Interplay of crustal architecture and syn-tectonic sedimentation in the hydrocarbons generation: examples from the North and Central Atlantic Conjugate Margins

Abstract

The recent long offset commercial seismic data combined with wide-angle deep seismic profiles acquired on East Canada and its conjugate margins of Morocco and Iberia depict a new image of the North and Central Atlantic margin anatomy. The most striking feature is the large asymmetry of the conjugate margins. The East Canada margin is characterized by a steep west dipping Moho geometry with relative narrow necked and exhumed crust domains, while the conjugate margins of Iberia and Morocco shows large “boudinage” of crustal domains with a gentle east dipping Moho geometry. The syn-rift sequence of both East Canada and Morocco margin is characterized by a long-lived salt deposition starting from Carnian and Norian, with some basalts intercalated. On both margins the post-rift sequence consists of Lower Jurassic carbonates, shale and sandstones and, starting from Middle Jurassic, the deposition of large carbonate platforms, reservoir of Panuke Field, Nova Scotia, and Cap Juby in Morocco. During the Cretaceous, on both margins a shallow to deep marine clastic deposition occurs. Marine source rocks were deposited during Jurassic and Cretaceous time. The key structural feature of the basins is the long-lived salt tectonics, taking place from early Jurassic until present day. Such activity is coeval with the deposition of the main clastic Upper Jurassic and Cretaceous clastic. Salt canopies are very common in the deep and ultra-deep water setting and may represent excellent opportunity for sub-salt play exploration. The key points for the exploration potential evaluation in terms of hydrocarbon generation and type of fluids are the interplay of the crustal architecture of the margins, combined with the role of the salt and syn-tectonic deposition of the reservoirs. In this context, simple models of hydrocarbon generation and reservoir deposition are non-applicable and a more complex “partitioned” model of the crust combined with a detailed structural and depositional evolution of the margins should be considered.

AAPG Datapages/Search and Discovery Article #90325 © 2018 AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin, Lisbon, Portugal, May 2-3, 2018