Publication details for Prof Roger Clive SearleNeves, M.C., Searle, R.C. & Bott, M.H.P. (2003). Easter microplate dynamics. Journal of Geophysical Research: Solid Earth 108(B4): 2213.
- Publication type: Journal Article
- ISSN/ISBN: 0148-0227
- DOI: 10.1029/2001JB000908
- Keywords: microplate, stresses, strength, oceanic lithosphere, asthenosphere viscosity
- Further publication details on publisher web site
- Durham Research Online (DRO) - may include full text
Author(s) from Durham
We use two-dimensional elastic finite element analysis, supplemented by strength estimates, to investigate the driving mechanism of the Easter microplate. Modelled stresses are compared with the stress indicators compiled from earthquake focal mechanisms and structural observations. The objective is to constrain the tectonic forces that govern the Easter microplate rotation, and to test the microplate driving hypothesis proposed by Schouten et al. (1993). We infer that the mantle basal drag cannot drive the microplate rotation but opposes it, and that the asthenospheric viscosity is no more than about 1x10^18 Pa s. At most the basal drag comprises 20% of the force resisting microplate rotation.
The outward pull of the main plates can drive the rotation by shear drag applied along the northern and southern boundaries of the microplate.
However, we propose an additional driving force which arises from the strong variation of the ridge resistance force along the east and west rifts, so that the main driving torques come from the pull of the major plates acting across the narrowing and slowing rifts. This requires the strength to increase substantially towards the rift tips due to thickening of the brittle lithosphere as the spreading rate slows.
Anderson, R. N., D.W. Forsyth, P. Molnar, and J. Mammerickx, Fault plane solutions of earthquakes on the Nazca plate boundaries and the Easter plate, Earth Planet. Sci. Lett., 24, 188-202, 1974.
Barclay, A., D. R. Toomey, and S. C. Solomon, Microearthquake characteristics and crustal Vp/Vs structure at the Mid-Atlantic Ridge, 35°N, J. Geophys.
Res., 106, 2017-2034, 2001.
Brace, W. F., and D. L. Kohlstedt, Limits on lithospheric stress imposed by laboratory experiments, J. Geophys. Res., 85, 6248-6252, 1980.
Buck, W. R., and E. M. Parmentier, Convection beneath young oceanic
lithosphere: Implications for thermal structure and gravity, J. Geophys.
Res., 91, 1961-1974, 1986.
Byerlee, J. D., Friction of rocks, Pure Appl. Geophys., 116, 615-626, 1978.
Chen, Y., and W. J. Morgan, A nonlinear rheology model for mid-ocean ridge axis topography, J. Geophys. Res., 95, 17,583-17,604, 1990.
Cloetingh, S., and R. Wortel, Stress in the Indo-Australian plate, Tectonophysics, 132, 49-67, 1986.
Coblentz, D. D., and R. M. Richardson, Statistical trends in the in the intraplate stress field, J. Geophys. Res., 100, 20,245-20,255, 1995.
Coblentz, D. D., and R. M. Richardson, Analysis of the South American intraplate stress field, J. Geophys. Res., 101, 8643-8657, 1996.
Cogne´, J. P., J. Francheteau, V. Courtillot, R. Armijo, M. Constantin, J. Girardeau, R. Hekinian, R. Hey, D. F. Naar, and R. Searle, Large rotation of the Easter microplate as evidenced by oriented paleomagnetic samples from the ocean floor, Earth Planet. Sci. Lett., 136, 213-222, 1995.
Courtillot, V., Plaques, microplaques et de´chirures lithosphe´riques:
hie´rarchie de structures tectoniques de l'e´chelle du Globe a` celle du terrain, Bull. Soc. Ge´ol. Fr., 981- 984, 1980.
DeMets, C., R. G. Gordon, D. F. Argus, and S. Stein, Current plate motions, Geophys. J. Int., 101, 425-478, 1990.
Detrick, R. S., P. Buhl, E. Vera, J. Mutter, J. Orcutt, J. Madsen, and T. Brocher, Multi-channel seismic imaging of a crustal magma chamber along the East Pacific Rise, Nature, 326, 35-41, 1987.
Dziewonski, A. M., and J. H. Woodhouse, An experiment in systematic study of global seismicity: Centroid moment tensor solutions for 201 moderate and large earthquakes of 1981, J. Geophys. Res., 88, 3247-3271, 1983.
Eberle, M. A., and D. W. Forsyth, An alternative, dynamic model of the axial topographic high at fast spreading ridges, J. Geophys. Res., 103, 12,309-12,320, 1998.
Engeln, J. F., and S. Stein, Tectonics of the Easter plate, Earth Planet.
Lett., 68, 259-270, 1984.
Engeln, J. F., S. Stein, J. Werner, and R. G. Gordon, Microplate and shear zone models for oceanic spreading center reorganizations, J. Geophys.
Res., 93, 2839-2856, 1988.
Forsyth, D. W., Mechanisms of earthquakes and plate motions in the East Pacific, Earth Planet. Sci. Lett., 17, 189-193, 1972.
Francheteau, J., P. Patriat, J. Segoufin, R. Armijo, M. Doucoure, A.
Yelles-Chaouche, J. Zukin, S. Calmant, D. F. Naar, and R. C. Searle, Pito and Orongo fracture zones: The northern and southern boundaries of the Easter microplate (southeast Pacific), Earth Planet. Sci. Lett., 89, 363-374, 1988.
Herron, E. M., Two small crustal plates in the South Pacific near Easter Island, Nature Phys. Sci., 240, 35-37, 1972.
Hey, R. N., D. F. Naar, M. C. Kleinrock, W. J. Phipps Morgan, E. Morales, and J.-G. Schilling, Microplate tectonics along a superfast seafloor spreading system near Easter Island, Nature, 317, 320-325, 1985.
Huang, P. Y., and S. C. Solomon, Centroid depths of mid-ocean ridge
earthquakes: Dependence on spreading rate, J. Geophys. Res., 93, 13,445-13,477, 1988.
Kong, L. S. L., S. C. Solomon, and G. M. Purdy, Microearthquake characteristics of a mid-ocean ridge along-axis high, J. Geophys. Res., 97, 1659-1685, 1992.
Kruse, S. E., S. F. Tebbens, D. F. Naar, Q. Lou, and R.T. Bird, Comparison of gravity anomalies at pseudofaults, fracture zones, and nontransform discontinuities from fast to slow spreading areas, J. Geophys. Res., 105, 28,399-28,410, 2000.
Kuo, B. Y., D. W. Forsyth, and E. M. Parmentier, Flexure and thickening of the lithosphere at the East Pacific Rise, Geophys. Res. Lett., 13, 681-684, 1986.
Lachenbruch, A. H., A simple mechanical model for oceanic spreading centers, J. Geophys. Res., 78, 3395-3417, 1973.
Larson, R. L., R. C. Searle, M. C. Kleinrock, H. Schouten, R. T. Bird, D.
F. Naar, R. I. Rusby, E. E. Hooft, and H. Lasthiotakis, Roller-bearing tectonic evolution of the Juan Fernandez microplate, Nature, 356, 571-576, 1992.
Liggett, J. A., Fluid Mechanics, 495 pp., McGraw-Hill, New York, 1994.
Lin, J., and E. M. Parmentier, A finite amplitude necking model of rifting in brittle lithosphere, J. Geophys. Res., 95, 4909-4923, 1990.
Lin, J., G. M. Purdy, H. Schouten, J.-C. Sempere, and C. Zervas, Evidence from gravity data for focused magmatic accretion along the Mid-Atlantic Ridge, Nature, 344, 627-632, 1990.
Lonsdale, P., Structural pattern of the Galapagos microplate and evolution of the Galapagos triple junctions, J. Geophys. Res., 93, 13,551-13,574, 1988.
Luyendyk, B. P., M. J. Kamerling, and R. R. Terres, Geometric model for Neogene crustal rotations in southern California, Geol. Soc. Am. Bull., 91, 211-217, 1980.
Martinez, F., D. F. Naar, T. B. Reed IV, and R. N. Hey, 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, 1991.
McKenzie, D. P., and J. A. Jackson, The relationship between strain rates, crustal thickening, paleomagnetism, finite strain and fault movements within a deforming zone, Earth Planet. Sci. Lett, 65, 182-202, 1983.
McKenzie, D. P., and J. A. Jackson, A block model of distributed deformation by faulting, J. Geol. Soc. London, 143, 349-353, 1986.
Naar, D. F., and R. N. Hey, Recent Pacific-Easter-Nazca plate motions, in Evolution of Mid Ocean Ridges, Geophys. Monogr. Ser., vol. 57, edited by J. M. Sinton, pp. 9-30, AGU, Washington, D.C., 1989.
Naar, D. F., and R. N. Hey, Tectonic evolution of the Easter microplate, J. Geophys. Res., 96, 7961-7993, 1991.
Neumann, G. A., and D. W. Forsyth, The paradox of the axial profile:
Isostatic compensation along the axis of the Mid-Atlantic Ridge, J.
Geophys. Res., 98, 17,891-17,910, 1993.
Neves, M. C., Models of stress at mid-ocean ridges and their offsets, Ph.D. thesis, Univ. of Durham, Durham, U. K., 2000.
Owens, R., The morphology and tectonics of the Reykjanes Ridge, Ph.D.
thesis, Univ. of Oxford, Oxford, U. K., 1996.
Pacanovsky, K. M., D. M. Davis, R. M. Richardson, and D. D. Coblentz, Intraplate stresses and plate-driving forces in the Philippine Sea plate, J. Geophys. Res., 104, 1095-1110, 1999.
Phipps Morgan, J., E. M. Parmentier, and J. Lin, Mechanisms for the origin of mid-ocean ridge axial topography: Implications for the thermal and mechanical structure of accreting plate boundaries, J. Geophys. Res., 92, 12,823-12,836, 1987.
Poliakov, A. N. B., and W. R. Buck, Mechanics of stretching elasto-plasticviscous layers: Applications to slow-spreading mid-ocean ridges, in Faulting and Magmatism at Mid-Ocean Ridges, Geophys. Monogr.
Ser., vol. 106, edited by W. R. Buck et al., pp. 305-324, AGU, Washington, D. C., 1998.
Purdy, G. M., L. S. L. Kong, G. L. Christeson, and S. C. Solomon, Relationship between spreading rate and the seismic structure at mid-ocean ridges, Nature, 355, 815-817, 1992.
Richardson, R. M., and L. M. Reding, North American plate dynamics, J.
Geophys. Res., 96, 12,201-12,223, 1991.
Richardson, R. M., S. C. Solomon, and N. H. Sleep, Tectonic stress in the plates, Rev. Geophys., 17, 981-1019, 1979.
Rusby, R. I., Tectonic pattern and history of the Easter microplate, based on GLORIA and other geophysical data, Ph.D. thesis, Univ. of Durham, Durham, U. K., 1992.
Rusby, R. I., and R. C. Searle, Intraplate thrusting near the Easter microplate, Geology, 21, 311-314, 1993.
Rusby, R. I., and R. C. Searle, A history of the Easter microplate, 5.25 Ma to present, J. Geophys. Res., 100, 12,617-12,640, 1995.
Schouten, H., K. D. Klitgord, and D. G. Gallo, Edge-driven microplate kinematics, J. Geophys. Res., 98, 6689-6701, 1993.
Searle, R. C., R. I. Rusby, J. Engeln, R. N. Hey, J. Zukin, P. M. Hunter, T. P.
LeBas, H.-J. Hoffman, and R. Livermore, Comprehensive sonar imaging of the Easter microplate, Nature, 341, 701-705, 1989.
Searle, R. C., R. T. Bird, R. I. Rusby, and D. F. Naar, The development of two oceanic microplates: Easter and Juan Fernandez microplates East Pacific Rise, J. Geol. Soc. London, 150, 965-976, 1993.
Searle, R. C., et al., The Reykjanes Ridge: structure and tectonics of a hotspot influenced, slow-spreading ridge, from multibeam bathymetric, gravity and magnetic investigations, Earth Planet. Sci. Lett., 160, 463- 478, 1998.
Shah, A. K., and W. R. Buck, Causes for axial high topography at midocean ridges and the role of crustal thermal structure, J. Geophys. Res., 106, 30,865-30,879, 2001.
Sigmundsson, F., Post-glacial rebound and asthenosphere viscosity in Iceland, Geophys. Res. Lett., 18, 1131-V 1134, 1991.
Sleep, N. H., and B. R. Rosendahl, Topography and tectonics of midoceanic ridge axes, J. Geophys. Res., 84, 6831-6839, 1979.
Solomon, S. C., N. H. Sleep, and R. M. Richardson, On the forces driving plate tectonics: Inferences from absolute plate velocities and intraplate stress, Geophys. J. R. Astron. Soc., 42, 769-801, 1975.
Tapponnier, P., and J. Francheteau, Necking of the lithosphere and the mechanics of slowly accreting plate boundaries, J. Geophys. Res., 83, 3955-3970, 1978.
Toomey, D. R., and G. M. Purdy, Microearthquakes beneath the median valley of the Mid-Atlantic Ridge near 23N: Tomography and tectonics, J. Geophys.
Res., 93, 9093-9112, 1988.
Turcotte, D. L., and G. Schubert, Geodynamics: Applications of Continuum Physics to Geological Problems, 450 pp., John Wiley, New York, 1982.
Wang, K., J. He, and E. E. Davis, Transform push, oblique subduction resistance, and intraplate stress of the Juan de Fuca plate, J. Geophys.
Res., 102, 661-674, 1997.
Wang, X., and J. R. Cochran, Gravity anomalies, isostasy, and mantle flow at the East Pacific Rise crest, J. Geophys. Res., 98, 19,505-19,531, 1993.
Wolfe, C. J., et al., Microearthquake characteristics and crustal velocity structure at 29N on the Mid-Atlantic Ridge: The architecture of a slow-spreading segment, J. Geophys. Res., 100, 24,449-24,472, 1995.
Wortel, M. J. R., M. J. N. Remkes, R. Govers, S. A. P. L. Cloetingh, and P. T. Meijer, Dynamics of the lithosphere and the intraplate stress field, Philos. Trans. R. Soc. London, Ser. A, 337, 111-126, 1991.
Yelles-Chaouche, A., J. Francheteau, and P. Patriat, Evolution of the Juan Fernandez microplate during the last three million years, Earth Planet.
Sci. Lett., 86, 286-296, 1987.
Zoback, M. L., First- and second-order patterns of stress in the
The World Stress Map Project, J. Geophys. Res., 97, 11,703-11,728, 1992.