September Geology and GSA Today media ...(microbial zoning can be explained as an ...)

Tourmaline B-isotopes fingerprint marine evaporites as the source of high-salinity ore fluids in iron oxide copper-gold deposits, Carajas Mineral Province (Brazil)

Roberto Xavier et al., Instituto de Geosciencias, Universidade Estadual de Campinas, Rue Pandia Calogeras, Campinas, Sao Paolo 13083-970, Brazil. Pages 743-746.

Xavier et al.'s paper describes the first application of tourmaline boron isotope data to iron oxide copper-gold deposits, using as a case study three world-class deposits of the Carajas Mineral Province, northern Brazil. The data essentially indicate that marine evaporites, and not magmatic fluids, are the source of boron and high salinity in these deposits.

Biogeochemical controls on photic-zone euxinia during the end-Permian mass extinction

Katja Meyer et al., Dept. of Geosciences, 801 Deike Building, Pennsylvania State University, University Park, Pennsylvania 16802, USA. Pages 667-670. NSF funding received.

The largest Phanerozoic mass extinction marks the end of the Permian period and coincides with evidence of environmental change in the oceans and on land. Multiple lines of evidence suggest the oceans may have become anoxic and sulfidic, and previous work hypothesized that hydrogen sulfide release to the atmosphere could link the marine and terrestrial crises. Meyer et al. used an earth-system model to investigate the conditions necessary for hydrogen sulfide buildup and release to the atmosphere. They found that greater than three-fold increases in oceanic phosphate, a key nutrient derived from rock weathering, leads to hydrogen sulfide accumulation in the deep ocean and in upwelling zones of the surface ocean. Unique hydrogen sulfide-consuming bacteria thrive in sulfidic photic z
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