阿尔泰造山带富蕴基性麻粒岩折返过程:来自裂变径迹热年代学的限定  

Exhumation of the Fuyun basic granulite in Altaid Orogenic Belt:Constraints from fission-track thermochronology

作　　者：林秀斌[1,2] 陈汉林[1,2] 杨树锋[1,2] 厉子龙[1,2] 余星[1,2] 程晓敢[1,2] 

机构地区：[1]浙江大学地球科学系,杭州310027 [2]教育部含油气盆地构造研究中心,杭州310027

出　　处：《岩石学报》2010年第2期413-420,共8页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划项目(2007CB411307和2001CB409801);国家自然科学基金(40672147);国家科技重大专项(2009ZX05009-001)联合资助

摘　　要：论文在阿尔泰造山带富蕴县乌恰沟基性麻粒岩的锆石SHRIMP年代学、地球化学、变质温压条件和形成的大地构造背景研究基础上,利用麻粒岩、围岩片麻岩和侵入到麻粒岩的辉绿岩岩墙的裂变径迹热年代学探讨了麻粒岩从深部折返至地表的过程。裂变径迹年代学研究发现基性麻粒岩的锆石裂变径迹年龄为三叠纪,而麻粒岩、围岩片麻岩和侵入到麻粒岩的辉绿岩岩墙的磷灰石裂变径迹年龄均显示为晚白垩世至新生代早期。对磷灰石裂变径迹测试所得到的径迹长度和单颗粒年龄数据进行热史模拟表明,三叠纪时,基性麻粒岩抬升至约地表以下7.8km的上地壳,温度冷却至锆石裂变径迹的封闭温度;晚白垩世至新生代早期(约100～50Ma),麻粒岩、围岩片麻岩和辉绿岩抬升至约地表以下3.5km,温度冷却至磷灰石裂变径迹的封闭温度;约50～15Ma,三者滞留在约地表以下1.7km的磷灰石部分退火带;约15Ma以来,喜马拉雅运动使得它们被抬升剥蚀至地表。On the basis of previous studies of SHRIMP U-Pb chronology,geochemistry,metamorphic temperature/pressure conditions and tectonic setting,fission-track thermochronology has been conducted in this study to determine the exhumation of the basic granulite.Zircon fission-track shows Triassic and apatite fission-track shows Late Cretaceous to Early Cenozoic ages.Thermal history modeling of the fission-track data,combined with previous studies,indicate that the basic granulite was exhumed to the upper crust under about 7.8km in Triassic.From Late Cretaceous to Early Cenozoic(around 100 -50 Ma),the basic granulite,meta-diabase and the wall rock gneiss were cooled to the blocking temperature of apatite fission-track,which was about 3.5km below the surface.From approximately 50 to 15 Ma,they stayed at the partly-annealed zone of apatite fission-track,about 1.7km below the surface.Since about 15 Ma to present,they were uplifted and denudated to the surface.

关 键 词：阿尔泰造山带 富蕴 基性麻粒岩 裂变径迹 折返 

分 类 号：P588.347[天文地球—岩石学]