关键词: 上绿水桥岩体, 铝质A型花岗岩, LA-ICP-MS定年, 地球化学, 非造山环境

Abstract:

The Shanglüshuiqiao instrusion exposed in Ji’an area of Jilin Province mainly consists of miarolitic K-feldspar granite．The granites in the Shanglüshuiqiao instrusion are characterized by high SiO₂(75.94%-76.34%) and TFeO/MgO value（39.6-66.1），enrichment in alkali（ALK=8.29%-9.63%）and K(K₂O=5.14%-5.20%，K₂O/Na₂O=1.47-1.68)，low CaO and TiO₂．On the primitive mantle-normalized spider diagrams，the granites show positive K, Rb and Th anomalies and negative Ba, Sr,  Ti, Nb,Ta and P anomalies. Moreover，They have particularly intensive Eu negative anomalies and their chondritenormalized REE patterns are of the seagull shape. Research on the major and trace elements of these granites indicates that they are aluminous A-type granite. By LA-ICP-MS dating，the Shanglvshuiqiao intrusion was formed in the early Cretaceous (U-Pb age of (117.8±2.3)Ma).  The low ratios of Ce/Nb、Y/Nb and Yb/Ta reveal that the instrusion is non-orogenic A₁-type granite. They are the shallow geological response of the lithosphere thinning event of the eastern North China plate in the southern Jilin Province．

Key words: Shanglüshuiqiao instrusive, aluminous A-type granite, LA-ICP-MS dating, geochemistry, non-orogenic setting