龙门山造山带-川西前陆盆地系统构造事件研究

STUDY ON THE TECTONIC EVENTS IN THE SYSTEM OF THE LONGMEN MOUNTAIN-WEST SICHUAN FORELAND BASIN, CHINA

通过对构造事件形成的产物 (岩浆岩、各种矿物等 )进行氩 -氩年龄测定、裂变径迹年龄测定、ESR年龄测定和计算机模拟 ,得出龙门山造山带 -川西前陆盆地系统自印支期以来 ,共发生了 7次构造事件 :(1)卡尼期末的构造事件 (D1 ) ,形成 S1 和 F1 ,并有区域低温动热变质作用 ;(2 )诺利期末的构造事件 (安县运动 ,D2 ) ,产生川西前陆盆地上三叠统须四段与下伏地层不整合接触和须四段砾岩的分布 ,并有较强的岩浆作用 ;(3)燕山期 (12 0～ 130 Ma,D3) ,有较强的岩浆作用和变质作用 ;(4 )喜马拉雅期 6 0 Ma左右的构造事件 (D4) ;(5 )喜马拉雅期 30～ 40Ma的构造事件 (D5 ) ;(6 )喜马拉雅期 2 0～ 2 5 Ma的构造事件 (D6 ) ;(7)喜马拉雅期 10 Ma的构造事件 (D7)。后 4次构造事件使龙门山造山带

There are seven tectonic events in the system of the Longmen Mountain West Sichuan Foreland Basin, depending on the Ar Ar dating, zircon and apatite fission track analyses and dating, ESR dating and computer modeling. The first tectonic event (D 1) took place at the end of the Carnian stage, formed S 1 cleavage and F 1 fold, and resulted in the regional low temperature dynamical metamorphism. The second tectonic event (D 2) at the end of Norian stage resulted in the formation of conglomerate of the Fourth Member of Upper Triassic Xujiahe Formation, the unconformity between the Fourth Member of Upper Triassic Xujiahe Formation and its underlying rocks, and strong magmatism. The third event (D 3) happened at 120~130 Ma and made strong magmatism and metamorphism. The other four tectonic events (D 4, D 5, D 6, D 7) took place at 60 Ma, 30~40 Ma, 20~25 Ma, and 10 Ma, respectively and made the system of the Longmen Mountain West Sichuan Foreland Basin thrusting and uplifting.