Bulletin of the Geological Society of Malaysia, Volume 45, May 2002, pp. 247 – 252

Petrology of dioritic rocks from the Pemanggil Island, Johore

Mohd Basri Ismail¹, Marzuki Asmuri¹, Azman A. Ghani¹, Mohd. Rozi Umor² & Mohd. Anuar Ismail¹

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.

https://doi.org/10.7186/bgsm45200237