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地质力学学报:2020,26(5):759-790
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扬子板块西缘新元古代典型中酸性岩浆事件及其深部动力学机制:研究进展与展望
(1.大陆动力学国家重点实验室, 陕西 西安 710069;2.西北大学地质学系, 陕西 西安 710069)
Petrogenesis and geodynamic implications of Neoproterozoic typical intermediate-felsic magmatism in the western margin of the Yangtze Block, South China
(1.State Key Laboratory of Continental Dynamics, Xi'an 710069, Shannxi, China;2.Department of Geology, Northwest University, Xi'an 710069, Shannxi, China)
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投稿时间:2020-06-29    修订日期:2020-08-09
中文摘要: 华南板块发育有巨量新元古代岩浆岩,因而是研究罗迪尼亚(Rodinia)超大陆演化期间华南板块地幔属性、地壳演化和壳幔相互作用最理想的场所。虽然在扬子西缘新元古代镁铁质和酸性岩浆作用方面已有大量的研究,但是在系统研究中酸性花岗岩类所代表的不同深部动力学意义的方面还较为薄弱。文章基于团队近期对于扬子板块西缘新元古代典型花岗岩类的研究成果,系统揭示不同深度层次的岩浆作用。最新研究支持扬子西缘新元古代受控于俯冲构造背景,除发生俯冲流体和板片熔体交代地幔作用外,最新识别的ca.850~835 Ma高Mg#闪长岩指示俯冲沉积物熔体也参与了地幔交代作用。Ca.840~835 Ma过铝质花岗岩的发现说明扬子西缘新元古代时期不仅存在新生镁铁质下地壳的熔融,也发生了俯冲背景下成熟大陆地壳物质的重熔。Ca.780 Ma Ⅰ型花岗闪长岩-花岗岩组合揭示了俯冲阶段后期板片回撤断离后软流圈地幔瞬时上涌引发的不同地壳层次的岩浆响应。从ca.800 Ma的增厚下地壳来源的埃达克质花岗岩到ca.750 Ma的酸性地壳来源的A型花岗岩的出现,表明扬子西缘新元古代时期经历了俯冲有关的地壳增厚到俯冲后期弧后扩张背景下的区域性地壳减薄。
Abstract:The South China Block preserves voluminous Neoproterozoic magmatism, it is thus an ideal site for understanding the mantle nature, crustal evolution, and crust-mantle interaction during the assembly and breakup of the Rodinia supercontinent. Although the previous studies have paid more attention to the mafic and felsic rocks, the systematic deep dynamics of intermediate-felsic intrusive rocks is unsubstantial. Based on the recent studies on the Neoproterozoic typical granitoid magmatism, this study provides a systematic insight on the magmatic response of different depth under subduction setting. The new study reveals that the western margin of the Yangtze Block was located at the subduction setting. Apart from the subduction fluids- and slab melts-related mantle metasomatism, the newly recognized ca.850~835 Ma high-Mg# diorites suggest that there existed the subducted sediment melts-related mantle metasomatism. In addition, the identification of ca.840~835 Ma peraluminous granites indicates that the western margin of the Yangtze Block underwent not only the melting of the juvenile mafic lower crust but also the reworking of the mature continental crust during the Neoproterozoic. Moreover, the ca.780 Ma I-type granodiorites-granites stand for the magmatic response of different crustal depth induced by the upwelling of asthenosphere mantle. The occurrence from ca.800 Ma thickened lower crust-derived adakitic granites to ca.750 Ma felsic crust-derived A-type granites suggest the geodynamic transition from regionally crustal thickening to extensional thinning under subduction background.
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基金项目:国家自然科学基金委创新群体项目(41421002);国家自然科学基金面上项目(41772052)
引用文本:
赖绍聪,朱毓,2020.扬子板块西缘新元古代典型中酸性岩浆事件及其深部动力学机制:研究进展与展望[J].地质力学学报,26(5):759-790.DOI:10.12090/j.issn.1006-6616.2020.26.05.062
LAI Shaocong,ZHU Yu,2020.Petrogenesis and geodynamic implications of Neoproterozoic typical intermediate-felsic magmatism in the western margin of the Yangtze Block, South China[J].Journal of Geomechanics,26(5):759-790.DOI:10.12090/j.issn.1006-6616.2020.26.05.062

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