The Karakoram Terrane (KT) in the western margin of the Himalayan-Tibetan orogen preserves the record of the Tethyan oceanic lithospheric subduction beneath the Asian Plate and metamorphism linked to the subduction of the Indian slab and the India-Asia collision. This terrane is also significant for understanding the changes in tectonics over time in the continent-continent collision zones related to mantle dynamics, slab underthrusting, or large-scale strike-slip faults. Despite a long geological research history over the past 140 years, this terrane's magmatic, petrogenetic, deformation, and uplift history remains enigmatic. This is mainly because of non-consensus over the distribution, source, and processes for the emplacement of variably occurring I-and S-type granitoids and changing tectonic processes through time. Thus, to resolve these issues, this paper reviews the KT's magmatic, deformation, and uplift history. Apart from its Neoproterozoic basement, two main stages of Andean-type magmatism have been identified in the KT. Stage 1 happened during ∼160-100 Ma, forming hornblende (Hbl)-biotite (Bt)-bearing and Bt-bearing granitoids. The field evidence, hybrid isotope signatures, and thermodynamic whole-rock major element modeling show that the formation of these granitoids involves assimilation with upper crustal rocks. The Stage 2 Hbl-Bt bearing Pangong Transpression Zone (PTZ) granitoids in the eastern KT were formed during ∼83-56 Ma; they show juvenile isotopic signatures and, thus, their origin from the mantle. The major element thermodynamic modeling of these granitoids suggests that these rocks were formed due to fractional crystallization. Our compilation and analysis of geochemical, isotopic, and geochemical modeling suggest that these granitoids belong to the Ladakh magmatic arc rather than the Karakoram Batholith granitoids of the KT, contrary to earlier beliefs. The origin of Eocene-Oligocene leucogranites of the KT remains controversial with the variable inferred processes of their origin, like water-flux melting of granitoids, dehydration melting of metapelites, and slab-breakoff, shearing or compression-induced partial melt generation. This study assesses these scenarios by compiling geochronological, geochemical, and isotopic data to understand the role of these processes in partial melt generation over spatial and temporal scales. Our assessment suggests that the monzogranites and hbl-bearing leucogranites are generated as a result of slab-breakoff and KF shearing-induced melting of the existing igneous sources, while the two-mica±grt leucogranites are sourced from the melting of supracrustal metapelitic rocks due to crustal thickening. This paper provides the compilation of cooling rates from all the published mid-to-low temperature thermochronometric ages to assess the different phases of the uplift of the KT on spatial and temporal scales. Our compilation suggests that the KT was uplifted mainly in three phases: (a) during the Early-Late Cretaceous as evidenced by pre-India-Asia collisional metamorphism and crustal thickening, (b) lithospheric-delamination driven uplift as a result of the slab breakoff of the subducting Indian lower crust during the Oligo-Miocene, and (c) in its final phase because of the underthrusting of the Indian Plate beneath the KT during the Pliocene. The interplay of tectonic uplift and glacial erosion carved the present-day topography of the KT into steeper hill slopes and relief with steeper river channel gradients since the Plio-Quaternary.

中文翻译：

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新元古代以来喀喇昆仑地体的地质演化


喜马拉雅-青藏造山带西缘的喀喇昆仑地体（KT）保存了特提斯大洋岩石圈俯冲到亚洲板块之下的记录以及与印度板片俯冲和印度-亚洲碰撞有关的变质作用。该地体对于了解与地幔动力学、板片逆冲或大规模走滑断层相关的大陆-大陆碰撞带的构造随时间的变化也具有重要意义。尽管过去 140 年有着悠久的地质研究历史，但该地体的岩浆、成岩、变形和隆升历史仍然是个谜。这主要是因为对于可变出现的I型和S型花岗岩的分布、来源和就位过程以及随时间变化的构造过程没有达成共识。因此，为了解决这些问题，本文回顾了KT的岩浆、变形和隆升历史。除了新元古代基底外，KT 地区还发现了安第斯型岩浆作用的两个主要阶段。第一阶段发生在~160-100 Ma期间，形成角闪石（Hbl）-黑云母（Bt）和含Bt花岗岩。现场证据、混合同位素特征和热力学全岩主元素模型表明，这些花岗岩的形成涉及与上地壳岩石的同化。位于 KT 东部的第 2 阶段 Hbl-Bt 含班公变形带 (PTZ) 花岗岩形成于~83-56 Ma；它们显示出幼年同位素特征，因此表明它们起源于地幔。这些花岗岩的主要元素热力学模型表明这些岩石是由于分步结晶而形成的。 我们对地球化学、同位素和地球化学模型的汇编和分析表明，这些花岗岩属于拉达克岩浆弧而不是喀喇昆仑岩基花岗岩，这与早期的看法相反。 KT 始新世-渐新世淡色花岗岩的起源仍然存在争议，因为其起源的推断过程多种多样，例如花岗岩的水通量熔融、变泥岩的脱水熔融以及板片断裂、剪切或压缩引起的部分熔融生成。本研究通过编译地质年代学、地球化学和同位素数据来评估这些情景，以了解这些过程在空间和时间尺度上部分熔融生成中的作用。我们的评估表明，二长花岗岩和含 hbl 的淡色花岗岩是由于现有火成岩来源的板片断裂和 KF 剪切引起的熔融而生成的，而二云母±grt 淡色花岗岩则来源于表壳变泥质岩的熔融，这是由于到地壳增厚。本文提供了所有已发表的中低温热测年年龄的冷却速率的汇编，以评估 KT 在空间和时间尺度上隆起的不同阶段。我们的编制表明，KT主要在三个阶段发生隆升：（a）早白垩世-晚白垩世，前印度-亚洲碰撞变质作用和地壳增厚证明了这一点；（b）板片导致的岩石圈拆沉驱动的隆起渐中新世期间俯冲印度下地壳的断裂，以及（c）由于上新世期间印度板块向KT下方的逆冲而处于其最后阶段。 自普里奥-第四纪以来，构造隆起和冰川侵蚀的相互作用将 KT 现今的地形雕刻成更陡的山坡和更陡的河道梯度。