巴尔喀什成矿带晚古生代地壳增生与构造演化  

Late Paleozoic crustal growth and tectonic evolution in Balkhash metallogenic belt(Kazakhstan),Central Asia

作　　者：刘刚[1] 陈宣华[1] 董树文[1] 陈正乐[2] 韩淑琴[2] 杨屹 叶宝莹[4] 施炜[2] 

机构地区：[1]中国地质科学院,北京100037 [2]中国地质科学院地质力学研究所,北京100081 [3]新疆维吾尔自治区地质矿产开发勘查局第一区调大队,乌鲁木齐830011 [4]中国地质大学,北京100083

出　　处：《岩石学报》2012年第7期1995-2008,共14页Acta Petrologica Sinica

基　　金：国家科技支撑计划重点项目暨国家305项目(2007BAB25B02)资助

摘　　要：巴尔喀什成矿带是中亚成矿域重要的晚古生代斑岩铜钼成矿带。巴尔喀什成矿带晚古生代花岗岩类(石炭-二叠纪)主要为高钾钙碱性系列,晚期出现钾玄岩系列岩石,主要为I型花岗岩类;石炭纪处在同碰撞和火山弧环境,二叠纪为后碰撞环境。分析表明,博尔雷属于经典的岛弧花岗岩区,科翁腊德、阿克斗卡和萨亚克属于埃达克岩(Adakite)区。巴尔喀什成矿带内花岗岩类εNd(t)值为(-5.87～+5.94),εSr(t)值为(-17.16～+51.10)。以巴尔喀什中央断裂为界,成矿带东、西分带,断裂两侧具有不同的地壳生长历史:断裂以东的萨亚克和阿克斗卡地区εNd(t)值较高,具有亏损地幔组分特征,为古生代增生的新生陆壳;以西的科翁腊德和博尔雷εNd(t)值较低,主要是壳幔岩浆混合的结果,反映了古老基底的存在,主要为新元古代增生地壳。成矿带花岗岩类206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值范围分别为18.3346～20.9929、15.5213～15.7321和38.2874～40.0209,为造山带花岗岩类,具有与天山、阿尔泰和准噶尔花岗岩类的亲缘性。The Balkhash metallogenic belt in Kazakhstan is a famous porphyritic Cu-Mo metallogenic belt in the Central Asian metallogenic domain. The Late Paleozoie granitoids from Balkhash metallogenic beh are mainly of high-K ealc-alkaline and Ⅰ-type granites, with shoshonite in the late stage. Geochemistry analyses and tectonic discrimination show a change of tectonic setting from syn-collision and volcanic arc in Carboniferous to post-collision in Permian. The Late Paleozoic granitoids from Borly porphyry deposit formed in classical island-arc environment, though that from Kounrad, Aktogai and Sayak are adakitic. The εNd （t） values for the Late Paleozoic granitoids here are between -5.87 and ＋5.94, and εsr（t）values from - 17.16 to ＋51.10. The continental crustal growth histories are different on the both sides of Central Balkhash fault. On the east side, εNd （t） values from Aktogai and Sayak are very high with character of depleted mantle, suggesting the crustal growth in the Late Paleozoic. On the west side, εsd （t） values from Borly and Kounrad are slightly low, suggesting the existence of the New Proterozoic basement and the mixing of crust and mantle during magmatism. The granitoids have ^206 pb/^204 Pb, ^207 pb/^204 Pb, and ^208pb/^204 Pb values ranging in 18. 3346 - 20. 9929, 15.5213 - 15. 7321 and 38. 2874 -40. 0209, respectively, showing the affinity of the Late Paleozoic magmatism in Balkhash with that in Tianshan, Ahai and Junggar areas.

关 键 词：地壳增生 构造环境 SR-ND-PB同位素 巴尔喀什成矿带 

分 类 号：P597[天文地球—地球化学] P595[天文地球—地质学]