9304939 Kerrick Collisional orogenesis may provide a climatically important source of CO2, thus requiring a re-examination of the role of mountain building and orogenic metamorphism in long-term global change. The elevated paleoatmospheric CO2 levels proposed for the Eocene may have resulted from CO2 released during Eocene regional metamorphism that affected extensive segments of the Tethys and Circum-Pacific orogenic belts. Based on the geologic record, the regional metamorphism in the Tethyan Himalayan orogen alone may have provided enough CO2 to produce a significant Eocene climatic impact. The quantities and fluxes of CO2 released to the atmosphere by decarbonation reactions in carbonate and carbonaceous lithologies (e.g., siliceous dolomites, marls, black shales) during prograde regional metamorphism represents a much neglected problem. From estimates of the size of the Himalayan orogen affected by Eocene metamorphism, the proportion of metacarbonate and graphitic rocks involved in this metamorphism, and geochronologic analysis of the duration of prograde metamorphism, and Eocene atmosphere could have received a large flux of metamorphic CO2 (> 1019 moles/Ma). Geochronologic analyses reveal a remarkable similarity in peak metamorphic ages (i.e., 40-50 Ma) for many areas within the Tethys and Circum-Pacific orogens, thus supporting the concept of a major, world-wide Eocene regional metamorphism. There are two primary thrusts of our proposed interdisciplinary research: (1) analysis of the geologic record to quantify the amount and rate of metamorphic CO2 production during the Eocene, and (2) modeling the impact of metamorphic CO2 fluxes on the Eocene atmosphere. ***
