Northeastern Section - 53rd Annual Meeting - 2018

Paper No. 29-7
Presentation Time: 10:35 AM


JOHNSON, Joel E., Dept. of Earth Sciences, University of New Hampshire, 56 College Rd, James Hall, Durham, NH 03824

As a new faculty member in the Department of Earth Sciences at UNH I was introduced to Northern New England geology during UNH and NEIGC field trips with Jo Laird, Peter Thompson, and Wally Bothner. Throughout my subsequent 12 years at UNH, I have had the great pleasure of co-teaching petrology and running field trips with Jo and teaching structural geology from Peter’s materials and perspective. These experiences allowed me to embrace New England geology through the lens of metamorphic petrology and structural geology and to use this perspective to understand subseafloor geology at a modern spreading ridge offshore Svalbard. In 2013, I was fortunate to join colleagues in the Center for Arctic Gas Hydrate, Environment and Climate at the University of Tromsø, the Arctic University of Norway on an expedition to seismically image and sample shallow gas and gas hydrate on the west Svalbard continental margin. The seismic data reveal gas and gas hydrate-charged sediments on the flank of the spreading ridge and, remarkably, the underlying crustal structure. Ultraslow spreading in this region and throughout the Arctic is accommodated by large offset detachment faults, which can exhume ultramafic rocks of the mantle and act as conduits to enhance serpentinization. In this presentation, I will discuss the processes associated with serpentinization of oceanic crust and the linkages between the crustal structure and overlying sediment cover that suggest some of the methane in this region may be formed from the products of serpentinization. To visualize the process of serpentinization, I end the presentation in northern New England and Newfoundland, where similar settings may have existed during the Ordovician, and discuss samples of serpentinized ultramafic rocks from those areas with renewed interest and perspective.