Gravity and seismic study of crustal structure along the Juan de Fuca Ridge axis and across pseudofaults on the ridge flanks
Carbotte, Suzanne M.
Nedimovic, Mladen R.
Canales, J. Pablo
MetadataShow full item record
Variations in topography and seismic structure are observed along the Juan de Fuca (JdF) Ridge axis and in the vicinity of pseudofaults on the ridge flanks left by former episodes of ridge propagation. Here we analyze gravity data coregistered with multichannel seismic data from the JdF Ridge and flanks in order to better understand the origin of crustal structure variations in this area. The data were collected along the ridge axis and along three ridge-perpendicular transects at the Endeavor, Northern Symmetric, and Cleft segments. Negative Mantle Bouguer anomalies of −21 to −28 mGal are observed at the axis of the three segments. Thicker crust at the Endeavor and Cleft segments is inferred from seismic data and can account for the small differences in axial gravity anomalies (3–7 mGal). Additional low densities/elevated temperatures within and/or below the axial crust are required to explain the remaining axial MBA low at all segments. Gravity models indicate that the region of low densities is wider beneath the Cleft segment. Gravity models for pseudofaults crossed along the three transects support the presence of thinner and denser crust within the pseudofault zones that we attribute to iron-enriched crust. On the young crust side of the pseudofaults, a 10–20 km wide zone of thicker crust is found. Reflection events interpreted as subcrustal sills underlie the zones of thicker crust and are the presumed source for the iron enrichment.
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 12 (2011): Q05008, doi:10.1029/2010GC003439.
Showing items related by title, author, creator and subject.
Wavenumber–frequency spectra of inertia–gravity and mixed Rossby–gravity waves in the equatorial Pacific Ocean Farrar, J. Thomas; Durland, Theodore S. (American Meteorological Society, 2012-11)In the 1970s and 1980s, there was considerable interest in near-equatorial variability at periods of days to weeks associated with oceanic equatorial inertia–gravity waves and mixed Rossby–gravity waves. At that time, the ...
Cacchione, David A. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1970-09)A series of laboratory experiments were conducted in a glass wave tank to investigate the propagation of internal gravity waves up a sloping bottom in a fluid with constant Brunt-Vaisala frequency. Measurements of the ...
An experimental study on mixing induced by gravity currents on a sloping bottom in a rotating fluid Ohiwa, Mitchihiro (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2002-09)Mixing induced by gravity currents on a sloping bottom was studied through laboratory experiments in a rotating fluid. The dense fluid on the sloping bottom formed a gravity current that could be in regimes where the ...