Morphotectonic fabric of the Orozco Transform Fault: Results From a Sea Beam investigation

We have used data collected with the Sea Beam system to produce a detailed regional bathymetric map of the medium to fast slipping (90 mm/yr) Orozco Transform Fault. The morphotectonic fabric of the 90 × 50 km transform domain is spatially heterogeneous and is composed of relatively shallow areas ( 3200 m). The plate boundary geometry is clearly identified morphologically and is characterized by a series of linked basins and troughs that approximate a zed pattern in plan view. East-west trending basins define the northern and southern boundaries of the transform domain, and these troughs are thought to mark the location of strike-slip tectonism. A central, north-south trending ridge with an axial valley, called here the Mid-Orozco spreading center, is thought to represent a short (30 km) ridge segment that links two transform faults. Morphotectonic relationships developed along the southeastern flank of the survey area suggest that this plate boundary geometry has recently become unstable and is presently undergoing a transformation as the tip of the East Pacific Rise axis propagates northward across the transform domain bypassing the Mid-Orozco spreading center. If the southern ridge axis continues to propagate northward it will link with the aseismic extension of the northern strike-slip strand and the present-day plate boundary will evolve into a simple ridge-transform-ridge (R-T-R) geometry with an offset of approximately 70 km.

[1]  Kim A. Kastens,et al.  Structural and volcanic expression of a fast slipping Ridge-Transform-Ridge-Plate Boundary: Sea MARC I and photographic surveys at the Clipperton Transform Fault , 1986 .

[2]  P. J. Fox,et al.  East Pacific Rise from Siqueiros to Orozco Fracture Zones: Along‐strike continuity of axial neovolcanic zone and structure and evolution of overlapping spreading centers , 1984 .

[3]  A. Tréhu.  Lateral velocity variations in the Orozco Transform Fault inferred from observed incident angles and azimuths of P-waves , 1984 .

[4]  P. J. Fox,et al.  Tectonics at the intersection of the East Pacific Rise with Tamayo Transform fault , 1984 .

[5]  P. J. Fox,et al.  A tectonic model for ridge-transform-ridge plate boundaries: implications for the structure of oceanic lithosphere , 1984 .

[6]  J. Mammerickx.  The morphology of propagating spreading centers: New and old , 1984 .

[7]  S. Solomon,et al.  Earthquakes in the Orozco Transform Zone: Seismicity, source mechanisms, and tectonics , 1983 .

[8]  Robert D. Ballard,et al.  The East Pacific Rise near 21°N, 13°N and 20°S: inferences for along-strike variability of axial processes of the Mid-Ocean Ridge , 1983 .

[9]  J. Delaney,et al.  A detailed study of the Cobb Offset of the Juan de Fuca Ridge: Evolution of a propagating rift , 1983 .

[10]  J. Ewing,et al.  Rivera Ocean Seismic Experiment (ROSE) overview , 1982 .

[11]  W. Prothero,et al.  Microearthquakes on the East Pacific Rise at 21°N and the Rivera Fracture Zone , 1982 .

[12]  K. Klitgord,et al.  Northern East Pacific Rise' Magnetic Anomaly and Bathymetric Framework , 1982 .

[13]  K. Macdonald.  Mid-Ocean Ridges: Fine Scale Tectonic, Volcanic and Hydrothermal Processes Within the Plate Boundary Zone , 1982 .

[14]  A. Tréhu.  Seismicity and structure of the Orozco transform fault from ocean bottom seismic observations , 1982 .

[15]  J. Francheteau,et al.  East Pacific rise at 21°N: the volcanic, tectonic, and hydrothermal processes of the central axis , 1981 .

[16]  Cyamex Scientific Team,et al.  Submersible structural study of Tamayo transform fault: East Pacific Rise, 23°N (project RITA) , 1981 .

[17]  F N Spiess,et al.  East Pacific Rise: Hot Springs and Geophysical Experiments , 1980, Science.

[18]  K. Kastens,et al.  The Tamayo transform fault in the mouth of the Gulf of California , 1979 .

[19]  K. Crane.  MORPHOLOGICAL WAVE FORMS; EVIDENCE FOR A PROPAGATING RIFT , 1979 .

[20]  Robert D. Ballard,et al.  3. SHEET FLOWS, COLLAPSE PITS, AND LAVA LAKES OF THE RIFT VALLEY , 1979 .

[21]  K. Kastens,et al.  Deep tow studies of the Tamayo transform fault , 1979 .

[22]  V. Renard,et al.  Sea Beam, Multi-Beam Echo-Sounding in "Jean Charcot" - Description, Evaluation and First Results , 1979 .

[23]  K. Crane.  The intersection of the Siqueiros Transform Fault and the East Pacific Rise , 1976 .

[24]  G. Johnson,et al.  Transform faults and longitudinal flow below the Midoceanic Ridge , 1975 .

[25]  D. Oldenburg,et al.  Thermal Model of Ocean Ridges , 1973 .

[26]  J. Tchalenko.  Similarities between Shear Zones of Different Magnitudes , 1970 .

[27]  M. Glenn.  Introducing an Operational Multi-Beam Array Sonar , 1970 .

[28]  H. W. Menard,et al.  Origin of Fracture Zone Topography , 1969, Nature.

[29]  H. W. Menard,et al.  Changes in Direction of Sea Floor Spreading , 1968, Nature.