The pattern of K/Ar ages of biotites from the granites of Penang: its interpretation in the light of available Rb/Sr and U/Pb data


Author : T.S. Kwan & F.L. YapPublication : Bulletin of the Geological Society of MalaysiaVolume : 19Page : 281-289Year : 1986


Description

Bulletin of the Geological Society of Malaysia, Volume 19, April 1986, pp. 281 – 289

 

The pattern of K/Ar ages of biotites from the granites of Penang: its interpretation in the light of available Rb/Sr and U/Pb data

T.S. KWAN and F.L. YAP

Geological Survey of Malaysia, P.O. Box 1015, Ipoh

 

Abstract: Available Rb/Sr whole-rock and zircon U/Pb data indicate that the granites of Penang Island were probably emplaced in the late Triassic between 22 Ma and 206 Ma. The results of K/Ar analysis of 31 biotite samples from the granites of Penang Island are presented.

A general decrease of apparent biotite ages in a south-south-easterly trend from 209 Ma to 160 Ma is evident. In the northern third of the island, the apparent biotite K/Ar ages of 209 Ma to 201 Ma are concordant with a published Rb/Sr isochron of 206 Ma. Apparent ages of 199 Ma to 179 Ma were measured from samples from the rest of the island except at the southeastern coast where 2 significantly younger ages of 170 Ma and 160 Ma were measured. This trend of younging apparent ages suggests rejuvenation on a regional scale. 

https://doi.org/10.7186/bgsm19198621