Confirmation and Preliminary Study of Aluminous A-Type Granites in the Wuyi Mountain Area, Eastern Jiangxi Province, China

摘要

Widespread in the Wuyi Mountain area of eastern Jiangxi are petrochemically peralu- minous granites and they are characterized as being high in silica (SiO_2 > 75/100) and highly alkaline (ALK = 6.9/100 - 7.5/100) with K_2O > Na_2O and rather high ratios of FeO~T/MgO (11.3 -17.9). The rocks have low contents of CaO, MgO, TiO_2 and P_2O_5. The granites are en- riched in REE (ΣREE = 210.3 - 496.8 μg/g) with remarkable negative Eu anomalies, but de- pleted in Eu, Ba, Sr, V, Co, and Ni, with 10000 × Ga/Al ratios, varying from 6.1 to 9.8. It is clear that these granites are obviously different from the I- and S-type granites, but are quite similar to those typical A-type granites such as aluminous A-type granites in the coastal areas of Fujian Province.