ABSTRACT: Possible controls on the formation of oil-prone coals and coal-bearing strata

Fleet, Andrew¹, and Stephen Cawley²
(1) The Natural History Museum, London, United Kingdom 
(2) BP-Amoco, Aberdeen, United Kingdom

The formation of coals and coal-bearing strata which give rise to significant volumes of oil (i.e. of liquid petroleum), like those of southeast Asia, have probably been controlled by three principal factors: botanical input, depositional environment and early diagenesis. These factors generally, but not exclusively, limit such oil-prone coals to Cretaceous and younger, tropical to sub-tropical lower delta plain sequences.

The botanical input will have varied through time as plant communities evolved and will have been governed by climate and other environmental factors. In general relatively abundant input of potentially oil-prone detritus, which can become preserved as exinite, has only been available since Cretaceous times. Tropical and sub-tropical climates would have resulted in high biological productivity and so favoured abundant input.

The preservation of this potentially oil-prone organic detritus in abundance seems to be occurred in lower delta plain settings. This can be deduced from the distribution of oil-prone coals but the mechanism for such preferential preservation is unclear.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia