Gossans

The presence of sulfates and ferric‐bearing assemblages in the Martian regolith implies that oxidative weathering of iron‐ and sulfur‐bearing minerals has occurred through time on the surface of Mars. A model of acid weathering has been proposed for the iron‐rich basalts on Mars. In this model, aqueous oxidation of iron sulfides released SO42− and H+ ions that initiated the dissolution of basaltic ferromagnesian silicates and released Fe2+ ions. The Fe2+ ions eventually underwent ferrolysis reactions and produced insoluble hydrous ferric oxide phases. Measurements of the time‐dependence of acid weathering reactions have shown that pyrrhotite (Fe7S8) is rapidly converted to pyrite (FeS2) plus dissolved ferrous iron, the rate of pyrite formation decreasing with rising pH and lower temperatures. The rate of oxidation of aqueous Fe2+ ions derived from weathering of iron sulfides by dissolved atmospheric oxygen is known to be pH‐dependent; rates are fast above pH 4.5 at ambient temperatures on the Earth's surface and much slower in acidic groundwater. On Mars, oxidation rates of dissolved Fe2+ ions in equatorial melt‐waters in contact with the atmosphere (PO2 = 10−5 atm) are estimated to lie in the range 0.3–3.0 ppb Fe yr−1 over the pH range 2 to 6. These oxidation rates are more than 105 times slower than corresponding reactions near the freezing point of water on Earth. Oxidation of Fe2+ ions is estimated to be extremely slow in brine eutectic solutions that might be present on Mars and to be negligible in the frozen regolith. Such slow oxidation rates of aqueous Fe2+ ions in acidic groundwater (now permafrost) during the evolution of the Martian regolith would aid the stability, solubility and transport of iron in solution and other dissolved species over the surface of Mars.

show abstract

Recognizing, in lateritic cover, detritus shed from the Archaean Gossan Hill Cu–Zn–Au volcanic-hosted massive sulphide deposit,Western Australia

Smith

Singh

2007

GEEA

View full text Add to dashboard Cite

Cenozoic cover about the Golden Grove Gossan Hill volcanic-hosted massive sulphide (VHMS) deposit consists of lateritic colluvium, remnants of lateritic duricrust, associated lateritic soils and lateritic gravels. Clasts in these materials were investigated for features diagnostic of the mineralized system. The pebble-sized clasts showed: (a) preservation of tuffaceous and other volcanic textures with relict cassiterite (an associate of the ore zone sulphides); (b) relict micrometre-scale Cu, Zn, As or Pb sulphide inclusions in quartz; (c) micrometre-scale gold grains; (d) interpreted ferruginous pseudomorphs after base metal sulphides; and (e) elevated trace amounts of Cu, As, Zn or, more rarely, Sb or Bi in the core matrix of clasts, and in cutans on some of the clasts. All samples studied from an area extending laterally c. 600 m from the central strike of the VHMS ore system are positive, despite intensive weathering, to one or more of these diagnostic criteria. The background samples (2 km to 5 km from the ore system) are negative to all the criteria. A qualitative indication of proximity to the ore system can be derived by listing the occurrence of each of the diagnostic criteria within mineralized clasts in individual samples. A more specialized case of general models for interface sampling is proposed for exploring areas of thick transported cover in deeply weathered terrain. The model focuses on recognizing the described diagnostic criteria in basal cover from samples provided by drill core or cuttings.

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

customersupport@researchsolutions.com

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Gossans

Cited by 3 publications

References 96 publications

Hydrothermal oxidation in the Biwabik Iron Formation, MN, USA

Hydrothermal oxidation in the Biwabik Iron Formation, MN, USA

Rates of oxidative weathering on the surface of Mars

Recognizing, in lateritic cover, detritus shed from the Archaean Gossan Hill Cu–Zn–Au volcanic-hosted massive sulphide deposit,Western Australia

Contact Info

Product

Resources

About