Recent and Miocene carbonate sediments from Indonesia. Available in 2 volumes.

Abstract

Mapping and sediment sampling in reefs of the Pulau Seribu group (southwest
Java Sea) shows the existence of ten physiographic zones and subzones
represented by seven lithofacies. Reefs in the northern part of the archipelago
are smaller, more closely spaced and morphologically sim pler than those in the
south. This pattern is attributed to differences in subsidence rate. A th reedimensional
model is proposed for the evo lution of these reefs but borehole data
are requi red to test this model.
Miocene limestones are described in detail from hydrocarbon reservoirs in
the Batu Raja Formation of the same area. Brief comparisons a re made with
surface outcrops of approximately coeval carbonate developments. The
lithofacies developed within these limestones reflect variations in hydrodynam ic
regime and basement topography . Ele\le.n diagenetic processes affected the
Batu Raja limestones and the dist ribution of these is primarily related to
sealevel fluctuations. Early diagenesis was marine and characterised by
micritisation and preCipitation of fibrous and bladed cements. Dolomitisat ion
occurred in the mixed- water zone and its variable intensity is attributed to the
configuration of the carbonate body relative to this zone. Subsequently the
limestones were subjected to freshwater phreatic zone diagenesis resulting in
dissolution and cementation, and a t a late stage underwent burial compaction.
Secondary porosity, which \ar9e1.y determines the suitability of these limestones
as hydrocarbon reserVOirs, is a function of the variable intensity of dissolution
and cementation, burial compaction, dolomitisation and possibly micrite
neomorphism.
The sedimentary processes that generated the Batu Raja buildups are
inferred f rom comparisons with the Pulau Seribu and other Recent analogues.
The contrasting pinnacle form of the Pulau Seribu patch reefs compared with the
low relief of the Batu Raja buUdups results from differences in the initial
substrate topography and subsequent subsidence rate

Date of Award	Mar 1986
Original language	English