塔里木早二叠世大火成岩省的成因模式

发布时间：2018-05-12 02:37

本文选题：大火成岩省 + 早二叠世　；参考：《中国科学:地球科学》2017年10期

【摘要】：近20年来,塔里木早二叠世大火成岩省在各类火成岩的空间分布、时间序列、地球化学特征、地幔源区和岩浆演化等方面有了深入的认识,为揭示大火成岩省的成因模式和演化过程奠定了坚实的基础.本文将主要基于塔里木大火成岩省存在的两阶段岩浆产物,结合前期研究基础和前人研究成果,系统论证塔里木早二叠世大火成岩省成因的两阶段熔融模式.模式认为塔里木大火成岩省的形成与地幔柱活动有关,其地幔柱作用形式兼具"巴哈纳型"和"德干型"两种特点,即早期高热的地幔柱引起了岩石圈地幔的低程度部分熔融,后期地幔柱上升绝热减压引起地幔柱自身部分熔融.在早期熔融事件中,地幔柱主要表现为上部岩石圈熔融所需的热供给,后期熔融过程中地幔柱成为熔融发生的主要场所和物质供给源.第一阶段喷发的两类玄武岩具有高~(87)Sr/~(86)Sr、低~(143)Nd/~(144)Nd的同位素特征,富集大离子亲石元素和高场强元素,为富集的大陆岩石圈地幔部分熔融的产物,具有"巴哈纳型"特征;而第二阶段产出的基性-超基性侵入岩具有相对两类玄武岩较低的~(87)Sr/~(86)Sr,较高的~(143)Nd/~(144)Nd比值,为地幔热柱熔融的产物,具有"德干型"特征.其中第一阶段,可细分为Group1和Group2两类玄武岩,Group2玄武岩相对Group1玄武岩具有较低的~(87)Sr/~(86)Sr,较高的~(143)Nd/~(144)Nd比值.Group2玄武岩显示连接Group1玄武岩和第二阶段岩浆作用的过渡类型特征,表明塔里木早二叠世大火成岩省是地幔柱与岩石圈地幔持续相互作用的结果.关于塔里木大火成岩省成因模式的研究有助于增进对塔里木大火成岩省岩浆作用、深部地质过程和地球动力学过程的全面认识,有利于丰富大火成岩省的成因理论和地幔柱活动理论.
[Abstract]:In the last 20 years, the Tarim early Permian great igneous province has had a deep understanding of the spatial distribution, time series, geochemical characteristics, mantle source and magmatic evolution of all kinds of igneous rocks. It lays a solid foundation for revealing the genetic model and evolution process of the great igneous province. In this paper, based on the two-stage magma products in Tarim great igneous province, the two-stage melting model of the origin of the Tarim early Permian great igneous province is systematically demonstrated in combination with the previous research results and the previous research results. The model suggests that the formation of the Tarim igneous province is related to the mantle plume activity, and the mantle plume is characterized by both the Bahanna type and the Degan type, that is, the early high heat mantle plume caused the low degree partial melting of the lithospheric mantle. The partial melting of the mantle plume is caused by the rise of the mantle plume and the adiabatic decompression of the mantle plume. In the early melting events, the mantle plume was mainly the heat supply needed for the melting of the upper lithosphere, and the mantle plume was the main place and material source of the melting in the later melting process. The two types of basalts erupting in the first stage are characterized by the isotopic characteristics of high ~ (87 ~ (87) Sr ~ (- / -) ~ (86) N ~ (-1) and ND ~ (14) ~ (4) N ~ (-1) and enriched large ion lithophile elements and high field strength elements, which are the products of partial melting of the continental lithospheric mantle and have the characteristics of "Bahanna type". The basic-ultrabasic intrusive rocks produced in the second stage have the characteristics of "Degan type", which are the products of mantle plume melting and have the characteristics of "Degan type", which are lower than those of two types of basalts. The first stage can be subdivided into two types of basalts: Group1 and Group2 basalts, Group2 basalts have a lower ratio of Group1 basalts than Group1 basalts, and higher ratios of Group1 basalts to Group1 basalts show the transitional type characteristics of Group1 basalts and the second stage magmatism. It shows that the early Permian great igneous province of Tarim is the result of the continuous interaction between mantle plume and lithospheric mantle. The study of the genetic model of the great igneous province in Tarim contributes to an overall understanding of magmatism, deep geological processes and geodynamic processes in Tarim great igneous province, It is propitious to enrich the genetic theory and mantle plume activity theory of the great igneous province.
【作者单位】：国家海洋局第二海洋研究所海底科学实验室;浙江大学地球科学学院;
【基金】：浙江省自然科学基金项目(编号:LY17D020001) 国家海洋局基本科研业务费专项资金项目(编号:JG1518、2017QNA3015) 国家自然科学基金项目(批准号:41506070、41603029)资助
【分类号】：P588.1

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