藏东北构造古地理特征及冈瓦纳北界的时空转换  

Tectono-paleogeographic characteristics in northeastern Tibet, China and spatial-temporal transition of the northern boundary of Gondwana

作　　者：王根厚[1] 梁定益[1] 张维杰[1] 贾建称[2] 周志广[1] 万永平[1] 于海亮[1] 

机构地区：[1]中国地质大学 [2]中国煤炭科学研究总院西安分院,陕西西安710054

出　　处：《地质通报》2007年第8期921-928,共8页Geological Bulletin of China

基　　金：国家自然科学基金项目(编号:49802019);中国地质调查局项目<1:25万仓来拉幅区域地质调查>(编号:200313000001)资助。

摘　　要：研究区位于南北向三江构造带与东西向羌塘构造带的衔接处,是特提斯构造域的重要组成部分。研究区包含金沙江、澜沧江、双湖-昌宁、班公湖-怒江4条古特提斯洋壳带及昌都-芒康、羌北、索县-左贡、多玛-安多4个微陆块的相关部位。4条缝合带时分时合,其间的微陆块则"藕断丝连"。前奥陶纪金沙江带属于泛冈瓦纳"泛非软基底"的北界,早古生代它还是"泛非"混合生物群与扬子区系的界线。泥盆纪—石炭纪,古特提斯形成南北2支,即金沙江带和双湖-昌宁带,与其间亲扬子的中间岛块群(昌都-芒康、羌北、索县-左贡)形成"多岛海"格局,此间,双湖-昌宁转换为冈瓦纳的北界,多玛-安多微陆块为亲冈瓦纳相。早、中二叠世,中间岛块(群)裂解为亲扬子的昌都-芒康和亲冈瓦纳的羌北、索县-左贡三岛块,形成多岛洋,冈瓦纳北界转换到澜沧江带。晚二叠世,古特提斯消亡,形成Pangaea联合古陆,研究区为陆间多岛海。晚三叠世印支运动阶段,金沙江、澜沧江和双湖-昌宁带相继转换为陆内造山带;与此同时,班公湖-怒江带与雅鲁藏布江带形成中特提斯北、南2支,其间为中间陆块群(基墨里),班公湖-怒江带是晚侏罗世—早白垩世消亡的,"基墨里"岛块群是晚白垩世增生在亚洲大陆之上的。喜马拉雅地块是喜马拉雅运动阶段才最后俯冲到亚洲大陆之下,转换为亚洲大陆。The study region is located in the junction between the N-S-trending Sanjiang tectonic belt and E-W-trending Qiangtang tectonic belt. It is an important component part of the Tethys tectorfic domain, including the Jinshajiang, Lancang River, Shuanghu-Changning and Bangong Co-Nujiang Paleo-Tethyan oceanic crustal belts and related parts of the Qamdo- Markam, Qiangbei, Sog-Zogang and Doima-Amdo microblocks. Four sutures sometimes were separated and sometimes converged and the microblocks between them were apparently separated but actually joined. The pre-Ordovician Jinshajiang belt is the northern boundary of the Pan-African soft basement of Pan-Gondwana, and in the early Paleozoic it was still the boundary of the Pan-African mixed biota and the Yangtze realm. In the Devorfian to Carboniferous, the Paleo-Tethys diverged into the north and south branches, i.e. the Jinshajiang belt and Shuanghu-Changning belt, which, together with the median island block swarm of Yangtze affinity （Qamdo-Markam, Qiangbei and Sog-Zogang） between them, formed the framework of the ＂archipelagic sea＂. Then the Shuanghu-Changning belt was transformed in the northern boundary of Gond-wana and the Doima-Amdo microblock was of Gondwana affinity. In the Early-Mid Permian, the median island blocks （block swarm） broke up into three island blocks： the Qamdo-Markam block of Yangtze affinity and the Qiangbei and Sog-Zogang blocks of Gondwana affinity, forrmng an archipelagic sea. The northern boundary of Gondwanaland was converted into the Langcangjiang belt. In the Late Permian, the Paleo-Tethya died out, forming Pangaea with an archipelagic sea in the study region. During the Late Triassic Indosinian orogeny, the Jinshajiang, Langcangjiang and Shuanghu-Qamdo belts were transformed into intracontinental orogenic belts. Meanwhile, the Bangong Co-Nujiang and Yarlung Zangbo belts formed the north and south branches of the Meso-Tethys, with a median microblock swarm named ＂Cimmerides＂ between them. In Late Jurassic to Early Cretaceou

关 键 词：藏东北 特提斯 多岛洋 洋壳带 生物区系 冈瓦纳北界 构造转换 

分 类 号：P542.4[天文地球—构造地质学]