MIOCENE PALYNOLOGY OF THE BARITO BASIN, SOUTH KALIMANTAN PALINOLOGI UMUR MIOSEN DI CEKUNGAN BARITO, KALIMANTAN SELATAN

Abstract

This study has succesfully disclosed the rich assemblage of palynomorph within the Miocene sediment ofthe Barito Basin, South Kalimantan. It is characterised by the the last occurrence of Florschuetzia trilobata(Middle/ Late Miocene boundary) and the fi rst occurrence of F. meridionalis (Early/ Middle Mioceneboundary). In addition, other Miocene markers appear to mark this age such as spores of Stenochlaeniditespapuanus (Late Miocene) and Scolocyamus magnus (Early/ Middle Miocene). Mean while, the regularoccurrence of brackish palynomorphs along the studied sections indicates marine infl uence during depositionincluding Zonocostites ramonae, Florschuetzia meridionalis (mangrove pollen), Florschuetzia levipoli andSpinizonocolpites echinatus (back-mangrove pollen). The depositional environment initially occurs in thefreshwater environment of delta plain during Early to Middle Miocene (lower well sections) as suggestedby domination of freshwater pollen in the absence of marine micro-fossils. It gradually shifts in to deepermarine setting in delta front to pro delta (with possible shallow marine environment) during Middle toLate Miocene (upper well sections) as indicated by the increase of brackish palynomorphs combined withmarine micro-fossils. This study identifi es peak of riparian pollen Myrtaceidites sp. which is potential forwell correlation. This pollen is common within the lower well sections suggesting the presence of riverdeposits. On the other hand, considerable appearance of freshwater palynomorphs may be an indication ofwell development of low land forests under wet climate condition.