北海道における地殻，上部マントルの熱的構造：総合報告

概要

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Many researchers have studied the thermal state of the crust and the upper mantle andits tectonic implications in Hokkaido, Japan. Terrestrial heat flow data have revealed thefollowing characteristic features: (1) High heat flow (84〜125 mW/m2) is observed in thebackarc side of the volcanic front, while low heat flow (< 42 mW/m2) is observed in the forearcside, showing the typical thermal aspects of the island arc. (2) The central axis zone ofHokkaido (the Kamuikotan and Hidaka metamorphic belts) shows relatively low heat flow(42〜80 mW/m2). The low heat flow zone extends for Sakhalin. (3) Extremely low (25〜34mW/m2) and high (125 〜210 mW/m2) heat flow is distributed locally on theIshikari-Tomakomai low land and its neighbor on the west, respectively.Based on the heat flow data and other geophysical data, such as the seismic velocitystructure, aeromagnetic data, and so on, the Curie point depth, the solidus temperaturedepth, temperature at the Moho, and the mantle heat flow have been estimated. Theestimated thermal structure implies the temperature of the lower crust comes to the solidustemperature beneath the backarc side of Hokkaido. The result is well supported by theelectrical resistivity soundings: the low resistive layer (10~40 ohm-m) develops in the lowercrust and is ascribed to the effect of partial melting of the crustal rocks.
北海道大学大学院理学研究院自然史科学部門（地球物理学）の論文
2007-03-15