青海都兰县阿斯哈金矿区花岗斑岩岩石地球化学、锆石U-Pb年代学与Hf同位素研究

发布时间：2018-02-25 16:39

本文关键词： 花岗斑岩岩石地球化学 LA-ICP-MS锆石U-Pb年代学岩石成因构造环境阿斯哈金矿区东昆仑　出处：《大地构造与成矿学》2017年04期 　论文类型：期刊论文

【摘要】：阿斯哈金矿区钻孔中新发现的花岗斑岩,呈岩脉、岩株或舌状分布。岩石呈灰-灰白色,细-中粒斑状结构,块状构造。主要矿物为石英、斜长石、钾长石、黑云母及少量角闪石,副矿物有磁铁矿、钛铁矿、锆石、磷灰石和榍石等。全岩高硅(SiO_2=70.03%~72.83%),高钾(K_2O=3.96%~5.21%),低P_2O_5(0.09%~0.10%),低FeO~T/MgO(1.76~3.91),A/CNK值(1.04~1.29)多数小于1.1,为高钾钙碱性系列弱过铝质-过铝质花岗岩类岩石,具有I型花岗岩特征。样品具有轻稀土富集和中等负Eu异常(δEu=0.71~0.78)特征,且富集大离子亲石元素(LILE:K、Rb、Th、U等)、亏损高场强元素(HFSE:Nb、Ta、Ti等)。LA-ICP-MS锆石U-Pb定年结果显示,其结晶年龄为222.1±3.9 Ma(MSWD=5.4,n=15),形成于晚三叠世。锆石Hf同位素组成(ε_(Hf)(t)=-4.3~-1.4)和二阶段Hf模式年龄(t_(DM2)=1.34~1.53 Ga),表明新发现的花岗斑岩源于古老地壳物质的深熔或重熔,并可能有幔源物质的加入。上述特征表明,阿斯哈金矿区花岗斑岩形成于东昆仑晚古生代-早中生代构造-岩浆旋回的碰撞晚期-后碰撞阶段,可能是晚三叠世幔源岩浆底侵下地壳岩石部分熔融的产物,并在形成过程中有幔源物质的加入。此外,研究区花岗斑岩的侵位与沟里地区(包括阿斯哈)金多金属矿床的形成具有内在的联系。
[Abstract]:The newly discovered granitic porphyry, distributed in vein, plant or tongue, is of gray-gray-white structure, fine-grained porphyry structure and block structure in the Asaha gold ore area. The main minerals are quartz, plagioclase, potash feldspar, the main minerals are quartz, plagioclase, potash feldspar. Biotite and a small amount of amphibole, minor minerals such as magnetite, ilmenite, zircon, apatite and sphene etc. The samples have the characteristics of light rare earth enrichment and moderate negative EU anomaly (未 Eu0.71 ~ 0.78), and the enrichment of large ion lithophile element LILE: K ~ (+) RbSU, etc., and the depletion of the high field strength element, HFSE: NbLi ~ (1) Ti, et al. LA-ICP-MS zircon U-Pb dating results show that the high field strength elements of the samples are characterized by zircon U-Pb dating. The crystallization age is 222.1 卤3.9 MaMSWDV 5.4NU 15G, formed in the late Triassic. The zircon HF isotopic composition (蔚 ~ + HfTU) -4.3 ~ (-1.4) and the two-stage HF model age ~ (-1) D _ (2) O ~ (1) ~ (34) ~ (1.53) Gaa indicate that the newly discovered granitic porphyry originated from the deep or remelting of the ancient crustal material, and the results show that the new type of granite porphyry originated from the deep melting or remelting of the ancient crustal material. The above characteristics indicate that the granitic porphyry was formed in the late Paleozoic to early Mesozoic tectonic-magmatic cycle of East Kunlun during the late collisional and post-collision stages, the characteristics of which indicate that the granitic porphyry was formed in East Kunlun during the late Paleozoic to early Mesozoic tectonic and magmatic cycles. It may be the product of partial melting of crust rock in late Triassic mantle magma submersion, and the addition of mantle source material in the formation process. In addition, The emplacement of granitic porphyry in the study area is intrinsically related to the formation of gold polymetallic deposits in Gouli area (including Asha).
【作者单位】：中化地质矿山总局云南地质勘查院;云南大学资源环境与地球科学学院;昆明理工大学国土资源工程学院;昆明理工大学资产管理处;
【基金】：国家自然科学基金(41272111) 山东黄金集团基本科研业务费专项基金(201122010100)联合资助
【分类号】：P597;P618.51

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