东南极普里兹湾地区超高温变质作用  

Ultra-high temperature metamorphism in the Prydz Bay region,East Antarctica

作　　者：表璇 王伟[1,3] 吴江 保红 刘晓春 赵越[1,3] Biao Xuan;Wang Wei;Wu Jiang;Bao Hong;Liu Xiaochun;Zhao Yue(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;China University of Geosciences(Beijing),Beijing 100083,China;Key Laboratory of Paleomagnetism and Tectonic Reconstruction,Ministry of Natural Resources,Beijing 100081,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]中国地质大学(北京),北京100083 [3]自然资源部古地磁与构造重建重点实验室,北京100081

出　　处：《极地研究》2022年第4期516-529,共14页Chinese Journal of Polar Research

基　　金：国家自然科学基金(41941004,42172068);地质调查项目(DD20221810)资助

摘　　要：东南极普里兹湾地区主要包括西福尔丘陵、赖于尔(茹尔)群岛、拉斯曼丘陵、姐妹岛等。普里兹湾地区普遍记录高温-超高温变质作用,在赖于尔(茹尔)群岛地区发育典型超高温变质作用,最近研究表明超高温变质作用可能分布更广,如拉斯曼丘陵、姐妹岛等地区也可能有超高温变质作用的记录。普里兹湾地区超高温变质作用矿物组合多样,该地区的斜方辉石+夕线石、假蓝宝石+石英等矿物组合可以明确指示超高温变质作用,含假蓝宝石但不含石英的矿物组合、尖晶石+石英的矿物组合、含刚玉的矿物组合等也可能指示超高温变质作用,这些组合是否反映超高温条件还需根据具体矿物成分结合可靠温度计及相平衡模拟计算等方法进行精确限定。超高温变质作用的潜在热源不同,可以归为自生热和外来热;其中自生热主要有放射性生热、机械热;外来热主要是深部热源经过热对流、热传导等方式提供。超高温变质作用可能发生在不同构造背景,如洋脊俯冲、弧后盆地、造山带下地壳拆沉等。已有的研究显示普里兹湾地区记录了不同期次构造变质事件,是一个典型的多期变质叠加造山带。最近的研究表明超高温变质作用主要形成于泛非期,但具体时间、演化特征、构造背景以及热源仍存在争议,需进一步研究限定。The Prydz Bay region of East Antarctica consists of different terrains including the Vestfold Hills,the Rauer Group,the Larsemann Hills,and Søstrene Island.The Prydz Bay region has undergone high to ultra-high temperature(UHT)metamorphism,with the Rauer Group typically experiencing UHT conditions.Recent studies suggest that UHT metamorphism may occur more widespread,and the Larsemann Hills,Søstrene Island may also have undergone UHT metamorphism.The UHT metamorphism in the Prydz Bay region resulted in various mineral assemblages.The assemblages of orthopyroxene+sillimanite and sapphirine+quartz can reliably indicate UHT metamorphism in the region.Mineral assemblages including sapphirine(without quartz),spinel-quartz,or corundum may indicate UHT conditions,but whether these mineral assemblages reflect UHT conditions need to be further constrained by reliable thermometry or phase equilibrium modelling based on mineral composition analysis.Different heat sources for UHT metamorphism have been proposed and can be generally classified into two types:autogenic heat and external heat.Autogenic heat mainly includes radioactive heat and mechanical heat,whereas external heat can be provided through conduction and/or convection of a deep heat source.UHT may occur in different tectonic settings including ridge subduction,back-arc basins,and delamination of the lower crust.Previous studies have shown that the Prydz Bay region is a typical orogenic belt with overprinting of different metamorphic events.Recent studies support that UHT metamorphism occurred during the Pan-African period.However,the exact timing,evolutional process,tectonic setting,and heat source of UHT metamorphism are still controversial and thus call for further study.

关 键 词：普里兹湾地区 超高温变质作用 矿物组合 构造背景 热源 

分 类 号：P588.3[天文地球—岩石学]