Multiple stages of continental rifting in Eastern Peninsular Malaysia: new insights from Jurassic-Cretaceous granitoids

Mesozoic granitoids in Peninsular Malaysia provide crucial information on the temporal-spatial relationship between the Tethyan and Palaeo-Pacific domains. This paper presents new ages and geochemical data for newly identified Jurassic-Cretaceous granites and meta-granites from East Malaya. These granitoids can be divided into three groups. Group 1 consists of high-K calc-alkaline granites and granodiorites (171-162 Ma) with variable epsilon Nd(t) values of -7.4-+0.5, zircon epsilon Hf(t) values of -7.4-+8.6, and high initial ratios for Pb-206/Pb-204 (20.04-20.65), Pb-207/Pb-204 (15.73-15.79) and Pb-208/Pb-204 (39.80-40.20). The melting of metasedimentary rocks with a juvenile mafic component formed Group 1 samples. Group 2 granite porphyries (c. 131 Ma) with A-type affinities and Group 3 granitic gneisses (c. 130 Ma) with I-type affinities share similar epsilon Nd(t) values (-7.2 to -5.5), zircon epsilon(Hf)(t) values (-10.1-+6.5), and initial ratios for Pb-206/Pb-204 (18.81-19.02), Pb-207/Pb-204 (15.71-15.77) and Pb-208/Pb-204 (38.95-39.59). Although Group 2 and 3 samples were derived from an 'ancient' meta-mafic source region, Group 2 shows evidence for the involvement of a juvenile mafic component. All these granitoids are akin to the Permian-Triassic igneous rocks in East Malaya. The Jurassic-Cretaceous igneous rocks in Eastern Peninsular Malaysia were formed during multiple stages of continental rifting in response to Palaeo-Pacific slab rollback pulses rather than by Tethyan evolutionary processes.