Depositional-environments-and-oil-potential-of-retaceous-source-rocks-within-the-Seychelles-microcontinent_1998_Marine-and-Petroleum-Geology.pdf

Marine and Petroleum Geology 04 "0887# 274Ð390
Depositional environments and oil potential of Jurassic:Cretaceous
source rocks within the Seychelles microcontinent
Phillip S[ Plummer\ Patrick R[ Joseph\ Patrick J[ Samson
Seychelles National pany\ PO Box 129\ Victoria\ Mahe\ Seychelles
Received 3 December 0886^ 09 March 0887^ 29 March 0887
Abstract
The Seychelles microcontinent became isolated between the Somali\ Mascarene and Arabian basins of the Indian Ocean as a result
of the Mesozoic fragmentation of Gondwana[ Major rifting events occurred during the Triassic!Middle Jurassic and Late Cretaceous
"Cenomanian!Santonian and Maastrichtian# during which shaly source rock facies accumulated in principally marginal marine:deltaic
environments[ Between these times\ post!rift passive margin deposition within restricted to open marine environments produced
shaly source rocks during late Middle Jurassic!Early Cretaceous\ Campanian!Maastrichtian and Paleocene times[
Recent geochemical analysis of cuttings from the Seagull Shoals!l well has identi_ed an oil!prone liptinitic "Type II# coaly shale
within early Middle Jurassic abandoned deltaic deposits[ This coaly source rock is regionally developed\ having also been identi_ed
in the Majunga and Morondava basins of Madagascar[ Oil!prone Type anic matter has also been identi_ed in the Owen Bank
A!0 well within restricted marine shales of late Middle Jurassic age[ These shales are part of a thick post!rift source rock sequence
that extends into the Early Cretaeous and is in part correlative with the proven Late Jurassic Uarandab Shale of Somalia[ Analysis
of Campanian marine shales from Reith Bank!0 well identi_ed signi_cant dilution of anic carbon content posite\
compared to picked\ well cuttings samples[ This _nding supports a published inference that these post!rift shales have source rock
potential[ The very limited drilling of the various Jurassic:Cretaceous source rock sequences in Seychelles "onl