摘要
皖南太平花岗闪长岩为一典型的同熔型花岗岩类(或I型),其I_(Sr)=0.7069,I_(Nd)=0.512127。用Sr、Nd同位素数据,以平均地幔、平均地亮作为二个端元组分,以二元混合方程模拟计算,太平花岗闪长岩源区岩石为由地亮端元30.6％加上地幔端元69.4％组成的混合物,成分上相当于角闪紫苏辉石岩,模拟的矿物组合:橄榄石34％,斜方辉石26％,单斜辉石6％和斜长石25％。报据Rb、K、Rb/Sr、K/Rb、Ce、Nd、Sm、Gd、Dy等9种元素和元素对比值计算,这一源区物质接近15％的部分熔融形成太平花岗闪长岩的初始岩浆。模拟表明:华南同熔型花岗岩及其源区物质是以地慢为主的幔、壳混合物。
Taiping granodiorite in south Anhui provence is a typical syntexis type(or I type)granitoid. It has the initial Sr and Nd ratios of 0.7069 and 0.512127 respectively. The source rock of Taiping granodiorite is a mixture consisting of 30.6% bulk crust plus 69.4% aver-age mantle materials, determined by modelling calculation for the mixing of the bulk crust and average mantle as two endmember components. This source rock compositionally cor-responds to amphibole hypersthenite, and in normative mineral composition consists of olivine 34%, orthopyroxene 26%, clinopyroxene 6% and plagioclase 25%, determined by modelling caluculation. The initial magma of Taiping granodiorite was formed by approximatery 15% partial melting from this source rock, according to a calculation of the partial melting equation for Rb, K, Ce, Sm, Gd, Dy abundances and Rb/ Sr, K/ Rb, ratios in the estimated source rock and Taiping granodiorite. Results suggest that in regrad to original material, the syntexis type granitoids in south China are usually originated by themixing of the mantle and crust materials.
出处
《南京大学学报（自然科学版）》
CAS
CSCD
1990年第4期720-729,共10页
Journal of Nanjing University（Natural Science）
关键词
花岗岩
幔壳混源型
同溶型
成因
syntexis type granites
Sr-Nd isotopes
two-endmember mixing model
partial melting
