Bimodal Cenozoic Volcanism in Central Sarawak: Hot Spots or Extension?. Nur Iskandar Taib Geology Department, University of Malaya, Kuala Lumpur [email protected] Several Cenozoic volcanic edifices are present in the Upper Rajang Valley, central Sarawak. Early Miocene Bukit Mersing
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Nur Iskandar Taib
Geology Department, University of Malaya,
USUN Rajang Valley, central Sarawak.APAU
REE plot Rajang Valley, central Sarawak.
Bukit Mersing – more enriched than Plio-Pleistocene basalts
Steep REE patterns, no Eu anomaly
OIB-type parent melt, no evidence of continental contamination
Incompatible element (Spider) plot Rajang Valley, central Sarawak.
Bukit Mersing – more enriched than Plio-Pleistocene basalts in incompatible elements also
No significant Nb (and other HFSE) depletion
Also indicates OIB-type parent melt with no arc/subduction signature
Plio-pleistocene basalts have similar isotopic signature to basalts from Semporna of the same age.
Components/contaminants ruled out – I-MORB, Sulu and Celebes Sea crust. Also EM1, HIMU and DMM mantle components. EM2 as a mantle component remains a possibility.
Macpherson et al. (2010) interpretation for Semporna basalt – REE parent melt (as represented by SCS seamounts) contaminated with Archean domains within the basement.
If true the basement underneath the Rajang Valley is continental in nature.
After MacPherson et al. (2010)
Extension vs. Hot Spots basalts from Semporna of the same age.
don't have yet
Other explanations basalts from Semporna of the same age.
Cenozoic volcanism in SEA basalts from Semporna of the same age.
Eruption in 1923
So how connected is all this?
IN MEMORY OF basalts from Semporna of the same age.
CHARLES S. HUTCHISON
Professor Emeritus, University of Malaya
Who pointed me in this direction in the first place