Abstract
During the Fall of 1979, a manned submersible program, utilizing DSRV ALVIN, was carried out at the intersection of the East Pacific Rise (EPR) with the Tamayo Transform boundary. A total of seven dives were completed in the vicinity of the EPR/Tamayo intersection depression and documented the geologic relationships that characterize the juxtaposition of these types of plate boundaries. The young volcanic terrain of the EPR axis can be traced into and across the Tamayo Transform valley but becomes buried by sedimentary talus that is being shed from sediment scarps along the unstable sediment slope that defines the north side of the intersection depression. Within 4 km of the transform boundary, the dominant trend (000°) of the fissures and faults that disrupt the rise-generated volcanics is markedly oblique to the regional direction of sea floor spreading (120°). Since no evidence was found to suggest that these structures accommodate significant amounts of strike-slip displacement, they are taken to reflect a distortion of the EPR extensional tectonic regime by a transform generated shear couple. The floor of the Tamayo Transform valley in this area is inundated by mass-wasted sediment, and the principal transform displacement zone is characterized at the surface by a narrow (<1.5 km) interval of fault scarps in sediment that trends parallel with the transform valley. Extrapolated to the west, this zone links with zones of transform deformation investigated during earlier submersible studies (CYAMEX and Pastouret, 1981). Evidence of low-level hydrothermal discharge was seen at one locality on the EPR axis and at another 8 km west of the axis at the edge of the zone of transform deformation.
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References
BenderJ. F., HansonJ. N., and LangmuirC. H.: 1981, ‘Basalt Glasses from the East Pacific Rise-Tamayo Transform Intersection: Geochemical Evidence for Complex Magma Generation Processes’, Trans. Amer. Geophys. Union. 62, 423.
Bender, J. F., Langmuir, C. H., and Hanson, J. N.: 1984, ‘Petrogenesis of Basalts from the Tamayo Region, East Pacific Rise: Evidence that Partial Melting is Responsible for Systematic Variations in Glass Chemistry with Distance from a Transform Fault’, Jour. Petrol. (in press).
ChinneryM. A.: 1966, ‘Secondary Faulting’, Can. Jour. Earth Science, 3, 163–174.
CourtillotV., TapponierP., and VaretJ.: 1974, ‘Surface Features Associated with Transform Faults: A Comparison Between Observed Examples and an Experimental Model’, Tectonophy, 24, 317–329.
CraneK.: 1976, ‘The Intersection of the Siquieros Transform Fault and the East Pacific Rise’, Mar. Geology 21, 25–46.
CYAMEX Scientific Team and Pastouret, L.: 1981, ‘Submersible Structural Study of the Tamayo Transform Fault, East Pacific Rise at 23°N’, Mar. Geophys. Res. 4, 381–401.
FoxP. J. and GalloD. G.: 1982, ‘A Mantle Weld at Ridge Transform Intersections: Implications for the Development of Oblique Structures’, Trans. Amer. Geophys. Union 63, 446.
Fox, P. J. and Gallo, D. G.: 1984, ‘A Tectonic Model for Ridge-Plate Boundaries: Implications for the Structure of Oceanic Lithosphere’, Tectonophysics (in press).
GalloD. G. and FoxP. J.: 1979, ‘The Influence of Transform Faults on the Generation of Oceanic Lithosphere’, Trans. Amer. Geophys. Union 60, 376.
GalloD. G., RosencrantzE. R., and RowleyD. B.: 1980, ‘Oblique Structures at Ridge-Transform Intersections: Implications for Ridge Dynamics and Pole Determinations’, Trans. An Geophys. Union 61, 358.
KarsonJ. A. and DickH. J. B.: 1983, ‘Tectonics of Ridge-Transform Intersections at the Kane Fracture Zone’, Mar. Geophys. Res. 6, 51–98.
KastensK. A., MacdonaldK. C., BeckerK., and CraneK.: 1979, ‘The Tamayo Transform Fault in the Mouth of the Gulf of California’, Mar. Geophys. Res. 4, 129–152.
LarsonR. L., MenardH. W., and SmithS. M.: 1968, ‘Gulf of California: A Result of Ocean Floor Spreading and Transform Faulting’, Science 161, 781–784.
LarsonR. L.: 1972, ‘Bathymetry, Magnetic Anomalies and Plate Tectonics History of the Mouth of the Gulf of California’, Geol. Soc. Am. Bull. 83, 3345–3360.
LewisB. T. R.: 1979, ‘Periodicities in Volcanism and Longitudinal Magma Flow on the East Pacific Rise at 23°N’, Geophys. Res. Lett. 6, 753–756.
LewisB. T. R., SyndsmanW. E., McClainJ. S., HolmesM. L., and ListerC. R. B.: 1983, ‘Site Survey Results at the Mouth of the Gulf of California, Leg 65’, Deep Sea Drilling Project, Init. Repts. DSDP 65, 309–323.
LonsdaleP.: 1978, ‘Near-Bottom Reconnaisance of a Fast-Slipping Transform Fault Zone at the Pacific-Nacza Plate Boundary’, Jour. Geol. 86, 451–472.
MacdonaldK. C., KastensK., SpiessF. M., and MillerS. P.: 1979, ‘Deep-Tow Studies of the Tamayo Transform Fault’, Mar. Geophys. Res. 4, 37–70.
McClainJ. S. and LewisB. T. R.: 1980, ‘A Seismic Experiment at the Axis of the East Pacific Rise’, Mar. Geol. 35, 147–170.
McKinstryH. E.: 1953, ‘Shears of the Second Order’, Amer. Jour. Sci. 251, 401–414.
OTTER Scientific Team: 1984, ‘The Geology of the Oceanographer Transform: The Ridge-Transform Intersection’, Mar. Geophys. Res. 6, 109–141 (this issue).
RiedelW.: 1929, ‘Zur Mechanic Geologischer Brucherscheinungen’, Zentralb. Mineral. Geol. Pal. 1929B, 354–368.
SearleR. C.: 1979: ‘Side-Scan Sonar Studies of North Atlantic Fracture Zones’, J. Geol. Soc. London 136, 283–293.
StroupJ. B. and FoxP. J.: 1981, ‘Geologic Investigations in the Cayman Trough: Evidence for Thin crust along the Mid-Cayman Rise’, J. Geol. 89, 395–420.
Tamayo Scientific Team: 1980a, ‘Tectonics of a Ridge-Transform Intersection Zone: Tamayo-East Pacific Rise, Gulf of California’, EOS. Trans. Amer. Geophys. Union 61(32), 574.
Tamayo Scientific Team: 1980b, ‘Submarine Landsliding at the Eastern End of the Tamayo Transform Fault, Gulf of California’, EOS, Trans. Amer. Geophys. Union 61(17), 359.
Tamayo Scientific Team: 1980c, ‘East Pacific Rise-Tamayo Transform Fault Intersection’, Geol. Soc. Amer. Abstracts with Programs 12(7), 461–462.
TchalenkoJ. S.: 1970, ‘Similarities between Shear Zones of Different Magnitudes’, Geol. Soc. Am. Bull. 81, 1625–1640.
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Tamayo Tectonic Team., Gallo, D.G., Kidd, W.S.F. et al. Tectonics at the intersection of the East Pacific Rise with Tamayo Transform fault. Mar Geophys Res 6, 159–185 (1984). https://doi.org/10.1007/BF00285958
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DOI: https://doi.org/10.1007/BF00285958