The primary objective of this proposal is to collect a suite of glassy volcanic rocks from the Mid Atlantic Ridge, measure the full suite of volatiles, major elements, trace elements, and isotopes, and evaluate their geochemical variability with respect to their geological setting.  An ROV or submersible is required for this project because the seafloor eruption style will be critical in relating the samples to local and regional tectonics.  The field work for this project began with Atlantis/Alvin/Sentry cruise AT33-03 in 2016, which was cut short (due to oil leaks in both z-drives) after only 30% of the work was completed (9 days out of 27).  This cruise will involve 19 days on station between 13°30’ and 14°05’N on the Mid-Atlantic Ridge.  The use of Alvin will allow us to collect well located samples and to determine if vesicularity and volatile abundances relate to their geologic setting and at what scale (i.e. segment wide, 'tectonic' vs. 'magmatic', adjacent to detachment faults, etc.).  This will include sampling on the segment scale (e.g., magmatic segment center and detachment faulted terrain), and the local scale related to seamounts/source vents, lava flow size and origin, and proximity to detachment faults.  The use of Alvin will also allow controlled sampling of glassy samples, not just with respect to geologic setting, but to ensure preservation of the volatiles.  Selected glassy samples will be collected in anaerobic sea-floor samplers that retain (some) sea floor pressure and temperature, thus minimize air contamination (Kurz and Curtice, 2009), reducing the reliance on post-analysis corrections.   These vessels will also permit collection of any gas exsolved at the surface because the samples can be kept immersed, allowing them to warm slowly (exsolved gases will then be collected in copper tubes).  This will reduce the uncertainties associated with estimates of “pre-degassing” volatile contents. In addition to existing sonar data, we will use  AUV Sentry make local high-resolution bathymetry and sonar maps north of 13 š50 (i.e., the magmatic segment) to define the geologic context of those samples.

      The primary objective of this proposal is to collect a suite of glassy volcanic rocks from the Mid Atlantic Ridge, measure the full suite of volatiles, major elements, trace elements, and isotopes, and evaluate their geochemical variability with respect to their geological setting.  An ROV or submersible is required for this project because the seafloor eruption style will be critical in relating the samples to local and regional tectonics.  The field work for this project began with Atlantis/Alvin/Sentry cruise AT33-03 in 2016, which was cut short (due to oil leaks in both z-drives) after only 30% of the work was completed (9 days out of 27).  This cruise will involve 19 days on station between 13°30’ and 14°05’N on the Mid-Atlantic Ridge.  The use of Alvin will allow us to collect well located samples and to determine if vesicularity and volatile abundances relate to their geologic setting and at what scale (i.e. segment wide, 'tectonic' vs. 'magmatic', adjacent to detachment faults, etc.).  This will include sampling on the segment scale (e.g., magmatic segment center and detachment faulted terrain), and the local scale related to seamounts/source vents, lava flow size and origin, and proximity to detachment faults.  The use of Alvin will also allow controlled sampling of glassy samples, not just with respect to geologic setting, but to ensure preservation of the volatiles.  Selected glassy samples will be collected in anaerobic sea-floor samplers that retain (some) sea floor pressure and temperature, thus minimize air contamination (Kurz and Curtice, 2009), reducing the reliance on post-analysis corrections.   These vessels will also permit collection of any gas exsolved at the surface because the samples can be kept immersed, allowing them to warm slowly (exsolved gases will then be collected in copper tubes).  This will reduce the uncertainties associated with estimates of “pre-degassing” volatile contents. In addition to existing sonar data, we will use  AUV Sentry make local high-resolution bathymetry and sonar maps north of 13 š50 (i.e., the magmatic segment) to define the geologic context of those samples.

      The primary objective of this proposal is to collect a suite of glassy volcanic rocks from the Mid Atlantic Ridge, measure the full suite of volatiles, major elements, trace elements, and isotopes, and evaluate their geochemical variability with respect to their geological setting.  An ROV or submersible is required for this project because the seafloor eruption style will be critical in relating the samples to local and regional tectonics.  The field work for this project began with Atlantis/Alvin/Sentry cruise AT33-03 in 2016, which was cut short (due to oil leaks in both z-drives) after only 30% of the work was completed (9 days out of 27).  This cruise will involve 19 days on station between 13°30’ and 14°05’N on the Mid-Atlantic Ridge.  The use of Alvin will allow us to collect well located samples and to determine if vesicularity and volatile abundances relate to their geologic setting and at what scale (i.e. segment wide, 'tectonic' vs. 'magmatic', adjacent to detachment faults, etc.).  This will include sampling on the segment scale (e.g., magmatic segment center and detachment faulted terrain), and the local scale related to seamounts/source vents, lava flow size and origin, and proximity to detachment faults.  The use of Alvin will also allow controlled sampling of glassy samples, not just with respect to geologic setting, but to ensure preservation of the volatiles.  Selected glassy samples will be collected in anaerobic sea-floor samplers that retain (some) sea floor pressure and temperature, thus minimize air contamination (Kurz and Curtice, 2009), reducing the reliance on post-analysis corrections.   These vessels will also permit collection of any gas exsolved at the surface because the samples can be kept immersed, allowing them to warm slowly (exsolved gases will then be collected in copper tubes).  This will reduce the uncertainties associated with estimates of “pre-degassing” volatile contents. In addition to existing sonar data, we will use  AUV Sentry make local high-resolution bathymetry and sonar maps north of 13 š50 (i.e., the magmatic segment) to define the geologic context of those samples.