Exploration and Development of Geothermal Water Resources for Agricultural Use in Hokuriku District

Abstract

The relation between geothermal gradients and the geology is investigated in Hokuriku district.Central Japan. Geothermal gradients are mainly inferred from reviewing borehole logs for hot springs.These are classified into the following five groups according to geological distribution. 1) Large geotherma I grad i ents (0. 06~0. 10"C/m) wi th some hot spr i ngs arround the Recent vo I canoes. formi ng mounta ins. 2)Mostly large geothermal gradients(o.04~0.10"C/m) with some hot spring son the g ran i tic roc k s. form in g moutains. 3)Moderate to large geothermal gradients(O. 04~0. 10"C/m) with many hot springs on the Neogene volcanics and so on. forming lowmountains flnd hi lis. It is thought that these areas have been I ifting up in the Recent. 4)Moderate to small geothermal gradients (less than 0.04"C/m) on the allviums and thick sedimentary rocks in the Neogene. It is thought that these areas have been sinking in the Recent.Occasionally hot springs are 0 b t a i ned by d r i I ling m0 ret han 1. 00Om dee P. 5) M0 s t I y sma I I g e 0 the r m a I g r ad i e n t s ( I e ssthan O. 03"C/m) with rare hot springs on the strata in the Paleogene. the Mesozoic and the Paleozoic and metamorphic rocks (schist and gneiss).