Cretaceous and Neogene lavas of Sabah – origin and tectonic significance

Shariff A. K. Omang and Sanudin Tahir. (1995) Cretaceous and Neogene lavas of Sabah – origin and tectonic significance. Bulletin of the Geological Society of Malaysia, 38. pp. 21-30. ISSN 2637-109X

Text 702001-100928-PDF.pdf Restricted to Repository staff only Download (445kB)

Abstract

A combination of field and geochemical investigations of the Cretaceous and Neogene lavas of Sabah (CNLS) allow some control on the relative timing of events in its tectono-magmatic history. The low-K tholeiitic lava (Telupid basalt of Cretaceous age) or so-called ‘boninitic suite‘, interpreted as a product of partial melting of hydrated oceanic lithosphere in the mantle wedge, suggesting that the first magma formed in response to intra-oceanic subduction. As subduction proceeded, the magma composition changed to the calc-alkaline suite (high-K calc-alkaline lavas of Neogene Tungku and Tanjung Batu andesites), probably because of the hydrated asthenosphere of the mantle wedge confirming an oceanic, supra-subduction zone origin for this volcanic arc assemblage. An evolutionary sequence can be envisaged for the CNLS which begins with the establishment of an oceanic island arc where supra-subduction zone extension led to the genesis of tholeiitic lava and/or boninitic (Telupid basalt) and followed by formation of the volcanic arc (Tungku andesite). Next, followed by Tungku arc-splitting, as extension continued, a marginal basin (Sulu Sea) developed. Later, incomplete closing of the Sulu Sea caused the southwards subduction beneath the older arc and formation of the Tanjung Batu andesite.

Actions (login required)

View Item