一种新的陆内俯冲类型——龙门山型俯冲成因机制研究

ON THE MECHANISM OF A NEW TYPE OF INTRACONTINENTAL SUBDUCTION——THE LONGMENSHAN SUBDUCTION

刘树根 罗志立 曹树恒

Liu Shugen Luo Zhili Cao Shuheng

成都地质学院 2. 四川省地质矿产局, 成都

Chengdu College of Geology 2. Sichuan Bureau of Geology and Mineral Resources

龙门山冲断带是中国典型的冲断构造带之一.本文在详细研究龙门山冲断带岩石圈结构和龙门山冲断带形成前构造背景的基础上,结合地球物理和天然地震资科,认为龙门山冲断带是由深部物质的调整而带动四川盆地(扬子板块)的岩石圈沿其内部的若干塑性层向龙门山和川西高原发生多层次(上地幔顶部层、下部地壳层、中部地壳层和上部地壳层),多阶段(印支末期、燕山期和喜山期)的俯冲所形成,并把这种既不同于B型俯冲,也不同于A型俯冲的俯冲模式,称之为龙门山型俯冲,简称为L型俯冲.在此基础上,论述了龙门山地区的油气地质条件.

The Longmcnshan Thrust Belt is one of the typical thrust belts in China.Based on the detail studies of the lithosphere structures in the Longmenshan Region and the structural environment previous to the formation of the thrust belt,and combined with the geophysical and earthquake informations,the authors of this Paper suggested that the Longmenshan Thrust Belt developed under the mechanism of intracontinental subduction is resulted from the adjustment of deep-seated matter which made the lithosphere of the Sichuan Basin subducting to the Longmenshan and the western plateau of Sichuan.The thrusting movements took place along multiple plastic layers within the lithosphere (the upper part of the mantle,the lower,middle and upper crustal layers) during polystages (the latest of the Indosinian,the Yashanian,the Himalayan periods).The type of the subduction model is quite different both from B-subduction and A-subduction,and it is named as the type of the Longmenshan Subduction,abbreviated to the L-subduction.On the basis of the studies mentioned above,the geological conditions of oil/gas are elucidated in the paper for the Longmenshan Region.

https://doi.org/10.11781/sysydz199104314