段丰浩,李永军,2,王冉,2,纪征宝,程万里,郭鑫
(1.长安大学地球科学与资源学院,陕西 西安 710054;2.西部矿产资源与地质工程教育部重点实验室,陕西 西安 710054;
西准噶尔托里县都伦河东岩体锆石U-Pb年龄及地质意义
段丰浩1,李永军1,2,王冉1,2,纪征宝3,程万里1,郭鑫1
(1.长安大学地球科学与资源学院,陕西 西安 710054;2.西部矿产资源与地质工程教育部重点实验室,陕西 西安 710054;
3.新疆维吾尔自治区地质矿产勘查开发局第七地质大队,新疆 乌苏 833000)
西准噶尔地体晚古生代岩浆活动强烈,其中以达尔布特构造-岩浆带最为显著。近年来,对该带大岩基研究较多,而对该带小岩体的研究主要集中在包古图一带成矿斑岩上,对其余小岩体研究较为局限。位于西准噶尔托里县的都伦河东岩体内外接触带有较强的孔雀石化、硅化、碳酸盐化、绿泥石化、黄铁矿化等蚀变与矿化,岩体内部发育镁铁质微粒包体。本次于寄主石英闪长岩中获得(312.6±4.2)Ma(n=21,MSWD=0.15,95%置信度)的LA-ICP-MS锆石U-Pb年龄,其与包古图小岩体(Au-Cu矿化)和夏尔莆小岩体(Cu-Mo矿化)的成岩时代基本一致,各岩体形成的构造环境大致相同。该可靠年龄为研究本区与小岩体有关,与岩浆混合作用有关的Au-Cu-Mo成矿作用时代提供了年代学约束。
岩浆混合花岗岩;锆石U-Pb年龄;成矿作用时代;都伦河东岩体;西准噶尔
西准噶尔地区产出大量的中酸性侵入岩,其中以达尔布特构造-岩浆带最为显著。除少数岩体研究程度较高以外,大部分岩体研究程度均很低。根据产状可将这些侵入体分为以庙尔沟、阿克巴斯陶、红山、克拉玛依岩体等为代表的以巨大岩基形式产出的花岗岩体和以包古图Ⅱ号、V号岩体等为代表的以小岩株或岩脉形式产出的小岩体(图1)。近年来,对该带出露的大岩基研究较多(伍建机等,2001;韩宝福等,2006;高山林等,2006;庞振甲等,2010;贺敬博等,2011;冯乾文等,2012;高睿等,2013;胡洋等,2015),而对出露的小岩体(岩脉)研究较为局限,且主要集中在包古图一带的含矿斑岩上(张连昌等,2006;宋会侠等,2007;唐功建等,2009;刘玉琳等,2009;Shen et al., 2009,2012;申萍等,2010;魏少妮等,2011,2015;尹继元等,2013),对同一构造-岩浆带上的其他小岩体研究较少。
都伦河东岩体位于西准噶尔托里县扎依尔山阔依塔斯地区,前人对该岩体研究工作只停留在野外地质调查上,尚缺乏高精度的同位素年代学资料,很大程度上制约了区域岩浆活动和构造演化的研究。本次研究主要对都伦河东岩体中石英闪长岩进行锆石U-Pb年代学工作,确定该岩体的精确侵位时代,为探讨达尔布特构造-岩浆带铜、金金属成矿提供年代学证据。
都伦河东岩体位于达尔布特断裂西南端,呈不规则椭圆状,长轴近南北向,长约5.5km,东西约3.8km,出露面积约18km2,侵入于石炭纪地层中(图1a),与围岩多为港湾状外倾接触。围岩局部有混染交代现象,岩体外接触带往往呈较深色调,是由接触变质导致的角岩化等蚀变引起。围岩蚀变较发育,岩石呈碎裂状,内外接触带有较强的孔雀石化、硅化、碳酸盐化、绿泥石化、黄铁矿化等蚀变与矿化。笔者等在野外地质工作中,首次发现都伦河东岩体为岩浆混合花岗岩,这是继夏尔莆岩浆混合花岗岩(张兵等,2009;李永军等,2013)之后,西准地区再次发现的发育镁铁质微粒包体的岩浆混合花岗岩体。寄主岩石主要为一套中粒石英闪长岩、中粗粒花岗闪长岩、中粗粒黑云母花岗闪长岩组合。镁铁质微粒包体岩性主要为闪长(玢)岩,细粒-微粒结构,粒径大都小于1mm,多为0.5~0.8mm,部分包体粒径可达到1.5~2mm,但粒度总体来说要比其寄主岩石细,两者相差近一个数量级。包体大小不一,相差悬殊,形态主要有椭圆状、浑圆状,部分呈透镜状以及撕裂状,部分包体呈现出“拖尾”等流线型形态。此外,野外露头尺度上显示包体与寄主岩石强烈成分交换的现象极为普遍,包体中还可见寄主岩石斜长石捕掳晶(图2)。镁铁质包体在寄主岩石中均有分布但极不均匀,其中花岗闪长岩中镁铁质包体数量最少,出露面积仅占整体的0.1%左右,分布零星;黑云母花岗闪长岩中包体数量也极少,出露面积约占整体的0.3%;石英闪长岩中包体最为发育,数量最多,出露面积约占整体的15%。包体越密集分布的岩石,其寄主岩石基性程度越高,这与经典的岩浆混合花岗岩体中包体分布规律基本相同(朱金初等,2006;李永军等,2013)。
图1 都伦河东岩体地质简图Fig.1 The geological map of the Dulunhe granite
(a).包体中斜长石捕掳晶; (b).包体与寄主岩石强烈成分交换; (c).石英闪长岩; (d).花岗闪长岩 Pl.斜长石; Qz.石英; Am.角闪石; Bi.黑云母图2 都伦河东岩体岩浆混合特征及镜下显微照片Fig.2 The Macroscopic characteristics of magma mixing and Microscopic photos of the Dulunhe granite
用于LA-ICP-MS锆石U-Pb测年的样品采自都伦河东岩体近中心部位寄主石英闪长岩中(样品编号DLHRZ1-1)。采样点坐标:北纬45°14.422',东经83°14.165′(图1a)。
锆石分选在廊坊诚信地质服务有限公司完成。首先使用重液浮选和电磁分离方法挑选锆石,在双目镜下挑选出晶形和透明度较好的代表性锆石以环氧树脂固定制成样品靶,抛光至暴露出锆石中心面,用反射光、透射光照相。然后用体积百分比为3%的HNO3清洗样品并镀碳,进行阴极发光(CL)照相。照相之后用3%的HNO3清洗靶标的表面。
锆石的激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)原位U-Pb定年在西北大学大陆动力学国家重点实验室完成。实验采用的ICP-MS为美国Agilent 公司生产的Agilent 7500 a,激光剥蚀系统为德国M-icroLas公司生产的GeoLas 200 M,激光剥蚀束斑直径约为30μm,激光剥蚀样品的深度为20~40 μm。锆石年龄采用标准锆石91 500作为外部标准物质。笔者择29Si作为内标,采用Glitter(ver4.0,Macquarie University)对锆石的同位素比值及元素含量进行计算,最终的年龄计算及谐和图是采用Isoplot(ver3.0)完成的,详细的实验原理和流程及仪器参数参见(柳小明等,2002;YUAN et al.,2008)。
本次处理所获得的的石英闪长岩锆石大多为无色透明或浅黄色,晶形发育较好,多呈长柱状、正方双锥状自形晶体,长约100~250μm,宽约80~160μm,长宽比3∶1~1∶1;阴极发光图像(图3)显示大部分锆石均具有清晰的内部结构和典型的岩浆震荡环带以及明暗相间的条带结构,属于岩浆结晶锆石(吴元保等,2004),可以反映岩浆冷却结晶及岩体侵位的时代。
图3 都伦河东岩体石英闪长岩中典型锆石阴极发光(CL)图像Fig.3 CL images of zircon gains from the quartiz diorite of the Dulunhe granite
锆石U-Pb测试分析结果列于表1。21个样品点的207Pb/206Pb值非常接近(0.051 95~0.053 70),表明该批锆石为同期岩浆成因锆石。
21个样品的Th含量为21.97×10-6~448.42×10-6,U含量为45.06×10-6~456.92×10-6,Th/U值较高(0.34~0.98),并呈现出较好的正相关,指示锆石属典型岩浆成因(吴元保等,2004)。21个测点年龄值较集中,206Pb/238U年龄为(312.6±4.2)Ma(n=21,MSWD=0.15,95%置信度,图4),时代为晚石炭世早期。
西准噶尔地区晚古生代岩浆活动强烈,时代主要集中在石炭纪—早二叠世(韩宝福等,2006;苏玉平等,2006;Tang et al., 2010;尹继元等,2011;Geng et al., 2009)。从成岩时代上看,以碱性花岗岩类为主的大岩基时代主要集中在308~296Ma(韩宝福等,2006;苏玉平等,2006;Geng et al., 2009),而对于以石英闪长岩和花岗闪长岩等为主的中酸性小岩体而言,前人研究主要局限在包古图一带的含矿斑岩上。本次研究获得的都伦河东岩体成岩时代,与该岩体侵入于早石炭世希贝库拉斯组这一地质事实相吻合。该结果也与近年来报道的包古图一带小岩体的成岩时代(310~320Ma)(宋会侠等,2007;刘玉琳等,2009;唐功建等,2009;申萍等,2010;魏少妮等,2011,2015;Shen et al., 2012;张照伟等,2014)基本一致,证实这些小岩体是近同期形成的,略早于区域大岩基的成岩时代,且两者均位于达尔布特深大断裂两侧,成因相近。因此,推断其与包古图一带的小岩体相似,是俯冲作用的产物。
图4 (a)都伦河东岩体石英闪长岩锆石U-Pb谐和图和(b)年龄直方图Fig.4 (a) Concordia plots of zircon U-Pb dating results and (b)age histogramof the quartiz diorite of the Dulunhe granite
都伦河东岩体位于西准噶尔铜、钼、金成矿带(何国琦等,2006;朱永峰等,2007,2014),铜、金矿床大多赋存于晚泥盆世—石炭纪岩浆岩中(王强等,2006;朱永峰等,2007;申萍等,2008)。包古图中酸性小岩体和脉岩的成岩时代为310~320Ma(宋会侠等,2007;刘玉琳等,2009;唐功建等,2009;申萍等,2010;魏少妮等,2011,2015),包古图斑岩型铜矿中辉钼矿Re-Os同位素年龄为(310±3.6)Ma(宋会侠等,2007)和(316.0±6.4)Ma(刘玉琳等,2009);夏尔莆岩体成岩时代为297.6~300.8Ma(李永军等,2013;Wang et al.,2013),其铜-钼矿Re-Os同位素年龄为(294.6±4.6)Ma(Wang et al.,
2013),其成岩与成矿年龄仅相差几个百万年,成因关系密切。和夏尔莆岩体一样,都伦河东岩体在成岩过程中显著的壳幔岩浆混合作用与铜、钼、金矿化关系密切(李永军等,2012;王玉往等,2012;邢丽萍等,2014)。此外,都伦河东岩体内外接触带较强的孔雀石化、硅化、碳酸盐化、绿泥石化、黄铁矿化等蚀变与矿化,以及与镁铁质微粒包体密切共生关系等,为成矿作用研究提供了新信息。因此探讨都伦河东岩体的精确锆石U-Pb年龄可为本区铜、钼、金矿化时代提供年代学约束。
都伦河东岩体LA-ICP-MS锆石U-Pb年龄为(312.6±4.2)Ma,形成于晚石炭世早期,与包古图一带小岩体成岩时代基本一致。综合本区区域岩浆活动、构造演化等成果,笔者等认为都伦河东岩体可能形成于对成矿极为有利的俯冲相关环境,与西准噶尔达尔布特构造-岩浆带铜、金等成矿作用关系密切,显示较好的成矿潜力,值得进一步研究。
致谢:论文撰写过程中得到了长安大学杨高学副教授的帮助和建议,审稿专家为笔者提出了宝贵的意见和建议,在此对他们的帮助表示真诚的感谢!
冯乾文,李锦轶,刘建峰,等.新疆西准噶尔红山岩体及其中闪长质岩墙的时代:来自锆石LA-ICP-MS定年的证据[J].岩石学报,2012,28(9):2935-2949.
FENG Qianwen,LI Jinyi,LIU Jianfeng,et al. Ages of the Hongshan granite and intruding dioritic dyke swarms,in western Junggar,Xinjiang,NW China: Evidence form LA-ICP-MS zircon chronology[J].Acta Petrologica Sinica,2012,28(9):2935-2949.
高山林,何治亮,周祖翼.西准噶尔克拉玛依花岗岩体地球化学特征及其意义[J].新疆地质,2006,24(2):125-130.
GAO Shanlin,HE Zhiliang,ZHOU Zuyi. Geochemical Characteristics of the Karamay Granitoids and their Significance in West Junggar,Xinjiang[J].Xinjiang Geology,2006,24(2):125-130.
高睿,肖龙,王国灿,等.西准噶尔晚古生代岩浆活动和构造背景[J].岩石学报,2013,29(10):3413-3434
GAO Rui,XIAO Long,WANG Guocan,et al. Paleozoic magmatism and tectonic setting in West Junggar[J]. Acta Petrologica Sinica,2013,29(10):3413-3434.
韩宝福,季建清,宋彪,等.新疆准噶尔晚古生代陆壳垂向生长(Ⅰ)—后碰撞深成岩浆活动的时限[J].岩石学报,2006,22(5):1077-1086.
HAN Baofu,JI Jianqing,SONG Biao,et al. Late Paleozoic vertical growth of continental crust around the Junggar Basin,Xinjiang,China (Part Ⅰ):Timing of post-collisional plutonism[J].Acta Petrologica Sinica,2006,22(5):1077-1086.
贺敬博,陈斌.西准噶尔克拉玛依岩体的成因:年代学、岩石学和地球化学证据[J].地学前缘,2011,18(2):191-211.
HE Jingbo,CHEN Bin. Petrogenesis of Karamay plutons in the west Junggar:Constraints from geochronology,petrology and geochemistry[J].Earth Science Frontiers,2011,18(2):191-211.
胡洋,王居里,王建其,等.新疆西准噶尔庙尔沟岩体的地球化学及年代学研究[J].岩石学报,2015,31(2):505-522.
HU Yang,WANG Juli,WANG Jianqi,et al. Geochemistry and geochronology of the Miaoergou granite pluton in West Junggar,Xinjiang[J].Acta Petrologica Sinica,2015,31(2):505-522.
何国琦,朱永峰.中国新疆及邻区地质矿产对比研究[J].中国地质,2006,33(3):451-460.
HE Guoqi,ZHU Yongfeng. Comparative study of the geology and mineral resources in Xinjiang,China,and its adjacent regions[J].Geology in China,2006,33(3):451-460.
刘玉琳,郭丽爽,宋会侠,等.新疆西准噶尔斑岩铜矿年代学研究[J].中国科学D辑:地球科学,2009,39(10):1466-1472.
LIU Yulin,GUO Lishuang,SONG Huixia,et al. Geochronology of Baogutu porphyry copper deposit in Western Junggar area[J].Sci China Ser D-Earth Sci,2009,39(10):1466-1472.
李永军,王冉,李卫东,等.西准噶尔达尔布特南构造—岩浆岩带斑岩型铜—钼矿新发现及找矿思路[J].岩石学报,2012,28(7):2009-2014.
LI Yongjun,WANG Ran,LI Weidong,et al. Discovery of the porphyry copper-molybdenum deposits and prospecting reflections in southern Darbut teoctonic magmatic belts,West Junggar, China[J].Acta Petrologica Sinica,2012,28(7):2009-2014.
李永军,李甘雨,康磊,等.西准噶尔夏尔莆岩体岩浆混合的锆石U-Pb年代学证据[J].岩石学报,2013,29(9):3023-3030.
LI Yongjun,LI Ganyu,KANG Lei,et al. Evidence of zircon U-Pb geochronology for magma mixing of Xiaerpu granite in West Junggar[J].Acta Petrologica Sinica,2013,29(9):3023-3030.
柳小明,高山,袁洪林,等. 193nm LA-ICP MS对国际地质标准参考物质中42种主量和微量元素的分析[J].岩石学报,2002,18(3):408-418.
LIU Xiaoming,GAO Shan,YUAN Honglin,et al. Analysis of 42 major and trace elements in glass standard reference materials by 193nm LA-ICP MS[J].Acta Petrologica Sinica,2002,18(3):408-418.
庞振甲,李永军,赵玉梅,等.西准阿克巴斯陶铝质A型花岗岩厘定及意义[J].新疆地质,2010,28(2):119-124.
PANG Zhenjia,LI Yongjun,ZHAO Yumei,et al. The Determination and Its Significance of Akebasitao Aluminous A-type Granites in West Junggar,Xinjiang[J].Xinjiang Geology,2010,28(2):119-124.
宋会侠,刘玉琳,屈文俊,等.新疆包古图斑岩铜矿矿床地质特征[J].岩石学报,2007,23(8):1981-1988.
SONG Huixia,LIU Yulin,QU Wenjun,et al. Geological characters of Baogutu porphyry copper deposit in Xinjiang,NW China[J].Acta Petrologica Sinica,2007,23(8):1981-1988.
申萍,沈远超,刘铁兵,等.新疆西北缘晚古生代金铜成矿作用与构造演化[J].岩石学报,2008,24(5):1087-1100.
SHEN Ping,SHEN Yuanchao,LIU Tiebing,et al. Late Paleozoic gold and copper mineralization and tectonic evolution in northwestern Xinjiang,China[J].Acta Petrologica Sinica,2008,24(5):1087-1100.
申萍,沈远超,潘成泽,等.新疆哈图—包古图金铜矿集区锆石年龄及成矿特点[J].岩石学报,2010,26(10):2879-2893.
SHEN Ping,SHEN Yuanchao,PAN Chengze,et al. Zircon age and metallogenic characteristics of the Hatu-Baogutu Au-Cu metallogenic concentric region in Xinjiang[J]. Acta Petrologica Sinica,2010,26(10):2879-2893.
苏玉平,唐红峰,侯广顺,等.新疆西准噶尔达拉布特构造带铝质A型花岗岩的地球化学研究[J].地球化学,2006,35(1):55-67.
SU Yuping,TANG Hongfeng,HOU Guangshun,et al. Geochemistry of aluminous A-type granites along Darabut tectonic belt in West Junggar,Xinjiang[J].Geochimica,2006,35(1):55-67.
唐功建,王强,赵振华,等.西准噶尔包古图成矿斑岩年代学与地球化学:岩石成因与构造、铜金成矿意义[J].地球科学:中国地质大学学报,2009,34(1):56-74.
TANG Gongjian,WANG Qiang,ZHAO Zhenhua,et al. Geochronology and Geochemistry of the Ore-Bearing Porphyries in the Baogutu Area (Western Junggar):Petrogenesis and Their Implications for Tectonics and Cu-Au Mineralization [J].Earth Science-Journal of China University of Geosciences,2009,34(1):56-74.
伍建机,陈斌.西准噶尔庙尔沟后碰撞花岗岩微量元素和Nd-Sr同位素特征及成因[J].新疆地质,2004,22(1):29-35.
WU Jianji,CHEN Bin. Trace Element and Nd-Sr Isotope Characteristics of the Post-Collisional Granitoids from Miaoergou West Junggar,and Implication for Petrogenesis[J].Xinjiang Geology,2004,22(1):29-35.
魏少妮,程军峰,喻达兵,等.新疆包古图Ⅲ号岩体岩石学和锆石SHRIMP年代学研究[J].地学前缘,2011,18(2):212-222.
WEI Shaoni,CHENG Junfeng,YU Dabing,et al. Petrology and SHRIMP zircon ages of intrusive body Ⅲ in Baogutu Area,Xinjiang[J].Earth Science Frontiers,2011,18(2):212-222.
魏少妮,朱永峰.新疆西准噶尔包古图地区中酸性侵入体的岩石学、年代学和地球化学研究[J].岩石学报,2015,31(1):143-160.
WEI Shaoni,ZHU Yongfeng. Petrology,geochronology and geochemistry of intermediate-acidic intrusions in Baogutu area,West Junggar,Xinjiang[J].Acta Petrologica Sinica,2015,31(1):143-160.
吴元保,郑永飞.锆石成因矿物学研究及其对U-Pb年龄解释的制约[J].科学通报,2004,49(16):1589-1604.
WU Yuanbao,ZHENG Yongfei. A study on the genetic mineralogy of zircon and the constrain on the interpretation for U-Pb age [J].Chinese Science Bulletin,2004,49(16):1589-1604.
王强,赵振华,许继峰,等.天山北部石炭纪埃达克岩—高镁安山岩—富Nb岛弧玄武质岩:对中亚造山带显生宙地壳增生与铜金成矿的意义[J].岩石学报,2006,22(1):11-30.
WANG Qiang,ZHAO Zhenhua,XU Jifeng,et al. Carboniferous adakite-high-Mg andesite-Nb-enriched basaltic rock suites in the Northern Tianshan area: Implications for Phanerozoic crustal growth in the Central Asia Orogenic Belt and Cu-Au mineralization[J].Acta Petrologica Sinica,2006,22(1):11-30.
王玉往,王京彬,龙灵利,等.岩浆混合作用的类型、标志、机制、模式及其与成矿的的关系—以新疆北部为例[J].岩石学报,2012,28(8):2317-2330.
WANG Yuwang,WANG Jingbin,LONG Lingli,et al. Type,indicator,mechanism,model and relationship with mineralization of magma mixing: A case study in North Xinjiang[J].Acta Petrologica Sinica,2012,28(8):2317-2330.
邢丽萍.新疆西准噶尔夏尔莆花岗岩含矿性研究[J].地质与资源,2014,23(3):280-283.
XING Liping. Study on the Ore Potentiality of the Xiaerpu Granite in Western Junggar,Xinjiang[J].Geology and Resources,2014,23(3):280-283.
尹继元,袁超,王毓婧,等.新疆西准噶尔晚古生代大地构造演化的岩浆活动记录[J].大地构造与成矿学,2011,35(2):278-291.
YIN Jiyuan,YUAN Chao,WANG Yujing,et al. Magmatic Records on the Late Paleozoic Tectonic Evolution of Western Junggar,Xinjiang[J].Geotectonica et Metallogenia,2011,35(2):278-291.
尹继元,陈文,喻顺,等.西准噶尔包古图富镁闪长质岩墙的时代、地球化学特征以及铜金成矿意义[J].中国地质,2013,40(4):1030-1043.
YIN Jiyuan,CHEN Wen,YU Shun,et al. Age,geochemical features and Cu-Au mineralization significance of the magnesian dioritic dykes in Baogutu area of west Junggar[J].Geology in China,2013,40(4):1030-1043.
张连昌,万博,焦学军,等.西准包古图含铜斑岩的埃达克岩特征及其地质意义[J].中国地质,2006,33(3):626-631.
ZHANG Lianchang,WAN Bo,JIAO Xuejun,et al. Characteristics and geological significance of adakitic rocks in copper-bearing porphyry in Baogutu,western Junggar[J].Geology in China,2006,33(3):626-631.
张兵,康磊,王晓刚,等.新疆西准噶尔夏尔莆岩体中微粒镁铁质包体特征及意义[J].新疆地质,2009,27(3):207-211.
ZHANG Bing,KANG Lei,WANG Xiaogang,et al. Features and Meaning of Mafic Microgranular Enclave in Xiaerpu Granite in West Junggar,Xinjiang[J].Xinjiang Geology,2009,27(3):207-211.
朱金初,张佩华,谢才富,等.桂东北里松花岗岩中暗色包体的岩浆混合成因[J].地球化学,2006,35(5):506-516.
ZHU Jinchu,ZHANG Peihua,XIE Caifu,et al. Magma mixing origin of the mafic enclaves in Lisong Granite,NE Guangxi,western Nanling Mountains[J].Geochimica,2006,35(5):506-516.
张照伟,李文渊,张江伟,等. 新疆天山石炭—二叠纪大规模岩浆成矿事件与形成机制探讨[J].西北地质,2014,47(1):36-51.
ZHANG Zhaowei,LI Wenyuan,ZHANG Jiangwei,et al. Mineralization and Formation Mechanism of Carboniferous-Permian Large-scale Magmatic Ore Deposits in Tianshan Orogenic Belt and Adjacent Area,Xinjiang[J].Northwestern Geology,2014,47(1):36-51.
朱永峰,何国琦,安芳.中亚成矿域核心地区地质演化与成矿规律[J].地质通报,2007,26(9):1167-1177.
ZHU Yongfeng,HE Guoqi,AN Fang. Geological evolution and metallogeny in the core part of the Central Asian metallogenicdomain[J].Geological Bulletin of China,2007,26(9):1167-1177.
朱永峰.中亚成矿域核心区地质演化和巨型成矿带划分[J].矿床地质,2014.33(3):471-485.
ZHU Yongfeng. Geological evolution and division of giant metallogenic belts in core part of Central Asian Metallogenic Region[J].Mineral Deposits,2014,33(3):471-485.
GENG Hongyan,SUN Min,YUAN Chao,et al. Geochemical, Sr-Nd and zircon U-Pb-Hf isotopic studies of Late Carboniferous magmatism in the West Junggar, Xinjiang: Implications for ridge subduction? [J].Chemical Geology,2009,266:364-389.
SHEN Ping,SHEN Yuanchao,LIU Tiebing,et al. Geochemical signature of porphyries in the Baogutu porphyry copper belt,western Junggar,NW China[J].Gondwana Research,2009,16(2):227-242.
SHEN Ping,SHEN Yuanchao,PAN Hongdi,et al. Geochronology and isotope geochemistry of the Baogutu porphyry copper deposit in the West Junggar region,Xinjiang,China[J].Journal of Asian Earth Sciences,2012,49:99-115.
WANG Ran,LI YongJun,HAN Xin,et al. U-Pb and Re-Os Geochronology of Karamay Porphyry Mo-Cu Deposit in Western Junggar,NW China[J].Resource Geology,2013,63(4):412-420.
YUAN Honglin,GAO Shan,DAI Mengning,et al. Simultaneous determinations of U-Pb age,Hf isotopes and trace element compositions of zircon by excimer laser-ablation quadrupole and multiple-collector ICP-MS[J].Chemical Geology,2008,247(1-2):100-118.
Zircon U-Pb Age and Geological Significance of Dulunhe Granite in Tuoli,Western Junggar
DUAN Fenghao1, LI Yongjun1,2, WANG Ran1,2, JI Zhengbao3, CHENG Wanli1, GUO Xin1
(1. Earth Science and Resources College, Chang’an University, Xi’an 710054, Shaanxi, China;2. Key Laboratory of Western China’s Mineral Resources and Geological Engineering,Ministry of Education, Xi’an 710054, Shaanxi, China; 3. No.7 Geological Survey Party,Xinjiang Bureau of Geology and Mineral Resource Exploration, Wusu 833000, Xinjiang, China)
There are large numbers of intrusive granites exposed along the Daerbute tectonic-magmatic belt in the center of western Junggar. Many researches have been conducted on the batholites instead of small granite intrusions, which mainly distributed in porphyry mineralization belt of the Baogutu region. Wallrock alterations such as malachitization, silicification, carbonatization, chloritization and pyritization are well developed in Dulunhe granite, which is located in Kuoyitasi area of Zayier Mountain, and abundant mafic microgranular enclaves can be found in these host rocks, however, accurate geochronology data is still insufficient. High-precision LA-ICP-MS zircon U-Pb dating reveals that the quartz diorite in the Dulunhe granite is formed at (312.6±4.2)Ma(n=21, MSWD=0.15, 95% confidence degrees) in early late Carboniferous. Combined with previous researches, the authors suggest that the age of Dulunhe granite is consistent with small granites like Baogutu granite (Au-Cu mineralization) and Xiaerpu granite (Cu-Mo mineralization); both of them are probably formed in the subduction-related setting. This reliable age provides chronology constraints for the study of regional mineralization age that related to small granite and magma mixing of Au-Cu-Mo deposit.
magma mixed granite; zircon U-Pb dating; mineralization age; Dulunhe granite; west Junggar
2015-03-14;
2015-04-29
新疆两权中央留成专项资金项目(Y14-5-LQ06)、国家自然科学基金(41303027)、中央高校基本科研业务费专项基金(2014G1271058)
段丰浩 (1991-),男,在读硕士研究生,构造地质学专业。E-mail:chddfh@163.com
P588.12
A
1009-6248(2015)03-0140-09