Evidence of Early Palaeozoic volcanism inPeninsular Malaysia is largely represented by felsic Gerik-Dinding meta-volcanic rocks; however, reliable absolute ages for the meta-volcanic rocks are still lacking. This restricts correlation of these meta-volcanic rocks with other Early Palaeozoic East Gondwana Proto-Tethys margin tectonic elements identified in the evolution of Southeast Asia. Here, we report petrographic data and zircon U-Pb age of the Gerik-Dinding metavolcanic rocks. Zircons from three Gerik-Dinding meta-volcanic rock samples yield Early to Middle Ordovician weighted mean 206 Pb/ 238 U ages between 480 and 460 Ma. The formation age of the meta-volcanic rocks coincides with the post-collision stage from the final amalgamation of Asian micro-continental fragments with the East Gondwana Proto-Tethys margin. Tectonic processes such as lithospheric delamination during the post-collision period could have induced the hot asthenosphere to underplate the continental crust and trigger crustal anatexis. With these findings, the Early Palaeozoic tectonic history of Peninsular Malaysia needs careful review.

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The Bukit Bunuh in Malaysia has recently been identified as an impact structure after the discovery of possible impact-melt-like rocks and impact breccias from this area. The impact event is believed to have occurred around 1.34-1.84 Ma. Twelve impact-related rocks from this suspected impact structure were analysed in the present study for platinum group of element (PGE) content. The sample population includes proximal impactites (two impact-melt rocks and three impact breccias) and possible impact-related rocks (four mylonites) and basement granite (three in number). The results showed no observable clear distinction between the impactites and basement granite. Compared to other asteroid impact sites in the world, the impactites and impact-related rocks in the Bukit Bunuh structure clearly contain a lower concentration of PGEs. Even though previous studies reported possible evidences of shock metamorphism in the Bukit Bunuh structure and electrical resistivity survey favoured the presence of asteroid impact structure in this area as well, the absence of a clear projectile signature in our study on PGE hinders further discussion on the existence and nature of the impact. We suggest that the absence of any PGE signature in the Bukit Bunuh impactites could be indicative either of (1) an achondrite projectile, or (2) an oblique impact or (3) the presence of a volatile-rich layer.

North-eastern trending mafic dykes are found intruding granitic body in Ajil area, Eastern Belt of Peninsular Malaysia. The intrusions display sharp, vertical to sub-vertical contacts to granitic host and consist mainly of plagioclase and clinopyroxene. Majority of the dykes are quartz tholeiite with some olivine tholeiite. All dykes display enrichment in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) and depletion in high field strength elements (HFSE) and Pb. Low compatible elements' content such as MgO, Ni and Cr implied that crystal fractionation were controlled by olivine and clinopyroxene. The dykes were originated from shallow lithospheric mantle, the source region of which has been influenced by hydrous metasomatism. The emplacement of the dykes took place in fault-controlled within-plate tectonic setting.

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