摘要
对出露于甘肃夏河地区,隶属西秦岭的印支晚期复式岩体的地质地球化学研究表明。其岩石具有与典型埃达克岩相似的特征:SiO2多数(72%~58%),高Al2O3(16.7%~14.6%),Sr多数大于(400×10^-6),低Y(16×10^-6~7×10^-6)和Yb(1.7×10^-6~0.56×10^-6),明显亏损Nb和Ta,稀土元素分异强烈,富集LREE,低HREE,并有较弱的Eu负异常(δEu为0.9~0.4)在(La/Yb)N-Yb和Sr/Y-Y图解上样品主要落入埃达克质岩区域。该套埃达克质岩的厘定,对研究秦岭造山带晚古生代古特提斯洋的构造演化、地球动力学特征具有重要意义。
The late Indosinian granitoids in Xiahe area of Gansu Province belong to west Qinling orogenic belt. A study of their petrochemical and geochemical characteristics shows that they have the typical characteristics of "adakite". These rocks have the following characteristics: Most of SiO2 (70%-58%), high Al2O3(16.7%-14.6%) and Sr (most of them〉400×10^-6), and low in Sr/Y(16×10^-6~7×10^-6) and Y ratio (1.7×10^-6~0.56×10^-6); There exist very prominent negative Nb and Ta anomaly in the trace element spidergram. REE distribution pat- terns show strong REE segregation and belong to the type of enriched LREE, but depletion in HREE, and weak negative Eu (δEu=0.9~0.4) auanomaly can be observed; and most samples fall into the extent of adakite on (La/ Yb)N-YbN and Sr/Y-Y diagrams. Therefore, the discovery of the adakitic rocks have great significance for the study on Late Paleozoic tectonic evolution of Qinling orogenic belt.
出处
《甘肃地质》
2008年第3期6-12,共7页
Gansu Geology
关键词
埃达克岩
花岗岩类岩石
地球化学
西秦岭
甘肃夏河
adakitic rock
granitoids
geochemistry
West Qinling
Xiahe County of Gansu Province