This project was an integrated multichannel seismic investigation of the intermediate-spreading Juan de Fuca Ridge. The primary goals were: (1) to determine the location, size and physical properties of crustal magma bodies along the ridge and relate these properties to the recent eruptive history of the ridge, (2) to measure the variation in velocity and thickness of the indicators of magmatic state, and (3) to characterize the alteration history of the upper crust as a function of sedimentation history, crustal age and basement relief. Funding was provided by NSF grants OCE-0002488, OCE-0002551, and OCE-0002600.

This project was an integrated multichannel seismic investigation of the intermediate-spreading Juan de Fuca Ridge. The primary goals were: (1) to determine the location, size and physical properties of crustal magma bodies along the ridge and relate these properties to the recent eruptive history of the ridge, (2) to measure the variation in velocity and thickness of the indicators of magmatic state, and (3) to characterize the alteration history of the upper crust as a function of sedimentation history, crustal age and basement relief. Funding was provided by NSF grants OCE-0002488, OCE-0002551, and OCE-0002600.

This project was an integrated multichannel seismic investigation of the intermediate-spreading Juan de Fuca Ridge. The primary goals were: (1) to determine the location, size and physical properties of crustal magma bodies along the ridge and relate these properties to the recent eruptive history of the ridge, (2) to measure the variation in velocity and thickness of the indicators of magmatic state, and (3) to characterize the alteration history of the upper crust as a function of sedimentation history, crustal age and basement relief. Funding was provided by NSF grants OCE-0002488, OCE-0002551, and OCE-0002600.

This project was an integrated multichannel seismic investigation of the intermediate-spreading Juan de Fuca Ridge. The primary goals were: (1) to determine the location, size and physical properties of crustal magma bodies along the ridge and relate these properties to the recent eruptive history of the ridge, (2) to measure the variation in velocity and thickness of the indicators of magmatic state, and (3) to characterize the alteration history of the upper crust as a function of sedimentation history, crustal age and basement relief. Funding was provided by NSF grants OCE-0002488, OCE-0002551, and OCE-0002600.

This 3D multichannel seismic reflection study on board the Langseth sought to obtain geometrically correct images of the magma system using 3D migration processing. The goal was to obtain 3D seismic data that could be used to derive a detailed map of layer 2A and estimates of the crustal velocity field that can be interpreted in terms of porosity and used to map potential fluid pathways.

This 3D multichannel seismic reflection study on board the Langseth sought to obtain geometrically correct images of the magma system using 3D migration processing. The goal was to obtain 3D seismic data that could be used to derive a detailed map of layer 2A and estimates of the crustal velocity field that can be interpreted in terms of porosity and used to map potential fluid pathways. Funding was provided by NSF grants OCE-0327885 and OCE-0327872.

This dataset contains the time-migrated MCS data along two ridge-to-trench transects across the Juan de Fuca (JdF) plate, from Endeavour Ridge to offshore Washington state and from Axial Volcano to offshore Oregon state, and one 400 km-long trench-parallel transect extending from 44.3N to 47.8N acquired during the 2012 R/V Langseth survey. The seismic reflection images of the two ridge-to-trench transects reveal the crustal structure of the JdF plate, distribution and extent of faults across the plate interior as the crust ages and near the deformation front in response to subduction bending, and a series of distinctive, ridgeward-dipping (20-40 degrees) lower crustal reflections in ~6-8 Ma crust along both transects. The trench-parallel transect characterize the along-strike structural variations of the sediment section and the JdF plate prior to subduction, in particular the structures associated with propagator wakes, a seamount, and four major strike-slip faults. Funded by NSF grants OCE10-29411.

This cruise along the Southeast Indian Ridge collected both MCS and OBH data in order to investigate the effects of temperature variations on magma supply and the crustal accretion process. The objectives were to determine the internal structure of the crust, particularly Layer 2A (extrusive) thickness and its relationship both to melt supply and to axial and abyssal hill crustal structure and to axial and ridge flank morphology, in order to better understand the crustal accretion process. Funded by NSF grant OCE99-11720.

This Two-ship Experiment on a Ridge Axis (TERA) provided the first detailed geophysical constraints on the crustal structure along the East Pacific Rise south of the Garrett fracture zone, a major focus of the RIDGE initiative. The R/V Maurice Ewing< and Thomas Washington (TERA01WT) were to collect three types of data: (1) 20 closely-space, single-ship multichannel seismic reflection profiles along the EPR; (2) 25 two-ship expanding spread profiles along and parallel to the rise axis in this same area; and (3) a 700-km-long multichanel seismic reflection profile along the EPR from the Garrett fracture zone to the large overlapping spreading center at 20.5S. The objectives were to use these data to test the spreading rate dependence of magma chamber size; to examine the relationship between crustal magma chambers and along-axis changes in morphology, segmentation and basalt geochemistry; and to resolve better how the first-order seismic structure of oceanic crust, including Moho and seismic layer 3, developed during the first few hundred thousand years after crustal formation. Funded by NSF grants OCE90-12707, OCE90-12781, OCE90-12596, and OCE91-02899.

This 3D multichannel seismic reflection study on board the Langseth sought to obtain geometrically correct images of the magma system using 3D migration processing. The goal was to obtain 3D seismic data that could be used to derive a detailed map of layer 2A and estimates of the crustal velocity field that can be interpreted in terms of porosity and used to map potential fluid pathways. Funding was provided by NSF grants OCE-0327885 and OCE-0327872.