Browsing Earth and Environmental Sciences by Author "Gordon, Gwyneth"
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An expanded shale δ98Mo record permits recurrent shallow marine oxygenation during the Neoarchean
Ostrander, Chadlin; Kendall, Brian; Olson, Stephanie; Lyons, Timothy; Gordon, Gwyneth; Romaniello, Stephen; Zheng, Wang; Reinhard, Christopher; Roy, Moutusi; Anbar, Ariel (Elsevier, 2020-01-20)Multiple attempts have been made using the ancient shale record to track the molybdenum isotope composition (δ98Mo) of seawater during the final two-hundred million years of the Archean Eon (2.7 to 2.5 billion-years-ago, ... -
Fully oxygenated water columns over continental shelves before the Great Oxidation Event
Ostrander, Chadlin; Nielsen, Sune; Owens, Jeremy; Kendall, Brian; Gordon, Gwyneth; Romaniello, Stephen; Anbar, Ariel (Nature, 2019-02-25)Late Archaean sedimentary rocks contain compelling geochemical evidence for episodic accumulation of dissolved oxygen in the oceans along continental margins before the Great Oxidation Event. However, the extent of this ... -
Marine redox conditions during deposition of Late Ordovician and Early Silurian organic-rich mudrocks in the Siljan ring district, central Sweden
Lu, Xinze; Kendall, Brian; Stein, Holly J.; Li, Chao; Hannah, Judith L.; Gordon, Gwyneth W.; Ebbestad, Jan Ove R. (Elsevier, 2017-05-10)The Late Ordovician Period witnessed the second largest mass extinction in the Phanerozoic Eon and the Hirnantian glaciation. To infer ocean redox conditions across the Ordovician-Silurian transition, we measured the U (as ... -
Multiple negative molybdenum isotope excursions in the Doushantuo Formation (South China) fingerprint complex redox-related processes in the Ediacaran Nanhua Basin
Ostrander, Chadlin; Swapan, Sahoo; Kendall, Brian; Jiang, Ganqing; Planavsky, Noah; Lyons, Timothy; Nielsen, Sune; Owens, Jeremy; Gordon, Gwyneth; Romaniello, Stephen; Anbar, Ariel (Elsevier, 2019-09-15)The Ediacaran Doushantuo Formation offers one of the most complete and extensively studied records of end- Neoproterozoic biotic and environmental change. Here, we report multiple coeval negative molybdenum (Mo) ... -
Redox conditions across the Cambrian–Ordovician boundary: Elemental and isotopic signatures retained in the GSSP carbonates
Azmy, Karem; Kendall, Brian; Brand, Uwe; Stouge, Svend; Gordon, Gwyneth W. (Elsevier, 2015-12-15)Lime mudstone samples (rhythmites) were collected at high resolution from outcrops of the Cambrian–Ordovician GSSP boundary section at Green Point (western Newfoundland, Canada). The sequence (~45 mthick) consists of slope ... -
Uranium and molybdenum isotope evidence for an episode of widespread ocean oxygenation during the late Ediacaran Period
Kendall, Brian; Komiya, Tsuyoshi; Lyons, Timothy W.; Bates, Steve M.; Gordon, Gwyneth W.; Romaniello, Stephen J.; Jiang, Ganqing; Creaser, Robert; Xiao, Shuhai; McFadden, Kathleen; Sawaki, Yusuke; Tahata, Miyuki; Shu, Degan; Han, Jian; Li, Yong; Chu, Xuelei; Anbar, Ariel (Elsevier, 2015-05-01)To improve estimates of the extent of ocean oxygenation during the late Ediacaran Period, we measured the U and Mo isotope compositions of euxinic (anoxic and sulfidic) organic-rich mudrocks (ORM) of Member IV, upper ...