珊瑚、牙形刺、腕足类等动物群的古生物地理属性 ,根据牙形刺和类化石 ,确定长期争论的丁家寨组的时代为Artinskian期 ,小型单体珊瑚Cyathaxonia动物群可出现在从早石炭世到二叠纪的多种沉积环境中 ,不一定指示冷水冈瓦纳型。根据沉积特征及对环境特别敏感的珊瑚和类动物群的分布特点 ,结合全球构造事件 ,恢复保山地块的古地理演化模式。早石炭世以碳酸盐岩沉积为主 ,含礁型复体珊瑚和高分异度的大型单体珊瑚及丰富的有孔虫化石 ,保山地块应位于低纬度地区。受Namurian抬升运动的影响 ,晚石炭世沉积缺失 ,向南漂移 ,至早二叠世 (Cisuralian) ,保山地块再次接受海侵 ,沉积物以碎屑岩为主 ,含杂砾岩及冷温动物群 ,位于中低纬度地区。Artinskian晚期至Kungurian期 ,保山地块转而向北漂移 ,至中二叠世Wordian期 ,已处于低纬度地区 ,以碳酸盐岩沉积为主 ,含低分异度的有孔虫及复体珊瑚。这一演变模式与掸泰马、腾冲、拉萨、西羌塘、南帕米尔、阿富汗中南部及伊朗南部等地块可以对比 ,说明它们同属于基默里区或边缘冈瓦纳区。
The Carboniferous and Permian of the Baoshan block consist of three major depositional sequences: the Lower Carboniferous carbonate sequence, the Lower Permian siliciclastic sequence, and the Middle Permian carbonate sequence. These three sequences were interrupted by two major regressive events: the Namurian Uplift ranging in age from Serpukovian to Gzhelian and the Post Sakmarian Regression occurring after Artinskian in Baoshan block but its precise time interval is still unclear. Baoshan block was characterized by warm water, highly diverse, and abundant faunas during the Early Carboniferous, by cold water and low diverse faunas during the Early Permian, and by warm water but low diverse faunas during the Middle Permian. The conodont Sweetognathus bucaramangus fauna provides age constrain to the top boundary of the siliciclastic deposits, which contain glacio marine origin diamictites, to be Sakmarian to Early Artinskian. Paleozoogeographically, affiliation of the faunas in Baoshan block experienced apparent changes from the Eurasian in the Early Carboniferous, the Peri Gondwanan in the Early Permian to the Marginal Cathaysian/Cimmerian in the Middle Permian. Cimmerian blocks are more or less comparable one another in the Carboniferous and Permian. During the Middle Permian, the eastern Cimmerian blocks such as Sibumasu (s.s), Baoshan, and Tengchong are not far from the tropical palaeoequator, but further than the western Cimmerian blocks in light of the presence or absence of the index taxa such as fusulinids Eopolydiexodina and Neoschwagerina , corals Thomasiphyllum and Wentzellophyllum persicum.
出处
《古生物学报》
CAS
CSCD
北大核心
2000年第4期493-506,共14页
Acta Palaeontologica Sinica
基金
国家自然科学基金委青年基金!(No .496 0 2 0 2 1)
特殊学科点人才基金资助
关键词
保山地块
石炭系
二叠系
动物群
古地理演化
Baoshan block, Carboniferous and Permian, faunal characteristics, paleozoogeography, Cimmerian
