1-1-1-1-1-1-1-1-1-1-1-1-1-1 From: Andrea Di Capua <andrea.dicapua@xxxxxxxxxxx> Hi everyone, The Commission on Volcanogenic Sediments of IAVCEI is inviting you to its 2nd webinar on the 30th of August, 3pm NZST. The webinar is titled "Active Deepwater Multidirectional Tractional Sands at Havre Volcano: a New Facies Model for Deep Marine Deposition", given by Shannon Frey of the University of Tasmania. Abstract The deep ocean is a complex setting where sediment transport and deposition depends on numerous processes, including vertical settling, sediment density currents, and reworking by bottom currents. Bottom currents are traditionally considered persistent flows that can last for thousands of years and are associated with extensive accumulations of sediments (e.g. contourites). However, in deep-ocean settings with significant topography, such as submarine volcanoes or seamounts, currents can be steered, deflected, or amplified, significantly affecting sediment deposition. How deep-ocean currents are modified and how this influences sediment deposition at shorter timescales remains under-acknowledged considering the ubiquitous presence of topographic features on the deep seafloor, and consequently is poorly understood. This is in contrast with current deep-ocean depositional models which focus on large-scale and persistent systems. Here, we present very high-resolution bathymetry data (1 m) and extensive seafloor video footage around a deep (>950 mbsl) submarine volcano (Havre volcano, Kermadec arc), coupled with mid-ocean ARGO float data. Havre submarine volcano erupted in 2012, and data from 2015 and 2022 provide exceptional information on the rapid, complex, and commonly ephemeral reworking of silt and sand in deep water, leading to the proposal of a new facies name; Deepwater Multidirectional Tractional Sands (DMTS). DMTS is characterized by chaotic erosional and depositional bedforms that are spatially and temporally inconsistent and do not conform with a single governing hydrodynamic regime. With new estimates showing that large topographic obstacles on the seafloor are widespread and common, the observed phenomena may be more common than anticipated. Additionally, traditional paleocurrent and basin analysis interpretations commonly rely on assumed consistency of bottom-current flow. Our results indicate the need for an improved understanding of complex current, topography, and sediment interactions in the mid- to deep-ocean. To take part in the webinar, please register at https://events.teams.microsoft.com/event/2fc433a4-fb67-4258-8165-5b813076b8c7@34c64e9f-d27f-4edd-a1f0-1397f0c84f94 <https://urldefense.com/v3/__https://events.teams.microsoft.com/event/2fc433a4-fb67-4258-8165-5b813076b8c7@34c64e9f-d27f-4edd-a1f0-1397f0c84f94__;!!IKRxdwAv5BmarQ!ZuB1dMR-fMcQKmG8R5WHSMhLS6ss56mkdJi6APJJhX0O9OHCsNtXWbs_hZPpbDYdZVlbRhI8HOLdWPIpGGKFXQN0yw$> 1-1-1-1-1-1-1-1-1-1-1-1-1-1 ------------------------------
