关键词: 闪长岩, 地球化学特征, 滴水沟岩体, 内蒙古

Abstract:

The Dishuigou dioritic intrusion is located in the Langshan arc at the northern margin of the North China Craton (NCC), Inner Mongolia. It is emplaced in the Late CarboniferousEarly Permian according to the previous zircon UPb dating data. In this paper, the major and trace (including rare earth) elements composition of the Dishuigou diorite are reported. The result shows relatively enriched in large ion lithophile elements (LILE) such as the Rb, Ba, Th, K, and P, and depleted in high field strength elements (HFSE) such as the Nb, Ta, and Ti, and high Rb/Sr (005-010) and Ba/Rb (1145-2216) values, and low A/CNK (<11). In combination with the strong fractionation REE (LREE/HREE=297-331) and LREE (La/Sm=275-357), and insignificant Eu anomalies (δEu=092-113), suggesting the dioritic intrusion formed in an arc environment and derived from mantle melt mixed with crust material during ascending. It is concluded that the southward subduction of the paleoAsian oceanic slab in Late CarboniferousEarly Permian resulted in the formation of the Dishuigou dioritic intrusion based on the regional evolution the Langshan arc.

Key words:

diorite, geochemical characteristic, Dishuigou intrusion, Inner Mongolia