Accession Number : ADA320821

Title :   Fine-Scale Record of Faulting in ONR Natural Laboratories.

Descriptive Note : Final rept. 1 Jan 94-31 Mar 96,

Corporate Author : WOODS HOLE OCEANOGRAPHIC INSTITUTION MA

Personal Author(s) : Tucholke, Brian E. ; Jaroslow, Gary E. ; Stewart, W. K. ; Kleinrock, Martin C.

PDF Url : ADA320821

Report Date : 15 JAN 1997

Pagination or Media Count : 38

Abstract : We analyzed fault patterns in ocean crust on the west flank of the Mid-Atlantic Ridge at 25 deg 25' - 27 deg 10'N, 45 deg 00' - 49 deg 00'W, using HMR1 long-range sidescan-sonar data and multibeam bathymetry. Our studies show that brittle strain on normal faults varies with respect to intrasegment tectonic setting and with respect to variation in magma input at the rift axis. Our analyses clearly document that patterns of inward and outward facing normal faults account for the shape of the rift valley in slow spreading crust, and they show that these faults control typical abyssal hill morphology. We also analyzed near bottom, fine scale survey data and demonstrated for the first time that fault scarps in igneous ocean crust experience extensive, long term denudation (10-20 m.y. off axis). We developed analytical techniques that will be widely applicable to analysis of sonar data from all ocean environments. The insights into basement roughness and backscatter patterns from ocean crust gained from this study also directly benefitted efforts to understand acoustic reverberation from the ocean bottom and subbottom within ONR's Acoustic Reverberation Special Research Program.

Descriptors :   *FAULTS(GEOLOGY), *GEOMORPHOLOGY, *MIDATLANTIC RIDGE, BACKSCATTERING, BATHYMETRY, GEOLOGICAL SURVEYS, REVERBERATION, ABYSSAL ZONES, ACOUSTIC DATA, OCEANIC CRUST, TECTONICS, IGNEOUS ROCK.

Subject Categories : Geology, Geochemistry and Mineralogy

Distribution Statement : APPROVED FOR PUBLIC RELEASE