Lithostratigraphy of the Misool Archipelago, Irian Jaya, Indonesia

Abstract

The Misool Archipelago contains one of the most complete and richly fossiliferous Mesozoic sequences in southeast Asia and the southwest Pacific. The excellent exposures offer an opportunity to establish a reference biostratigraphy for the region as well as a detailed lithostratigraphy. Metamorphics form a basement overlain by ?Triassic flysch which was block-faulted and uplifted during the Carnian, after which platform carbonates were deposited followed by a period of non-deposition. Marine sedimentation resumed in the Early Jurassic with fine clastics and bathyal carbonates. Early Cretaceous volcanism was accompanied by a change to a fluvio-deltaic environment. By Tertiary times sediment supply waned and a marine carbonate regime was established. Marl was deposited after Late Oligocene folding and by middle Miocene times a carbonate regime was re-established until Quaternary uplift formed the Misool Archipelago. The Misool stratigraphy is a continuation of the northwestern Australian rift-drift sequence formed during the breakup of northern Gondwana. It provides precise timing for these events and hence vital information for the assessment of hydrocarbon potential.