Heat-Flow Studies in the Peru Trench Subduction Zone

Yamano, Makoto; Uyeda, Seiya

doi:10.2973/odp.proc.sr.112.171.1990

Cited by 27 publications

(20 citation statements)

References 28 publications

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“…Generally, there is a good agreement between measurements of near‐seabed conductivity and results from drilling. For example, Yamano & Uyeda (1990) measured a conductivity of 0.82 W m −1 K −1 on piston cores from the Peruvian Margin and drilling gave a mean value of 0.85 W m −1 K −1 (Fig. 6 and Table 2).…”

Section: Discussionmentioning

confidence: 99%

Gas hydrate stability and the assessment of heat flow through continental margins

Grevemeyer¹,

Villinger²

2001

Geophysical Journal International

112

142

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Summary A prominent feature across some continental margins is a bottom‐simulating reflector (BSR). This seismic reflection generally coincides with the depth predicted for the base of the gas hydrate stability field. Because the occurrence of gas hydrates is controlled by temperature and pressure conditions, it has been suggested that BSRs mark an isotherm and they have therefore been used to estimate the heat flow through continental margins; crucial parameters are the temperature at BSR depth and at the seafloor and the thermal conductivity structure between the BSR and the seabed. However, very often the required parameters are not available and therefore they have been derived from models for gas hydrate stability and empirical relationships to obtain thermal conductivities from seismic velocities. Here, we use downhole temperature, thermal conductivity, porosity and logging data from 10 Ocean Drilling Program (ODP) sites drilled into and through the gas hydrate field to investigate the quality of estimates. Our analyses and application of constraints to the Makran margin off Pakistan indicate the following. (i) The temperature at BSR depth could be approximated by a seawater–methane system, although capillary forces, chemical impurities or non‐equilibrium conditions can lower (or increase) the temperature. If calibration by heat probe measurements is possible, errors of geothermal gradients are less than 10 per cent, otherwise uncertainties of 20 per cent (or even higher) may arise. In addition, seasonal variations of bottom water temperature have to be considered, because they may affect thermal gradients by up to ∼10 per cent. (ii) The impact of typical quantities of low‐thermal‐conductivity gas hydrate on the bulk thermal conductivity is insignificant. (iii) The thermal conductivity profile between the BSR and the seabed can generally be approximated by a mean value. Thus, (iv) seabed measurements should be used instead of empirical relationships, which may produce errors of 5–30 per cent. Consequently, in addition to high‐quality seismic data, a prerequisite should be a large data set of thermal conductivities and oceanographic data. Heat probe measurements are recommended to constrain geothermal gradients. In this case the uncertainty of heat flow is 5–10 per cent of the estimated heat flow. If these data are not available errors/uncertainties can reach 50–60 per cent of the calculated value.

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Section: Discussionmentioning

confidence: 99%

Gas hydrate stability and the assessment of heat flow through continental margins

Grevemeyer¹,

Villinger²

2001

Geophysical Journal International

112

142

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“… a 1, Arndt et al [1997]; 2, Èermák and Rybach [1982]; 3, Haenel et al [1988]; 4, Hamza et al [2005]; 5, Henry and Pollack [1988]; 6, Ehlers [2005]; 7, Kappelmeyer and Haenel [1974]; 8, Mel'nikova et al [1975]; 9, Moiseenko et al [1970]; 10, Schön [1996]; 11, Dortman [1976]; 12, Vorsteen and Schellschmidt [2003]; 13, Pollack [1982]; 14, Springer [1999]; 15, Yamano and Uyeda [1990]; 16, Springer and Förster [1998]; 17, Henry [1981]; 18, Uyeda et al [1980]; 19, Klein et al [1999]. …”

Section: Thermal Model Of Thermochronometer Cooling Agesmentioning

confidence: 99%

Quantifying canyon incision and Andean Plateau surface uplift, southwest Peru: A thermochronometer and numerical modeling approach

et al. 2009

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[1] Apatite and zircon (U-Th)/He ages from Ocoña canyon at the western margin of the Central Andean plateau record rock cooling histories induced by a major phase of canyon incision. We quantify the timing and magnitude of incision by integrating previously published ages from the valley bottom with 19 new sample ages from four valley wall transects. Interpretation of the incision history from cooling ages is complicated by a southwest to northeast increase in temperatures at the base of the crust due to subduction and volcanism. Furthermore, the large magnitude of incision leads to additional threedimensional variations in the thermal field. We address these complications with finite element thermal and thermochronometer age prediction models to quantify the range of topographic evolution scenarios consistent with observed cooling ages. Comparison of 275 model simulations to observed cooling ages and regional heat flow determinations identify a best fit history with 0.2 km of incision in the forearc region prior to $14 Ma and up to 3.0 km of incision starting between 7 and 11 Ma. Incision starting at 7 Ma requires incision to end by $5.5 to 6 Ma. However, a 2.2 Ma age on a volcanic flow on the current valley floor and 5 Ma gravels on the uplifted piedmont surface together suggest that incision ended during the time span between 2.2 and 5 Ma. These additional constraints for incision end time lead to a range of best fit incision onset times between 8 and 11 Ma, which must coincide with or postdate surface uplift.

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“…The lowest heat flow over the subduction complex and forearc basin is assumed to result from thermal blanketing effect by the overlying plate and accreted sediments above the subducting oceanic plate [e.g., Langseth et al , 1990]. It has been speculated that heat flow seaward of the trench may be low compared to that for average crust of the same age, due to increased hydrothermal circulation resulting from flexing and normal faulting of the plate prior to subduction, but infrequently mentioned in print [e.g., Yamano and Uyeda , 1990; Langseth and Silver , 1996].…”

Section: Introductionmentioning

confidence: 99%

Heat flow and flexure at subduction zones

Stein

2003

Geophysical Research Letters

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[1] It is often suggested that heat flow in the incoming plate at subduction zones is lower than expected for crust of that age due to increased hydrothermal circulation from flexure (extending about 300 km seaward of the trench) and faulting (observed starting about 50-75 seaward of the trench). Testing this suggestion using global heat flow data shows no significant difference between heat flow near the trench and the global means for the same age crust. However, on average, heat flow in the overriding plate is about 60% of that in the incoming plate.

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Heat-Flow Studies in the Peru Trench Subduction Zone

Cited by 27 publications

References 28 publications

Gas hydrate stability and the assessment of heat flow through continental margins

Gas hydrate stability and the assessment of heat flow through continental margins

Quantifying canyon incision and Andean Plateau surface uplift, southwest Peru: A thermochronometer and numerical modeling approach

Heat flow and flexure at subduction zones

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