Stratigraphy of the Mantanani Islands, Sabah

Abstract

The Mantanani Islands are esssentially underlain by sedimentary rocks. These are mainly bioclastic limestones and calcarenites. Lithostratigraphically, they may be divided into two units-a well-bedded unit conformably overlain by a relatively thicker massive conglomeratic unit. Their sedimentological features and faunal content suggest a warm shallow marine paleoenvironment. Deposition took place on a gentle slope of the shelf area, and was interupted by frequent influx of sediment that prevented full biohermal development. These rocks are mostly of at least Mid-Miocene age. Similar rocks known as the Balambangan Limestone Member are exposed on the southern tips ofBanggi and Balambangan Islands, north of Kudat Peninsula. Abstrak: Hanya batuan sedimen sahaja terdapat di kepulauan Mantanani. Ianya terdiri dari batu kapur bioklastik dan kalkarenit. Batuan ini terbahagi kepada dua unit lithostratigrafi. Unit bawah di wakili oleh batuan terlapis baik dan unit atas yang lebili tebal, konglomerat massif: Ciri-ciri sedimen dan kandungan faunanya mencadangkan paleoenvironmen laut tohor yang suam. Pengenapan berlaku diatas cerun landai dan sering diganggu oleh pembekalan sedimen yang menghalang perkembangan terunrbu sepenuhnya. Fosil-fosil menunjukkan batuan ini berunrur Miosen Tengah. Batuan berciri serupa yang dikenali sebagai Balambangan Limestone Member, terdedah di Pulau Banggi dan Pulau Balambangan yang terletak di utara Semenanjung Kudat.