Skip to main content
SpringerLink
Log in

Pito Rift: How a large-offset rift propagates

  • Published:
Marine Geophysical Researches Aims and scope Submit manuscript

Abstract

The Pito Rift area is the site of actively deforming oceanic lithosphere that has been primarily under extension for at least the past million years, based on kinematic reconstructions. The major morphologic features, Pito Deep and Pito Seamount, are aligned toward the Euler pole for relative motion between the Easter and Nazca plates. SeaMARC II side-scan and bathymetry data indicate that there are two general modes of faulting currently active in the Pito Rift area. One is associated with incipient rifting of old (∼3 Ma) Nazca lithosphere by large NW-SE normal faults, and the other is associated with a broad area of right-lateral transform shear between the Nazca and Easter plates. This transform shear is distributed over a broad region because of the northward growth of the East Rift and parallel tectonic rifting within the Pito Rift area. The majority of the Pito Rift area is composed of preexisting blocks of Nazca plate that are back-tilted away from Pito Deep and strike perpendicular to present and previous relative plate motions. This observation suggests that block-faulting and back-tilting are the primary mechanisms responsible for the distributed lithospheric extension, in agreement with gravity and magnetic analyses (Martinez et al., this issue).

The only recent volcanic flows observed in side-scan data are from the Pito Seamount area and to the outside of the outer pseudofault of the East Rift. The significance of the young flows near the outer pseudofault is not understood. We interpret the flows extending northwest from the Pito Seamount as representing a newly formed seafloor spreading axis within the Pito Rift area. Gravity and magnetic analyses (Martinez et al., this issue) together with SeaMARC II bathymetry and side-scan data support this interpretation.

Based on the tectonic evolution of the Easter microplate, we propose an evolutionary model for the formation of the Pito Rift area, where new ‘tectonic’ grabens form immediately west of the previous graben and with slightly more counterclockwise orientation. The duration and history of tectonic activity for each graben are not well constrained.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Anderson-FontanaS., EngelnJ. F., LundgrenP., LarsonR. L., and SteinS., 1986, Tectonics and Evolution of the Juan Fernandez Microplate at the Pacific-Nazca-Antarctic Triple Junction, J. Geophys. Res. 91, 2005–2018.

    Google Scholar 

  • BlackintonJ. G., HussongD. M., and KosalosJ. G., 1983, First Results from a Combination Side-Scan Sonar and Sea-Floor Mapping System (SeaMARC II), Offshore Technology Conference 4478, 307–311.

    Google Scholar 

  • BuckW. R., 1986, Small-Scale Convection Induced by Passive Rifting: the Cause for Uplift of Rift Shoulders, Earth Planet. Sci. Lett 77, 362–372.

    Google Scholar 

  • ChristieD. M. and SintonJ. M., 1981, Evolution of Abyssal Lavas along Propagating Segments of the Galapagos Spreading Center, Earth Planet. Sci. Lett. 56, 321–335.

    Google Scholar 

  • CroughS. T., 1978, Thermal Origin of Mid-Plate Hotspot Swells, Geophys. J. R. Astr. Soc. 55, 451–469.

    Google Scholar 

  • EngelnJ. F. and SteinS., 1984, Tectonics of the Easter Plate, Earth Planet. Sci. Lett 68, 259–270.

    Google Scholar 

  • EngelnJ. F., SteinS., WernerJ., and GordonR. G., 1988, Microplate and Shear Zone Models for Oceanic Spreading Center Reorganizations, J. Geophys. Res. 93, 2839–2856.

    Google Scholar 

  • FrancheteauJ., PatriatP., SegoufinJ., ArmijoR., DoucoureM., Yelles-ChaoucheA., ZukinJ., CalmantS., NaarD. F., and SearleR. C., 1988, Pito and Orongo Fracture Zones: the Northern and Southern boundaries of the Easter Microplate (Southeast Pacific), Earth Planet. Sci. Lett. 89, 363–374.

    Google Scholar 

  • FrancheteauJ., ArmijoR., CheineeJ-L., HekinianR., LonsdaleP. F., and BlumN., 1990, 1 Ma East Pacific Rise Oceanic Crust and Uppermost Mantle Exposed by Rifting in Hess Deep (Equatorial Pacific Ocean), Earth Planet. Sci. Lett. 101, 281–295.

    Google Scholar 

  • HagenR. A., BakerN. A., NaarD. F., and HeyR. N., 1990, A SeaMARC II Survey of Recent Submarine Volcanism near Easter Island, Mar. Geophys. Res. 12, 297–315.

    Google Scholar 

  • HandschumacherD. W., PilgerR. H., ForemanJ. A., and CampbellJ. R., 1981, Structure and Evolution of the Easter Plate, Geol. Soc. Am. Mem. 154, 63–76.

    Google Scholar 

  • HaxbyW. F. and WeisselJ. K., 1986, Evidence for Small-Scale Mantle Convection from Seasat Altimetry Data, J. Geophys. Res. 91, 3507–3520.

    Google Scholar 

  • HeyR. N., 1977, A New Class of Pseudofaults and their Bearing on Plate Tectonics: a Propagating Rift Model, Earth Planet. Sci. Lett. 37, 321–325.

    Google Scholar 

  • Hey, R. N. and Naar, D. F., 1987, Cruise Report, R/V Moana Wave, Leg 8711, Hawaii Institute of Geophysics, University of Hawaii, 1–23.

  • HeyR. N., DuennebierF. K., and MorganW. J., 1980, Propagating Rifts on Mid-Ocean Ridges, J. Geophys. Res. 85, 3647–3658.

    Google Scholar 

  • HeyR. N., NaarD. F., KleinrockM. C., Phipps MorganW. J., MoralesE., and SchillingJ-G., 1985, Microplate Tectonics along a Superfast Seafloor Spreading System near Easter Island, Nature 317, 320–325.

    Google Scholar 

  • HeyR. N., KleinrockM. C., MillerS. P., AtwaterT. M., and SearleR. C., 1986, Sea Beam/Deep-Tow Investigation of an Oceanic Propagating Rift System, J. Geophys. Res. 91, 3369–3393.

    Google Scholar 

  • HeyR. N., KlausA., IcayW., and NaarD. F., 1988, SeaMARC II Survey of the Propagating Limb of a Large Non-Transform Offset along the Fastest Spreading EPR Segment, Eos Trans. AGU 69, 1429.

    Google Scholar 

  • HeyR. N., SintonJ. M., and DuennebierF. K., 1989, Propagating Rifts and Spreading Centers, in WintererE. L., HussongD. M., and DeckerR. W., (eds.), The Eastern Pacific Ocean and Hawaii, Boulder, Colorado, Geol. Soc. Am., The Geology of North America, v. N, 161–176.

    Google Scholar 

  • HussongD. M. and FryerP., 1983, Back-Arc Seamounts and the SeaMARC II Seafloor Mapping System, Eos Trans. AGU 64, 627–632.

    Google Scholar 

  • KlausA., IcayW., NaarD. F., and HeyR. N., 1991, SeaMARC II Survey of a Propagating Limb of a Large Non-Transform Offset along the Fastest Spreading East Pacific Rise Segment, J. Geophys. Res. 96, 9985–9998.

    Google Scholar 

  • KleinrockM. C. and HeyR. N., 1989a, Detailed Tectonics near the Tip of the Galapagos 95.5° W Propagator: How the Lithosphere Tears and a Spreading Axis Develops, J. Geophys. Res. 94, 13801–13838.

    Google Scholar 

  • KleinrockM. C. and HeyR. N., 1989b, Migrating Transform Zone and Lithospheric Transfer at the Galapagos 95.5° W Propagator, J. Geophys. Res. 94, 13859–13878.

    Google Scholar 

  • LarsonR. L., SchoutenH., KleinrockM., and BirdR., 1988, The Juan Fernandez Microplate: an Example of Second Order Plate Motion and Ball Bearing Tectonics, Eos Trans. AGU 69, 1423.

    Google Scholar 

  • LonsdaleP., 1983, Laccoliths and Small Volcanoes on the Flank of the East Pacific Rise, Geology 11, 706–709.

    Google Scholar 

  • MacdonaldK. C., MillerS. P., HeustisS. P., and SpiessF. N., 1980, Three-Dimensional Modelling of a Magnetic Reversal Boundary from Inversion of Deep-Tow Measurements, J. Geophys. Res. 85, 3670–3680.

    Google Scholar 

  • MammerickxJ. and SandwellD., 1986, Rifting of Old Oceanic Lithosphere, J. Geophys. Res. 91, 1975–1988.

    Google Scholar 

  • MammerickxJ. and SharmanG. F., 1988, Tectonic Evolution of the North Pacific During the Cretaceous Quiet Period, J. Geophys. Res. 85, 3009–3024.

    Google Scholar 

  • MammerickxJ., NaarD. F., and TyceR. L., 1988, The Mathematician Paleoplate, J. Geophys. Res. 93, 3025–3040.

    Google Scholar 

  • MartinezF., NaarD. F., ReedT. B., and HeyR. N., 1991, Three-Dimensional SeaMARC II, Gravity, and Magnetics Study of Large-Offset Rift Propagation at the Pito Rift, Easter Microplate, Mar. Geophys. Res. 13, 255–285 (this issue).

    Google Scholar 

  • MorganW. J., 1972, Plate Motions and Deep Mantle Convection, Mem. Geol. Soc. Am. 132, 7–22.

    Google Scholar 

  • Naar, D. F., 1990, Large-Scale Plate Boundary Reorganization at the Easter Microplate, Ph.D. dissertation, Scripps Institution of Oceanography, University of California, 214 pp.

  • NaarD. F. and HeyR. N., 1986, Fast Rift Propagation along the East Pacific Rise near Easter Island, J. Geophys. Res. 91, 3425–3438.

    Google Scholar 

  • Naar, D. F. and Hey, R. N., 1989, Recent Pacific-Easter-Nazca Plate Motions, in Evolution of Mid Ocean Ridges, IUGG Symposium 8, AGU Geophysical Monograph 57, 9–30.

  • NaarD. F. and HeyR. N., 1991, Tectonic Evolution of the Easter Microplate, J. Geophys. Res. 96, 7961–7993.

    Google Scholar 

  • RusbyR. I., SearleR. C., EngelnJ., HeyR. N., NaarD., and ZukinJ., 1988, GLORIA and Other Surveys of the Easter and Juan Fernandez Microplates, Eos Trans. AGU 69, 1428.

    Google Scholar 

  • SchillingJ-G., SigurdssonH., DavisA. N., and HeyR. N., 1985, Easter Microplate Evolution, Nature 317, 325–331.

    Google Scholar 

  • SchoutenH., KlitgordK. D., and GalloD. G., 1988, Microplate Kinematics of the Second Order, Eos Trans. AGU 69, 488.

    Google Scholar 

  • Schouten, H., Klitgord, K. D., and Gallo, D. G., 1991, Microplate Kinematics of the Second Order, J. Geophys. Res. (in press).

  • SearleR. C., RusbyR. I., EngelnJ., HeyR. N., ZukinJ., HunterP. M., LeBasT. P., HoffmanH-J., and LivermoreR., 1989, Comprehensive Sonar Imaging of the Easter Microplate, Nature 341, 701–705.

    Google Scholar 

  • SempereJ-C., MeshkovA., ThommeretM., and MacdonaldK., 1988, Magnetic Properties of Some Young Basalts from the East Pacific Rise, Mar. Geophys. Res. 9, 131–146.

    Google Scholar 

  • SempereJ-C., GeeJ., NaarD. F., and HeyR. N., 1989, Three-Dimensional Inversion of the Magnetic Field over the Easter-Nazca Propagating Rift near 25° S, 112° 25′W, J. Geophys. Res. 94, 17409–17420.

    Google Scholar 

  • SenderK. L., ShorA., and HagenR., 1989, SeaMARC II Side-Scan Processing Techniques, Eos Trans. AGU 70, 11304.

    Google Scholar 

  • SintonJ. M., WilsonD. S., ChristieD. M., HeyR. N., and DelaneyJ. R., 1983, Petrological consequences of Rift Propagation on Oceanic Spreading Ridges, Earth Planet. Sci. Lett. 62, 193–207.

    Google Scholar 

  • SmithW. H. F., and WesselP., 1990, Gridding with Continuous Curvature Splines in Tension, Geophys. 55, 293–305.

    Google Scholar 

  • Stewart, W. K., 1988, Multisensor Modeling Underwater with Uncertain Information, Ph.D. Dissertation, Woods Hole Oceanographic Institution.

  • WeisselJ. K. and KarnerG. D., 1989, Flexural Uplift of Rift Flanks Due to Mechanical Unloading of the Lithosphere During Extension, J. Geophys. Res. 94, 13919–13950.

    Google Scholar 

  • WesselP. and SmithW. H. F., 1988, The GMT-SYSTEM: Version 1.0. Technical Reference and Cookbook, Internal Report, Lamont-Doherty Geological Observatory, Columbia University, New York.

    Google Scholar 

  • ZukinJ. and FrancheteauJ., 1990, A Tectonic Test of Instantaneous Kinematics of the Easter Microplate, Oceanologica Acta, vol. Spec. 10, 183–198.

    Google Scholar 

Download references

Author information

Author notes

  1. David F. Naar

    Present address: Department of Marine Science, University of South Florida, 33701, St. Petersburg, Florida, USA

Authors and Affiliations

  1. School of Ocean and Earth Science and Technology, University of Hawaii, 96822, Honolulu, Hawaii, USA

    David F. Naar, Fernando Martinez, R. N. Hey & Thomas B. Reed IV

  2. Scripps Institution of Oceanography, University of California, 92093, San Diego, La Jolla, California, USA

    David F. Naar

  3. Department of Geological Sciences, Northwestern University, 60201, Evanston, Illinois, USA

    Seth Stein

Authors
  1. David F. Naar
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Fernando Martinez
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. R. N. Hey
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Thomas B. Reed IV
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Seth Stein
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Naar, D.F., Martinez, F., Hey, R.N. et al. Pito Rift: How a large-offset rift propagates. Marine Geophysical Researches 13, 287–309 (1991). https://doi.org/10.1007/BF00366280

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00366280

Key words

Search

Navigation