| 武雪梅,张志平,雒晓刚,周彦慧,刘晓涛,汪宏涛,王晓东.西藏桑耶寺北岗结则雄花岗闪长岩体年代学、地球化学特征及地质意义[J].矿产勘查,2019,(6):1339-1350 |
| 西藏桑耶寺北岗结则雄花岗闪长岩体年代学、地球化学特征及地质意义 |
| The chronology, geochemical characteristics and geological significance of the Granodiorite in gangjiezexiong, north of sangye temple, Tibet |
| 投稿时间：2019-01-10 |
| DOI：10.1130/B26033.1. |
| 中文关键词: Ⅰ型花岗岩 地球化学特征 锆石U-Pb 板片回转 桑耶寺北 |
| 英文关键词: I type granodiorite, geochemical characteristics, zircon U-Pb, plate rotation, north of sangye temple |
| 基金项目:中国地质调查局项目(编号:121201010000150014-46、DD20160015-08)联合资助。 |
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| 中文摘要: |
| 桑耶寺北岗结则雄花岗闪长岩体位于冈底斯岩浆岩带中段,为确定该花岗闪长岩的形成时代、源区性质和构造背景,对其进行了LA-ICP-MS锆石U-Pb年代学和岩石地球化学研究。结果显示岩体侵位时间为50.29±0.42Ma,属于始新世。岩石SiO2含量为58.31%～62.3%,Na2O、K2O含量分别为3.08%～3.57%和2.59%～3.56%,岩石碱值NK/A为0.51%～0.59%,铝饱和指数A/CNK为0.85%～1.06%,属准铝质-过铝质系列岩石。稀土元素分布模式为轻稀土富集,负Eu异常明显。岩石富集大离子亲石元素Rb、Ba、K、U、Th,亏损高强场元素Nb、P、Ti等。以上特征表明,岩石为高钾钙碱性的I型花岗岩,结合岩石成岩年龄、地球化学特征以及区域构造演化,岗结则雄花岗闪长岩岩浆源区为下地壳基性岩部分熔融的产物,是印度-欧亚板块碰撞过程中一复杂地质过程的岩浆作用产物,可能与新特提斯洋板片回转有关。 |
| 英文摘要: |
| Gangjiezexiong Granodiorite in the north of sangye temple located in the middle part of gangdise magma belt. In order to determine the formation time, magma sources and tectonic setting of the tonalite,the paper analyzed the zircon LA-ICP-MS U-Pb age, isotope data and geochemistry of tonalite. The results show that the pluton emplacement time is 50.29±0.42 Ma, which is era of Eocene. The contents of SiO2(58.31%~62.3%), Na2O(3.08%~3.57%), K2O(2.59%~3.56%), NK/A (0.51%~ 0.59%) and A/CNK(0.85-1.06) in tonalite indicate that the tonalite belongs to a series of quasi-aluminous or –superalumil rocks. The distribution modes of REE is that there is a deficit in LREE and a strong negative Eu anomaly. The tonalite is characterized by the enrichment of LILEs (Rb、Ba、K、U and Th), relative depleting in elements(Nb, P ,Ti).Above features show that the rocks are I-type granites of calc-alkaline or high-K calc-alkaline. Combined the geochronological data, geochemical characteristics and the regional tectonic evolution, with the magmatic arc characteristics of rocks, it can be concluded that gangjiezexiong Granodiorite, the magmatic source area is the product of partial melting of basic rocks in the lower crust, and is the magmatic product of a complex geological process during the indo-eurasian plate collision, which may be related to the neo-tethyan plate rotation |
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