Paleozoic-aged brine and authigenic helium preserved in an Ordovician shale aquiclude
I.D. Clark et al., University of Ottawa, Department of Earth Sciences, Ottawa, Ontario K1N 6N5, Canada. First published on 11 July 2013, http://dx.doi.org/10.1130/G34372.1.
The subsurface isolation of nuclear waste, as well as CO2 and hazardous fluids from fracking relies on the integrity of geological barriers to protect the surface environment from contamination. This study has examined the origin and age of water and gas in sedimentary rocks which are being considered for construction of a nuclear waste repository in Ontario, Canada. New analytical methods were developed to extract fluids and gases from the pores in these highly impermeable shale and limestone rocks. Geochemical and isotope measurements show that these fluids are ancient, originating as hypersaline seawater during Silurian time some 400 million years ago. Helium has accumulated in the pore fluids from the slow decay of uranium in these rocks, retained in-situ for more than 260 million years, despite its being the most mobile component found in the subsurface. The results provide a glimpse of the geochemical makeup of these ancient fluids. Their great age and immobility provide confidence that we can find deep geological settings for the safe isolation of nuclear waste.
Elevated pCO2 leading to Late Triassic extinction, persistent photic zone euxinia, and rising sea levels
Caroline M.B. Jaraula et al. (Kliti Grice, corresponding), Curtin University, Western Australia Organic and Isotope Geochemistry Centre, Department of Chemistry, Curtin University, Perth, WA 6845, Australia. First published on 11 July 2013, http://dx.doi.org/10.1130/G34183.1<
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Geological Society of America