Abstract Straits and seaways are connections between basins, key areas for exchange and transfer of water, heat, biota and sediments, and they can influence regional and global climate. A better understanding of strait/seaway dynamics, their evolution and preserved deposits is, therefore, fundamental to reconstructing the palaeoecology, palaeogeography and stratigraphy of interconnected basins. Straits and seaways are also important for understanding climate dynamics in Earth's past, and for safely exploiting energy resources (fossil and renewable). This volume aims at improving the knowledge on this topic, and at providing a comprehensive collection of state-of-the-art works bringing together complementary disciplines. Even though studies on modern and ancient straits and seaways exist, they are not necessarily conceived towards a better geological understanding of these features as depositional systems in their own right. In this introduction, we emphasize the geological importance of straits and seaways, summarizing the content and key findings of the contributions on this topic. The articles included in this volume explore four main research themes related to straits and seaways: (1) occurrence and classification; (2) morphological features, facies and stratigraphic variability, sedimentary processes and dynamics; (3) tectonic and climatic controls, their feedback with climate changes; and (4) palaeogeographical reconstructions and preservation of associated deposits.

Abstract Straits and seaways are fundamental connectors of oceans, seas and more rarely lakes. They are ubiquitous in the modern geography and should be common in ancient landscapes. We compare their characteristics to improve our understanding of these features, with the aim to define better their geological use. We review geomorphological, oceanographic, geological and depositional characteristics based on well-documented modern and ancient examples, with a stronger focus on the rock record. ‘Strait’ and ‘seaway’ are differentiated by their spatial and temporal scale. This influences the type and persistence of oceanographic circulation and sediment distribution. Straits are individual depositional systems, with predictable bedform and facies changes along the sediment transport pathway, whereas seaways are larger and longer-lived physiographic domains, composed of numerous depositional systems. Therefore, their stratigraphic signature in the rock record should be significantly different. We conclude that straits and seaways are end members of a continuum, giving rise to the occurrence of intermediate cases with transitional characteristics. The distinctive geological usage of the terms ‘strait’ and ‘seaway’, even without sharp boundaries between end members, may be helpful for predicting their occurrence, stratigraphy, palaeogeography, biota distribution and potential distribution of reservoirs and seals for fossil resources and CO 2 storage.

Abstract The influence of bottom currents and tectonic activity on shelf sedimentary processes and sand distribution remains poorly constrained. A growing body of research highlights the importance and variability of the shelf sandstone bodies. To explore the roles of fluvial, wave and bottom current-controlled sediment distribution in the Western Interior Seaway, 21 marine sandstone outcrops in Wyoming and Colorado were analysed. Recurring facies associations include: paralic, tide-influenced coastal margins; mainly east and SE prograding, wave-dominated delta-fronts and shorefaces; heavily bioturbated, glauconitic sandstones; and traction current-dominated, tidally influenced, open-marine subaqueous delta and shelf deposits, with southward palaeocurrent directions. Intense reworking by a moderately diverse ichnofauna occurs in wave-dominated and glauconitic facies. Minimal burrowing occurs in cross-stratified subaqueous delta and shelf deposits. Lithofacies associations are interpreted to change basinward with increasing water depth. Ichnoassociations reflect the proximity of river mouths. Widespread, southward palaeocurrent directions, not restricted to a narrow longshore zone, on the shallow-marine shelf indicate the persistence of strong, along-shelf sand-transport which has not been previously documented in detail. Palaeobathymetric complexity caused by uplift of Laramide structures amplified and accelerated bottom and tidal currents and facilitated the erosion, transport and deposition of older sediments.