大别造山带地壳的元素丰度

Element Abundances of the Continental Crust in the Dabie Orogenic Belt

大别造山带具板片叠覆式构造形态。区域地壳具3个结构层,中地壳存在地震低速层和电性低阻层。地壳总体成分为花岗闪长岩质,深部地壳成分为中性。地壳稀土总量偏高、轻重稀土分馏程度高,铁族元素偏低、亲石元素富集。造山带内部横向不均一性明显,而地壳纵向演化分异程度低于一般大陆地壳。

The crust in the Dabie orogenic belt has a tectonic form of imbricated plates. The regional crust can be divided into three structural layers, and in the middle crust, there exist a low-velocity layer and a low-electrical resistivity layer. The crust of the orogenic belt has a granodioritic composition, and the deep crustal composition is mediosilicic. The crust is characterized by high 2 REE, a high degree of LREE and HREE fractionation, depletion in ferromagnesian elements and enrichment in lithophile elements in comparison with the values of Weaver and Tarney (1984), Taylor and Mclennan (1985), Shaw et al. (1986), and Gao Shan, Zhang Benren et al. (1990). An obvious lateral compositional difference exists inside the orogenic belt, whereas the vertical chemical differentiation from the lower to the upper crust is poorer than that of other well-studied continental crusts.