Sequence stratigraphic response to Aptian-Albian rifting in conjugate margin basins: a comparison of the Jeanne d’Arc Basin, offshore Newfoundland, and the Porcupine Basin, offshore Ireland

Abstract

Analysis of well and seismic data indicates that both the Jeanne d’Arc Basin on the Grand Banks of Newfoundland and the Porcupine Basin on the continental shelf off western Ireland were undergoing extension characterized by subsidence and rotation of fault blocks during mid-Aptian to late Albian times. Stratigraphic sequences in these conjugate basins developed in response to synchronous rift tectonism. The base of each syn-rift sequence is defined by an angular unconformity which formed in response to regional uplift. This mid-Aptian rift-onset unconformity is buried beneath a depositional sequence characterized by retrogradational coastal sediments overlain by progradational coastal sediments in each basin. However, the lower retrogradational deposits dominate the syn-rift sequence in the Jeanne d’Arc Basin, while the upper progradational deposits dominate the syn-rift sequence in the northern Porcupine Basin. The relative dominance of sediments deposited along either transgressive or regressive coastlines was mainly determined by the local interplay of variable rates of rift-induced subsidence and sediment input. The initiation of seafloor spreading between the Flemish Cap/Orphan Knoll and Goban Spur/Porcupine Bank continental margins near the end of Albian time resulted in the establishment of regional thermal subsidence, rapid coastal transgression and fully marine deposition above a locally-developed sequence-bounding unconformity.

Diachronous evolution of Late Jurassic–Cretaceous continental rifting in the northeast Atlantic (west Iberian margin)

“…This latter extensional episode preceded Berramian (S4) continental breakup at N40°15 0 (segment 3) [Whitmarsh and Miles, 1995], $10 Ma before late Aptian breakup in segment 4 where a stretching maximum is recorded during the Valanginian [Groupe Galice, 1979;Murillas et al, 1990;Boillot et al, 1995] (Figures 14 and 15). Therefore, extension during the advanced rifting stage is interpreted to have occurred before the Valanginian in segments 2 and 3, thus correlating synrift successions on the outer proximal margin west of the Lusitanian Basin with equivalent synrift strata in the Jeanne D'Arc Basin [e.g., Sinclair, 1995]. These considerations agree with the interpreted seismic data, in which two distinct rifting axes are recognized in west Iberia (Figure 15).…”

“…[45] Our interpretation does not exclude, in localized subbasins, the prolongation of synrift subsidence (or, in contrast, its early cessation) away from the interpreted stratigraphic boundaries, as documented in parts of the North Atlantic [Driscoll et al, 1995;Sinclair, 1995]. Likewise, the stratigraphic expression of equivalent riftrelated tectonic events may vary within, and among (1) distinct deep offshore basins, (2) separate crustal segments, and (3) conjugate pairs of margins [Hiscott et al, 1990a;Welsink and Tankard, 2009].…”

“…Relative dating of seismic units is based on published and unpublished information on the Lusitanian Basin [Atrops and Marques, 1986;Wilson et al, 1989], on the northwest Iberian margin [Groupe Galice, 1979;Boillot et al, 1989;Murillas et al, 1990;C. Moita et al, Porto Basin: Seismic interpretation report, unpublished report, MILUPOBAS project, 1996; Gabinete para a Pesquisa e Exploração de Petróleo (GPEP), Petroleum potential of Portugal, unpublished report, 1986], and on the Canadian/ Irish margins [Driscoll et al, 1995;Sinclair, 1995; Williams et al, 1999;Shipboard Scientific Party, 2004]. Together with Industry well data (wells Pe-1 and Go-1), dredge data published by Mougenot et al [1979] have been used locally to date some of the strata outcropping offshore Alentejo (Figure 1b).…”

“…Alternatively, Mesozoic subsidence in the outer proximal margin may be similar to that in the Grand Banks area. Here, discrete extensional episodes or rift pulses [e.g., Sinclair, 1995], occurring diachronously in distinct segments of the Newfoundland margin, add up to the final values of basement subsidence recorded in adjacent sedimentary basins [e.g., Hiscott et al, 1990a].…”

A Review of Tectonic Events on the Passive Margin of Eastern North America

“…5). The youngest of these strata likely are associated with post-rift salt movement (Tankard and Welsink, 1987) and/or the subsequent rifting and separation of the northern Grand Banks from Greenland/ Europe (Tankard and Welsink, 1987;Foster and Robinson, 1993;Sinclair, 1995b). Thus, rifting had ceased and drifting between the eastern Grand Banks and Iberia had commenced during late Early Cretaceous time in the northern part of the northern segment.…”