Trans‐Hudson Orogen of North America and Himalaya‐Karakoram‐Tibetan Orogen of Asia: Structural and thermal characteristics of the lower and upper plates
Trans‐Hudson Orogen of North America and Himalaya‐Karakoram‐Tibetan Orogen of Asia: Structural and thermal characteristics of the lower and upper plates
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北美跨哈德逊造山带和亚洲喜马拉雅-喀喇昆仑-西藏造山带：下板块和上板块的结构和热特征
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发表时间：
2006
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通讯作者：
N. Wodicka
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作者：
M. St;M. Searle;N. Wodicka
北美的跨哈德逊造山带（THO）和亚洲的喜马拉雅-喀喇昆仑-西藏造山带（HKTO）分别保存了古元古代和新生代的大陆-大陆碰撞记录，它们在规模、持续时间和特征上都非常相似。在THO中，下板块的构造演化涉及（1）早期薄皮逆冲推覆和巴罗变质作用，（2）序列外逆冲推覆和高温变质作用，以及（3）流体局部再平衡、深熔作用和浅色花岗岩形成。在香港热带气旋的印度下板块的地壳演化涉及（1）大陆地壳早期俯冲至超高压（UHP）榴辉岩深度，（2）区域性巴罗变质作用，以及（3）广泛的高温变质作用、深熔作用和浅色花岗岩形成。HKTO的高温变质作用深度较浅，这与印度下板块中地壳通道的早中新世至中中新世韧性流动相一致，从青藏高原南部到大喜马拉雅山脉。THO的下板块的熔融弱化没有在类似的规模上观察到，可能是由于缺乏泥质岩性。两个造山带上板块的构造活动包括碰撞前地壳块体的增生、安第斯型深成岩套的侵位和高温变质作用。同碰撞到碰撞后事件包括石榴石-黑云母-白云母浅色花岗岩、深熔花岗岩和零星变质作用（在THO碰撞开始后高达9000万年）的侵位。比较THO和HKTO的构造事件的类型和持续时间，支持至少在地球历史的后半期的构造均变论的概念，并强调了与经历现代造山作用的造山带相比，更古老的“挖出”造山带中岩石记录的互补性。
The Trans‐Hudson Orogen (THO) of North America and the Himalaya‐Karakoram‐Tibetan Orogen (HKTO) of Asia preserve a Paleoproterozoic and Cenozoic record, respectively, of continent‐continent collision that is notably similar in scale, duration and character. In THO, the tectonothermal evolution of the lower plate involves (1) early thin‐skinned thrusting and Barrovian metamorphism, (2) out‐of‐sequence thrusting and high‐T metamorphism, and (3) fluid‐localized reequilibration, anatexis, and leucogranite formation. The crustal evolution of the Indian lower plate in HKTO involves (1) early subduction of continental crust to ultrahigh pressure (UHP) eclogite depths, (2) regional Barrovian metamorphism, and (3) widespread high‐T metamorphism, anatexis, and leucogranite formation. The shallow depths of the high‐T metamorphism in HKTO are consistent with early to mid‐Miocene ductile flow of an Indian lower plate midcrustal channel, from beneath the southern Tibetan Plateau to the Greater Himalaya. Melt weakening of the lower plate in THO is not observed at a similar scale probably due to the paucity of pelitic lithologies. Tectonothermal events in the upper plate of both orogens include precollisional accretion of crustal blocks, emplacement of Andean‐type plutonic suites, and high‐T metamorphism. Syncollisional to postcollisional events include emplacement of garnet‐biotite‐muscovite leucogranites, anatectic granites, and sporadic metamorphism (up to 90 Myr following the onset of collision in THO). Comparing the type and duration of tectonothermal events for THO and HKTO supports the notion of tectonic uniformitarianism for at least the later half of dated Earth history and highlights the complementary nature of the rock record in an older “exhumed” orogen compared to one undergoing present‐day orogenesis.