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