摘要
昆山、城山和大龙山三个岩体的全岩Rb-Sr等时线年龄和^(87)Sr/^(86)Sr初始值在实验误差范围内完全相一致,分别为135Ma和0.707±0.001左右。结合氧同位素和稀土元素等资料分析,发现岩体的成岩物质来源于上地幔,母岩浆上升侵位过程中与地壳物质发生了同化混染,而且这种作用达到了充分的均一化。据壳幔混合模式计算,其中地幔锶和地壳锶分别约占53.8％和46.2％。这些岩体与深大断裂和地幔隆起有成因上的密切联系。
The Rb-Sr isochorn age of rock samples from Kunshan, Chengshan and Dalongshan was dated as 135 Ma and the initial 87Sr/86Sr ratio was estimated to be 0.707 ± 0.001, falling within the limit of experimental errors. The data on oxygen isotopes and rare elements indicate that the primary magma producing these igneous bodies Is of mantle derivation, but in the processes of its upward movement and emplacement the magma was contaminated by crustal materials and became completely homogeneous. According to the model of two-component mixing (mantle and crustal materials), 53.8% and 49.2% of Sr are estimated to have come from the mantle and the crust, respectively. Moreover, the emplacement of these igneous bodies is closely re-lated to the development of rifts as mantle upwarping.
出处
《地球化学》
CAS
CSCD
北大核心
1989年第3期202-209,共8页
Geochimica
