Multi-stage tectono-magmatic evolution of the Proto-Tethys Ocean: Constraints from Mid-Paleozoic granitoids in the East Kunlun-North Qaidam orogenic belt

IF 7.2 1区地球科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Gondwana Research Pub Date : 2025-10-10 DOI:10.1016/j.gr.2025.09.009

Mao Wang , Xianzhi Pei , Lei Pei , Ruibao Li , Zuochen Li , Chengjun Liu , Youxin Chen , Nan Hu , Li Qin , Xiao Wang

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Abstract

The East Kunlun-North Qaidam orogenic belt (EKO-NQO) preserves extensive magmatic records of the Proto- and Paleo-Tethys oceans, making it an ideal window for studying the Proto-Paleo-Tethys tectonic transition. Three Late Silurian–Early Devonian plutons (Hatu, Niantang, Chachaxiangka) in the EKO-NQO were selected for study. We also integrated recent high-quality geochemical and geochronological data to assess regional tectonic evolution. The ca. 415–417 Ma Hatu I-type granites in the South Kunlun Belt (SKB) are derived from partial melting of metabasalts in the middle/lower crust due to mantle-derived magma underplating, with minor juvenile crustal components input, during slab break-off and exhumation in the late-stage continental subduction. The ca. 414 Ma Hatu A-type granites (SKB) are mainly formed by dehydration melting of Paleo- to Mesoproterozoic crust, reflecting lithospheric thinning and delamination. The ca. 419–420 Ma Chachaxiangka adakite-like granites in the North Qaidam Belt (NQB) are formed through hydration melting of thickened lower crust during continental deep subduction-exhumation. The ca. 383–386 Ma Niantang A-type granites in the Aqikekulehu–Kunzhong ophiolitic mélange zone (AKM) are derived from partial melting of ancient metasedimentary basement (predominantly metapelites), with minor juvenile crust input, during lithospheric delamination and thinning. Based on existing studies, we propose a three-stage evolution model for the Ordovician-Devonian Proto-Tethys orogeny in EKO-NQO: (1) Cambrian- Middle Silurian Oceanic Subduction: NQB (>450 Ma), Qimantagh Belt (QMTG), North Kunlun Belt (NKB) and SKB (>430 Ma); (2) Early Silurian-Early Devonian Slab Break-off/Exhumation: NQB (450 – 415 Ma), QMTG (430 – 410 Ma), NKB and SKB (430 – 415 Ma; SKB: western collision, eastern subduction); (3) Early-Middle Devonian Delamination: NQB, NKB and SKB (<415 Ma, SKB western segment), QMTG (<410 Ma). The Early-Middle Devonian Niantang A-type granites (A₂-A₁ transition) in EKO-NQO indicate a gradual shift to intraplate setting, marking both the end of the Proto-Tethys and the onset of Paleo-Tethys.

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原特提斯洋多期构造岩浆演化：来自东昆仑-柴达木北造山带中古生代花岗岩类的制约

东昆仑-柴达木北造山带（eco - nqo）保存了大量的原始海洋和古特提斯海洋的岩浆记录，是研究原-古特提斯构造转变的理想窗口。选取ego - nqo地区晚志留世-早泥盆世3个岩体（哈图、年塘、察察香卡）进行研究。我们还综合了最近高质量的地球化学和地质年代学数据来评估区域构造演化。南昆仑带约415 ~ 417年马哈图ⅰ型花岗岩是在大陆俯冲晚期板块断裂和挖掘过程中，由于地幔源岩浆的底板作用，中下地壳变质玄武岩部分熔融，并有少量幼年地壳成分输入的产物。约414年马哈图a型花岗岩（SKB）主要由古元古代至中元古代地壳脱水熔融形成，反映了岩石圈减薄和分层作用。柴达木北缘约419 ~ 420年马察察香卡埃达克岩样花岗岩是在大陆深俯冲掘出过程中由加厚的下地壳水化熔融作用形成的。阿奇克库勒湖—昆中蛇绿质马年塘a型花岗岩是在岩石圈拆沉减薄过程中，由古变质基底（以变质岩为主）部分熔融而成，并有少量幼年地壳输入。在现有研究的基础上，我们提出了eke - nqo奥陶系-泥盆系原-特提斯造山运动的三阶段演化模式：(1)寒武系-中志留统大洋俯冲：NQB （>450 Ma）、Qimantagh带（QMTG）、北昆仑带（NKB）和SKB (>430 Ma)；(2)早志留世—早泥盆世板块断裂/掘出：NQB （450 ~ 415 Ma）、QMTG （430 ~ 410 Ma）、NKB和SKB (430 ~ 415 Ma)， SKB：西部碰撞，东部俯冲；(3)早-中泥盆世脱层：NQB、NKB和SKB （<415 Ma， SKB西段），QMTG （<410 Ma）。ego - nqo早-中泥盆世年塘a型花岗岩（A2-A1过渡）标志着板块内环境的逐渐转变，标志着原特提斯的结束和古特提斯的开始。

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来源期刊

Gondwana Research 地学-地球科学综合

CiteScore

12.90

自引率

6.60%

发文量

298

审稿时长

65 days

期刊介绍： Gondwana Research (GR) is an International Journal aimed to promote high quality research publications on all topics related to solid Earth, particularly with reference to the origin and evolution of continents, continental assemblies and their resources. GR is an "all earth science" journal with no restrictions on geological time, terrane or theme and covers a wide spectrum of topics in geosciences such as geology, geomorphology, palaeontology, structure, petrology, geochemistry, stable isotopes, geochronology, economic geology, exploration geology, engineering geology, geophysics, and environmental geology among other themes, and provides an appropriate forum to integrate studies from different disciplines and different terrains. In addition to regular articles and thematic issues, the journal invites high profile state-of-the-art reviews on thrust area topics for its column, ''GR FOCUS''. Focus articles include short biographies and photographs of the authors. Short articles (within ten printed pages) for rapid publication reporting important discoveries or innovative models of global interest will be considered under the category ''GR LETTERS''.