投稿时间：2017-02-28
修订日期：2017-07-26
网络发布日期：2017-12-28
中文摘要:喀拉通克镁铁质岩体群位于准噶尔地块东北缘，由13个小岩体组成。在以往的研究中，这些岩体多被视为同期形成。笔者新获得的锆石SHRIMP U-Pb年龄显示，镁铁质岩体群发育晚石炭世和早二叠世2个时期的岩体，其中Y3岩体闪长岩、苏长岩以及G21岩体淡色辉长岩的年龄分别为290 Ma、283 Ma和281 Ma，与Y1和Y9含矿岩体的年龄在误差范围内一致；Y5岩体辉长岩和闪长岩的年龄均为320 Ma，明显早于其他岩体。结合区域构造演化资料分析，晚石炭世Y5岩体是俯冲环境下岩浆作用的产物，这与以往研究较多的早二叠世后碰撞伸展环境下形成的岩体不同。在该矿区，具有工业价值的硫化物矿体主要赋存在Y1~Y3以及Y9岩体中，其中Y1和Y9岩体中富硫化物的矿体主要分布在岩体中部，而Y2和Y3岩体中矿体主要分布在底部的苏长岩中，在Y1-Y2以及Y2-Y3岩体结合部位均可见块状矿体。矿体空间分布及其与通道对应关系显示镁铁质含矿岩体可能形成于不同的岩浆通道系统或通道的不同部位。矿物学变化显示Y3、Y9和G21演化程度相对高于Y1和Y2岩体；同时，前者硫化物矿石多为中等稀疏浸染状和星点状，后者多为稠密浸染状和块状矿石，且前者浸染状矿石的Ni/Cu比值（0.15~2.00）总体小于后者（0.14~4.48）。上述特征表明含矿岩体的岩浆相对演化程度与矿化富集程度有一定的关系。综合分析地质、物探资料以及成矿特征，笔者认为Y1-Y3岩体深部仍具有寻找成矿岩体的潜力。G21岩体的演化程度较高，但具有与Y2、Y3岩体相似的重力异常和源区性质，推测该地段深部可能存在体积更大的岩体。
Abstract:The Kalatongke mafic intrusions, which consist of 13 small intrusions, numbered as Y1~Y11, G21 and G22, are located on the northern margin of Junggar terrane. Due to their spatial proximity and similar lithologies, these intrusions were previously considered to be coeval in previous studies. In this paper the authors report the first zircon SHRIMP U-Pb ages for the diorite and norite in the Y3 intrusion (290 Ma and 283 Ma, respectively) and the leucogabbro in the G21 intrusion (281 Ma), which are identical to the zircon U-Pb ages for the sulfide-bearing norite and gabbro units of the Y1 and Y9 intrusions. The zircon U-Pb ages for diorite and gabbro in the Y5 intrusion are 320 Ma, obviously earlier than the ages of the other intrusions. The chronological data of mafic intrusions in the Kalatongke area show that the mafic intrusions can be divided into two stages, i.e., Late Carboniferous and Early Permian. Together with the holistic geological records, the authors hold that the Kalatongke Y5 intrusion was formed in a subduction setting, different from things of other Permian intrusions in the Kalatongke area. Significant sulfide mineralization was found in Y1, Y2, Y3 and Y9 mafic intrusions. In Y1 and Y9 intrusions, the sulfide orebody occurs in the lower and central parts of the intrusion, whereas in Y2 and Y3 intrusions, the sulfide orebody is close to the base of both intrusions. In addition, some massive sulfide orebodies were found between Y1 and Y2 as well as Y2 and Y3. The different orebody features indicate that sulfur-bearing intrusions in the Kalatongke area might have been formed in more than one magma conduit or in different parts of the magma conduit. The variation of mineralogical characteristics indicates that the parental magma of Y3, Y9 and G21 evolved in higher degree than Y1 and Y2 intrusions. In addition, heavy disseminated and massive sulfide ores are always observed in the Y1 and Y2 deposits, whereas weakly disseminated sulfide ores are always found in the Y3 and G21 deposits, and the disseminated sulfide ores of the former have higher Ni/Cu ratios than that of the latter. The correlation suggests that there exists the relationship between the degree of evolution of the parental magmas and the enrichment of mineralization. Geological and geophysical data as well as mineralization suggest that the Y1-Y3 intrusions still have exploration potential at depth. Although the parental magmas for the G21 intrusion are more fractionated than those for the Y1, Y2 and Y3 intrusions, the G21 intrusion is similar to Y2 and Y3 intrusions in the aspects of the gravity anomaly and source characteristics. It is thus proposed that there may exist a large-scale intrusion beneath the G21 intrusion.
keywords:geology zircon SHRIMP U-Pb age mafic intrusions metallogenic feature ore exploration at depth Kalatongke Ni-Cu deposits
文章编号：
中图分类号：P618.41;P618.63
文献标志码：
基金项目:国家自然科学面上基金（编号：41372101）和长安大学中央高校基金（编号：CHD310827171007）的联合资助
引用文本：
冯延清,钱壮志,段俊,焦建刚,徐刚,任萌,陈炳龙.2017.新疆喀拉通克铜镍矿镁铁质岩体形成时代、成矿特征与深部找矿前景[J].矿床地质,36(6):1387~1401FENG YanQing,QIAN ZhuangZhi,DUAN Jun,JIAO JianGang,XU Gang,REN Meng,CHEN BingLong.2017.Formation age,metallogenic features and exploration prospect in the deep part of the Kalatongke Cu-Ni deposits, Xinjiang[J].Mineral Deposits36(6):1387~1401
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