地质学报2016，Vol.90Issue(4)：708-727,20.
阿尔金喀腊大湾地区中酸性火山岩SHRIMP 年龄及其构造环境
Zircon SHRIMP U-Pb Dating of Intermediate-Felsic Volcanic Rocks from the Kaladawan Area,Altun Mountains and Its Tectonic Environment
摘要
Abstract
The Kaladawan area of Altun Mountains is located in the central segment of the Hongliugou-Lapeiquan structural belt,which is bounded by the NE-striking Altun strike-slip faults to the north and the E-W-trending northern Altun fault.The area is widely developed with volcanic-sedimentary rocks, which were determined to be Mesoproterozoic in age by previous studies.In this study zircon SHRIMP U-Pb dating for the intermediate-felsic volcanic rocks from the volcanic-sedimentary rocks was conducted and yielded an age of 477~485 Ma,which confirms the existence of intermediate and felsic magmatic activity in the Kaladawan area during early Paleozoic.Petrogeochemical study also indicates that the volcanic rocks reflect the tectonic setting of active continental margin (Island arc)and magma source is characteristic of I-type and I-S transition type.In combination with dating and tectonic setting tracing of the ophiolitic mélange,high pressure metamorphic mudstone, eclogite, intermediate-felsic intrusive rocks in the Hongliugou-Lapeiquan structural belt,the authors suggest that the intermediate-felsic volcanic rocks in the Kaladawan area are related to a tectonic setting of active continental margin (Island arc)and the age is roughly consistent with the final phase of ophiolitic mélange, representing that the syn-collision intermediate-felsic volcanic rocks resulting from the subduction of oceanic crust process.The Hongliugou-Lapeiquan structural belt can be divided into 3 evolutional stages:①a period of oceanic crust expansion in the Late Proterozoic-Cambrian (the age of ophiolitic mélange is 510~580Ma and the expansion was slightly earlier);②a period of subduction-collision of oceanic crust plates in Early Ordovician-Middle Ordovician early (the age of intermediate-acidic volcanic rocks (including intrusive rock and volcanic rock)is 477 ~488Ma,part of granite has an age of 467Ma and high pressure metamorphic rocks of regressive metamorphism age is 479 ~491Ma);③a period of post-collision to extension in Late Ordovician-Silurian (the ophiolitic mélange metamorphic basement is 450 ~455Ma in age,which represent final emplacement of ophiolitic mélange,and collision and post-collision S-type granite has the age of 417 ~431Ma,which shows the post-collision to extension settings).关键词
中酸性火山岩/SHRIMP 年龄/构造环境与演化/喀腊大湾地区/阿尔金山Key words
intermediate-felsic volcanic rocks/SHRIMP dating/tectonic setting and evolution/Kaladawan area/Altun Mountains引用本文复制引用
陈柏林,杨屹,王世新,王永,周永贵,郝瑞祥,李松彬,蒋荣宝,陈正乐,韩凤彬,崔玲玲,李丽,赵树铭,祁万修..阿尔金喀腊大湾地区中酸性火山岩SHRIMP 年龄及其构造环境[J].地质学报,2016,90(4):708-727,20.基金项目
本文为“十一·五”、“十二·五”国家科技支撑计划重点项目（编号2006BAB07B02-04、2011BAB06B08-04）和地质矿产调查专项（编号1212011085043）的资助成果。 （）
