Bulletin of the Geological Society of Malaysia, Volume 8, Dec, 1977, pp. 121 – 122
Jabatan Geologi, Universiti Malaya, Kuala Lumpur
The age relationship between the Kuantan basalt and the dolerite dykes has recently received much attention. Fitch (1952) suggested that the dolerite dykes found in the locality were feeder dykes of the basalt flow that overlie acid plutonic rocks. Later, work by Bignell (1972) disproved Fitch‘s earlier suggestion. He found one dolerite dyke from Tg. Tembeleng by K-Ar radiometric dating to be at least 111 ± 4 m.y. In addition, recent palaeomagnetic studies by Haile (1974) supported Bignell‘s result. The basalt had a reverse sense of magnetization with respect to the present day field, corresponding to the Matuyama Reverse Epoch. A remanent magnetism more or less opposite to the basalt was recorded from the dolerite. Abdul Hanif Hussein (1974) analysed samples of dolerite and basalt and found that they are chemically different. He found that the dolerite should be classified into the olivine tholeiite group and basalt into alkalic olivine basalt and basanite. These studies evidently indicate that not all the basic igneous activities are contemporaneous. In this note, field evidence will be provided to show that one such dolerite is probably much older than the basalt.