Abstract The Celtic Sea basins include the North Celtic Sea basin, Fastnet basin, St. George's Channel basin, Cardigan Bay basin, South Celtic Sea basin, and Bristol Channel basin. They form a series of linked, failed-rift basins. The tectonic and sedimentary Mesozoic history of the area can be closely related to the staged opening of the North Atlantic. The Celtic Sea basins show gross similarities to other North Atlantic basins in orientation and timing of development. Three discrete phases of extension and fault-controlled subsidence can be recognized, each followed by a period of thermally controlled passive subsidence: Phase Extension Passive Subsidence 1 Permian to Triassic Hettangian to Oxfordian 2 Kimmeridgian Tithonian to Berriasian 3 Berriasian to Aptain Aptian to Maestrichtian Reactivation of northeast-southwest Caledonian and east-west Variscan structural features is proposed as the major control on basin development. The deep pre-Mesozoic structures presumably interacted with the extension vectors associated with the opening of the North Atlantic to produce the complicated tectonic patterns seen within individual Celtic Sea basins.

Abstract Detailed assessment of high-resolution elemental and isotopic geochemical datasets collected from the marl–limestone alternations cropping out at La Cerradura (Subbetic domain of the Betic Cordillera, Spain) and chrono- and chemostratigraphic correlation with the reference Mochras borehole (Cardigan Bay Basin, UK) unveiled valuable new insights into understanding of late Pliensbachian–early Toarcian palaeoenvironmental dynamics in a key geographical area between the northern European seaway and the Tethys Ocean. This study shows that deposition in the study area took place under dominantly oxic water column conditions, indicated, for example, by the generalized lack of enrichment in organic matter and redox metals typically associated with anoxia and euxinia. Carbon isotope stratigraphy (δ 13 C TOC) allowed recognition of the spinatum (= emaciatum in the Submediterranean Province), Pliensbachian–Toarcian, and early Toarcian Oceanic Anoxic Event negative carbon isotopic excursions and the late Pliensbachian positive carbon isotopic excursion. It is here suggested that the observed periodic changes in lithology and sedimentary geochemistry occur at orbital frequencies (i.e. long and short eccentricity and, tentatively, precession), hinting at an astronomical control of the local–regional climate and environment during the Pliensbachian and Toarcian in the mid- to low-latitude South Iberian palaeomargin area.