Abstract:

Penglu and Zhanggongshan micro-blocks occurred in the Huanan orogenic belt, which separated the Yangtze Plate from the Cathaysia Plate.The Chenglang fault separated the Penglu micro-block to the west from the Zhanggongshan micro-block to the east. However, when and how the Penglu and Zhanggongshan micro-blocks joined together still leave unsolved.Samples from Pre-cambrian granites in Xingzi metamorphic dome which were nearby the Chenglang fault zone and ultrabasic dykes intruded along the Chenglang fault were collected and analyzed with ICP-MS methods.Variable trace element discrimination diagrams indicate a continental environment for Xingzi granites and volcanic-island arc environment for the ultrabasic dyke.The formation of structural styles and geochronological data suggest a volcanic arc formed between the Zhanggongshan and Penglu micro-blocks, and this volcanic arc was produced by the northwestward subduction of Zhanggongshan micro-block underneath the Penglu micro-block. It is inferred that where after the collision of the Yangtze and Cathaysia plates, formed the Huanan orogenic belt, and involved in these earlier micro-blocks.

Key words: Yangtze Plate, Cathaysia Plate, Penglu Block, Zhanggongshan Block, ultrabasic dyke, Xingzi granite, Chenglang fault zone, northern Jiangxi