| 拉萨地体南缘桑日地区晚白垩世火山岩的年代学、岩石地球化学及成因 |
| 投稿时间：2022-01-20 修订日期：2022-03-01 |
| 关键词:southern margin of the Lhasa Terrane Sangri area Late Cretaceous Neo-Tethys ocean Volcanic rocks |
| 基金项目:四川省科技计划项目(2020JDJQ0042)、国家自然科学基金(41502079、41972084)、国家重点研发计划课题(2018YFC0604105)、成都理工大学珠峰科学研究计划(2020ZF11047)、西北大学大陆动力学国家重点实验室开放基金(18LCD04)、自然资源部深地资源成矿作用与矿产预测重点实验室开放基金(ZS1911)、中国地质调查局项目(DD20190167、DD20160346). |
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| 摘要: |
| Chronology, geochemical characteristics, and genesis of Late Cretaceous volcanic rocks in Sangri area, southern margin of the Lhasa Terrane |
| Intermediate-acid volcanic rocks are widely exposed in Sangri area of the southern margin of Lhasa terrane. The superposition of multiple magmatic activities makes the magmatic rocks in the area complex in composition and large span in age. In order to study the formation age，tectonic setting and genetic mechanism of volcanic rocks in this area，we selected the intermediate-acid volcanic rocks near Tamu Village in the west of Sangri County as the research object，and carried out zircon U-Pb dating，whole rock major and trace elements, and Sr-Nd isotope analysis. The contents of SiO2 and MgO in Late Cretaceous volcanic rocks in Sangri area are 55.79%-74.26% and 1.31%-4.34%，respectively. They also have high Sr (average 779×10-6)，low Y (8.36×10-6 ~ 15.8×10-6)，Yb (0.92×10-6 ~ 1.38×10-6) and high Sr/Y ratio (36.28 ~ 105.59). Geochemical characteristics show that the Late Cretaceous volcanic rocks in Sangri area are adakite rocks. At the same time，the Late Cretaceous Sangri volcanic rocks in Sangri area are enriched in LILE elements of Rb，Sr and Pb，and depleted in HFSE of Nb，Ta and Ti，with low initial values of 87Sr/86Sr (0.704152 ~ 0.704515) and high initial values of 143Nd/144Nd (0.512676 ~ 0.512750). Based on petrogeochemical characteristics and regional geological data，the Late Cretaceous volcanic rocks in Sangri area were formed in an active continental margin related to the northward subduction of the Neo-Tethyan oceanic crust，and were the products of partial melting of the Neo-Tethyan oceanic crust. During the rising process of ocean crust melt， the material of mantle wedge was added and underwent separation crystallization. |
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