| 刘宗昊,康志强,杨锋,乔泽东,马诚佑,申妍菲.特提斯喜马拉雅带东部陆热地区火山岩年代学、地球化学及成因研究[J].地质找矿论丛,2024,39(2):219-231 |
| 特提斯喜马拉雅带东部陆热地区火山岩年代学、地球化学及成因研究 |
| Study on Geochronology, Geochemistry and Genesis of Volcanic Rocks in the Lure area of eastern Tethys Himalayan belt |
| 投稿时间：2024-01-10 |
| DOI：10.6053/j.issn.1001-1412.2024.02.010 |
| 中文关键词: 特提斯喜马拉雅带 火山岩 地球化学 锆石U-Pb测年 陆热地区 西藏 |
| 英文关键词:Tethys Himalayan belt volcanic rock geochemistry zircon U-Pb dating Lure area Tibet |
| 基金项目:国家自然科学基金项目“特提斯喜马拉雅带中、东段镁铁质岩石成因及其对新特提斯洋早期演化历史的约束”(编号:42173048)、国家重点研发计划项目“难熔元素和同位素分析技术的综合应用研究”(编号:2020YFA0714804)、广西博士研究生创新项目“西藏山南地区基性侵入岩成因机制及深部动力学研究”(编号:YCBZ2022119)联合资助。 |
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| 中文摘要: |
| 本文首次开展了对特提斯喜马拉雅带东部陆热地区的中酸性火山岩进行了系统的锆石LA-ICP-MS U-Pb年代学、全岩主元素、微量元素研究,结果表明:陆热地区酸性火山岩主要为英安岩和流纹岩,样品锆石U-Pb定年获得了141.1 Ma±1.3 Ma、135.3 Ma±6.6 Ma两个年龄值;稀土元素分配图呈明显的右倾模式,轻重稀土分馏明显,Eu负异常;在微量元素原始地幔标准化蛛网图中,样品富集大离子亲石元素(LILE),亏损Nb、Ta、Ti等高场强元素(HFSE),显示出壳源岩浆的特征。陆热地区中性火山岩为安山岩,样品锆石的U-Pb年龄为133.9 Ma±4.9 Ma,样品稀土元素分配图呈明显的右倾型模式,且没有明显的Eu异常。在微量元素原始地幔标准化蛛网图中,样品无Nb、Ta负异常,且其Mg#值较高(42.9),相容性元素Ni、Co、Cr、V等含量相对较高,显示出一定的幔源岩浆特征。本研究认为,陆热地区酸性火成岩是在地壳伸展减薄的拉伸环境以及Kerguelen地幔柱活动的双重作用下,幔源岩浆底侵使上地壳发生部分熔融形成;中性火成岩则是与Kerguelen地幔柱活动有关的基性岩浆经历了一定程度的分离结晶,并沿着构造裂缝上涌喷出形成。 |
| 英文摘要: |
| This paper deals with the first systematic study of zircon LA-ICP-MS U-Pb geochronology, whole-rock major and trace elements of intermediate-acid volcanic rocks in the Lure area of the eastern Tethyan Himalayan belt. The acidic volcanic rocks are mainly dacite and rhyolite with zircon U-Pb dating age values of 141.1 Ma±1.3 Ma and 135.3 Ma±6.6 Ma respectively. The REE pattern shows obvious right-leaning mode with obvious fractionation of LREE and HREE and negative Eu anomaly, the primitive mantle normalized spider diagram enrichment of large ion lithophile elements (LILE) and depletion of high field strength elements (HFSE) such as Nb, Ta and Ti which are characteristic of crust-derived magma. The intermediate volcanic rocks is andesite with zircon U-Pb age 133.9 Ma±4.9 Ma. The REE pattern shows clear right-leaning mode without obvious Eu anomaly. The primitive mantle normalized spider diagram shows no Nb and Ta negative anomaly, higher Mg# values (42.9) and relatively high content of compatible element of Ni, Co, Cr and V. These data are characteristic of mantle-derived magma. The author considers that the acidic igneous rock in the Lure area is formed by partial melting of upper crust resulted from the mantle-derived magma diapir under environment of crustal extension and thinning and active Kerguelen mantle plume. The intermediate igneous rock is formed by the Kerguelen mantle plume activity-related basic magma which is separated and crystallized then moved along the structural fractureand and erupted. |
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