Stephen J. Romaniello
Arizona State University
GeologyGeochemistrySeawaterIsotope fractionationIsotopes of uranium
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Publications 55
#1Keyi Cheng (UNM: University of New Mexico)
#2Maya Elrick (UNM: University of New Mexico)H-Index: 19
Last. Stephen J. Romaniello (ASU: Arizona State University)H-Index: 16
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1 CitationsSource
#1Allison T. Greaney (UCSB: University of California, Santa Barbara)
#2Roberta L. Rudnick (UMD: University of Maryland, College Park)H-Index: 61
Last. Ariel D. Anbar (ASU: Arizona State University)H-Index: 57
view all 6 authors...
Abstract Molybdenum isotopes in twenty-four composites of glacial diamictites spanning depositional ages of 2900 to 300 Ma show a systematic shift to lighter compositions and a decrease in Mo concentration over time. The diamictites fall into three age groups relative to the Great Oxidation Event (GOE): pre-GOE (2.43 – 2.90 Ga), syn-GOE (2.20 – 2.39 Ga), and post-GOE (0.33 – 0.75 Ga). Pre-GOE composites have an average δ 98 MoNIST3134 of +0.03‰ (± 0.18‰), syn-GOE composites average − 0.29 ‰ (± 0...
#1Feifei Zhang (Yale University)H-Index: 7
#2Tais W. Dahl (UCPH: University of Copenhagen)H-Index: 14
Last. Ariel D. Anbar (ASU: Arizona State University)H-Index: 57
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Abstract The global Hangenberg Crisis near the Devonian-Carboniferous boundary (DCB) represents one of the major Phanerozoic mass extinction events, which shaped the roots of modern vertebrate biodiversity. Marine anoxia has been cited as the proximate kill mechanism for this event. However, the detailed timing, duration, and extent of global marine redox chemistry changes across this critical interval remain controversial because most of the studies to date only constrain changes in local or re...
1 CitationsSource
Abstract Coupled Mo-U isotope data from the Upper Devonian Kettle Point Formation (Ontario, Canada) provide a cautionary tale regarding interpretation of global ocean redox conditions using data from euxinic black shales. In the Gore of Chatham core, the Kettle Point black shales have high Mo concentrations (48–473 μg/g) and consistently high Mo/U ratios (≥3 times the Mo/U ratio of modern seawater), suggesting a euxinic depositional environment. These shales yield an inverse correlation (r = 0.8...
#1H. Cui (Vrije Universiteit Brussel)
#1Huan CuiH-Index: 11
Last. Philippe ClaeysH-Index: 31
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The terminal Ediacaran contains dramatic changes in biogeochemical cycles, many of which are closely coupled with evolutionary transitions in the corresponding fossil records. Dynamic redox conditions may have caused a profound impact on early animal evolution. Our work highlights the significance of integrated bio-, litho-, and chemo-stratigraphy in geobiology research of the deep time.
#1Aleisha C. Johnson (ASU: Arizona State University)H-Index: 1
#2S.M. Aarons (UCSD: University of California, San Diego)H-Index: 7
Last. Ariel D. Anbar (ASU: Arizona State University)H-Index: 57
view all 8 authors...
Abstract Recent work has demonstrated that titanium (Ti) isotopes undergo mass-dependent isotope fractionation during magmatic differentiation, leaving evolved silicic melts preferentially enriched in heavy Ti isotopes. Preferential incorporation of light Ti isotopes in crystallizing Fe-Ti oxides is thought to be the mechanism responsible for this fractionation in magmatic rocks. To test this hypothesis, we present Ti isotope measurements of Fe-Ti oxide mineral separates of Kilauea Iki lava lake...
#1Zachary A. Torrano (ASU: Arizona State University)
#2Gregory A. Brennecka (WWU: University of Münster)H-Index: 17
Last. M. Wadhwa (ASU: Arizona State University)
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Abstract Calcium-aluminum-rich inclusions (CAIs) are the first solids to form in the early Solar System, and they exhibit nucleosynthetic anomalies in many isotope systems. The overwhelming majority of isotopic data for CAIs is limited to inclusions from the CV chondrite Allende and a few other CV, CO, CM, and ordinary chondrites. It is therefore important to ascertain whether previously reported values for CAIs are representative of the broader CAI-forming region and to make a more rigorous ass...
#1Chadlin M. Ostrander (ASU: Arizona State University)H-Index: 3
#2Swapan K. Sahoo (UNLV: University of Nevada, Las Vegas)H-Index: 4
Last. Ariel D. Anbar (ASU: Arizona State University)H-Index: 57
view all 11 authors...
Abstract 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) isotope excursions (to as low as δ98MoNIST+0.25 = −2.24 ± 0.10‰; 2SD) in shales from four separate sites in South China (Rongxi, Taoying, Wuhe, and Yuanjia) that preserve the Doushantuo Formation. The negative δ98Mo excursions appear coincident with previously discovered and seem...
1 CitationsSource
#1Geoffrey J. Gilleaudeau (ASU: Arizona State University)H-Index: 7
#2Stephen J. Romaniello (ASU: Arizona State University)H-Index: 16
Last. Ariel D. Anbar (ASU: Arizona State University)H-Index: 57
view all 12 authors...
Abstract Reconstructing Earth's oxygenation history is key to deciphering environmental controls on early biospheric evolution. During the mid-Proterozoic Eon, low (but potentially variable) atmospheric pO2 led to highly heterogeneous marine redox conditions, with most studies indicating a relatively shallow depth of oxygen penetration. The relative proportion of oxic, anoxic and iron-rich (ferruginous), and anoxic and sulfide-rich (euxinic) conditions on the global seafloor is difficult to quan...
#1Feifei ZhangH-Index: 7
#2Shuhai Xiao (VT: Virginia Tech)H-Index: 54
Last. Ariel D. Anbar (ASU: Arizona State University)H-Index: 57
view all 11 authors...
4 CitationsSource