The Evolution of the Kamila Shear Zone, Kohistan, Pakistan
The Evolution of the Kamila Shear Zone, Kohistan, Pakistan
复制标题
巴基斯坦科希斯坦卡米拉剪切带的演变
DOI：
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
M. P. Williams
中科院分区：
文献类型：
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作者：
P. Treloar;K. Brodie;M. Coward;M. Q. Jan;M. A. Khan;R. Knipe;D. Rex;M. P. Williams
卡米拉剪切带是在科希斯坦与印度喜马拉雅碰撞之前，在巴基斯坦北部科希斯坦岛弧复合体内发育的一个中深地壳构造。Chilas杂岩的变辉长岩向南穿过剪切带被搬运到特提斯构造带上盘的高压岩石堆上。剪切带由一系列角闪岩相韧性高应变带组成，虽然糜棱岩带很常见，但组构强度不同。剪切准则和运动学指标具有一致的SW-聚散。高温韧性剪切的微观结构证据很少被保存，织物已被叠印后变形过程的再结晶，退火和晶粒生长。随后的历史折返过程中的温度下降的温度倒退和变形的叠加剪切带，主要影响粗粒岩石不受早期的晶体塑性变形的渐进序列记录。剪切主要涉及碎裂斜长角闪岩到绿片岩相变形，最终导致较低的绿片岩相剪切和糜棱岩化，以及少量碎裂和断层泥填充断层岩的分布网络的发展。
The Kamila Shear Zone is a deep to mid crustal structure developed within the Kohistan island arc complex of North Pakistan prior to Himalayan collision between Kohistan and India. Meta-gabbros of the Chilas complex were transported southwards across the shear zone onto a stack of high pressure rocks that had been assembled in the hanging wall of the Tethyan subduetion zone. The shear zone is constituted by an anastomosing array of amphibolite facies ductile high strain zones within which fabric intensity varies although mylonitic zones are common. Shear criteria and kinematic indicators have a consistent SW-vergence. Little microstructural evidence for the high temperature ductile shearing is preserved, fabrics having been over-printed by post-deformational processes of recrystallisation, annealing and grain growth. A subsequent history of exhumation during decreasing temperature is documented by a progressive sequence of down temperature retrogression and deformation in superimposed shear zones which predominantly affected coarse grained rocks unaffected by the earlier crystal plastic deformation. The shearing involved dominantly cataclastic amphibolite to greenschist facies deformation culminating in lower greenschist facies shearing and mylonitisation, and the development of a distributed network of minor cataclastic and gouge-filled fault rocks.