| 安徽铜陵地区幔源镁铁质团块研究及其地质意义 |
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| 关键词:mafic clots microgranular dioritic enclaves crust-mantle interaction Tof-SIMS |
| 基金项目:国家自然科学基金项目(编号: 41140025; 40672045; 41372086);中国地质调查局危机矿山接替资源找矿项目(编号: 20089938);山东省“泰山学者”建设工程(编号: 鲁政办字〔2013〕122号) |
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| Mantle Mafic Clots in Tongling Area, Anhui Province, and Their Geological Significance |
| It is generally accepted that mantle input under crust-mantle interaction plays an important role in sustainable magma fractionation and eventually leads to release of magmatic fluids and formation of world class W, Sn and other types of ore deposits. Many models dealing with the evolution of mantle-derived magmas are derived from numerical simulations based on isotopic geochemistry, temperature and pressure or physical geography data. Few models use detailed chemical analysis of mantle-derived rock enclaves. The authors found direct evidence for crust-mantle interaction in Tongling area, East China, in the form of mafic clots (MFC), which are interpreted to represent fragments of altered alkaline basaltic magma in magma chambers at the base of the continental crust (BCC). These MFC are unevenly distributed within the microgranular dioritic enclaves (MME) which, in turn, are included in the host quartz monzodiorite. The authors have combined all available data with new element distribution maps of the MFC in order to present a general framework model for the evolution of mafic to siliceous magmas. Observations and researches indicate that the MFC were formed from the fractional crystallization and evolution alkaline basaltic magma in magma chambers at the BCC. The basaltic magma resulting from previous partial melting of the upper mantle was eventually brought to the magma chambers at the BCC by magmatic underplating and crust-mantle interaction at 140 Ma. And the MME were formed from the fractional crystallization and evolution dioritic magma by the assimilation of the derived magma from the base of the continental crust with the metamorphic rocks in a crust magma chamber at the depth of 12~16 km. The discovery of the MFC and MME effectively prove that the dioritic magma in the middle crust originated from the mixing basaltic magma of mantle-crust at the BCC. |
| LI Da-peng,DU Yang-song,YU Xue-feng,QIN Xin-long,Steve SCOTT,WANG Shu-xing,Filipa MARQUES.2014.Mantle Mafic Clots in Tongling Area, Anhui Province, and Their Geological Significance[J].Acta Geoscientica Sinica,35(5):608-618. |
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