Alan David Rooney

Alan David Rooney
Yale University | YU · Department of Geology and Geophysics

PhD, Durham University, UK

About

53
Publications
16,496
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Introduction
My research principally focuses on the interactions between tectonic, geochemical and climatic processes. I employ isotope geochemistry; in particular, the Re-Os geochronometer and Os and Sr isotopes. My research interests are spread across three main categories; 1) Proterozoic Earth history, 2) tracing ocean-ice sheet dynamics throughout the Quaternary; and 3) improving our understanding of hydrocarbon systems.
Additional affiliations
October 2012 - present
Harvard University
Position
  • PostDoc Position
October 2010 - September 2012
Durham University
Position
  • PostDoc Position
February 2005 - February 2006
Stockholm University
Position
  • Master's Student
Education
October 2007 - February 2011
Durham University
Field of study
  • Earth Sciences

Publications

Publications (53)
Article
The timing of deformation and associated gold mineralization in SE California, USA, is contentious, partly due to the challenges involved with dating ductile deformation. We therefore combine modern geo- and thermochronology with field and microscopic observations to show that the Cargo Muchacho Mountains preserve evidence of northward thrusting in...
Article
The late Cambrian Steptoean positive carbon isotope excursion (SPICE) represents a major perturbation to the global carbon cycle and was associated with trilobite extinctions and expansion of anoxic and/or euxinic water masses during episodes of eustatic sea-level change. We present a new Re-Os age together with Os and Nd isotope stratigraphy and m...
Article
The Tonian–Ediacaran Hecla Hoek succession of Svalbard, Norway, represents one of the most complete and well-preserved Neoproterozoic sedimentary successions worldwide. With diverse fossil assemblages, an extensive carbonate δ13C record, and sedimentary evidence for two distinct Cryogenian glaciations, this succession will continue to yield insight...
Article
The Hecla Hoek succession of northeastern Svalbard, Norway, is an ~7 km thick Tonian–Ordovician sedimentary succession that overlies Stenian–Tonian felsic igneous and metasedimentary rocks. The carbonate-dominated upper Tonian–Ediacaran (ca. 820–600 Ma) Akademikerbreen and Polarisbreen groups have yielded important insights into Earth’s Neoproteroz...
Article
Full-text available
The rise of complex macroscopic life occurred during the Ediacaran Period, an interval that witnessed large-scale disturbances to biogeochemical systems. The current Ediacaran chronostratigraphic framework is of insufficient resolution to provide robust global correlation schemes or test hypotheses for the role of biogeochemical cycling in the evol...
Article
Full-text available
Geobiology explores how Earth's system has changed over the course of geologic history and how living organisms on this planet are impacted by or are indeed causing these changes. For decades, geologists, paleontologists, and geochemists have generated data to investigate these topics. Foundational efforts in sedimentary geochemistry utilized sprea...
Article
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The extent to which Paleozoic oceans differed from Neoproterozoic oceans and the causal relationship between biological evolution and changing environmental conditions are heavily debated. Here, we report a nearly continuous record of seafloor redox change from the deep-water upper Cambrian to Middle Devonian Road River Group of Yukon, Canada. Bott...
Article
Full-text available
The terminal Mesoproterozoic was a period of widespread tectonic convergence globally, culminating in the amalgamation of the Rodinia supercontinent. However, in Laurentia, long-lived orogenesis on its eastern margin was punctuated by short-lived extension that generated the Midcontinent Rift ca. 1110–1090 Ma. Whereas this cratonic rift basin is ty...
Article
The age and nature of the Neoproterozoic – early Paleozoic rift–drift transition has been interpreted differently along the length of the North American Cordillera. The Ediacaran “upper” group (herein elevated to the Rackla Group) of the Coal Creek inlier, Yukon, Canada, represents a key succession to reconstruct the sedimentation history of northw...
Article
Here we present Re-Os geochronological data from two carbonaceous shale units from the Hornby Bay and Amundsen basins that provide important chronological markers for Mesoproterozoic stratigraphic successions within northern Canada. Shale from the basal Escape Rapids Formation yields a robust depositional age of 1067.3 ± 13.5 Ma for the lowermost S...
Article
Significance Our understanding of the interactions between animal evolution, biogeochemical cycling, and global tectonics during the Ediacaran Period (635 to 541 Ma) is severely hampered by lack of a robust temporal framework. The appearance and extinction of the earliest fossil animals are hypothesized to correlate with upheavals in biogeochemical...
Article
The snowball Earth hypothesis predicts a strong hysteresis resulting in discrete multimillion-year glaciations followed by globally synchronous deglaciation. Here we present new U-Pb zircon and Re-Os sedimentary rock geochronology and Os isotope chemostratigraphy from post-Sturtian sequences in south China to test the synchroneity of deglaciation....
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Full-text available
The snowball Earth hypothesis proposes that if polar ice sheets were to advance equatorward of a mid-latitude threshold, runaway ice-albedo effects would lead to a stable, globally ice-covered climate state that would require extremely high atmospheric pCO 2 levels (supplied by volcanic degassing over millions of years) for deglaciation. Geologic e...
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Geochronology is essential for understanding Earth's history. The availability of precise and accurate isotopic data is increasing; hence it is crucial to develop transparent and accessible data reduction techniques and tools to transform raw mass spectrometry data into robust chronological data. Here we present a Monte Carlo sampling approach to f...
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Full-text available
Well-preserved strata of the late Tonian Chuar Group exposed in the Grand Canyon host fossil evidence for the development of eukaryotic predation, the presence of unique biomarkers, and large changes in C, S, and Mo isotope chemostratigraphy. Despite the importance of this critical succession, few radioisotopic age constraints are available to plac...
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Biomineralization marks one of the most significant evolutionary milestones among the Eukarya, but its roots in the fossil record remain obscure. We report crystallographic and geochemical evidence for controlled eukaryotic biomineralization in Neoproterozoic scale microfossils from the Fifteenmile Group of Yukon, Canada. High-resolution transmissi...
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High-resolution Os isotope stratigraphy can aid in reconstructing Pleistocene ice sheet fluctuation and elucidating the role of local and regional weathering fluxes on the marine Os residence time. This paper presents new Os isotope data from ocean cores adjacent to the West Greenland ice sheet that have excellent chronological controls. Cores MSM-...
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The Neoproterozoic Tsagaan-Olom Group is exposed in the Zavkhan Terrane of southwestern Mongolia and hosts unique geochemical, paleoclimate, and paleontological records that have become central to our understanding of this pivotal interval of Earth history. New sedimentological, stratigraphic, geochronological, and geochemical data provide context...
Conference Paper
Ordovician (485.4 – 443.8 Ma) strata record biotic diversification pulses of marine fauna and the growth of the Gondwanan ice sheets, which culminated in the latest Ordovician glaciation and mass extinction. These phenomena were set against the closure of the Iapetus Ocean, onset of the Appalachian-Caledonian orogeny, and large fluctuations in the...
Conference Paper
Full-text available
The EARTHTIME Initiative was conceived by Sam Bowring and Doug Erwin in 2001 as a response to the advances being made in methods used to quantify time in the stratigraphic record. In the preceding decades the precision and resolution of radio-isotopic dating methods had improved significantly in parallel with increasingly quantitative analysis of t...
Conference Paper
Biomineralization marks one of the most significant evolutionary milestones among the eukarya. Although metazoan mineralized skeletons are abundant in the post-Ediacaran fossil record, the advent of biologically-controlled mineralization, and the role of environment in prompting this innovation, are poorly understood. Here, we report crystallograph...
Article
Full-text available
The snowball Earth hypothesis predicts globally synchronous glaciations that persisted on a multimillion year time scale. Geochronological tests of this hypothesis have been limited by a dearth of reliable age constraints bracketing these events on multiple cratons. Here we present four new Re-Os geochronology age constraints on Sturtian (717-660 M...
Article
Full-text available
The Neoproterozoic Era was an interval characterized by profound environmental and biological transitions. Existing age models for Neoproterozoic nonglacial intervals largely have been based on correlation of carbonate carbon isotope values, but there are few tests of the assumed synchroneity of these records between basins. In contrast to the ash-...
Article
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Biostratigraphy underpins the Phanerozoic time scale, but its application to pre-Ediacaran strata has remained limited because Proterozoic taxa commonly have long or unknown stratigraphic ranges, poorly understood taphonomic constraints, and/or inadequate geochronological context. Here we report the discovery of abundant vase-shaped microfossils fr...
Article
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A substantial body of evidence suggests that subsurface water masses in mid-Proterozoic marine basins were commonly anoxic, either euxinic (sulfidic) or ferruginous (free ferrous iron). To further document redox variations during this interval, a multiproxy geochemical and paleobiological investigation was conducted on the approximately 1000-m-thic...
Article
Full-text available
After nearly a billion years with no evidence for glaciation, ice advanced to equatorial latitudes at least twice between 717 and 635 Mya. Although the initiation mechanism of these Neoproterozoic Snowball Earth events has remained a mystery, the broad synchronicity of rifting of the supercontinent Rodinia, the emplacement of large igneous province...
Article
Full-text available
A significant body of evidence suggests that the marine environment remained largely anoxic throughout most of the Precambrian. In contrast, the oxygenation history of terrestrial aquatic environments has received little attention, despite the significance of such settings for early eukaryote evolution. To address this, we provide here a geochemica...
Chapter
Full-text available
DefinitionUtilization of the rhenium–osmium (Re–Os) radioisotope geochronometer to (1) determine the depositional age of organic-rich rocks (ORR), (2) establish the Os isotope (187Os/188Os) composition of sedimentary successions, and (3) date the timing of hydrocarbon (oil) generation related to thermal maturation of an organic-rich sedimentary roc...
Article
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Successful application of the 187Re-187Os geochronometer has enabled the determination of accurate and precise depositional ages for organic-rich sedimentary rocks (ORS) as well as establishing timing constraints of petroleum generation. However, we do not fully understand the systematics and transfer behaviour of Re and Os between ORS and petroleu...
Article
New Re–Os geochronology for the Ballachulish Slate Formation of the Dalradian Supergroup, Scotland yields a depositional age of 659.6 ± 9.6 Ma. This age represents the first successful application of the Re–Os system to rocks that have extremely low Re and Os abundances (<1 ppb and <50 ppt, respectively). The Re–Os age represents a maximum age for...
Article
Full-text available
The exceptionally well-preserved sedimentary rocks of the Taoudeni basin, NW Africa represent one of the world's most widespread (> 1 M km2) Proterozoic successions. Hitherto, the sedimentary rocks were considered to be Mid Tonian based on Rb–Sr illite and glauconite geochronology of the Atar Group. However, new Re–Os organic-rich sediment (ORS) ge...

Projects

Projects (2)
Project
EARTHTIME is an international community initiative that seeks to accelerate the development and application of integrated methods for the quantification of geological time. The EARTHTIME mission: To accelerate the development and application of integrated methodologies for the quantification geological of time for the underpinning of Earth sciences.
Project
Radiometric ages for pre- syn- and post-glacial stratigraphy of Sturtian and Marinoan age deposits