摘要
潘吉亚超大陆是地球历史上距今最近的超大陆。普遍认为潘吉亚超大陆始于二叠纪冈瓦纳和劳亚大陆的拼合,三叠纪时期围绕欧亚大陆东南缘的东南亚地区继续生长,这也是衔接外围泛大洋的唯一可传输区。但在潘吉亚超大陆最终定型过程中,东南亚众多中小块体的形成和汇聚过程仍然令人费解。明确该区三叠纪的岩浆性质(古老还是新生)和块体属性(异地还是原地),对理解东南亚特提斯众多中小块体的汇聚过程以及大陆地壳的生长至关重要。婆罗洲岛是东南亚众多中小块体中最大的块体并占据了中心部位,被认为记录了中生代多个古老块体(微陆块)的汇聚碰撞过程。本文研究表明,西婆罗洲三叠纪花岗岩类(古晋和施瓦纳西北部)在元素和同位素地球化学方面,显示出与印支花岗岩(古老地壳性质)和北婆罗洲花岗岩(新生地壳性质)混合的特征,这表明该区自三叠纪开始发育新生组分(地幔物质)。综合区域资料,婆罗洲花岗岩类的锆石显示出两期(约240和210 Ma)显著正εHf(t)值的特征,表明有显著的新生组分的加入,造成潘吉亚—欧亚大陆东南缘婆罗洲地体的原地生长和潘吉亚—欧亚大陆边缘(苏门答腊、爪哇和婆罗洲)向东南方向的进一步生长。这种原地生长可能并不仅仅是古太平洋或特提斯的单一体系下俯冲-增生作用的结果,而可能与两大体系在潘吉亚传输区(特提斯洋和泛大洋之间)的物质能量交换有关。
The Pangea supercontinent is the youngest one in Earth′s history.It is generally believed that its main body was formed by the assembly of Gondwana and Laurasia continents in the Permian.During the Triassic period,the Southeast Asia continent continually grew around the southeastern edge of Eurasia Continent.It is the only conveyable zone connecting with the Panthalassa Ocean.However,the formation and convergence of many small-and medium-sized blocks in Southeast Asia during the final formation of the Pangaea supercontinent are still not clearly understood.The identification of Triassic magma source(ancient vs.juvenile)and block signatures(allochthonous vs.autochthonous)in Southeast Asia is crucial to understand processes of the convergence of many small-and medium-sized blocks and the growth of continental crust in the Tethys of Southeast Asia.Among many small-and medium-sized blocks in Southeast Asia,the Borneo Island is the largest block occupied the central part of Southeast Asia.It is generally considered to have recorded processes of convergence and collision of several ancient blocks(small continental blocks)in the Mesozoic era.Our research results show that the Western Borneo Triassic granitoids(in the Kuching and NW Schwaner zones)have mixed characteristics of the Indochina granitoids(with ancient crust signature)and the Northern Borneo granitoids(with juvenile crust signature)in terms of elemental and isotopic geochemistry,indicating that the juvenile components(mantle materials)had been developed in the area since the Triassic.The regional data compilation shows that all zircons of the Borneo granitoids are characterized with two-stage ages(about 240 Ma and 210 Ma)and positiveεHf(t)values,indicating two-stage significant contributions of juvenile components to those granitic magmas.These contributions of juvenile components resulted in the autochthonous crustal growth of the Borneo terrane in the southeastern margin of Pangea-Eurasia Continent and the further crustal growth of the Pangea-Eurasia Con
作者
李舢
LI Shan(College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 101408,China)
出处
《矿物岩石地球化学通报》
CAS
CSCD
北大核心
2024年第4期746-754,I0003,共10页
Bulletin of Mineralogy, Petrology and Geochemistry
基金
中国科学院人才计划项目(E3ER0401A2)
国家自然科学基金资助项目(42161144007)。
