Analisis Karakteristik Panasbumi Daerah Outflow Gunung Arjuno-welirang Berdasarkan Data Geologi, Geokimia, dan Geofisika (3g)

The research has been done to analyzed characteristics of geothermal outflow at Mt. Arjuno-Welirang area, based on geology, geochemistry, and geophysics data. Geochemistry data is used to determine type of fluid, temperature of reservoir, and framer of reservoir rocks. Geochemistry data in outflow area produces bicarbonate water (HCO3) with the temperature of reservoir in this area about 145°C to 175°C and the framer of reservoir rock is basaltics. Analysis of characteristics geothermal system components (caprock and reservoir) based on physical properties i.e. resistivity and density. Resistivity value is resulted from 2D magnetotellurics model and density value is resulted from 3D gravity model. From these results, impermeable (caprock) area have a resistivity value about ≤ 10 Ohm.m with curve pattern in which side is thicker and density values is between 1,49 gr/cm3 and 2,4 gr/cm3 with distribution patterns from west to east and the depth of top layer from caprock is about 500 to 1000 m, and type of material is secondary clay mineral and controlled by Fault Puncung. For the permeable (reservoir) in this area have a resistivity values at between 10 and 60 Ohm.m and density value is between 2,4 gr/cm3 and 2,67 gr/cm3 with the depth about ≥1,5 km and type of material rock is andesit-basaltic lava that produce of old lava bodies Mt.Arjuno-Welirang complex that spread out at west to south which earlier Kuarter age