|
Research by Geographic Region Marine Magnetism - Research Highlights by Geographic RegionPlease note, most of this website is still under construction. Mid-Atlantic RidgeKane Megamullion 2004 project utiizing ROV Jason-2 and autonomous vehicle ABE was funded by NSF-ODP as a site survey of potential drill targets for accessing lower crust and upper mantle rocks exposed on the seafloor near 23°30'N. Click below to find out more. Sea surface magnetic data were collected over the west flank of the Mid-Atlantic Ridge between 25° N and 27° N as part of the ONR (Office of Naval Research) Acoustic Reverberation Study Research Project (ARSRP). Click below to find out more. High resolution magnetic field data have also been collected over hydrothermal vents using submersible and deeptowed vehicles. The hot fluids emanating from hot vents tends to chemically alter the magnetic minerals and thus destroy any magnetic signal. The TAG hydrothermal site on the Mid-Atlantic ridge is one place where we have documented the presence of a magnetic low over the vent site. Juan de Fuca Ridge, North East Pacific OceanMagnetic surveying of a steep scarp that exposes a cross-section of ocean crust was conducted in 1995 at the Blanco Fracture Zone which marks the southern boundary of the Juan de Fuca plate in the northeast Pacific. Magnetic field measurements were made using the deep diving submersible ALVIN and also the French submerisble NAUTILE. An important problem in marine magnetism concerns the vertical structure of oceanic crust and what part of the crust is responsible for creating magnetic anomalies that are measured at the sea surface. Click below for more details on these results. We are using magnetic field mapping to look at the change in volcanic lava (also known as seismic layer 2A) thickness in comparison to the seismic images of layer 2A. Magnetic field anomalies arise not only because of thickness variations in the amount of extrusive lava but also due to the age of the lavas. New lava is typically very magnetic and creates a strong magnetic field signal when first formed. Click below for more details on these results. Atlantis Bank South West Indian Ridge, Indian OceanWestern Pacific OceanThe western Pacific Ocean is the location of the world's oldest ocean crust (~175 Million year old crust which places it in the Jurassic age period). There has long been a debate over whether the Jurassic period was a time of no magnetic reversals like the Cretaceous quiet zone or a time of very rapid reversal of simply a time when the earths field was weaker. Few magnetic measurements have been able to determine which of these scenarios is correct with any accuracy. Sea surface magnetic measurements of this old crust are easily contaminated by noise because of the equatorial location of the crust and the seafloor is very deep (6.5 km). In 1991 I and my colleagues from the University of Washington (Seattle) and Texas A&M University undertook a deeptow survey of this oldest Pacific crust to try and determine if magnetic anomaly reversals could be measured in such old crust. Click below for more details on these results. © Woods Hole Oceanographic Institution. All rights reserved |