Three-dimensional shallow crustal emplacement at the 9 degrees 03 ' N overlapping spreading center on the East Pacific Rise: Correlations between magnetization and tomographic images

Citation:
Bazin, S, Harding AJ, Kent GM, Orcutt JA, Tong CH, Pye JW, Singh SC, Barton PJ, Sinha MC, White RS, Hobbs RW, Van Avendonk HJA.  2001.  Three-dimensional shallow crustal emplacement at the 9 degrees 03 ' N overlapping spreading center on the East Pacific Rise: Correlations between magnetization and tomographic images. Journal of Geophysical Research-Solid Earth. 106:16101-16117.

Date Published:

Aug

Keywords:

de-fuca ridge, geomagnetic intensity variations, mid-atlantic ridge, midocean ridges, reykjanes-ridge, sea-beam, seamarc-ii, segmentation, seismic layer 2a, upper oceanic-crust

Abstract:

We report a three-dimensional (3-D) seismic reflection and tomographic survey conducted at the 9 degrees 03'N overlapping spreading center (OSC) on the East Pacific Rise to understand crustal accretion at this feature. Inversions of travel time data from 19 ocean bottom hydrophones provide a 3-D image of the shallow velocity structure beneath the nontransform offset and associated discordance zone. Seismic analysis indicates that layer 2A thickness varies between 100 and 900 in and averages 430 in throughout the study area. The heterogeneous upper crustal structure at the OSC region contrasts with the simpler symmetric structure flanking the midsegments of the East Pacific Rise. The crust affected by the OSC migration carries evidence for the complex accretion at the axial discontinuity where the overlap basin may act as a lava pond. An area of thick layer 2A covers the southern half of the overlap basin and the propagating ridge tip and shows good correlation with a high magnetization region. Comparison of the magnetic field anomaly derived from the seismic structure model with the observed sea surface magnetic anomaly suggests that a significant portion of the high magnetization can be related to magnetic source thickness variation rather than solely to the geochemistry of the volcanic rocks.

Notes:

n/a

Website

DOI:

10.1029/2001jb000371