Dolomite or calcite, quartz and kaolinite in various proportions were reacted at 250-300~ temperatures and pressures up to 90 bars in a hydrous environment. Reactions which approached completion produced talc, calcite, montmorillonite, anorthite (both metastable hexagonal and stable triclinic polymorphs) and the rare Ca-zeolite, garronite. These reactions are applicable to diagenesis, low-grade...

The Boltysh crater has an entire suite of crater-fill impactites preserved, including two impact meltbearing breccias. Smectite occurrence in the breccias suggests two stages of alteration; an early hydrothermal mineralization, and a later, low temperature weathering. δD and δO of smectite separates are currently being measured and will be presented.

The mapping of hydrothermal alteration zones associated with epithermal gold deposits on the island of Lesvos in Greece has been carried out using Landsat Thematic Mapper (TM) satellite and ground remote sensing data. The initial analysis of the satellite data using the minimum noise fraction, matched filter and spectral unmixing techniques identified the altered rock outcrops clearly. The iden...

Kimberlite volcanism involves the emplacement of olivine-rich volcaniclastic deposits into volcanic vents or pipes. Kimberlite deposits are typically pervasively serpentinised as a result of the reaction of olivine and water within a temperature range of 130-400 °C or less. We present a model for the influx of ground water into hot kimberlite deposits coupled with progressive cooling and serpen...

The term "Carlin-type" deposit has been applied to a number of low-grade, sedimentary rock-hosted gold deposits that have been discovered and brought into production in the western United States since the 1960s. Carlin-type deposits are characterized by replacement of carbonate and silty carbonate rocks by silica, pyrite, barite, various arsenic, mercury, antimony, and thallium minerals and by ...