Geochemical Characteristics and LA-ICP-MS Zircon U-Pb Geochronology of Xujiawan Monzogranite in the Eastern Part of North Huaiyang and Their Geological Significance

Abstract

The Xujiawan monzogranitic intrusion is located at the junction of the Tongbai-Tongcheng fault and the Tancheng-Lujiang fault in North Huaiyang tectonic belt. The rocks intruded into the Neoproterozoic metamorphic rocks as stocks. In this study, major and trace element contents of the rocks are determined by Atomic Absorption Spectrometer and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Results show that these rocks have high contents of SiO2 and Al2O3 and are alkali-rich and peraluminous with low Mg# values. They are rich in large ion lithophile elements such as Rb and Ba, but are poor in Sr. They are rich in high field strength elements such as Y, Th, Nb, Hf, U, but are poor in Ta, P, Ti. In general, these rocks are deplete in HFSE but enriched in LILE. They have high LaN/YbN and LREE/HREE ratios and have weak Ce anomalies. Major and trace elements indicate that these rocks belong to peraluminous A-type granite. LA-ICP-MS Zircon U-Pb dating of Xujiawan monzogranite yield ages of 128.0 0.9 Ma to 129.6 1.4 Ma, indicating that these intrusions were produced by the early Cretaceous magmatism. Xujiawan monzogranite may have formed in a post-collisional extensional setting. The magma may be derived from the mantle and contaminated by the continental crust.

Keywords

• north huaiyang tectonic belt
• monzogranite
• geochemistry
• la-icp-ms zircon u-pb dating
• early cretaceous