Bulletin of the Geological Society of Malaysia, Volume 45, May 2002, pp. 247 – 252
1Department of Geology, University of Malaya, 50603 Kuala Lumpur, Malaysia
2Geology programme, School of Environmental and Natural Resources Sciences, Faculty of Science and Technology, University Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
Abstract: The three types of dioritic rocks occurring in the Pemanggil Island are pyroxene hornblende diorite, porphyritic pyroxene hornblende diorite and microdiorite. The rock intruded into the volcanic rock probably of Permian age. Geochemical data shows that the SiO2 content increases from pyroxene hornblende diorite to porphyritic pyroxene hornblende diorite to microdiorite. LIL log-log plot suggests that crystal fractionation plays an important role in the magmatic evolution of the Pemanggil dioritic magmas and plagioclase, hornblende and biotite are the major precipitating phases.