AUV MARUM-SEAL Dive 71-73: High resolution bathymetry and backscatter of Venere Mud Vulcano

Submarine mud volcanoes develop through the extrusion of methane-rich fluids and sediments onto the seafloor. The morphology of a mud volcano can record its extrusive history and processes of erosion and deformation affecting it. The study of offshore mud-volcano dynamics is limited because only few have been mapped at resolutions that reveal their detailed surface structures. More importantly, rates and volumes of extruded sediment and methane are poorly constrained. The 100 m high twin cones of Venere mud volcano are situated at ~1600 m water depth within Squillace Canyon along the Ionian Calabrian margin, Mediterranean Sea. Seafloor bathymetry, and backscatter data obtained by a ship-based system and an autonomous underwater vehicle (AUV) allow mapping of mudflow deposits of the mud volcano and bedforms in the surrounding canyon. Repeated surveying by AUV document active mud movement at the western summit in between 2014 and 2016. Through sediment coring and tephrochronology, ages of buried mudflow deposits are determined based on the sedimentation rate and the thickness of overlying hemipelagic sediments. An average extrusion rate of 27000 m^3/year over the last ~882 years is estimated. These results support a three-stage evolutionary model of Venere mud volcano since ~4000 years ago. It includes the onset of quiescence at the eastern cone (after ~2200 years ago), erosive events in Squillace Canyon (prior to ~882 years ago), and mudflows from the eastern cone (since ~882 years). This study reveals new interactions between a mud volcano and a canyon in the deep sea

AUV MARUM-SEAL Dive 70: RAW-Data of High Resolution Bathymetry and Backscatter of Chapopote Asphalt Volcano

Purpose of the cruise M114 At the so-called asphalt volcanoes in the southern Gulf of Mexico heavy oil is seeping at the seafloor where it remains as asphalt deposits. Discovered and preliminarily surveyed during SO174 and M67/2 expeditions, these sites are subject for detail studies during M114 focusing on mapping with autonomous underwater vehicle (AUV MARUM-SEAL), deep-towed sidescan sonar (DTS-1), sediment echosounder (Parasound), multibeam echosounder (EM122), and remotely operated vehicle MARUM-ROV Quest. The overarching objective is to better understand the impact, fate, and decay rates of oil in the deep-sea environment. Heavy oil and gas bubbles are emitted from the 1200 to 2900 m deep seafloor in the hy-drocarbon province Campeche Knolls in the southern Gulf of Mexico. The viscous heavy oil flows across the seafloor, loses volatile compounds, solidifies, and is converted to asphalt with time. Due to the fact that the heavy oil remains at the seafloor, these sites are natural laboratories to study the impact of oil on deep-sea ecosystems, and the time scales of oil and asphalt degradation. These subjects are very timely, and can help understanding effects of deep water oil spills as caused by the 2010 Deepwater Horizon accident in the northern Gulf of Mexico. We propose to study the extent of oil emissions and asphalt deposits using sidescan sonar and to investigate them further employing ROV Quest. A further major topic of the proposed cruise addresses the question whether or not methane can reach the sea surface and may contribute to the pool of greenhouse gases. The fact that seepage of oil-coated gas bubbles leads to oil slicks at the sea surface and enhanced methane concentrations was recently shown in the north-ern Gulf. It can be assumed that similar efficient transport processes for methane exists in the area of the Campeche Knolls, where oil slicks have been observed in association with about ~30 individual seafloor structures

AUV MARUM-SEAL Dive 70: High Resolution Bathymetry and Backscatter of Chapopote Asphalt Volcano

Abstract & Purpose of the cruise M114 At the so-called asphalt volcanoes in the southern Gulf of Mexico heavy oil is seeping at the seafloor where it remains as asphalt deposits. Discovered and preliminarily surveyed during SO174 and M67/2 expeditions, these sites are subject for detail studies during M114 focusing on mapping with autonomous underwater vehicle (AUV MARUM-SEAL), deep-towed sidescan sonar (DTS-1), sediment echosounder (Parasound), multibeam echosounder (EM122), and remotely operated vehicle MARUM-ROV Quest. The overarching objective is to better understand the impact, fate, and decay rates of oil in the deep-sea environment. Heavy oil and gas bubbles are emitted from the 1200 to 2900 m deep seafloor in the hy-drocarbon province Campeche Knolls in the southern Gulf of Mexico. The viscous heavy oil flows across the seafloor, loses volatile compounds, solidifies, and is converted to asphalt with time. Due to the fact that the heavy oil remains at the seafloor, these sites are natural laboratories to study the impact of oil on deep-sea ecosystems, and the time scales of oil and asphalt degradation. These subjects are very timely, and can help understanding effects of deep water oil spills as caused by the 2010 Deepwater Horizon accident in the northern Gulf of Mexico. We propose to study the extent of oil emissions and asphalt deposits using sidescan sonar and to investigate them further employing ROV Quest. A further major topic of the proposed cruise addresses the question whether or not methane can reach the sea surface and may contribute to the pool of greenhouse gases. The fact that seepage of oil-coated gas bubbles leads to oil slicks at the sea surface and enhanced methane concentrations was recently shown in the north-ern Gulf. It can be assumed that similar efficient transport processes for methane exists in the area of the Campeche Knolls, where oil slicks have been observed in association with about ~30 individual seafloor structures