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西藏嘎拉勒铜金矿床作为构造背景反演指示针的成岩成矿年代学研究较为匮乏,使得该成矿带区域背景-构造-岩浆-成矿活动系列研究步履维艰,利用LA-ICP-MS(laser ablation inductively coupled plasma mass spectrometry)锆石U-Pb测年、辉钼矿Re-Os定年及Lu-Hf同位素技术,首次全面厘定了区内侵入岩侵位时序、探讨了岩石成因并确定了成矿时代.结果表明,成矿前闪长岩成岩年龄为155.8±2.3Ma,侵位于晚侏罗世初期,εHf(t)值分布于-14.68~-8.34,平均值-11.74,是班公湖-怒江特提斯洋南向俯冲的产物;花岗闪长岩为矿区成矿母岩,其成岩年龄为88±1Ma(MSWD=0.56,n=21),εHf(t)值分布于5.84~9.20,平均值7.72,成矿后花岗斑岩成岩年龄为84.67±0.80Ma(MSWD=1.9,n=18),εHf(t)值分布于6.32~9.78,平均值8.40,二者均为晚白垩世侵位,为拉萨地体与羌塘地体汇聚的产物;矿区辉钼矿Re-Os等时线年龄为88.55±0.60Ma(MSWD=0.60,n=8),与成矿母岩(花岗闪长岩)成岩年龄一致.研究表明,在班公湖-怒江特提斯洋南向俯冲至碰撞过程中在矿区内均有相应的岩浆活动响应,嘎拉勒铜金矿床则为典型的碰撞期成矿作用的产物.
The study of the Galalá copper-gold deposit in Tibet as a tectonic background inversion indicator is lack of diagenesis and metallogenic chronology, making the research on the background-tectono-magmatic-ore-forming activity of the metallogenic belt difficult, using LA-ICP-MS the U-Pb dating of zircon, the Re-Os dating of molybdenite and the Lu-Hf isotope technique, the sequence of intrusive emplacement in the area was first fully determined and the genesis of the rock was discussed. The results show that the diagenetic age of the former diorite was 155.8 ± 2.3Ma and the invasion was located in the early stage of Late Jurassic. The εHf (t) values ranged from -14.68 to -8.34 with an average of -11.74. - the southward tectonic subduction of the Tethys Ocean in the Nujiang River; granodiorite is a metallogenic host rock with a mineralization age of 88 ± 1 Ma (MSWD = 0.56, n = 21) and εHf (t) 9.20, with an average of 7.72. The granitic porphyry diagenetic age after mineralization was 84.67 ± 0.80Ma (MSWD = 1.9, n = 18), εHf (t) was distributed between 6.32 and 9.78 with an average of 8.40, The Cretaceous emplacement is the product of convergence between the Lhasa terrane and the Qiangtang terrane. The Re-Os isochron age of molybdenite is 88.55 ± 0.60Ma (MSWD = 0.60, n = 8) The study shows that there is a corresponding magmatic activity response in the mining area during the subduction to strike of the Tengchong-Nujiang Tethys Ocean, while the Galalé copper-gold deposit is typical The product of mineralization during the collision.