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Palaeoproterozoic tectonothermal evolution and deep crustal processes in the Jiao-Liao-Ji Belt,North China Cratona review [查看] S.Z.LI、G.C.ZHAO、SANTOSH、X.LIU、L.M.DAI

The Palaeoproterozoic Jiao-Liao-Ji Belt is located in the eastern margin of the Eastern Block of the North China Craton. In this paper, we synthesize the tectonothermal evolution and deep crustal processes in the Jiao-Liao-Ji Belt based on recent information. A mantle plumerelated underplating from 2.53 to 2.36 Ga is envisaged which led to the emplacement of the 2.47–2.33 Ga alkali granite plutons and mafic dyke swarms, followed by the development of the Jiao-Liao-Ji Rift and bi-modal volcanism. The underplating resulted not only in different sedimentary environments in the upper crust, but also in a differentiation of the initial thermal structure in the rift. This controlled the metamorphism and style of P-T-t paths in the different parts of the rift. Subsequent underplating resulted in the emplacement of the A-type Liaoji granites of ca. 2.17 Ga in the lower crust, and the formation of associated pegmatites of 2.2 and 2.0 Ga, together with the development of a bedding-parallel extension. However, the main orogeny occurred between 1.93 and 1.88 Ga with closing of the rift, compressional deformation and high-pressure granulite metamorphism in the southern part of the orogen. Subsequently, lithospheric blocks were possibly delaminated at 1.85 Ga; anorogenic magmatic rocks such as rapakivi granite, alkaline granites and syenite were intruded, and pegmatite veins and mafic dyke swarms were emplaced cross-cutting all the earlier structural traces. We identify that the underplating styles, collision processes and delamination types in the deep lithosphere controlled the tectonothermal evolution of the crust in the Jiao-Liao-Ji region.