湖南粤北花岗岩类岩石成因的痕量元素模拟

Trace Element Modelling for Petrogenesis of Granitoids in Southern Hunan and Northern Guangdong

对湘南粤北的扶溪岩体、九峰岩体、南岭地区基底地层的四堡群,以及板溪群、震旦-奥陶纪等岩石进行了主元素及痕量元素含量测定。同时对扶溪和九峰两岩体测定了Sm-Nd同位素含量,初步判断该二岩体的源岩可能是元古代的具陆壳性质的岩石。利用非实比平衡部分熔融公式对上述岩体的岩石成因作了痕量元素定量模拟,进一步确证了该二岩体的形成过程及源岩性质。

Major element and trace element contents have been determined for Fuxigranodiorite body and Jiufeng adamellite body in southern Hunan and nor-thern Guangdong, and also for such basement strata in Nanling region as SibaoGroup, Banxi Group and Sinian--Ordovician rocks. In addition, Sm-Nd isotopicdata have been Obtained for Fuxi and Jiufeng rock bodies, with isochron agesbeing 463 Ma and 159 Ma, ε_(Nd)(t)--6.8 and--10.4 and t_(DM) 1728 Ma and1896 Ma respectively. It is preliminarily concluded that source rocks of thesetwo rock bodies might have been Proterozoic continental crustal rocks in nature.Trace element quantitative modelling for petrogenesis of thesee rock bodieswas carried out with the aid of the formula for batch partial melting, i. e.C~?/C^0 = 1/[D_0+ F(1--P)]The data Obtained, combined with the geological andgeochemical characteristics, have led the authors to believe that the Fuxi gra-nodiorite, being a product of the crystallization of a melt, was formed by 50%partial melting of Sibao Group or similar Lower--Middle Proterozoic rocks, whe-reas the Jiufeng adamellite by 55% partial melting of Banxi Group or similarrocks in the region.