On the Jard-sur-Mer area, these minerals are also found higher in the sedimentary series suggesting that fluid flow through the impermeable layer. The final locally updated plate model supports the hypothesis of compartmentalization of the continental region of the Goban Spur margin, highlights the significant role of inherited structures, and renews linkages between the Goban Spur and its potential conjugates during oblique rifting.Īll around the Aquitain basin, fluid circulates at the interface between the basement and impermeable shale (Toarcian) within high porosity levels (Hettangian) as evidenced by many mineral deposits including baryte, fluorine and galena. The present-day crustal thicknesses on the Goban Spur from the locally updated plate model agree with those derived from gravity inversion, providing a possible remedy for the crustal thickness discrepancy generated by existing models. In addition, the seismic reflection data are used to assist in adjusting the geometry of the modelled zone of deformation on the Goban Spur. More importantly, the seismic reflection data show zones of focused faulting, which are incorporated into the plate model as inherited weakness zones.
The new long-offset seismic reflection data reveal the complex architecture of the Goban Spur basins, which are filled with highly variable sediment thicknesses, suggestive of a protracted and polyphased rifting history. This study seeks to resolve this discrepancy by locally updating an existing plate model of the southern North Atlantic by incorporating constraints from four newly-presented seismic reflection profiles. Specifically, crustal thicknesses calculated for the Goban Spur from existing plate models show a discrepancy with those derived from independent geophysical methods like gravity inversion and seismic refraction modelling. To date, kinematic plate reconstruction models have struggled to restore the tectonic evolution of the Goban Spur, offshore Ireland. Our results offer new insights on the role of: (1) structural inheritance in partitioning extensional strain, (2) transfer zones as able to influence the sedimentary record of basins during crustal thinning, and (3) pre-rift salt décollements as able to separate the structural styles of sub- and supra-salt successions. The Mauléon North Pyrenean Basin and its north adjacent Tartas and Arzacq basins thus formed part of a series of rift basins that progressed in maturity southward, from a simple sag basin (Tartas) to a slightly asymmetric basin (aborted detachment, Arzacq) to a hyperthinned basin (Mauléon).
The goban irvine drivers#
Two drivers of subsidence are thus envisaged in the Arzacq Basin: a Neocomian-Aptian crustal thinning stage, followed by reactivation of Paleozoic faults in Albian time accompanied by salt diapirism and gravity cover sliding. The Tartas Basin maintained a symmetric regime throughout the Early Cretaceous, except along the Barlanès transfer zone where the Lussagnet salt diapir originated. Several inherited Paleozoic structures were reactivated as transfer zones and appear to be responsible for this depocenter shift, the emplacement of salt diapirs, at same time regionally limiting gravity sliding.
This change was controlled by gravity sliding of the pre-rift sedimentary cover in the eastern Arzacq Basin moving its depocenter south, and by salt diapirism in the western Arzacq Basin moving its depocenter north. The Arzacq Basin shifted from a symmetric to a slightly asymmetric configuration. These basins did not suffer major brittle deformation during rifting stage, but nevertheless record a major change in their configuration between the Aptian and the Albian. Here, we address the Early Cretaceous tectono-sedimentary evolution of the Arzacq and Tartas rift basins and the lithospheric processes associated with their genesis. However, the two basins differ from recent models in having a pseudo-symmetric morphology. They belong to an Albian rift system, where recent studies have stressed the role of simple-shear thinning on the genesis of regional asymmetric basins. Arzacq and Tartas were two Cretaceous basins developing in the Bay of Biscay as secondary depocentres in the larger Aquitaine Basin.