Differences between Rock-forming and Related Ore-forming Times for the Mesozoic Granitoids of Crust Remelting Types in the Nanling Range,South China,and Its Geological Significance

The temporal differences between the emplacement of Mesozoic granitoids of crust remelting types and related mineralizations are quite common in the Nanling Range area, South China. Three major cases are recognized. (1) The host granitic rocks of those granite-type uranium deposits are mostly of the Indosinian Period (235~205 Ma), whereas the uranium mineralization took place in the late Yanshanian Period (younger than 140 Ma). (2) The first stage of the Yanshanian Period (170~150 Ma) was the time when most crust remelting granitic plutons developed. However, the associated mineralizations of W, Sn and other rare metals mostly occur in the second stage of the Yanshanian Period (150~139 Ma). (3) Many shallow-emplaced granitic rocks developed in the late Yanshanian Period (139~ 98 Ma), which are closely related with Sn and U mineralizations. There are also differences between rock-forming and ore-forming times. It is suggested that this temporal difference might reflect their differences in material sources as well as geotectonic settings, and further more, the primary difference of the mechanisms between granite formation and ore formation. It is concluded that the large-scale metallogeny in the Nanling Range area was essentially related with extension geotectonic setting, crust—mantle interaction, high heat flow, and the participation of deep-sourced fluids.