On the mechanism of heating up of the Indo-Australian plate

Verzhbitsky, E. V.; Lobkovsky, L. I.

doi:10.1016/0264-3707(93)90015-x

Cited by 16 publications

(7 citation statements)

References 28 publications

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“…This makes it impossible to evaluate whether the assumed geotherm of 15 K km −1 is realistic. Heat flow data in the CIB indicate higher surface heat flow than expected for a lithosphere of this age, but the most likely explanation is a shallow temperature perturbation, as might be induced by deformation or serpentinization [ Weissel et al , 1980; Stein and Weissel , 1990; Verzhbitsky and Lobkovsky , 1993]. …”

Section: Discussionmentioning

confidence: 99%

Spacing of faults at the scale of the lithosphere and localization instability: 2. Application to the Central Indian Basin

Montési

Zuber

2003

J. Geophys. Res.

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[1] Tectonic deformation in the Central Indian Basin (CIB) is organized at two spatial scales: long-wavelength ($200 km) undulations of the basement and regularly spaced faults. The fault spacing of order 7-11 km is too short to be explained by lithospheric buckling. We show that the localization instability derived by Montési and Zuber [2003] provides an explanation for the fault spacing in the CIB. Localization describes how deformation focuses on narrow zones analogous to faults. The localization instability predicts that localized shear zones form a regular pattern with a characteristic spacing as they develop. The theoretical fault spacing is proportional to the depth to which localization occurs. It also depends on the strength profile and on the effective stress exponent, n e , which is a measure of localization efficiency in the brittle crust and upper mantle. The fault spacing in the CIB can be matched by n e $ À300 if the faults reach the depth of the brittleductile transition (BDT) around 40 km or n e $ À100 if the faults do not penetrate below 10 km. These values of n e are compatible with laboratory data on frictional velocity weakening. Many faults in the CIB were formed during seafloor spreading. The preexisting faults near target locations separated by the wavelength of the localization instability were preferentially reactivated during the current episode of compressive tectonics. The longwavelength undulations may result from the interaction between buckling and localization.

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Section: Discussionmentioning

confidence: 99%

Spacing of faults at the scale of the lithosphere and localization instability: 2. Application to the Central Indian Basin

Montési

Zuber

2003

J. Geophys. Res.

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“…Our first order calculation (using Lachenbruch & Sass 1980Carslaw & Jaeger 1959, modified for thrust faults) indicates that the maximum contribution does not exceed 5 mW m −2 . It has also been proposed that widespread exothermic serpentinization in the CIB may be a cause of the anomalous surface heat flow (Verzhbitsky & Lobkovsky 1993;Delescluse & Chamot-Rooke 2006).…”

Section: Heat Flow As An Indication Of Localized Lithospheric Weaknessmentioning

confidence: 99%

Instantaneous deformation and kinematics of the India-Australia Plate

Delescluse

Chamot‐Rooke

2007

Geophysical Journal International

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S U M M A R YActive intraplate deformation of the India-Australia Plate is now being captured by far-field global positioning system (GPS) measurements as well as measurements on a few islands located within the deforming zone itself. In this paper, we combine global and regional geodetic solutions with focal mechanisms of earthquakes to derive the present-day strain field of the India-Australia Plate. We first compile an updated catalogue of 131 Indian intraplate earthquakes (M > 5) spanning the period between the two Asian mega earthquakes of Assam 1897 and Sumatra 2004. Using Haines and Holt's numerical approach applied to a fully deformable India-Australia Plate, we show that the use of GPS data only or earthquakes data only has severe drawbacks, related, respectively, to the small number of stations and the incompleteness of the earthquakes catalogue. The combined solution avoids underestimation of the strain inherent to the Kostrov summation of seismic moments and provides details that cannot be reached by pure GPS modelling. We further explore the role of heterogeneity of the India-Australia Plate and find that the best model, in terms of geodetic vectors fit, relative distribution of strain, style and direction of principal strain from earthquakes, is obtained using the surface heat-flow as a proxy for rheological weakness of the oceanic lithosphere. The present-day deformation is distributed around the Afanasy Nikitin Chain in the Central Indian Basin (CIB)-where it is almost pure shortening-and within the Wharton Basin (WB) off Sumatra-where it is almost pure lateral strike-slip. The northern portion of NinetyEast ridge (NyR) appears as a major discontinuity for both strain and velocity. The new velocity field gives an India/Australia rotation pole located at 11.3 • S, 72.8 • E (−0.301 • Myr −1 ) overlapping with previous solutions, with continental India moving eastward at rates ranging from 13 mm yr −1 (southern India) to 26 mm yr −1 (northern India) with respect to Australia. Taking into account the intraplate velocity field in the vicinity of the Sumatra trench, we obtain a convergence rate of 46 mm yr −1 towards N18 • E at the epicentre of the 2004 Aceh megaearthquake. The predicted instantaneous shortening in the CIB and WB and extension near Chagos-Laccadive are in good agreement with the finite deformation measured from plate reconstructions and seismic profiles, suggesting a continuum of deformation since the onset of intraplate deformation around 7.5-8 Ma. Since no significant change in India convergence is detected at that time, we suggest that the intraplate deformation started with the trenchward acceleration of Australia detaching from India along a wide left-lateral oceanic shear band activating the NyR line of weakness as well as north-south fracture zones east of it. The predicted total amount of left lateral finite strain along these faults is in the range 110-140 km.

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“…The authors suggest that a shortening of 4.5% (50 km for 1100 km) would be enough to produce a heat £ux anomaly of 20 mW m 2 . Values exceed 200 mW m 2 in some places [32], and were suggested to reveal the exothermic reaction of serpentinisation due to lithospheric fracturing and water penetration [32]. Blocks of intraplate deformation display anomalous P-wave velocities in the lower crust, which may indicate the presence of serpentinised peridotites [33].…”

Section: Quantifying the Brittle And Folding Deformationmentioning

confidence: 99%

At what stress level is the central Indian Ocean lithosphere buckling?

Gerbault

2000

Earth and Planetary Science Letters

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Interna] contrasts in strength are responsible for lithospheric buclding. These are quantified by comparing the Indian Ooean data to two dimensional visco elasto plastic numerical models where the material properties depend on temperature and pressure. The central Indian Basin is known for its intraplate seismicity and long wavelength undulations of the sea floor and associated gravity signatures. To simula te the amplitudes of undulations that reach 1 km within about 11 Ma of compression and 60 km of shortening, the required mean yield strength of the lithosphere is 400 MPa. If either a hydrostatic fluid pressure is considered in the crust or a mechanical decoupling at the depth of the Moho, small crustal wavelengths are superimposed on the long wavelength deformation, in agreement with observations. It is then possible to match the alternative indication that buckling co=enced only 4 Ma ago, with a total amount of shortening of 30 km, and with a required yield strength of 200 MPa. About 10% of homogeneous thickening accompanies buckling. Taking into account variable thermal conductivity demonstrates that a change in the geotherm is suffi cient to increase buckling amplitudes by 10% within 5 Ma.

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On the mechanism of heating up of the Indo-Australian plate

Cited by 16 publications

References 28 publications

Spacing of faults at the scale of the lithosphere and localization instability: 2. Application to the Central Indian Basin

Spacing of faults at the scale of the lithosphere and localization instability: 2. Application to the Central Indian Basin

Instantaneous deformation and kinematics of the India-Australia Plate

At what stress level is the central Indian Ocean lithosphere buckling?

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