Tuesday, October 27, 2015

Science & Technology: Hydrothermal Circulation Causes Heat Flow Anomaly

Scientists discover the causes for heat flow anomalies near the Japan Trench.

Near the Japan Trench, a subduction zone where the dense oceanic Pacific plate plunges beneath the relatively light continental Okhotsk plate, the flow of heat is unexpectedly high. Kawada et al. constructed a thermal model explaining that hydrothermal circulation causes this heat flow anomaly.

Scientists have conducted heat flow surveys near the Japan Trench and discovered that the heat flow within 150 kilometers of the trench is higher than would be expected on an abyssal plain of the same age. The authors constructed a model and showed that this discrepancy can be explained by taking into account additional sources of heat transport, namely, enhanced hydrothermal circulation.

This happens because, as the plate nears the trench, it bends, which enhances the permeability of the crust. Water can thus circulate more deeply and be heated. This enhanced heat flow does not appear to significantly affect the thermal structure of the main subduction zone. (Geochemistry, Geophysics, Geosystems, doi:10.1002/2014GC005285, 2014)

Citation: Minnehan, C. (2015), Bending plate provides unexpected heat source, Eos, 96,doi:10.1029/2015EO036435. Published on 1 October 2015.