Quantitative Analysis of Abyssal Hills in the Atlantic Ocean: A Correlation Between Axis Mantle Temperature and Extensional Faulting.

Abstract

Abstract : A recent cruise to the ONR Atlantic Natural Lab gathered 100% Hydrosweep bathymetric coverage, >200% MRi side-scan coverage, gravity and magnetics over an area spanning three ridge segments along axis (-25deg25N to -27deg 10N) and crustal ages from 0 to 30 Ma west of the Mid-Atlantic Ridge. This data set represents a first opportunity for an extensive regional analysis of abyssal created at a slow spreading rate ridge. We apply the method of Goff and Jordan (1988) for the estimation of 2-D statistical properties of abyssal hill morphology from the gridded Hydrosweep bathymetry. Important abyssal hill parameters derived from this analysis include the rms height, characteristic width, plan-view aspect ratio, and lineament azimuth. The primary purpose of this work is to further constrain the relationship between abyssal hill morphology and the properties of the ridge crest at which they were formed. The analysis is segmented into two sub-studies: analysis of near axis (< 7 Ma) abyssal hills for each of the three segments, and analysis of temporal variations (-1-29 Ma) in abyssal hill morphology along the southern segment (the only segment that clearly persists over the entire age range sampled). The results of this analysis are compared and correlated with analysis of the gravity data and the determination of faulting characteristics based on the MR1 side-scan data.