2 items with the tag “atmospheric evolution

  • Climates and Evolution of Extrasolar Terrestrial Planets
    NAI 2013 VPL at University of Washington Annual Report

    Planetary climate results from the interplay of a large number of different physical processes, including radiative heating and cooling, advection and dynamics, latent heating and cloud effects, atmosphere-interior interactions, and the presence of life. Atmospheres and climate then evolve through time due to interplay between these processes and longer-term effects, such as atmospheric escape, orbital evolution, and other dynamical interactions. Since planetary climate determines surface habitability, we can better understand how planets maintain habitability over long time periods by studying and modeling the large network of interactions that determine the atmospheric state of a planet and how it changes through time.

    ROADMAP OBJECTIVES: 1.1 1.2
  • Project 3F -- Apatitic Latest Precambrian and Early Cambrian Fossils Provide Direct Evidence of Concentrations of Environmental Oxygen
    NAI 2014 University of Wisconsin Annual Report

    Means are not currently available to asses either quantitatively or semi-quantitatively the concentration of oxygen in Earth’s atmosphere over geological time. Despite this, the environmental availability of O2 has been repeatedly postulated to be a cause of major changes in Earth’s biota, most particularly at the Precambrian-Cambrian boundary-defining “Cambrian Explosion of Life,” a time in Earth history when large deposits of phosphate-rich apatite were deposited in shallow basins worldwide. This study shows that substitution of Sm+3 in the Ca I and Ca II sites of fossil-permineralizing, -infilling, and -encrusting apatite can differentiate between oxic, dysoxic, an anoxic settings of apatite formation. Further studies are to be undertaken to establish such REE-substitution as a quantitative O2 paleobarometer.

    ROADMAP OBJECTIVES: 4.1 4.2 6.1 6.2 7.2