东昆仑造山带早中生代幔源岩浆事件及其地质意义

发布时间：2018-05-15 06:43

本文选题：锆石U-Pb年龄 + 幔源岩浆　；参考：《地质与勘探》2017年05期

【摘要】：东昆仑造山带早中生代幔源岩浆底侵不仅为花岗岩类的广泛发育提供了能量和物质基础,也为厘定区域构造环境提供了新的约束。本文对区域上发育的小尖山岩体、拉陵高里沟脑2、3号岩体开展了精确的锆石U-Pb年代学研究,并与区域上镁铁质岩体做了对比。LA-ICP-MS U-Pb定年结果表明,小尖山岩体磁黄铁矿化辉长岩锆石~(206)Pb/~(238)U-~(207)Pb/~(235)U谐和年龄为247.1±1.1Ma,与前人获得的中细粒辉长岩年龄相差20Ma,暗示该岩体为多期岩浆活动的产物。拉陵高里沟脑2号和3号岩体辉长岩锆石~(206)Pb/~(238)U-~(207)Pb/~(235)U谐和年龄分别为(244.9±1.6)Ma和(238.4±4.1)Ma,二者年龄在测试误差范围内一致,为同期岩浆作用的产物。结合区域上已知镁铁质岩体的形成时代及地球化学特征,认为早中生代幔源岩浆形成于后碰撞伸展环境,活动时限为251~221Ma。该期幔源岩浆与地壳物质发生了广泛的物质与能量交换,是今后该区铜镍矿勘查的重要对象之一。
[Abstract]:The early Mesozoic mantle magmatic underplating in the East Kunlun orogenic belt not only provides the energy and material basis for the extensive development of granites, but also provides a new constraint for determining the regional tectonic environment. In this paper, the zircon U-Pb dating of the Xiaojianshan and Lalinggaoligounao 2 and 3 intrusions developed in the region has been carried out, and the results of U-Pb dating show that the zircon dating results are compared with those of the magnesite bodies in the region. The zircon of pyrrhotite pyroxene in Xiaojianshan is 247.1 卤1.1 Ma, indicating that it is the product of multi-stage magmatic activity. The harmonic age of pyrrhotite is 247.1 卤1.1 Ma. which indicates that the pyroxene is a product of multi-stage magmatic activity. The corresponding ages of gabbro zircon of Laling Gaoligou No. 2 and No. 3 are 244.9 卤1.6)Ma and 238.4 卤4.1 Ma, respectively, which are the same age range of magmatism and are the products of simultaneous magmatism, and the corresponding ages are 244.9 卤1.6)Ma and 238.4 卤4.1 Ma, respectively. They are the products of simultaneous magmatism. Based on the known age and geochemical characteristics of the magnesite in the region, it is considered that the early Mesozoic mantle-derived magma was formed in a post-collision extensional environment with a time limit of 251 ~ 221 Ma. In this period, the mantle magma and crustal material exchange widely, which is one of the important objects for the exploration of copper-nickel deposits in this area in the future.
【作者单位】：国土资源部岩浆作用成矿与找矿重点实验室中国地质调查局西安地质调查中心;
【基金】：国土资源部公益性行业科研专项项目(201511020) 国家自然科学基金(青年)项目(41402071,41302052) 中国地质调查局地质矿产调查项目(DD20160013)联合资助
【分类号】：P542;P597.3;P612

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