The newly mapped Northeast Rockall Basin lies between the Wyville-Thomson Ridge and an ESE lineament extending from the onshore Ness Shear Zone. It contains a window in the early Tertiary flood-basalts through which a syn-rift sedimentary succession is imaged on seismic data. This succession was mapped in detail, calibrated to wells and boreholes drilled on the basin margins, and integrated with results from gravity, magnetic and backstrip modelling. Modelling and seismic stratigraphic analysis show that the Wyville-Thomson Ridge is a late Eocene to Oligo-Miocene fault-propagation fold, comprising basalt at the seabed and folded low density sediments within its core. Together with the co-linear Munkegrunnur and Ymir Ridges, this fold developed from positive inversion above a composite, crustalscale ramp-flat detachment during N-S compression. Prior to mid-Tertiary inversion of the WyvilleThomson Ridge, the basin may have formed a link between the main part of the Rockall Trough to the south and the Faeroe-Shetland and East Greenland rift systems to the north. Triassic, Jurassic and Early Cretaceous syn-rift sediments have been penetrated in the adjoining West Lewis Basin, and the Northeast Rockall Basin may contain sediments with a similar age range beneath the Tertiary flood basalts. Estimates from modelling allude to a resurgence of rifting from mid-to latest Cretaceous times, perhaps coeval with voluminous axial volcanism in the adjacent Rockall Trough. This episode of syn-rift volcanism, underlying the Paleocene volcanics, prohibits deeper seismic resolution to the south of the lineament in the main part of the Rockall Trough. The present-day bathymetry has resulted from a complex interaction between the loci of Mesozoic stretching, renewed post-basalt subsidence and major late Eocene to Oligo-Miocene inversion.
Trace fossils from the Middle Devonian Caherbla Group of the Dingle Peninsula, southwest Ireland, record a diverse arthropod fauna inhabiting a hot-arid intracontinental rift setting. Aeolian dunefield and coeval fluvial interdune deposits interfinger spatially and temporally with alluvial fan sedimentary rocks. Three distinct trace fossil assemblages are recognized. The Taenidium-Scoyenia ichnocoenosis occurs in alluvial fan and fluvial channel deposits, and includes the large backfilled burrow Taenidium, interpreted as eoarthropleurid aestivation chambers. The Rusophycus-Protichnites ichnocoenosis, composed of arthropod trackways and surface pits, occurs in an interdune ponded area that was susceptible to ephemeral fluvial flow, with Rusophycus showing preferred orientation into the oncoming palaeocurrent. Both the TaenidiumScoyenia and Rusophycus-Protichnites ichnocoenoses are assignable to the globally recurring continental Scoyenia ichnofacies. They are clearly substrate-controlled and moisture-related due to the ephemeral nature of the fluvial system. The Palmichnium-Entradichnus ichnocoenosis occurs in aeolian dune deposits, and includes Palmichnium, attributed to large stylonurid eurypterids, and Diplichnites, attributed to eoarthropleurids. These trackways represent the activities of dune pioneers that left their fluvial habitat to forage for detritus. Interface burrows (Entradichnus, Palaeophycus) were also constructed by arthropods moving just under the sand surface and vertical burrows (Cylindricum, Pustulichnus) were made by arthropods digging downward. Trace preservation in the aeolian environment was probably enhanced by heavy nocturnal dew-fall or light rain. The Palmichnium-Entradichnus ichnocoenosis is assigned to the globally recurring aeolian OctopodichnusEntradichnus ichnofacies. This aeolian facies, and associated ichnofauna described herein, represents the oldest development of a unique erg system in the Old Red Sandstone (Devonian) of the southern British Isles, and one of the oldest and most diverse aeolian ichnofaunas to be reported worldwide.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.