More Discussion on the Formation and Development of the Longmen Shan Thrust-Nappe Structure in the Indosinian Movement
详细信息
- 责任者：Wang Jinqi(Sinopec Southwest Branch ; Chengdu ; Sichuan 610051 ; China)
- 刊名：Natural Gas Industry
- 出版年：2012
- 卷期：32(1)
- 关键词：印支运动 ; Indosinian Orogeny ; 造山运动 ; orogeny ; 龙门山 ; Longmen Mountains
- 页码：p.12-21
- 图表：5 illus., 24 refs.
- 分类号：0300
- issnNo：ISSN1000-0976
- isbnNo：CN51-1179/TE
摘要
The Longmen Shan Mountain is situated at the boundary area between the eastern and western geological structure of the Chinese continent.Since this mountain came into being from the Indosinian folds and thrusts,its original geography has been difficult to recover due to the structural superposition,reformation and concealment during the Yanshan and Himalayan Epoch.According to the basin-mountain coupling rule,this paper particularly reviews drilling and seismic data in the Sichuan Basin,then in combination with the features and evolution laws of the mountainous structure,discusses again the formation and development of the Longmen Shan Thrust-Nappe Structure in the Indosinian Movement and their relationship with oil and gas pooling in the Sichuan Basin.The following conclusions are drawn.(1) The sedimentary sources in the "Late Xujiahe" basin formation period are closely related to the earlier Indosinian movement;the Paleo-Tethys Ocean in the north and south wings of the Songpan-Ganzi area was first sealed then closed,and was pushed to the margin of the steady continent by the significantly combined force of hedging and thrusting.(2) The Longmen Shan Mountain was lifted up high and erected at the fold-and-thrust belt after the Anxian Movement,which was the main orphanse in the Longmen Shan Indosinian Epoch.(3) The crosslinking molasse alluvial fan system on an extremely large scale in the “Early Xujiahe” basin formation period shows its characteristics of "being strong in the north and weak in the south".(4) After the orogenic movement,the Longmen Shan Mountain experienced a rather long period of structural stability,and later was dominated by denudation,planation,and slow and gradual lake deposits,and no late-period Indosinian movement ever occurred before the Jurassic.(5) There were two totally different and inverted basins formed respectively in the “Early and Late Xujiahe” basin formation periods,where the favorable domains for hydrocarbon pooling were reserved: the West Sichuan(Chuanxi) Depression transformed from the continental margin dominates in the “Early Xujiahe” basin while sandbodies in the river marsh and lake march and inflow rivers dominate in the “Late Xujiahe”basin.