滇西泸水—怒江断裂带新生代构造变形解析及其意义
发布时间：2018-07-24 11:32
【摘要】：泸水-怒江断裂带位于喜马拉雅东构造结南缘高黎贡构造带中段,西临高黎贡剪切带,东邻澜沧江构造带及崇山剪切带,是研究调节与印度-亚洲碰撞相关的陆内变形的重要场所之一。本文以构造解析理论为指导,通过野外构造观测及显微构造、运动学涡度估计,地球化学分析、锆石U-Pb同位素年代学等研究,认为该断裂带变形物质与冈底斯S型花岗岩同源,并厘定出三期构造变形。D1:始新世-渐新世,在东西向挤压应力下纯剪切主导的收缩构造,发育紧闭同斜褶皱,南北向线理;D2:渐新世-中新世,由应变分解作用形成简单剪切主导的右旋挤压走滑韧性剪切变形,糜棱面理陡立倾向东西,线理均南北向延伸,发育大规模直立A型褶皱;D3:伸展背景下发育晚中新世的左行正走滑断层,具脆韧性-脆性构造变形。变质矿物组合的相平衡模拟与石英EBSD组构表明,该带经历了三期变质作用:(1)高角闪岩相(580℃-720℃,8.5-10.8Kbar);(2)高角闪岩相-麻粒岩相(730℃-820℃,5.8-7.7Kbar);(3)绿片岩相(440-680℃,3-5.5Kbar)。变质锆石的U-Pb分析表明D1纯剪切主导的收缩构造变形不晚于42.9±2.1Ma,D2挤压走滑韧性剪切变形不晚于30.86Ma,且剪切作用至少延续到20.62Ma,D3期脆韧性-脆性变形不早于11Ma。结合前人研究成果,本文认为该带经历了早期加压环境地壳加厚过程,后经历应变分解过程启动挤压走滑剪切运动来调节地块碰撞引起的陆内变形,最后作为腾冲地块边界,发育伸展走滑断裂并被剥露抬升至浅部发生脆韧性-脆性变形。
[Abstract]:The Lushui-Nujiang fault zone is located in the middle section of the Goligong structural belt on the southern margin of the eastern Himalayan tectonic junction, the Goligong shear zone in the west, the Lancangjiang structural belt and the Chongshan shear zone in the east. It is one of the important places to study the intercontinental deformation associated with India-Asia collision. Guided by the structural analysis theory, through field structural observation and microscopic structure, kinematic vorticity estimation, geochemical analysis, zircon U-Pb isotopic chronology, it is considered that the deformed material in this fault zone is homologous to Gangdis S-type granite. The three tectonic deformations. D1: Eocene to Oligocene, shearing dominated by pure shearing under east-west compressive stress, developed closed syncline folds, south-north alignment D2: Oligocene to Miocene, By strain decomposition, a simple shear-dominated strike-slip ductile shear deformation is formed, and the surface of the mylonium tends to move steeply in the direction of east-west, and the alignment extends from the south to the north. A large scale erect A-type fold D3: developed in the late Miocene Left-line strike-slip fault with brittle ductile and brittle structural deformation in the extensional setting. The facies equilibrium simulation of the metamorphic mineral assemblage and quartz EBSD fabric indicate that the zone has undergone three stages of metamorphism: (1) the high-amphibolite facies (580 鈩，
本文编号：2141242
[Abstract]:The Lushui-Nujiang fault zone is located in the middle section of the Goligong structural belt on the southern margin of the eastern Himalayan tectonic junction, the Goligong shear zone in the west, the Lancangjiang structural belt and the Chongshan shear zone in the east. It is one of the important places to study the intercontinental deformation associated with India-Asia collision. Guided by the structural analysis theory, through field structural observation and microscopic structure, kinematic vorticity estimation, geochemical analysis, zircon U-Pb isotopic chronology, it is considered that the deformed material in this fault zone is homologous to Gangdis S-type granite. The three tectonic deformations. D1: Eocene to Oligocene, shearing dominated by pure shearing under east-west compressive stress, developed closed syncline folds, south-north alignment D2: Oligocene to Miocene, By strain decomposition, a simple shear-dominated strike-slip ductile shear deformation is formed, and the surface of the mylonium tends to move steeply in the direction of east-west, and the alignment extends from the south to the north. A large scale erect A-type fold D3: developed in the late Miocene Left-line strike-slip fault with brittle ductile and brittle structural deformation in the extensional setting. The facies equilibrium simulation of the metamorphic mineral assemblage and quartz EBSD fabric indicate that the zone has undergone three stages of metamorphism: (1) the high-amphibolite facies (580 鈩，
本文编号：2141242
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