Journal of Petroleum Geology, Vol.16,
No.4, pp. 465-482, 1993
©Copyright 2000 Scientific Press,
Ltd.
THE TECTONO-STRATIGRAPHIC
DEVELOPMENT OF PATAGONIA,
AND ITS RELEVANCE TO HYDROCARBON EXPLORATION
M.P.R. Light *, M.L. Keeley *, M.P.
Maslanyj * and C. M. Urien **
* Intera Information Technologies,
Highlands Farm, Greys Road, Henley-on-Thames, Oxfordshire RG9
4PS.
** Urien y Asociados, Paraguay
609, Piso 6L, 1057 Buenos Aires, Argentina
Abstract
The history of terrane accretion along the
Pacific margin, that formed the Palaeozoic basement to Patagonia,
is discussed. This pre-existing NW-trending basement fabric was
periodically reactivated by shear stress, resulting from
near-continuous oblique Pacific subduction processes, producing
pull-apart and extensional grabens. During the Permo-Triassic, an
asymmetric passive rift developed east of an eastwardly-dipping
simple shear, following the axis of the proto-South Atlantic, and
was invaded by a shallow sea. The Falkland (Malvinas) Microplate
is shown to have docked with Patagonia in the Early/Mid Jurassic.
Clockwise symmetrical rotation and crustal deformation of the
Falklands (Malvinas) and other microplates between east-west
trending, dextral strike-slip faults controlled the development
of the southern transverse Atlantic margin basins. Early
restricted deposition in these basins (Early Jurassic-Neocomian)
led to the deposition of proved continental source-reservoir
associations. Rifting and transverse dextral strike slip shearing
propagated northwards, up the axis of the Atlantic. As terrane
collision progressed, the rift zone widened SWwards to the
Pacific and NEwards to the Colorado Basin. Atlantic sea-floor
spreading in the Neocomian, and subsequent thermal sag of the
Atlantic margin, is shown to have culminated in a major
transgression in the Maastrichtian, which formed a regional seal
for hydrocarbons.
