摘要
中三叠世末,三江联合地体形成,昌都—思茅构造带进入陆内演化阶段,堑垒相间的古地貌、具双峰式火山岩的火山-沉积组合、显双峰特点以及普具伸展因子的岩浆作用等显示,其在晚三叠世至新生代发生了广泛的陆内裂谷作用。裂谷岩浆活动主要为两侧火山地堑发育的双峰式火山活动,同期的岩浆侵入活动也呈双峰态势。岩浆喷发活动具有东强西弱的特点,其中东部江达—云岭—绿春地堑带,因局部出现洋壳而具有陆间裂谷性质;岩浆侵入活动自印支晚期向燕山期具有规模减小、范围增大的特点,到燕山期、喜马拉雅期,中央地带也发生岩浆侵入活动,形成中央热隆带。岩浆侵入活动具有明显继承性,由于昌都—思茅地体两侧于晚海西期至中三叠世发育陆源岩浆弧,岩浆岩在岩石化学上或多或少显弧岩浆特点。陆内裂谷作用在中生代经历了火山-地堑、陆内岩石圈挠曲凹陷演化阶段。裂谷作用持续到了新生代。
By the end of Middle Triassic after, the Three-river Composite Terrane the Changdu--Simao Tectonic Zone （CSTZ） experienced intracontinental evolutionary period. It is indicated that extensive intracontinental rift action from late Triassic to Cenozoic happened in the CSTZ referring to paleogeomorpholgy with alternate graben and horst,volcano-sedimentation association with bimdal volcanics,and magmatism with extension factor and bimodal character. The rifting magmatic action is mostly bimodal volcanicity in volcanic grabens located at both sides of the CSTZ formed and the synchronous magmatic irruption is also bimodal posture . The magmatic eruption is stronger in east side than in west side. The Jiangda--Yunling--Luchun graben zone in east has intercontinental rift property for its local ocean erust, from late Indo-Chinese to Yanshan epoch,the magmatic irruption^s intensity decreased and the extension accreted. Till Yanshan and Himalaynian epoch, the magmatic irruption extended to the central zone of the CSTZ, and the central thermal-uplift zone was formed. The magmatic action of the CSTZ had obvious succession. As continental margin magmatic arcs were developed on eastern side and weatern side of the CSTZ, magmatite formed from late Haixi to middle Triassic in the CSTZ showed arc magma features more or less. The intracontinental rifting of the CSTZ experienced volcanic graben and intracontinental lithosphere flextion-depresstion stages in Mesozoic. The intracontinental rifting went on to Cenozoic.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2006年第9期1295-1311,共17页
Acta Geologica Sinica
基金
国家"973"项目(编号2002CB412607)
中国地质调查局项目(编号70401154020)
中国地质调查局综合研究项目(编号200110200010
200420190004)
四川省矿物学
岩石学学科基金资助的成果
关键词
青藏东缘
昌都-思茅构造带
陆内裂谷作用
古地貌
活动型沉积组合
岩浆作用
east margin of Qinghai--Tibet
Changdu--Simao tectonic zone
intracontinental rifting
paleogeographic feature
active sedimentary association
magmatism
