CO2 degassing in the Oregon cascades

The carbon isotope content of dissolved inorganic carbon was measured for l arge cold springs in the central Oregon Cascades. Low C-14 activities in so me of the springs are interpreted to result from the dissolution of diffuse emissions of magmatic CO2, even though volcanic activity has not occurred in this area for more than 1300 yr. On the basis of dissolved magmatic carb on concentrations in the springs, we infer a diffuse magmatic CO2 degassing rate of 3.4 x 10(5) kg/yr per kilometer of are for the central Oregon Casc ades. The CO2 flux calculated from estimates of the mean magmatic intrusion rate and experimentally determined values of CO2 content in melts is consi stent with that determined from our measurements of the dissolved CO2 flux at springs.