Bulletin of the Geological Society of Malaysia, Volume 20, August 1986, pp. 503 – 521

Petrochemistry of gem-bearing basalt in the Nong Bon area, Trat Province, Eastern Thailand

THEERAPONGS THANASUTHIPITAK¹ AND THANAWUT SIRINAWAN²

¹Department of Geological Sciences, Chiang Mai University, Chiang Mai 50002, Thailand

²SEATRAD Centre, Tiger Lane, Ipoh, Malaysia

Abstract: Basaltic rocks of Nong Bon area average 30 m thick. They are generally massive with few vesicular layers. Megacrysts of clinopyroxene, garnet, ilmenite and magnetite, and xenoliths of ultramafic rocks are common in these rocks. Petrographic studies so far indicate that some of the rocks are olivine nephelinites, porphyritic with phenocrysts of olivine, clinopyroxene and spinel. Geochemical data are also available for the basanitoid basalt.

On the basis of the data available, the origin of corundum found in the study area cannot be genetically related with the basanitoid basalts. It is suggested that pre-existing corundum was picked up from a depth just above the level of formation of the basanitoid basalts.

https://doi.org/10.7186/bgsm20198624