Global Climatic Consequence of CO2 Released During Eocene Regional Metamorphism

9304939科里克碰撞造山作用可能提供气候上重要的二氧化碳来源，因此需要重新审视造山和造山变质作用在长期全球变化中的作用。始新世古大气二氧化碳水平的升高可能是始新世区域变质作用期间释放的二氧化碳影响特提斯和环太平洋造山带大段的结果。根据地质记录，仅特提斯喜马拉雅造山带的区域变质作用就可能提供足够的二氧化碳来产生重大的始新世气候影响。在区域变质过程中，碳酸盐和碳质岩性(如硅质白云岩、泥灰岩、黑色页岩)中的脱碳反应释放到大气中的二氧化碳的量和通量是一个被忽视的问题。根据对喜马拉雅造山带受始新世变质作用影响的规模、变质作用涉及的碳酸盐岩和石墨岩的比例以及变质作用持续时间的年代学分析，以及始新世大气可能获得了大量的变质CO2(1019摩尔/Ma)。年代学分析表明，特提斯造山带和环太平洋造山带内许多地区的峰期变质年龄(即40-50 Ma)具有显著的相似性，从而支持了全球始新世重大区域变质作用的概念。我们提出的跨学科研究有两个主要方向：(1)分析地质记录以量化始新世期间变质CO2的产生数量和速率，(2)模拟变质CO2通量对始新世大气的影响。***

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. ***