GEOLOGY OF THE PENGKALAN HULU-BETONG TRANSECT ...

intrusion of the granitoids mentioned obove. A circular feature can also be recognised
from lithological mapping and from satellite imageries.
Figure 43: Leucocratic, fine-to medium-grained, equigranular to inequigranular
texture, in nature and tourmaline-biotite granite, of Pa Ret Tu granite
(Trgrbp/pr). Location: Ai Yoe Weng village, Thailand.
3.3.6 Kawi granite (Trgrkw)
Distribution
The Kawi granite (Trgrkw) is only exposed on the Malaysian side. It occurs as small
isolated bodies in the Rimba Telui/Si Nakhon granite (Trgrrt/sn). It can be observed in the
Ulu Muda area.
Petrography
The Kawi granite (Trgrkw) is characterized by fine- to medium-grained, light grey,
leucocratic, equigranular biotite granite. The main mineral constituents are quartz, alkali
feldspar, plagioclase and biotite. Accessory minerals comprise apatite, zircon, sericite and
opaque minerals.
Age and correlation
On the Malaysian side, the nearest sample of the Rimba Telui/Si Nakhon granite
(Trgrrt/sn) to the Transect area is at Sungai Sok (6 o 02′ 15″ N, 100 o 48′ 30″ E). Bignell
(1972) concluded that this porphyritic biotite granite gives an age of 190 + 10 Ma (K/Ar),
which is late Triassic. Snelling (1965) was the first worker who had done an age dating of
the Bintang granite (Trgrbt) based on a specimen collected from Waterfall Road Quarry
(4 o 51′ 45″ N, 100 o 45′ 45″ E) in the Taiping area, 80 km further south to of the Transect
area. The age obtained from the whole rock and potash feldspar is a Late Triassic age,
200+8 Ma. Later, Darbyshire (1988) reported that modal age calculations for a sample
from Maxwell’s Hill gave 207 to 214 Ma (assuming initial ratios of 0.720–0.710
respectively), which confirms a Late Triassic age. Thus it can be concluded that both the
Rimba Telui/Si Nakhon granite (Trgrrt/sn) and Bintang granite (Trgrbt) was emplaced
probably during the Triassic period.
There is no direct evidence currently available regarding the absolute age of the Damar
granite (Trgrdm). It is only known that the Damar granite (Trgrdm) intruded the Early
Silurian-Devonian Kroh formation (SDkr). Geologically, the Damar granite (Trgrdm) has
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