Petrography and REE geochemical characteristics of felsic to mafic volcanic /hypabyssal rock in Nakhon Sawan and Uthai Thani provinces, central Thailand

Abstract

© 2017, Chiang Mai University. All rights reserved. The felsic to mafic volcanic/hypabyssal rocks in the area of Nakhon Sawan and Uthai Thani Provinces, Upper Central Plain Thailand were distributed in the area of Tha Tako, Krok Phra and Chum Ta Bong, covering an area of approximately 200 km2. The least-altered mafic to felsic volcanic/hypabyssal rock samples can be divided into five groups Group I rocks (calc-alkalic), Group II rocks (calc-alkalic), Group III rocks (tholeiitic), Group IV rocks (tholeiitic) and Group V rocks (shoshonitic) using REE patterns and N-MORB normalized multi-elements patterns. Group I rocks compose of rhyodacite/dacite andesite/basalt and diorite/gabbro. Group II rocks compose of diorite/gabbro. Group III and Group IV rocks compose of andesite/basalt and microdiorite/microgabbro. Group V rocks compose of rhyodacite/dacite. N-MORB normalized multi-element patterns suggest that Groups I, II and V rocks have characteristics of subduction-related magma and Groups III and IV rocks have been crystallized from MORB-like magma that contains crustal signature.