The crustal and upper mantle structure of the Hawaiian-Emperor Seamount Chain from marine seismic data

The seafloor is littered with seamounts that provide a window into fundamental questions regarding the rheological properties of the oceanic lithosphere and controls on magmatic addition to the crust in space and time. We focused on one of the most well-known examples of hotspot seamount chains, the Hawaiian-Emperor Seamount Chain. During two cruises in September-October 2018 and April-June 2019, respectively, we used R/V Marcus G. Langseth to acquire deep-penetration, multichannel seismic reflection data and wide-angle seismic data across the Hawaiian Island Chain and along and across the Emperor Seamount Chain. This wide separation in space and time of formation enables us to investigate how magmatic addition has varied with time and study the time-dependent response of the oceanic lithosphere to the resulting load. For acquisition of the seismic reflection data, we used a nominal 6600-cu-in tuned air gun array and a 15-km-long hydrophone streamer cable. For wide-angle seismic data, we used the same source with ocean-bottom seismometers spaced at ~15 km. The ocean-bottom seismometers were provided by Scripps Institution of Oceanography, GEOMAR Helmholz Centre for Ocean Research, and Woods Hole Oceanographic Institution. Preliminary analyses of the data have allowed imaging of the contact between the pre-existing oceanic crust and the volcanic seamounts, the structure of the surrounding Pacific Plate, and the effects of volcanic loading on the oceanic plate. In addition, integrated analyses of data from both cruises allows us to capture the effects of wide variations in the time elapsed since loading, the age of the lithosphere at the time of loading, and timing and volume flux of magma emplacement.