Chemical Weathering Reactions on Venus

The experimental studies of chemical weathering reactions on Venus are currently focused on reactions responsible for removing SO2 from the atmosphere of Venus, releasing COS and H2S into the atmosphere of Venus, and for altering iron-bearing minerals such as magnetite, hematite, ilmenite, pyrite, and pyrrhotite.  The rates of these reactions are being measured as a function of temperature, oxygen fugacity, and partial pressures of reactive gases by heating well characterized natural minerals and synthetic samples in controlled gas mixtures for known time periods (see figure).  The solid reaction products are then examined by scanning electron microscopy, X-ray diffraction, and chemical analysis techniques to identify the new phases and to quantify their abundances.  The kinetic data obtained are important for interpreting the results of the Magellan, Galileo Venus flyby, Pioneer Venus, Vega, and Venera spacecraft missions to Venus and the results of the Earth-based observations of the lower atmosphere below the clouds.

Basalt before and after experiment under Venus-like conditions.

Click here to see more pictures of chemical weathering reactions.

Click to view the abstracts on the papers relating to chemical weathering on Venus.

1) Stability of Micas on the Surface of Venus
2) The Sulfur Vapor Pressure over Pyrite on the Surface of Venus
3) Geochemistry of Surface-Atmosphere Interactions on Venus
4) Formation of Carbonyl Sulfide (OCS) from Carbon Monoxide and Sulfur Vapor and Applications to Venus
5) Hydrous Silicates and Water on Venus
6) Why Pyrite is Unstable on Venus
7) The Oxidation State of the Lower Atmosphere and Surface of Venus
8) Volatile Transport on Venus and Implications for Surface Geochemistry and Geology
9) The Rate of Pyrite Decomposition on the Surface of Venus
10) Basalt Oxidation and Hematite Formation on the Surface of Venus
11) The Abundance of Sulfur Dioxide Below the Clouds of Venus
12) Chemistry of the Surface and Lower Atmosphere of Venus
13) Venus Surface Mineralogy: Observational and Theoretical Constraints

Gas-Grain Chemistry in the Solar Nebula

The experimental and theoretical studies of solar nebula chemistry are concerned with using chemical and mineralogical observations of primitive meteorites to constrain conditions (pressure, temperature, oxygen fugacity) in the solar nebula at the time when the meteorites and other solid matter were being formed and thermally processed.   Both chemical and thermodynamic and chemical kinetic models are used to define these constraints.  Recent work has focused on the rates at which gas-grain reactions, such as those responsible for forming troilite (FeS) and magnetite (Fe3O4), for making organic compounds, and for destroying interstellar grains took place in the solar nebula.

Click to view the abstracts on the papers relating to gas-grain chemistry in the solar nebula.

1) Kamacite Sulfurization in the Solar Nebula
2) Experimental Studies of Magnetite Formation in the Solar Nebula
3) The Origin of Sulfide-Rimmed Metal Grains in Ordinary Chondrites
4) Experimental Simulations of Sulfide Formation in the Solar Nebula
5) The Rate of Iron Sulfide Formation in the Solar Nebula
6) The Kinetics and Mechanism of Iron Sulfide Formation in the Solar Nebula
7) Experimental Partitioning of Zirconium, Niobium, and Titanium between Platinum Group Metals and Silicate Liquid
8) Chemistry of the Solar Nebula
9) Lanthanide and Actinide Chemistry at High C/O Ratios in the Solar Nebula
10) Chemistry of the Rare Earth Elements in the Solar Nebula