Abstract:

Geology，petrography and element geochemistry for granites are studed from Yingchengzi gold-field, eastern Zhangguangcai Mountain. The granites are characterized by high SiO₂ （SiO₂=71.12%-75.66%）, high fractionated index （DI=90.53-94.42）, and belong to Potassic calc-alkaline rock（σ=2.37-3.94）. They are enriched in LILE (LREE/HREE=11.20-14.62,w（Rb）=（270.6-165.3）×10^-6, Na₂O/K₂O =0.18-0.67) and depleted in Ba，Nb，Sr，P and Ti, as well as negative Eu anomalys. These characteristics indicate that the granites belong to metaluminous and highly fractionated I-type granites, whose parent magma may be I-type granitic magma, and the magma for the granites is formed after fractional crystallization for parent magma dominated by plagioclase. Combined with zircon geochronology, it may be established that the magma was formed after the fractional crystallization for magma chamber during the Mashan period deep metamorphism, and the magma chamber was triggered by anatectic magmatism for the crust.The magma emplacement took place in intracontinental orogenic of the Mashan period, and the process may be lasted for about 20 Ma.

Key words: granite, element geochemistry, petrogenesis, Yingchengzi gold-field, Zhangguangcai Mountain