马来半岛东部晚三叠世岩浆作用及其古特提斯构造意义  

Late Triassic Magmatism in Eastern Peninsular Malaysia and Its Paleotethyan Tectonic Implications

作　　者：余永琪 钱鑫 王岳军 Mustapha Khairul Azlan 张玉芝 YU Yongqi;QIAN Xin;WANG Yuejun;MUSTAPHA Khairul Azlan;ZHANG Yuzhi(Guangdong Key Laboratory of Geodynamics and Geohazards/School of Earth Sciences and Engineering,Sun Yat-sen University/Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,Guangdong,China;Department of Geology,University of Malaya,Kuala Lumpur 50603,Malaysia)

机构地区：[1]中山大学地球科学与工程学院,广东省地球动力作用与地质灾害重点实验室,南方海洋科学与工程广东省实验室(珠海),广东珠海519082 [2]Department of Geology,University of Malaya,Malaysia Kuala Lumpur 50603

出　　处：《大地构造与成矿学》2024年第3期493-511,共19页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(42072256、42330302);国家重点研发计划项目(2023YFF0803701);南方海洋科学与工程广东省实验室(珠海)项目(SML2023SP239)联合资助。

摘　　要：马来半岛广泛发育的晚古生代‒早中生代岩浆作用完整地记录了古特提斯洋俯冲‒碰撞‒消亡的演化历史。该洋盆于中‒晚三叠世关闭,随之发生陆‒陆碰撞、地壳增厚以及造山带垮塌,区域上形成大规模的碰撞后火成岩,构成了东南亚古特提斯巨型火成岩带东部和中部花岗岩省的重要组成部分,但关于其岩石成因及构造背景仍然存在不同认识。因此,本文对马来半岛东部晚三叠世花岗岩开展了详细的岩相学、年代学以及地球化学研究,并结合区域地质资料综合探讨了晚三叠世岩浆作用的演化规律及深部动力学过程。研究表明马来半岛东部晚三叠世花岗岩可以分成两组:第一组为231~222 Ma,样品显示出较为富集的同位素特征((^(87)Sr/^(86)Sr)i=0.72040~0.72518,εNd(t)=−10.4~−6.7,εHf(t)=−11.5~+0.1),来自变火成岩和变杂砂岩的混合源区;第二组样品形成于218~216 Ma,对应的(^(87)Sr/^(86)Sr)i=0.70576~0.71464,εNd(t)=−9.1~−3.9,εHf(t)=−3.9~+1.9,表明其源区存在一定新生地壳物质的参与,且Ga/Al、FeO^(T)/(FeO^(T)+MgO)值及锆石饱和温度相对较高,具有典型的A型花岗岩特征。年代学结果表明古特提斯东部和中部花岗岩省晚三叠世岩浆作用的峰期为220 Ma,且具有相似的元素‒同位素变化规律,证实古特提斯洋碰撞后造山垮塌主要发生于220 Ma,软流圈上涌促使中‒下地壳物质发生部分熔融从而形成了区域大规模的岩浆作用。The well-preserved Late Paleozoic-Early Mesozoic igneous rocks in Peninsular Malaysia are important for investigating the Paleotethyan tectonic evolution.The Paleotethyan Ocean closed at the Middle-Late Triassic,and subsequent continental collision,crustal thickening,and orogenic collapsing have led to the development of numerous igneous rocks,which constitute the Eastern and Central Granite Provinces of the Paleotethyan giant igneous belt in SE Asia.However,there are many different viewpoints concerning their petrogenesis and tectonic setting.This study carried out detailed petrographic,geochronological,and geochemical studies on the Late Triassic granites of Eastern Peninsular Malaysia.We discussed the Late Triassic magmatic evolution and geodynamic process by analyzing the regional geological data.The Late Triassic granitoids in East Malaya can be divided into two groups.GroupⅠ231-222 Ma samples show more enriched isotopic signatures((^(87)Sr/^(86)Sr)i=0.72040-0.72518,εNd(t)=−10.4-−6.7,εHf(t)=−11.5-+0.1),suggestive of a mixed source of metaigneous and metagreywacke components.GroupⅡsamples were formed at 218-216 Ma with(^(87)Sr/^(86)Sr)i=0.70576-0.71464,εNd(t)=−9.1-−3.9,andεHf(t)=−3.9-+1.9,indicative of the input of juvenile mafic crust.In addition,GroupⅡdisplays A-type characteristics with high Ga/Al and FeO^(T)/(FeO^(T)+MgO)ratios and zircon saturation temperatures.The Late Triassic magmatism in Eastern and Central Provinces has a main age peak at 220 Ma,and the magmatism along the Paleotethyan Domain also shows similar elemental and isotopic variations,confirming that the collapse of the Paleotethyan post-collisional orogen took place at ca.220 Ma.The upwelling asthenosphere caused the melting of the middle-lower crustal juvenile materials,resulting in the regional large-scale magmatism.

关 键 词：晚三叠世 岩浆作用 地球化学 碰撞后 古特提斯洋 马来半岛 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]