A further understanding on genesis of Nanyili granite from Bikou area,Northwest margin of Yangtze Plate

【摘要】：正The Nanyili granite pluton locates in the Bikou area,northwestern margin of the Yangtze Block.This paper reported the geochemistry of the Nanyili granite and discussed its genesis,ore-forming material source.The granite has high SiO_2(70.27%～71.21%),Al_2O_3(14.97%～16.19%),K_2O(3.11%～3.83%) and Sr/Y(33.01～50.53) ratios,as well as low Y(7.92×10~(-6)～10.01×10~(-6),average 8.74×10~(-6)) and HREE(e.g.,Yb=0.56×10~(-6)～0.69×10~(-6)), strongly fractionated REE patterns with(La/Yb)_N=15.30～23.04,suggesting an affinity of C-type adakitic rocks. Consisdering the temporal-spatial pattern of the Nanyili granite,it is consisdered that the Nanyili granite pluton was likely to have formed in a typical post-collsional setting.It was possible that the collision between the North China and the Yangtze blocks during the Late-Triassic resulted in thickening of the crust obviously.Under the extension-thinning of the tectonic background,metamorphous basic rocks generating partially melts of adakitic