Weathering and Hydrothermal Alteration of Mica Minerals.

Chromium isotope fractionation during subduction-related metamorphism, black shale weathering, and hydrothermal alteration

Article history: Received 28 June 2015 Received in revised form 4 January 2016 Accepted 8 January 2016 Available online 12 January 2016 Chromium (Cr) isotopes are an emerging proxy for redox processes at Earth's surface. However, many geological reservoirs and isotope fractionation processes are still not well understood. The purpose of this contribution is to move forward our understanding of ...

Distribution and Origin of Clay Minerals During Hydrothermal Alteration of Ore Deposits

Laboratory Hydrothermal Alteration of Basaltic Tephra by Acid Sulfate Solutions: an Analog Process for Martian Weathering

Introduction: Sulfur is a major chemical component of the Martian surface materials and is thought to have a volcanic origin. Pathfinder and Viking chemical analyses revealed SO3 compositions of “soils” and dust from about 4 to over 7 wt. % [1,2]. Although we know that S is chemically important, we do not know its speciation. Small amounts of sulfates (e.g., Ca and Mg sulfates) and sulfides (e....

Impact-generated Hydrothermal Alteration on Mars: Clay Minerals, Oxides, Zeolites, and More

Introduction: In the Noachian, Mars’ crust was deeply affected by impact crater gardening [1], and subsequent hydrothermal alteration. While water was present in the Martian crust [2,3], frequent impacts [4,5] provided prominent heat sources that drove hydrothermal systems. Those systems were scattered randomly over the planet’s surface and variable in size, but generally spanned the diameter o...

Oxygen Isotope Changes during Mica Alteration

-Oxygen isotope analyses (bOtg) of micas that were artificially depleted in K* indicate little or no isotope exchange during the transformation. The oxidation of iron in K-depleted, iron-rich micas by H202 treatment resulted in 1.6 to 4.6~ decrease in ~O ~8 due to the fact that the equilibrium fracfionation factor is less than the initial difference between the starting 50 ~s of the fluid and m...