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Assembly/dispersion process of Peri-Gondowana Terranes

近冈多瓦纳地体的聚集/分散过程

基本信息

批准号：
11691133
负责人：
SUGIYAMA Tetsuo
金额：
$ 5.63万
依托单位：
Fukuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

Upper Paleozoic (Carboniferous and Permian) of the Baoshan Tarrane, as a Gondwana-derived fragment, consist of three major depositional sequences : the Lower Carboniferous carbonete 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 Tarrane. In the Lower Carboniferous, The abundant occurrence of ecologically different corals reflects a wide range of environmental variation during the initial transgression in a warm and shallow platform of Gondowana.The Lower Permian diamictite-bearing Dingjiazhai Formation contains a Cyathaxonia fauna. The notable absence of Kepingophyllidae, a widely distributed family in south China, is the main feature distinguishing the Baoshan block from South China. In the Middle Permian carbonate strata, there are only two coral genera-Wentzellophyllum and Sinopora, recording very low diversity. The occurrences listed above show a strong paleobiogeographical similarity between the Baoshan block and the Sibumasu terrane, both of which belonged to the Cimmerian Continent during the Carboniferous and Permian. The blocks belonging to the Cimmerian Continent rifted from northern periphery of Gondowana in late Early Permian and drifted to north. In Middle Permian they located warm but not tropical area in Tethys ocean. This scenario was supported by the fossil records collected from the Baoshan block.Stratigraphy of Late Paleozoic beds in Tenchong has somewhat resemblance with those of Baoshan block, but we need much more abundant fossil evidences. Changning-Menglian Suture zone has a lot of Late Paleozoic carbonate buildups, which are originated from reefal sediments on Paleo-Tethys oceanic plate. There is a possibility to discover important records during Late Paleozoic in these limestone beds.

保山塔朗岩是冈瓦纳大陆的产物，其上古生界（石炭-二叠系）主要由下石炭统碳酸盐岩、下二叠统硅质岩和中二叠统碳酸盐岩三个沉积序列组成。这三个序列被两个主要的海退事件所打断：从Serpukovian到Gzhelian的纳缪尔期海退和保山Tarrane的Artinskian之后发生的后Sakmarian海退。在下石炭统，不同生态类型的珊瑚的大量出现反映了Gondowana暖浅台地海侵初期的大范围环境变化。保山地块与华南地区的主要区别在于，在华南地区广泛分布的科--克平叶虫科的明显缺失。在中二叠世碳酸盐岩地层中，只有Wentzellophyllum和Sinopora两个珊瑚属，记录的多样性很低。上述产出表明，保山地块和Sibumasu地块在石炭纪和二叠纪都属于辛梅里亚大陆，两者之间具有很强的古生物地理相似性。早二叠世晚期，属于辛梅里亚大陆的地块从冈多瓦纳北方边缘裂陷并向北漂移。中二叠世位于特提斯洋温暖而非热带地区。腾冲晚古生代地层与保山地块晚古生代地层有一定的相似性，但需要更丰富的化石证据。昌宁-孟连缝合带晚古生代碳酸盐岩建造发育，其成因为古特提斯洋板块上的礁相沉积。在这些灰岩地层中有可能发现晚古生代的重要记录。