| 特提斯喜马拉雅错那洞穹隆的岩石组合、构造特征与成因 |
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| 引用本文： | 张林奎,张志,李光明,董随亮,夏祥标,梁维,付健刚,曹华文.特提斯喜马拉雅错那洞穹隆的岩石组合、构造特征与成因[J].地球科学,2018,43(8):2664-2683. |
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| 作者姓名： | 张林奎 张志 李光明 董随亮 夏祥标 梁维 付健刚 曹华文 |
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| 作者单位： | 中国地质调查局成都地质调查中心, 四川成都 610081 |
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| 基金项目： | 中国地质调查局项目DD20160015国家重点研发计划项目2016YFC060308国家自然科学基金项目41602214 |
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| 摘 要： | 目前关于新近发现的错那洞穹隆的精细构造、岩石组成、变质变形运动学特征等方面均不清楚，严重阻碍了其演化历程的还原以及成穹与成矿耦合关系的解剖工作.在详实的野外地质调查基础上，补充采集了穹隆中新发现的岩浆岩进行年代学研究.结果表明，错那洞穹隆由上（边部）-中（幔部）-下（核部）3个构造层组成，分别以上、下拆离断层为分界线.核部岩石组合主要为片麻岩、淡色花岗岩以及少量深熔混合岩，可见大量伟晶岩脉穿插；幔部为古生界，岩石组合为一套强变质变形片岩夹碳酸盐岩，从内至外具有蓝晶石+十字石+石榴石+黑云母的蓝晶石带→十字石+石榴石+黑云母的十字石带→石榴石+堇青石+黑云母的石榴石带→绿泥石+黑云母的绿泥石带的巴罗式变质分带特征；边部主要为三叠纪-侏罗纪浅变质沉积岩系，岩石组合为一套砂板岩及少量千枚岩.穹隆内从早至晚经历了南北向逆冲推覆、南北向伸展、东西向伸展3期次的构造运动，穹隆的形成主要与南北向伸展作用有关.穹隆中岩浆活动从早至晚可见有早古生代片麻岩（约500 Ma）、中生代辉绿岩（140 Ma）、渐新世变形二云母花岗岩/伟晶岩（26 Ma）、中新世弱定向二云母花岗岩（18 Ma）、含石榴石电气石花岗岩（16.8~15.9 Ma）5期.综合研究表明，错那洞穹隆的形成是早期伸展拆离核杂岩叠加晚期岩浆底劈热穹隆综合作用的结果，成穹构造的初始阶段与始新世-渐新世藏南拆离系（STDS）的运动密切相关.
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| 关 键 词： | 错那洞穹隆 构造组合 变质分带 特提斯喜马拉雅 锆石U-Pb定年 地球化学 构造地质学 |
| 收稿时间： | 2018-03-10 |
Rock Assemblage,Structural Characteristics and Genesis Mechanism of the Cuonadong Dome,Tethys Himalaya |
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| Abstract: | The structure assemblage, rock composition, and kinematics characteristics of metamorphic deformation of the newly discovered Cuonadong dome are not clear currently, which seriously hinders the restoration of its evolutionary process and the anatomy of the coupled relationship between the formation of plutonium and mineralization. Based on the detailed field geological survey, the newly discovered magmatic rocks in dome were additionally collected for chronological study in this paper. The results show that the Cuonadong dome is divided into three structural layers of upper (margin)-middle (mantle)-lower (core) by upper and lower detachment faults. The core rock assemblages are primarily composed of granite gneiss, leucogranite, and a little migmatite, with a large amount of intruded pegmatite veins. The mantle rock assemblage is a set of strongly metamorphic and deformable schist with interlayer carbonate. This rock assemblage has Barrovian metamorphism confirmed by mineral assemblages from the core to the margin of kyanite+staurolite+garnet+biotite→taurolite+garnet+biotite→garnet+cordierite+biotite→chlorite+biotite; The margin is primarily comprised of slightly metamorphic Triassic-Jurassic sedimentary rocks, which is constituted of sericite chlorite sand slate and a small amount of phyllite. The dome from early to late has experienced N-S trending thrusting, N-S extension and E-W extension, and the formation of the dome is primarily associated with the N-S extension. There are five episodes of magmatism in the dome at ~500 Ma (gneiss), 140 Ma (diabase), 26 Ma (deformed two-mica granite/pegmatite), 18 Ma (weakly oriented two-mica granite), 16.8-15.9 Ma (garnet-tourmaline-bearing granite). The study shows that the formation of the Cuonadong dome is the result of the combined effect of the early extension and detachment and the late magmatic diapir, and the movement of the South Tibetan detachment system during the Eocene-Oligocene is the primal factor. |
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