Accession Number : ADA305890

Title :   Tectonics of the East Pacific Rise: Studies of Faulting Characteristics and Magnetic and Gravity Anomalies.

Descriptive Note : Doctoral thesis,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Lee, Sang-Mook

PDF Url : ADA305890

Report Date : FEB 1995

Pagination or Media Count : 517

Abstract : Investigation of Sea Beam bathymetric data collected between 9 deg 10 and 9 deg 50'N of the East Pacific Rise suggests that normal faulting may continue to a distance of at least 30 km from the axis. Mechanical models were used to demonstrate that, while buoyancy arising from crustal magma chamber during a stage of a weak rise axis may explain the initiation of normal faults at 2-3 km from the axis, a rise axis with a finite strength is needed to explain their further development off-axis. Variation in the magnetization intensity of the magnetic source layer appears to be the primary cause of a southward increase in the axial magnetization high. A correlation was found between the short-wavelength (appox. 5 km) magnetization anomalies parallel to the rise axis and short reversal events reported within the Brunhes epoch. The occurrence of marked offsets in the linearity of axial magnetization anomalies and short-wavelength (< 30 km) residual gravity anomaly lows along the axis suggests that the rise axis in this area can be divided into segments of 10-15 km in length, with each segment defined by the locus and timing of most recent emplacement of magma in the axial crust. (AN)

Descriptors :   *FAULTS(GEOLOGY), *EAST PACIFIC RISE, STRESS STRAIN RELATIONS, MATHEMATICAL MODELS, GEOMAGNETISM, MAGNETIC FIELDS, STRESS ANALYSIS, OCEAN SURFACE, MATRICES(MATHEMATICS), DEFORMATION, INTENSITY, ANALYSIS OF VARIANCE, THESES, STRENGTH(MECHANICS), OCEANOGRAPHIC DATA, BATHYMETRY, SEISMIC DATA, MARINE GEOLOGY, CORRELATION, MASS FLOW, SEISMIC WAVES, GEOLOGICAL SURVEYS, HYDROPHONES, NUMERICAL METHODS AND PROCEDURES, EARTHQUAKES, PLATE TECTONICS, RANGE(DISTANCE), AIR WATER INTERACTIONS, MAGNETIZATION, OCEAN MODELS, AXIAL LOADS, SEDIMENTATION, OCEANIC CRUST, BUOYANCY, EARTH MANTLE, GRAVITATIONAL FIELDS, MAGNETIC ANOMALIES, GRAVITY ANOMALIES, VOLCANISM, SEISMOMETERS, LITHOSPHERE.

Subject Categories : Physical and Dynamic Oceanography
      Geology, Geochemistry and Mineralogy
      Seismology

Distribution Statement : APPROVED FOR PUBLIC RELEASE