Crustal-scale rheological transitions during late-orogenic collapse
Crustal-scale rheological transitions during late-orogenic collapse
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DOI：
10.1016/s0040-1951(01)00053-1
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发表时间：
2001-06
期刊：
影响因子：
2.9
通讯作者：
O. Vanderhaeghe;C. Teyssier
中科院分区：
文献类型：
--
作者：
O. Vanderhaeghe;C. Teyssier
造山运动涉及地壳增厚，随后在增厚的地壳中发生热弛豫和放射热产生，最终导致地壳熔化和岩浆侵入，使地壳粘度降低几个数量级并导致造山晚期塌陷。加拿大科迪勒拉山脉的塌陷表现在不列颠哥伦比亚省早第三纪舒斯瓦普变质核杂岩中，该杂岩显示出由两个基本流变不连续性分隔开的三层地壳部分：（1）脆性-韧性转变，上地壳控制盆地形成中的高角度正断层穿过该转变并合并成低角度滑脱带，在该低角度滑脱带中，淡色花岗岩针岩在岩浆下到低温条件下逐渐积水和变形； (2) 变质岩-辉长岩转变，岩石失去其坚固的框架并表现得像粘性岩浆。在造山晚期重力塌陷过程中，这种转变有可能使上地壳与岩石圈其余部分机械分离。
Orogeny involves crustal thickening followed by thermal relaxation and radiogenic heat production in the thickened crust, culminating in crustal melting and magma intrusion which decrease the crustal viscosity by several orders of magnitude and cause late-orogenic collapse. Collapse of the Canadian Cordillera is expressed in the Early Tertiary Shuswap metamorphic core complex, British Columbia, which displays a three-layer crustal section separated by two fundamental rheological discontinuities: (1) the brittle–ductile transition, across which high-angle normal faults in the upper crust control basin formation merge into a low-angle detachment zone where leucogranite laccoliths ponded and deformed progressively under submagmatic to low-temperature conditions; and (2) the metatexite–diatexite transition across which the rocks lose their solid framework and behave like a viscous magma. This transition has the potential to mechanically decouple the upper crust from the rest of the lithosphere during a late-orogenic gravitational collapse.