博格达造山带东段沙沟库都克闪长岩体地球化学特征、年代学及地质意义  

Geochemical Characteristics, Geochronology and its Geological Significance of the Diorite in Shagoukuduke Area,East of the Bogda Orogenic Belt

作　　者：汪晓伟[1,2] 崔方磊 孙吉明[1] 朱小辉[1] 朱涛[1] 白建科[1] 

机构地区：[1]中国地质调查局西安地质调查中心,陕西西安710054 [2]长安大学地球科学与资源学院,陕西西安710054

出　　处：《新疆地质》2015年第2期151-158,共8页Xinjiang Geology

基　　金：中国地质调查局地质调查项目西北基础地质综合调查与片区总结(1212011220649);国家自然科学基金项目西天山伊犁地块早石炭世典型沉积序列及对天山古生代洋陆转换时限的约制(41202077)共同资助

摘　　要：对新疆博格达造山带东段沙沟库都克闪长岩进行系统的LA-ICP-MS测年、岩石学和岩石地球化学分析，初步获得锆石U-Pb年龄为（341.9±1.3）Ma（MSWD=0.15），属早石炭世。岩石地球化学数据表明，该岩体以低TiO2、较高Al2O3、较低MgO、贫P2O5，较高的Na2O/K2O比值（1.93-2.65），ΣREE相对较低，ΣLREE/ΣHREE为4.17-5.70，Eu负异常不明显（δEu=0.79-0.88），富集大离子亲石元素（如K，Cs，Rb，Ba，Th，U等），亏损高场强元素（如Nb，Ta，P，Ti等）为特征。研究表明，该岩体可能为下地壳物质（源岩为底侵的玄武质岩石）受热部分熔融形成，源区可能存在石榴子石＋角闪石残留，形成于陆内裂谷环境，其动力学机制与石炭纪卡拉麦里蛇绿岩带或康古尔塔格-黄山深断裂代表的古大洋消减引起的陆内拉张作用有关。LA-ICP-MS dating technique, petrographic and geochemical analysis were used to the diorites located in Shagoukuduke area,the east of Bogda orogenic belt,in Xinjiang,and yielded zircon U-Pb age value of （341.9 ±1.3）Ma （MSWD=0.15）,belonging to the early Carboniferous.The diorites have low TiO2, MgO, P2O5 and have high Al2O3, Na2O/K2O=1.93-2.65. Their REE distribution patterns were characterized by LREE enrichment, right-oblique shape and deple-tion of Eu（δEu=0.79-0.88）. The trace elements generally have features of enrichment of K, Cs, Rb, Ba, Th and U, obvi-ous depletion of Nb, Ta, P and Ti.The authors hold that the material source of the diorites was probably related to the par-tial melting of the lower crustal granitic magma,whose source may exist the garnet and hornblende residue. Its geodynam-ic mechanics should be related to the intra-continental extension caused by the paleo-ocean subduction indicative of Kala-meili ophiolite or Kanguertage-Huangshan deep fault.

关 键 词：博格达造山带 闪长岩 锆石U-PB测年 陆内裂谷 岩石成因 

分 类 号：P597.3[天文地球—地球化学] P588.122[天文地球—地质学]