A constraint on the shear stress at the Pacific‐Australian plate boundary from heat flow and seismicity at the Kermadec forearc

Herzen, R. Von; Ruppel, C. D.; Molnár, Péter; Nettles, M.; Nagihara, S.; Ekström, Göran

doi:10.1029/2000jb900469

Cited by 68 publications

(53 citation statements)

References 44 publications

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“…Although no uncertainty is ascribed to these values, we assume that they might be representative of the thermal structure around the downdip limit of the locked fault zone; for reference, recent published measurements in other similar geodynamical contexts are ascribed uncertainties typically of the order of 5-6 mW m À2 for the same range of values [Von Herzen et al, 2001]. The other values, all on the island of Sumatra, may be affected by the volcanic arc and by the Sumatran Fault.…”

Section: à2mentioning

confidence: 99%

“…No uncertainty has been ascribed to these values. We have arbitrarily ascribed to these data uncertainties twice as large as those assigned to more recent similar measurements performed along the Kermadec forearc [Von Herzen et al, 2001]. Model C, which assumes some shear heating at the plate interface, predicts heat flows that are the most compatible with the available data: it is therefore our preferred model.…”

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confidence: 99%

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The Sumatra subduction zone: A case for a locked fault zone extending into the mantle

et al. 2004

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[1] A current view is that the portion of the subduction interface that remains locked in the time interval between large interplate earthquakes, hereinafter referred to as the locked fault zone (LFZ), does not extend into the mantle because serpentinization of the mantle wedge would favor stable aseismic sliding. Here, we test this view in the case of the Sumatra subduction zone where the downdip end of the LFZ can be well constrained from the pattern and rate of uplift deduced from coral growth and from GPS measurements of horizontal deformation. These geodetic data are modeled from a creeping dislocation embedded in an elastic half-space and indicate that the LFZ extends 132 ± 10/7 km from the trench, to a depth between 35 and 57 km. By combining this information with the geometry of the plate interface as constrained from two-dimensional gravimetric modeling and seismicity, we show that the LFZ extends below the forearc Moho, which is estimated to lie at a depth of $30 km, at a horizontal distance of 110 km from the trench. So, in this particular island arc setting, the LFZ most probably extends into the mantle, implying that either the mantle is not serpentinized, or that the presence of serpentine does not necessarily imply stable sliding. From thermal modeling, the temperature at the downdip end of the LFZ is estimated to be 260 ± 100°C. This temperature seems too low for thermally activated ductile flow, so that aseismic slip is most probably due to pressure and/ or temperature induced steady state brittle sliding, possibly favored by fluids released from the subducting slab.

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Section: à2mentioning

confidence: 99%

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confidence: 99%

The Sumatra subduction zone: A case for a locked fault zone extending into the mantle

et al. 2004

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“…A study of heat fl ow in the Central Andes yielded similar results (Springer, 1999); however, a recent study of heat fl ow in the Kermadec forearc yields signifi cantly higher estimates of shear stress (Von Herzen et aL, 2001). The latter study did not consider the contribution of radiogenic heating in the hanging wall to surface heat fl ow and so may overestimate shear forces.…”

Section: Comparisons With Results From Other Methodsmentioning

confidence: 90%

Shear stress in subducting continental margin from high-pressure, moderate-temperature metamorphism in the Ordenes Complex, Galicia, NW Spain

2005

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The Ordenes Complex, Galicia, NW Spain, preserves high-pressure, moderate-temperature metamorphism in continental margin rocks subducted during closure of the Rheic Ocean in the Variscan orogeny. The exposures extend across '" 90 km perpendicular to strike and include rocks that reached depths of 30 to 60 km. Estimates of P-T conditions of rocks found near the boundary between overriding and subducting plates range from 430 DC at 1.0 GPa to 520°C at 1.65 GPa. Structural reconstructions including these data indicate an angle of subduction between 15 and 30°.A mathematical solution and numerical models have been used to estimate shear heating experienced by this well-exposed paleo-subduction zone. Best fit of model to thermobarometric results occurs if shear stress in the upper reaches of the fault separating subducting and overriding slabs was'" 100 MPa (constant shear) or '" 10.0% of pressure (constant coefficient of friction) assuming a convergence rate of 6 cm year-I . At greater depths negative feedback between temperature and shear stress caused the system to approach steady state with decreasing shear stress and with little increase in temperature. The decrease in shear stress at temperatures above 400°C occurs as the rheological properties of the rock at higher temperature and (or) pressure allow more plastic behavior. This suggests that high-temperature metamorphism is unlikely to occur in subducting crust without special circumstances. A comparison of these results with estimates of shear stress infelTed from seismicity and heat flow at active convergent boundaries in the Pacific indicates that shear stress is best described as a pressure-dependent variable not as a constant shear stress.

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“…Here we studied the cooling effect due to the rapid thrusting of the Chelungpu fault based on the model proposed by Molnar and England (1990) and modified by Von Herzen et al (2001), the expression is as follows:…”

Section: Implications For the Chelungpu Fault Propertiesmentioning

confidence: 99%

Shallow Crustal Thermal Structures of Central Taiwan Foothills Region

Wu¹,

Chi²,

Hsu³

et al. 2013

Terr. Atmos. Ocean. Sci.

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Crustal thermal structures are closely related to metamorphism, rock rheology, exhumation processes, hydrocarbon maturation levels, frictional faulting and other processes. Drilling is the most direct way to access the temperature fields in the shallow crust. However, a regional drilling program for geological investigation is usually very expensive. Recently, a large-scale in-situ investigation program in the Western Foothills of Central Taiwan was carried out, providing a rare opportunity to conduct heat flow measurements in this region where there are debates as to whether previous measured heat flows are representative of the thermal state in this region. We successfully collected 28 geothermal gradients from these wells and converted them into heat flows. The new heat flow dataset is consistent with previous heat flows, which shows that the thermal structures of Central Taiwan are different from that of other subduction accretionary prisms. We then combine all the available heat flow information to analyze the frictional parameters of the Chelungpu fault zone that ruptured during the 1999, Chi-Chi, Taiwan, earthquake. The heat flow dataset gave consistent results compared with the frictional parameters derived from another independent study that used cores recovered from the Chelungpu fault zone at depth. This study also shows that it is suitable for using heat-flow data obtained from shallow subsurface to constrain thrusting faulting parameters, similar to what had been done for the strike-slip San Andreas Fault in California. Additional fieldworks are planned to study heat flows in other mountainous regions of Taiwan for more advanced geodynamic modeling efforts.

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A constraint on the shear stress at the Pacific‐Australian plate boundary from heat flow and seismicity at the Kermadec forearc

Cited by 68 publications

References 44 publications

The Sumatra subduction zone: A case for a locked fault zone extending into the mantle

The Sumatra subduction zone: A case for a locked fault zone extending into the mantle

Shear stress in subducting continental margin from high-pressure, moderate-temperature metamorphism in the Ordenes Complex, Galicia, NW Spain

Shallow Crustal Thermal Structures of Central Taiwan Foothills Region

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