北山地区洗肠井蛇绿岩带两侧变质沉积岩的岩石学、碎屑锆石U-Pb年龄特征及其构造意义  

Petrology,clastic zircon U-Pb age characteristics and tectonic significance of metamorphic sedimentary rocks on both sides of the Xichangjing ophiolitic belt in Beishan area

作　　者：田健 张永 辛后田 张国震 滕学建 TIAN Jian;ZHANG Yong;XIN HouTian;ZHANG GuoZhen;TENG XueJian(Tianjin Center,China Geological Survey(North China Center for Geoscience Innovation),Tianjin 300170,China;Shenyang Geological Survey Center of China Geological Survey,Shenyang 110034,China)

机构地区：[1]中国地质调查局天津地质调查中心(华北地质科技创新中心),天津300170 [2]中国地质调查局沈阳地质调查中心,沈阳110034

出　　处：《岩石学报》2025年第4期1338-1351,共14页Acta Petrologica Sinica

基　　金：中国地质调查项目(DD20240027)资助.

摘　　要：造山带中沉积作用的研究对于探讨俯冲过程及地质演化具有重要的意义。洗肠井蛇绿岩带分布在北山造山带中部,向西与红柳河-牛圈子-白云山蛇绿岩带相连,蛇绿岩带两侧发育广泛的早古生代地质体。本次工作通过对洗肠井蛇绿岩带两侧变质沉积岩碎屑锆石的综合分析,明确蛇绿岩带南侧变质砂岩的碎屑锆石年龄中缺少1300~1500Ma的年龄记录,具有与塔里木板块一致的年龄谱系;而蛇绿岩带北侧云母石英片岩发育1424Ma的峰值年龄,显示了与中天山地块一致的年龄谱系。结合前人发表的相关数据,本文认为北山造山带红柳河-洗肠井蛇绿岩带是重要的板块缝合带,它分割了南侧的塔里木板块与北侧的中天山地块。另外,红柳河-洗肠井带北侧变质沉积岩碎屑锆石最小年龄为490Ma或476Ma,与北侧公婆泉岩浆弧发育的岛弧玄武岩时代相匹配;南侧变质沉积岩碎屑锆石的最小年龄为490Ma或458Ma,与南侧花牛山岩浆弧发育的岛弧火山岩时代相匹配。我们认为,北山造山带中部早古生代岩浆作用和沉积作用与红柳河-洗肠井蛇绿岩代表的洋盆的双向俯冲有关,早古生代大洋板块的俯冲作用主要包括两个阶段:第一阶段形成弧前MORB型基性岩,第二阶段形成奥陶纪-中志留世的弧前-岛弧岩浆-沉积建造。The study of sedimentation in the orogenic belts is of great significance to the discussion of the subduction process and the geological evolution.The Xichangjing ophiolitic belt was distributed in the central part of the Beishan orogenic belt,connected to the Hongliuhe-Niuquanzi-Baiyunshan ophiolitic belt in the west.Extensive Early Paleozoic geological bodies were developed on both sides of the ophiolitic belt.Through the comprehensive analysis of detrital zircons from the metamorphic sedimentary rocks on both sides of the Xichangjing ophiolitic belt,it is clear that the south side of the ophiolitic belt is lack of 1300~1500Ma ages,showing an age spectrum consistent with Tarim Plate.Furthermore,the 1424Ma peak age in the north of the ophiolitic belt shows the same age spectrum as that of Central Tianshan Block.Based on the relevant data published,we believe that the Hongliuhe-Xichangjing belt in the Beishan orogenic belt is an important plate boundary,which divides Tarim Plate in the south and Central Tianshan Block in the north.In addition,the minimum age of the clastic zircon of the metamorphic sedimentary rocks in the north side of the Beishan orogenic belt is 490Ma or 476Ma,which matches the ages of island arc basalt from Gongpoquan arc;while the minimum age of the clastic zircon of the metamorphic sedimentary rocks in the south side of Hongliuhe-Xichangjing belt is 490Ma or 458Ma,which matches the ages of arc volcanic rocks from Huaniushan arc.We believe that the Early Paleozoic magmatism and sedimentation in the central part of the Beishan orogenic belt are related to the bidirectional subduction of the ocean basin represented by the Hongliuhe-Xichangjing ophiolite.The subduction of the Early Paleozoic oceanic plate mainly includes two stages:the first stage formed the fore-arc MORB-type basic rocks,and the second stage formed the Ordovician-Middle Silurian fore-arc and island-arc magma-sedimentary formation.

关 键 词：北山造山带 奥陶纪地层 塔里木板块 中天山地块 早古生代俯冲作用 

分 类 号：P588.21[天文地球—岩石学] P597.3[天文地球—地质学]