Tectonostratigraphic evolution of the Slyne Basin

Abstract

Abstract. The Slyne Basin, located offshore NW Ireland, is a narrow and elongated basin composed of a series of interconnected grabens and half-grabens, separated by transfer zones coincident with deep crustal structures formed during the Silurian- to Devonian-aged Caledonian Orogeny. The basin is the product of a complex, polyphase structural evolution stretching from the Permian to the Miocene. Initially, relatively low-strain rifting occurred in the Late Permian and again in the latest Triassic to Middle Jurassic, followed by a third phase of high-strain rifting during the Late Jurassic. These extensional events were punctuated by periods of tectonic quiescence during the Early Triassic and Middle Jurassic. Late Jurassic strain was primarily accommodated by several kilometres of slip on the basin-bounding faults, which formed through the breaching of relay ramps between left-stepping fault segments developed during earlier Permian and Early–Middle Jurassic rift phases. Following the cessation of rifting at the end of the Jurassic, the area experienced kilometre-scale uplift and erosion during the Early Cretaceous and a second, less severe phase of denudation during the Palaeocene. These post-rift events formed distinct regional post-rift unconformities and resulted in a reduced post-rift sedimentary section. The structural evolution of the Slyne Basin was influenced by pre-existing Caledonian structures at a high angle to the basinal trend. The basin illustrates a rarely documented style of fault reactivation in which basin-bounding faults are oblique to the earlier structural trend, but the initial fault segments are parallel to this trend. The result is a reversal of the sense of stepping of the initial fault segments generally associated with basement control on basin-bounding faults.

Multiple phase rifting and subsequent inversion in the West Netherlands Basin: implications for geothermal reservoir characterization

“…We have followed the well-established workflow for interpretation of seismic datasets in extensional settings (e.g. O'Sullivan et al, 2022), which involves a reconstruction of the seismic stratigraphy by integrating well data with the identification of different seismic facies, unconformities, and brightly marked reflective horizons. In detail, 9 horizons were interpreted for the whole 3D cube.…”

Subsurface storage capacity in underexplored sedimentary basins: Hydrogen and carbon dioxide storage on the Irish Atlantic margin

“…A third extensional phase began during the Late Jurassic, accompanied by kilometre-scale movement on the basin-bounding faults and the deposition of a thick sequence of fluvioestuarine mudstones and sandstones throughout the study area (Dancer et al, 1999;O'Sullivan et al, 2022). A second phase of halokinesis occurred in tandem, with new structures being formed and pre-existing structures created in the Early and Middle Jurassic being reactivated and modified .…”

“…The geology of the study area is a product of a complex geological evolution extending from the Carboniferous to the present day (Chapman et al, 1999;Dancer et al, 1999;O'Sullivan et al, 2022). The oldest rocks investigated in this study are Carboniferous strata deposited in several fault-bound basins which formed during back-arc extension as the Rheic Ocean was subducted beneath the Laurentian continent (Woodcock & Strachan, 2012).…”

“…2). The Erris Basin is a notable exception and was involved in the extension of the Rockall Basin, with over a kilometre of predominantly marine sediments accumulating in this basin during the Cretaceous (Chapman et al, 1999;O'Sullivan et al, 2022). Several structures underwent subtle modification and reactivation during this period of exhumation, with small reverse and normal movements on faults observed throughout the study area (Corcoran & Mecklenburgh, 2005;O'Sullivan et al, 2022).…”

“…However, the lack of any Cretaceous sediments to record fault movement during the Cretaceous does not preclude any post-rift movement on the bounding faults (e.g. O'Sullivan et al, 2022). Stacked structural traps are mapped in each storage play in the Inishmore structure; two large closures in the Upper Jurassic and Lower Triassic storage plays are observed bounded by the main fault which soles out in the Zechstein Group halite, while two smaller closures are observed in the Carboniferous storage play (Fig.…”