| Abstract |
Study has been made to measure filling temperatures and salinities of fluid inclusions in the cuttings of wells in the geothermal field, Iwate Prefecture, Japan, by means of the heating and freezing stage microscope. Fluid inclusions are composed mainly of high density liquid inclusions. In almost wells, the minimum fill in g temperature has a tendency to increase abruptly from near the surface to about 400 deep, and to be about constant from 212 to 236?C at the deeper parts. The minimum filling temperatures are in good agreement with the borehole temperatures. The salinities of fluid in primary and inclusions are ranging from 0.1 to 1.5 and 0.05 to 0.7 NaCl equivalent, respectively. The major results obtained are as The cap rock existing at the part of the A t least about 900 of overburden was possibly eroded after mineralization had taken The last trapping fluid probably the present deep geothermal f l u i d |