皖南中生代两期花岗岩成因及深部过程

下扬子皖南地区广泛发育两期中生代花岗岩，其年代学格架和成因还不清晰，从早期钙碱性I型花岗岩为主突变至晚期碱性A型花岗岩为主，所反映的地质演化过程尚无深入认识，对由挤压转为拉张的构造背景下，软流圈上涌、玄武岩浆底侵、岩石圈下部拆沉、壳幔相互作用等一系列深部过程发生与否和演化规律还不清晰。解决这些问题的关键是对岩浆物质来源和岩石成因的详细制约，以及岩石形成所对应的深部地质作用发生的方式和演化顺序的厘定。本项目拟对皖南地区中生代各种类型、不同时代的岩浆岩开展系统的岩石学、地球化学、锆石U-Pb 年代学和Hf-O同位素联合示踪研究，辅以前寒武纪变质基底锆石年代学和同位素分析，深入辨析岩石成因和岩浆过程，厘定岩浆源区性质，剖析各种深部地质作用发生的过程和方式。进而与下扬子沿江地区岩浆岩的研究成果进行系统对比，为下扬子地区不同构造单元晚中生代时期大陆动力学演化提供可靠的制约。

Two-stage Mesozoic granites are broadly cropped out in southern Anhui Province, the lower Yangtze region. As yet, petrogenesis and chronological framework about these granites are still ambiguous. There is not yet profoundly understanding about the geological evolutive processes reflected by that the early stage calc-alkaline I-type granite abruptly transformed into later stage alkaline A-type granite. Moreover, it is unclear about whether to take place and how to evolve for a series of deep geological processes, including upwelling of asthenosphere, underplating of basaltic magma and lithospheric delamination. The key accounting for these issues depends on detailed constraints on the origin of magma and petrogenesis as well as confirmation of the mode and evolutive sequence of deep geological processes which were corresponded by formation of these magmatic rocks under a tectonic setting of transformation from contraction to extension. Aimed to deciphering the petrogenesis and magmatic process, ascertaining the characteristics of magmatic source and exploring the deep geological processes, this work will focus on the integrated petrologic, geochemical and zircon U-Pb chronological and Hf-O isotopic studies on the Mesozoic magmatic rocks with different types and ages from southern Anhui. Accessorily, the zircon chronological and isotopic studies on the Precambrian metamorphic basement will also be concerned. Finally, by systematically contrasting with research about the magmatic rocks from the area along the Yangtze River, the continental dynamic evolution of different tectonic units in the lower Yangtze region in later Mesozoic will be researched and credibly constrained.