伊宁地块石炭纪火山岩及其对构造演化的约束  

Tectonic evolution of Yining Block:Insights from Carboniferous volcanic rocks

作　　者：李永军[1,2] 吴乐[1] 李书领[1] 李甘雨[1] 沈锐[1] 李钊[1] 王祚鹏 汪振宇[1] LI YongJun WU Le LI ShuLingI LI GanYu SHEN Rui LI Zhao WANG ZuoPeng(Earth Science ＆ Resources College, Chang＇ an University, Xi＇ an 710054, China Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, MLR, Xi＇an 710054, China)

机构地区：[1]长安大学地球科学与资源学院,西安710054 [2]国土资源部岩浆作用成矿与找矿重点实验室,西安710054

出　　处：《岩石学报》2017年第1期1-15,共15页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41273033;41303027);中央高校基金项目(310827153407);新疆维吾尔自治区地质专项(Y15-1-LQ01)联合资助

摘　　要：西天山伊宁地块的构造格局及其演化之认识久存争议,倍受关注。分歧焦点有三:(1)石炭纪有无洋盆存在?(2)若有洋盆,何时闭合?(3)'沟-弧-盆'消亡时究竟是单向俯冲还是双向俯冲?若是单向俯冲,俯冲方向是由北向南或是相反(即俯冲极性)?因此,这些重大地质问题均聚焦于本区的火山岩。石炭纪火山岩是伊宁地块中的最主要建造和指示构造演化的关键层位,争论长久而激烈。本文认为,伊宁地块早石炭世发育弧前-岛弧-弧后盆地钙碱性火山-沉积建造,是塔里木板块北缘的主要组成部分;而晚石炭世碱性系列双峰式火山岩及其沉积组合则是大陆裂谷火山-沉积建造,形成于区域性伸展构造环境,是准噶尔板块与塔里木板块缝合后的陆内建造,因而古洋盆的关闭时限是早石炭世晚期(鄯善运动)。依据区内早石炭世建造的空间分布和变化规律,作者们认为古天山洋盆与当今地学界作为典型的日本沟-弧-盆体系有着极好的相似性和空间分布可对比性。石炭纪火山岩为本区的构造演化研究提供了重要的约束信息。Although the Yining Block has long been focused on, specifics of the evolution and configuration during Carboniferous are still debated. There are three main controversial views. First one focuses on whether or not the Tianshan oceanic basin existed in Carboniferous. Second one is, if the oceanic basin existed, when closed it is. Meanwhile, the third topic is about the polarity of subduction. Therefore, these significant geologic issues focus on volcanic rocks. Carboniferous volcanic rocks are widespread in Yining Block; this association plays a key role for tectonic evolution, with acute controversies for a long time. This study showed that calc- alkaline volcano-sedimentary rocks were developed during Early Carboniferous in fore-arc-inter-arc-back-arc basin system in Yining Block from Tarim plate. By contrast, Late Carboniferous bimodal volcanic rocks and sedimentary association formed within regional extension tectonic setting and show affinity with continental rift, a responsible for intra-continental geological processes after the assembling of the Junggar and Tarim blocks. These observations suggest that the ancient oceanic basin should be close in late Early Carboniferous. The temporal-spatial distribution, which of the Early Carboniferous volcanic-sedimentary rock association, suggest that Tianshan ancient oceanic basin in Early Carboniferous is similar with the mordent typical trench-arc-basin system from Japan. Moreover, Carboniferous volcanic rocks provide the momentous information to restrict tectonic evolution in Yining Block.

关 键 词：火山岩 古构造格局与演化 石炭纪 伊宁地块 西天山 

分 类 号：P542[天文地球—构造地质学]