Fluid-inclusion evidence for past temperature fluctuations in the Kilauea East Rift Zone geothermal area, Hawaii

摘要: Heating and freezing data were obtained for fluid inclusions in hydrothermal quartz, calcite, anhydrite from several depths three scientific observation holes drilled along the lower East Rift Zone of Kilauea volcano, Hawaii. Compositions inclusion fluids range dilute meteoric water to highly modified sea concentrated by boiling. Comparison measured drill-hole temperatures with fluid-inclusion homogenization-temperature (Th) indicates that only about 15% could have formed under present thermal conditions. The majority studied must during one or more times past when fluctuated response emplacement nearby dikes their subsequent cooling. indicate SOH-4 well as much 64°C hotter than between 1000 1500 m depth they a maximum 68°C cooler below depth. Similarly, show near bottoms SOH-1 SOH-2 wells up 45 59°C, respectively, conditions; however, remainder Th values these two drill suggest trapped waters nearly same at slightly shallower depths. Several minerals (erionite, mordenite, truscottite, smectite, chlorite-smectite, chalcedony, anhydrite, hematite), occurring higher are found geothermal Iceland other areas, provide additional evidence recent heating trend.