| 青藏高原中侏罗世-早白垩世羌塘复合型前陆盆地充填模式 |
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| 引用本文： | 李勇,王成善,伊海生,石和,林金辉,朱利东,李祥辉.青藏高原中侏罗世-早白垩世羌塘复合型前陆盆地充填模式[J].沉积学报,2001,19(1):20-27. |
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| 作者姓名： | 李勇 王成善 伊海生 石和 林金辉 朱利东 李祥辉 |
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| 作者单位： | 成都理工学院沉积地质研究所 成都 610059 |
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| 基金项目： | 国家重点基础研究发展计划(973计划) |
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| 摘 要： | 根据沉积物碎屑组分、粗碎屑楔状体、边缘相、古流向和沉积、沉降中心等重建了盆地结构、古地理和古地貌,认为该盆地是在中侏罗世-早白垩世多岛洋体制下形成的一种复杂的、特殊类型的复合前陆盆地,它的形成和发展同金沙江缝合带与班公湖-怒江缝合带的碰撞和对冲有关,是盆地两侧板块边缘的大型逆冲作用的产物。在此基础上,根据中央隆起地貌景观交替性变化和盆地中“三砂二灰”的幕式沉积特点,将中侏罗世-早白垩世羌塘前陆盆地演化过程分为 5个阶段,其中巴通期和牛津-提唐期是羌塘盆地南北两侧构造活动相对平静期,而巴柔期、卡洛期、提唐-贝里阿斯期是羌塘盆地南北两侧构造活动强烈时期,强烈的逆冲推覆作用产生大量的构造负载,导致中央隆起强烈地挠曲隆升,造成了盆地中的幕式沉积,产生构造层序和层序,恢复了羌塘前陆盆地沉积记录与两侧缝合带的逆冲作用的相互关系.
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| 关 键 词： | 复合型前陆盆地 充填模式 中侏罗世- 早白垩世 羌塘\青藏高原 |
| 文章编号： | 1000-0550(2001)01-0020-08 |
| 收稿时间： | 2000-01-18 |
| 修稿时间： | 2000年1月18日 |
Fill Models of in the Qiangtang Composite Foreland Basin in Q inghai-Xizang Plateau, China |
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| LI Yong,WANG Cheng-shan,YI Hai-sheng,SHI He,LIN Jin-hui,ZHU Li-dong,LI Xiang-hui.Fill Models of in the Qiangtang Composite Foreland Basin in Q inghai-Xizang Plateau, China[J].Acta Sedimentologica Sinica,2001,19(1):20-27. |
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| Authors: | LI Yong WANG Cheng-shan YI Hai-sheng SHI He LIN Jin-hui ZHU Li-dong LI Xiang-hui |
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| Institution: | Chengdu University of Technology Chengdu 610059 |
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| Abstract: | Middle Jurassic-Early Cretaceous Qiangtang foreland basin is located between Jinshajiang suture belt and Bangong-Nujiang suture belt.It is an important petroliferous basin in the north of Qinghai-Xizang Plateau. This had been basin elongates in E-W direction with 800 km long and 200 km to 300 km wide. Both of the northern and southern margins of the basin are large suture belt and linked to thrusting of large suture belt, so the Qiangtang foreland basin belongs to composite foreland basin according to Jordan's classification of the forel and basin(1988).
The foreland basin had been filled with 3 000～6 000 m thick marine sediments of Middle Jurassic to Early Cretaceous. The spacial changes of the stratigraphy indicate that the basin texture looks like a symmetric body, and it can be subdi vided into three tectonic paleogeomorphic units from north to south, e.g. northern basin, center uplift, and southern basin. The sedimentary thickness in the north varies from 3 000 to 6 000 m, and from zero to 1 000 m in center uplift and from 3 000 to 5 000 m in the south, The thickness changes of filled, show that the occurrence of the Mesozoic filling stratigraphy is in the north and the south of the basin thicker,than in the center uplift of the basin. There are two centers of subsidence of the basin the front of suture belt. Both of them are located in the front of the suture belt of the south and north foredeep belt. T he basin is one of common foreland basins between suture belt and belongs to typical symmetric foreland basin.This kind of basin geometry is related to basement uplifts and thrusts in the cratonic edge of the mountain belt,wihich allows huge synsedimentary molasse sediments to be preserved.
Middle Jurassic to Early Cretaceous tectonic sequence is bounded by unconformity and composed of the Quemocuo formation,Buqu formation, Xiali formation, Suowa formation and Xueshan formation, which is more than 3 000 m in depth. A tectonic sequence is a body of genetically-related strata isolated by unconformity,and it had been deposited in a basin-formed stage responding to a thrusting episode. The provenance and constituent of the clasts in sandstone and conglomerate indicate that there are three provenances in the foreland basin,including Jinshaj iang suture belt, Bangong-Nujiang suture belt and the center uplift,of the later was formed in the late Triassic.There are three marginal facies belts in the basin recognized, two of them distribute in the front of suture belt,one of them d istributes in the both side of center uplift. The sedimentary facies can be symmetrically subdivided into four facies belt from center uplift to north or to south, namely center uplift, foreland slope, fore-deep, and the foothill of thrust belt. The statistic measured data of cross-bedding ,rippled mark and flute mold indicate that there are two palaeocurrents systems and one drainage distribution pattern in the basin, the center uplift was drainage division.
The uplifting amplitudes of the center uplift can provide information on the thrusting strength of both suture belt. The highland of the center uplift, charact erised by fan,fan delta conglomerate, mark that Jingshajiang tectonic belt or Bangong-Nujiang tectonic belt were thrusted severely to produce lots of tectonic load which led to rise the center uplift severely, whereas the topography of underwater uplift in the center uplift, characterised by carbonate bank and ramp, mark that the Jingshajiang tectonic belt or Bangong-Nujiang tectonic belt was in the course of static times.So the evolution of the basin can be divide in to five stages by the emplacement of large thrust sheets on both side of the basin by Bangong-Nujiang suture belt Jingshajiang suture belt. |
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| Keywords: | fill model composite foreland basin Qiangtang Middle Jurassic to Early Cretaceous Qinghai Xizang Plateau China |
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