MIOCENE PALYNOLOGY OF THE BARITO BASIN, SOUTH KALIMANTAN

Abstract

This study has succesfully disclosed the rich assemblage of palynomorph within the Miocene sediment of
the 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 Miocene
boundary). In addition, other Miocene markers appear to mark this age such as spores of Stenochlaenidites
papuanus (Late Miocene) and Scolocyamus magnus (Early/ Middle Miocene). Mean while, the regular
occurrence of brackish palynomorphs along the studied sections indicates marine infl uence during deposition
including Zonocostites ramonae, Florschuetzia meridionalis (mangrove pollen), Florschuetzia levipoli and
Spinizonocolpites echinatus (back-mangrove pollen). The depositional environment initially occurs in the
freshwater environment of delta plain during Early to Middle Miocene (lower well sections) as suggested
by domination of freshwater pollen in the absence of marine micro-fossils. It gradually shifts in to deeper
marine setting in delta front to pro delta (with possible shallow marine environment) during Middle to
Late Miocene (upper well sections) as indicated by the increase of brackish palynomorphs combined with
marine micro-fossils. This study identifi es peak of riparian pollen Myrtaceidites sp. which is potential for

well correlation. This pollen is common within the lower well sections suggesting the presence of river
deposits. On the other hand, considerable appearance of freshwater palynomorphs may be an indication of
well development of low land forests under wet climate condition.