Areas In Sabah Research Articles

Tectonic implications of the hydrated garnet peridotites near Mt Kinabalu, Sabah, East Malaysia

Hydrated garnetiferous peridotites form part of an ultramafic complex in the Mt Kinabalu area of Sabah, East Malaysia. Garnet peridotites are associated with abundant spinel lherzolites and rare plagioclase-bearing spinel lherzolites. The complex is in fault contact with the surrounding Tertiary strata. High-temperature peridotite mineral assemblages are overprinted by lower temperature hydrous assemblages characterized by abundant hornblende which is found filling interstices or thin veinlets. The small amounts of K, Na, Cl and F in the hornblende suggest that the metasomatic fluid may have been depleted in these elements. Carbon dioxide-rich, incompatible element-enriched, fluids are not thought to be the cause of the metasomatism since metasomatic phlogopite and carbonates, commonly reported from garnet peridotites and metasomatized alpine-type ultramafic rocks, are absent. The Mt Kinabalu garnet peridotites represent part of the sub-crustal mantle beneath Kalimantan which was metasomatized during ascent due to tectonism. The metasomatic fluid, poor in incompatible elements and H 2O-rich, may have been introduced into a sub-continental mantle wedge after dehydration of a subducted oceanic slab.

Studies on oil palm pollination by insects

AbstractIn Cameroun, about a dozen species of insects were associated with oil palm inflorescences. All except Prosoestus spp. visited female inflorescences after visiting male inflorescences during anthesis and transported pollen to the receptive female flowers. At a rough estimate, about 20 000 individuals visited each female inflorescence during the period of receptivity, and about 70% of the pollen transported was viable. In Peninsular Malaysia, Thrips hawaiiensis (Morg.) is almost certainly the main pollinating agent. Some 200 000 individuals were estimated to visit a single male inflorescence. They also visited female inflorescences, Where up to 7.3 thrips per flower were estimated to be present at any one time, each carrying 4–5 pollen grains, of which 76% were viable. In Peninsular Malaysia and Sabah, a momphid moth. Pyroderces sp., may contribute to oil palm pollination. As natural pollination of all oil palms in Cameroun and taller palms in Peninsular Malaysia is considered adequate while in most areas of Sabah where few insects visit the flowers it is inadequate, it is concluded that the insects observed achieve pollination so the oil palm should be considered an entomophilous rather than an anemophilous plant.