Tectonostratigraphic Evolution of the Orphan Basin, Offshore Newfoundland

Kimberly Thomas¹, Micheal Wojcik¹, David G. Roberts², Stephan Petmecky¹, Donald Tanasichuk³, Thomas Mason⁴, and David Derbecker^1
1 BP, Houston, TX
² BP Exploration, Sunbury-on-Thames, Middlesex, England
³ BP Canada, Calgary, AB
⁴ BP, Cairo, Egypt

A structural and stratigraphic analysis of the Orphan Basin, offshore Newfoundland, integrated with the Mesozoic regional tectonic evolution of the N. Atlantic provides a geologic framework for petroleum exploration. Analysis and plate reconstructions establish common linkages between the Orphan and Jeanne D'Arc Basins, offshore Newfoundland, in the areas of tectonic origin, reservoir and source rock provenance and hydrocarbon resource potential.

Four phases of rifting and drift, linking the Jeanne D'Arc (JDA), Flemish Pass (FP) and Orphan Basins, opened the N. Atlantic between the late Triassic and Cretaceous. Initially, L. Triassic SW-NE extension formed the precursors of these basins when separated Nova Scotia from Morocco. SSW-NNE Oxfordian rifting separated Iberia from Newfoundland forming an elongated, restricted basin in which the Orphan Basin was bounded on the north by the Porcupine Basin, offshore Ireland, and on the south by the JDA and FP Basins. Along this basin's western margin, rich source rocks were deposited in marginal marine to non-marine settings and analyses of oils from the JDA, FP, Porcupine and Celtic Sea Basins indicate genetic geochemical links.

Late Berriasian rifting and the Avalon Uplift, uplifted and structured the Rift 2 footwall into a series of deeply-rooted, highly rotated faulted blocks to form the basin's western shoulder. Northward propagation of Rift 3 rapidly deepened the Orphan Basin, potentially resulting in the deposition of deepwater turbidites. Finally, early Aptian NW-SE rifting separated Labrador from Greenland, the Orphan Knoll from the Porcupine Bank and the Flemish Cap from the Goban Spur.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005