摘要
南秦岭中生代张家坝岩体和新院岩体的LILE相对富集、HFSE贫化,高钾、富Sr((498～623)×10-6)、低Y((5.57～24)×10-6)和Yb((0.52～2.13)×10-6), Eu异常微弱,显示了地壳增厚背景下下部地壳物质部分熔融所形成的高钾钙碱性花岗岩特征.岩体内的包体中出现长宽比很高的针状磷灰石,且边缘发育冷凝边结构,包体与寄主岩间存在明显的成分间断,并构成了两个不同的岩浆演化趋势和它们所具有的不同稀土特征,证明它们为来自两个不同源区岩浆混合的产物,同时指示秦岭地区中生代时期发生了一次壳幔混合作用和重要的地壳垂向增生事件.
The Zhangjiaba and Xinyuan plutons of South Qinling were formed in the Mesozoic. They have high Al2O3, K2O contents, and are relatively enriched in LILE and poor in HFSE, with high Sr （498 × 10^-6 -623×10^-6） , low Y （5.57 × 10^-6 -24 × 10^-6） and Yb （0.52 × 10^-6 -2.13 ×10^-6） and with slightly negative or positive Eu anomalies. All these demonstrate the features of high-K calc-alkaline granitoids formed by partial melting of lower-crust materials under the thickened crust. On the other hand, needle-shaped apatite and quenched-edge texture are well developed in the enclaves in both plutons. There is a visible composition gap between enclaves and granitoids. Two different magmatic evolutional trends correspond to two different REE patterns. These evidences imply that they were resulted from mingling of two-end-member magmas derived from different sources, suggesting that there was a crust-mantle interaction in the Mesozoic and an important vertical growth of crust in Qinling area.
出处
《高校地质学报》
CAS
CSCD
北大核心
2005年第3期425-433,共9页
Geological Journal of China Universities
基金
国家自然科学基金(40372039
49132080)资助项目
关键词
南秦岭
花岗岩
后碰撞
壳幔作用
South Qinling
granitoid
post-collision
interaction between crust and mantle
