Downslope and along slope deep marine processes
Contourites and current dynamics in active margin settings
Dr Uisdean Nicholson1, Professor Gregory Moore3, Dr Debora Duarte2, Professor Dorrik Stow1
1Heriot-watt University, Edinburgh, United Kingdom, 2Andalusian Earth Sciences Institute, Granada, Spain, 3University of Hawaii, Honolulu, United States
Contourites and associated depositional and erosional products of bottom currents are widely recognised across most ocean basins. However, they are relatively understudied in active margins, partly because of tectonic deformation and sedimentary recycling in these dynamic settings. However, in convergent margins such as Hikurangi in New Zealand, the northwest Pacific, and the Indonesian archipelago, they are increasingly recognised as having an important role in modifying slope morphology. These tectonically active settings are typically structurally complex, leading to dynamic interactions between bottom currents and the seabed. Furthermore, contourite depositional systems in these settings can document long-term changes in ocean current conditions, and ocean gateway evolution that are critical to understand their role in regional and global climate and oceanographic change.
This session seeks to understand the latest developments in our understanding of contourite deposition and ocean current dynamics in active margin settings. This includes studies that address interactions between tectonic and oceanographic processes, physical oceanography in active margin settings, and the dynamics of ocean currents in such settings at different timescales.
Contourites and Mixed Depositional Systems
Dr Sara Rodrigues, Dr. Wouter de Weger, Dr. Debora Pascoal Duarte, Dr. Aleksei Portnov, Watcharaphong Phothadee, Professor F. Javier Hernandez-Molina1
1Andalusian Earth Sciences Institute (IACT), Spanish Research Council (CSIC), Armilla, Spain
Along-slope bottom currents and a series of secondary oceanographic processes interact at different scales to form sedimentary deposits referred to as contourite and mixed (turbidite-contourite) depositional systems. The recent surge in academic and industry research on deep-marine sedimentation has led to advancements in understanding these systems. However, the features and their formation processes remain largely unfamiliar to non-specialists. Contourites and mixed depositional systems represent a major domain of continental margin and adjacent abyssal plain sedimentation in the world’s oceans. These are recognised in Palaeozoic, Mesozoic and Cenozoic stratigraphic sections. The growing interest in these systems has led to a refined but still evolving understanding on their development and evolution. In addition, research must also continue to ascertain their role in deep-sea ecosystems, geological hazards, environmental policy and economic development. Key gaps in knowledge persist regarding their formation, role in oceanographic systems and their evolution over time. This session welcomes academic and industry researchers, and policy-makers interested in these deepwater sedimentary systems.
Controls on sedimentation at submarine active margins: bridging observations of modern processes and geological products
Dr Adam Mcarthur1, Dr Lorna Strachan, Dr Alan Orpin, Dr Kyle Bland, Dr Julien Bailleul
1University Of Leeds, United Kingdom
Submarine sedimentary systems are often difficult to observe in action, yet understanding sediment transport and depositional process are critical for characterising the highly-dynamic depositional environments and structural evolution at active margins. The geological record has preserved evidence of the controls of deposition and dispersal, which have been a focus of geological research for many decades. Processes such as mass-movements, gravity flows, and bottom currents sculpt seafloor environments across all water depths. Similarly, a source-to-sink perspective highlights the diverse range of tectonic and sedimentological settings within active margins, from shelf incising canyons, intraslope basins, emergent fault ridges, trenches, and abyssal plains. Sediment transport can be enigmatic, complicated by tortuous sediment dispersal patterns influenced by tectonics, slope instability, and climatically controlled sediment flux, with potential for enhanced bypass and capture of sediment on slopes. With ever advancing technologies to measure and observe submarine processes, allied with our growing capacity to operate at sea, new datasets are emerging that offer unprecedented insights into submarine processes and deposition. The importance of the interaction of biological and physical processes in deep-water settings are now recognised, modulating the balance of sedimentation, transport and sequestration of organic carbon in a variety of environments. This session aims to bring together a wide range of researchers focused on sedimentary systems, including modern and ancient processes and products, and modelling sedimentation on active margins, such as the Cascadia, Hikurangi, and Nankai subduction margins. In particular, we invite submissions aiming to integrate process sedimentology (e.g., seafloor observations and experimental) with the rock record (e.g., outcrop and subsurface) to unravel the controls on sediment transport, distribution and preservation on submarine active margins. We welcome studies yielding fundamental insights of sedimentation on active margins, temporal and spatial considerations for deposition, as well as applied studies, such as those identifying marine geohazards.
The role of subaqueous sediment gravity flows in carbon sequestration: processes and potential
Dr Joanna Pszonka1, Dr Xin Shan2
1Colorado School of Mines, Golden, the United States, 2First Institute of Oceanography, Qingdao, China
This session explores the critical role of submarine and sub-lacustrine sediment gravity flows in carbon sequestration. We welcome contributions exploring the processes and products of sediment gravity flows, as well as their impact on carbon burial and storage. We will discuss how these downslope processes facilitate organic carbon burial, mineral carbonation, and the long-term storage of carbon dioxide (CO₂) within sedimentary basins. By understanding the mechanisms (i.e., tectonic, climate, sea-level changes) that control carbon storage in subaqueous environments, we can identify potential strategies to enhance natural sequestration processes and contribute to climate change mitigation. This interdisciplinary session will bring together insights from geologists, marine scientists, and climate researchers to discuss the latest findings and innovative approaches to foster understanding of the carbon storage potential within subaqueous systems.
Understanding carbonate slope redeposition
Dr Ángel Puga-Bernabéu1, Professor Jody Webster2, Dr. Victorien Paumard3, Dr. Arnoud Slootman4
1Universidad De Granada, Granada, Spain, 2The University of Sydney, Sydney, Australia, 3The University of Western Australia, Perth, Australia, 4Colorado School of Mines, Golden, United States
Over the past decades, advances in carbonate sedimentology have brought our understanding of carbonate slope and deep-water systems to a level comparable to that of siliciclastic counterparts. Detailed studies from outcrops, cores, seismic data and numerical modelling have revealed the complexity of depositional processes in carbonate margins, ranging from sediment gravity flows to platform collapse and the influence of oceanic currents. These processes not only control depositional architecture and facies distribution but also have significant implications across multiple disciplines. In hydrocarbon exploration and production, the characterization of redeposited deposits such as calciturbidites and calcidebrites enhances reservoir prediction in deep-water systems. Additionally, understanding carbonate margin stability is critical for assessing geohazards, including submarine landslides and potential tsunamis. While traditionally studied in the context of energy resources and geohazards, redeposited deep-water carbonate systems may also hold potential for carbon capture and storage. Their porosity and permeability characteristics, along with associated sealing lithologies, could make them viable candidates for CO₂ sequestration in specific geological settings. Furthermore, the study of carbonate redeposition in the geological record contributes to paleoceanographic and paleoclimatic reconstructions, offering insights into sea-level changes and ocean circulation dynamics over time.
In this session, we especially seek (but not exclusively) innovative and multi-disciplinary contributions from detailed and comprehensive outcrop and subsurface studies to cutting-edge technologies on marine geology, analytic techniques, flume experiments and forward modelling, focused on: 1) controls on the sediment production and export from carbonate platforms and their significance for deciphering the environmental changes through time; 2) across vs along-slope sedimentary processes in carbonate margins; 3) slope and margin destabilization processes, with specific interest in flow transformation and particle segregation; and 4) basin modelling and sequence stratigraphy, especially focused on the differences between siliciclastic and carbonate-dominated deep-water sedimentary systems.