Geochemistry and petrology of syenite, monzonite and gabbro from the Central Belt of Peninsular Malaysia

Abstract

The Benom Igneous Complex is situated in the central part of of this belt forms a pear shaped batholith consists of a variety of igneous rocks ranging in composition from granitic to syenitic to monzonitic and gabbroic. The syenitic, monzonitic, gabbroic are found mainly in the western part of the batholith. The range of SiO 2 for each of the gabbro, syenite and monzonite are 46.5 to 49.1%, 52.9 to 56.9% and 56.6 to 64.7% respectively and characterized by high alkali content, shoshonitic with I type characteristics. They have very high LIL elements, i.e. Ba and Sr are nearly 1000 times rock/mantle. The high Ba and Sr values may results from the penetration of the lower lithosphere by a small volume of mantle material that is enriched in those elements.