摘要
古大洋的演化通常涉及多阶段与不同类型的俯冲过程, 并在俯冲上盘形成多类型的弧岩浆岩。因此, 系统整合弧岩浆岩的时空规律及岩石特征, 对重建古大洋的演化历史与解析板块构造动力学过程具有重要意义。本研究聚焦青藏高原中部班公湖-怒江缝合带, 建立了自中侏罗世以来的完整弧岩浆数据库, 并选择缝合带西段狮泉河地区和日土地区侏罗纪弧岩浆岩作为核心研究对象。基于系统的年代学、元素/同位素地球化学及岩相学分析, 识别出南、北两套不同性质的弧岩浆系统。北带(169~147Ma)表现出大陆弧(科迪勒拉型)特征。南带(165~122Ma)表现为从高镁安山岩/闪长岩(包括赞岐岩和玻安岩)向成熟钙碱性弧岩浆过渡的洋内弧(马里亚纳型)特征。结合北带~165Ma的渐进式洋脊俯冲事件, 本文提出了一个诱发式初始俯冲模型。该模型不仅深化了对中特提斯洋消减历史的理解, 更为多阶段弧岩浆的演化过程及初始俯冲诱发机制提供了参考案例。
The evolution of ancient oceans typically involves multiple stages and diverse subduction processes, resulting in various types of arc magmas in the overriding plate. Therefore, systematically integrating the temporal and spatial distribution patterns, along with the petrological characteristics of arc magmatism, can effectively reconstruct the evolutionary history of ancient oceans and decipher the dynamics of plate tectonics. This study focuses on the Bangong-Nujiang Suture Zone (BNSZ) in central Tibet and establishes a comprehensive arc magmatic database since the Middle Jurassic, with specific emphasis on the Jurassic arc magmatic rocks in the Shiquanhe and Ritu areas of the western BNSZ. Based on systematic geochronological, elemental/isotopic geochemical, and petrological analyses, we identify two distinct arc magmatic systems in the southern and northern belts of the BNSZ. Arc magmatism in the North Belt was active from ca. 169Ma to ca. 147Ma, exhibiting characteristics of a continental arc (Cordilleran-type arc system). The South Belt transitioned from high-Mg andesites/diorites (including sanukites and boninites) from 165Ma to 157Ma to mature calc-alkaline arc magmatism, which continued until ca. 122Ma, suggesting an intra oceanic arc system similar to the Izu-Bonin-Mariana arc system. Combined with the progressive ridge subduction event in the North Belt at ~165Ma, an induced subduction initiation model is proposed. The new model enhances understanding of the consumed history of Meso-Tethys Ocean and serves as a case study for comprehending multi-stage arc magmatic evolutionary processes and the mechanism of induced subduction initiation.
作者
李晨伟
李志军
邓李涛
钱裕杰
王琳
曾敏
LI ChenWei;LI ZhiJun;DENG LiTao;QIAN YuJie;WANG Lin;ZENG Min(College of Earth and Planetary Sciences,Chengdu University of Technology,Chengdu 610059,China;School of Earth Sciences,Yunnan University,Kunming 650500,China)
出处
《岩石学报》
2025年第5期1777-1796,共20页
Acta Petrologica Sinica
基金
国家自然科学基金项目(42172118、42302068、41872110)
四川省自然科学青年基金项目(24NSFSC0820)
成都理工大学珠峰计划(KYQD2022-09847、2020ZF11407)
云南大学引才计划(C1762101030017)联合资助详细信息。
关键词
初始俯冲
班怒带
弧岩浆演化
狮泉河
中-晚侏罗世
Subduction initiation
Bangong-Nujiang Suture Zone
Arc magmatic evolution
Ridge subduction
Middle-Late Jurassic
