ORCID Profile
0000-0001-6694-3675
Current Organisations
Coastal Carolina University
,
Universidad Nacional Autónoma de México
,
Macquarie University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Copernicus GmbH
Date: 30-06-2015
Abstract: Abstract. Global warming during the Paleocene Eocene Thermal Maximum (PETM) ~55 million years ago (Ma) coincided with a massive release of carbon to the ocean–atmosphere system, as indicated by carbon isotopic data. Previous studies have argued for a role for changing ocean circulation, possibly as a trigger or response to climatic changes. We use neodymium (Nd) isotopic data to reconstruct short high-resolution records of deep-water circulation across the PETM. These records are derived by reductively leaching sediments from seven globally distributed sites and comparing data with published data from fossil fish debris to reconstruct past deep ocean circulation across the PETM. The Nd data for the leachates are interpreted to be consistent with previous studies that have used fish teeth and benthic foraminiferal δ13C to constrain regions of convection. There is some evidence from combining Nd isotope and δ13C records that the three major ocean basins may not have had substantial exchanges of deep waters. If the isotopic data are interpreted within this framework, then the observed pattern may be explained if the strength of overturning in each basin varied distinctly over the PETM, resulting in differences in deep-water aging gradients between basins. Results are consistent with published interpretations from proxy data and model simulations that suggest modulation of overturning circulation had an important role for global recovery of the ocean–atmosphere system after the PETM.
Publisher: Frontiers Media SA
Date: 20-08-2019
Publisher: Springer Science and Business Media LLC
Date: 25-07-2022
DOI: 10.1038/S43247-022-00495-6
Abstract: The Ediacaran Period witnessed major environmental change and an expansion of eukaryotic life following the Marinoan glaciation. The Doushantuo Formation of south China has furnished much of our understanding of Earth System and biosphere evolution during this period, but its depositional setting–marine or non-marine–is still debated. Here we conduct mineralogical, petrographic and geochemical analyses of s les from the lower Doushantuo Formation in order to determine the origin of saponite clay minerals which are abundant in this interval. We find that the morphology and distribution of the saponite clays suggest they are of pre-compaction, authigenic origin. We infer that the lower Doushantuo sediments were deposited in a restricted, mildly evaporitic lagoonal basin, offering additional constraints on the environmental setting into which metazoan life emerged. Further, our findings confirm that Ediacaran seawater favored reverse weathering, with marine clay formation likely representing an important sink for various elements during the Precambrian.
Publisher: Frontiers Media SA
Date: 23-11-2022
DOI: 10.3389/FEART.2022.956912
Abstract: Sedimentary rocks contain a unique record of the evolution of the Earth system. Deciphering this record requires a robust understanding of the identity, origin, composition, and post-depositional history of in idual constituents. Petrographic analysis informed by Scanning Electron Microscope - Energy Dispersive Spectroscopy (SEM-EDS) mineral mapping can reveal the mineral identity, morphology and petrological context of each imaged grain, making it a valuable tool in the Earth Scientist’s analytical arsenal. Recent technological developments, including quantitative deconvolution of mixed-phase spectra (producing “mixels”), now allow rapid quantitative SEM-EDS-based analysis of a broad range of sedimentary rocks, including the previously troublesome fine-grained lithologies that comprise most of the sedimentary record. Here, we test the reliability and preferred mineral mapping work flow of a modern Field-Emission scanning electron microscope equipped with the Thermofisher Scientific Maps Mineralogy mineral mapping system, focusing on mud/siltstones and calcareous shales. We demonstrate that SEM-EDS mineral mapping that implements 1) a strict error minimization spectral matching approach and 2) spectral deconvolution to produce ‘mixels’ for mixed-phase X-ray volumes can robustly identify in idual grains and produce quantitative mineralogical data sets comparable to conventional X-ray diffraction (XRD) analysis ( R 2 & 0.95). The correlation between SEM-EDS and XRD-derived mineralogy is influenced by mineral abundance, processing modes and mapped area characteristics. Minerals with higher abundance (& wt%) show better correlation, likely the result of increased uncertainty for XRD quantification of low-abundance phases. Automated spectral deconvolution to produce ‘mixels’ greatly reduces the proportion of unclassified pixels, especially in the fine-grained fraction, ultimately improving mineral identification and quantification. Mapping of larger areas benefits bulk mineralogy analysis, while customized area size and shape allows high-resolution in situ mineralogical analysis. Finally, we review SEM-EDS-based mineral mapping applications in the Earth Sciences, via case studies illustrating 1) approaches for the quantitative differentiation of various mineral components including detrital (allogenic), syndepositional (authigenic) and burial diagenetic phases, 2) the origin and significance of lamination, 3) the effectiveness and appropriateness of sequential leaching in geochemical studies, and 4) the utility of mineral maps to identify target grains within specific petrological contexts for in situ geochemical or geochronological analysis.
Publisher: Elsevier BV
Date: 06-2016
Publisher: Elsevier BV
Date: 04-2015
Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 09-2016
Publisher: Geological Society of America
Date: 07-10-2015
DOI: 10.1130/G37114.1
Publisher: Elsevier BV
Date: 02-2022
Publisher: Frontiers Media SA
Date: 21-12-2017
Publisher: Copernicus GmbH
Date: 07-04-2016
Abstract: Abstract. Global warming during the Paleocene–Eocene Thermal Maximum (PETM) ∼ 55 million years ago (Ma) coincided with a massive release of carbon to the ocean–atmosphere system, as indicated by carbon isotopic data. Previous studies have argued for a role of changing ocean circulation, possibly as a trigger or response to climatic changes. We use neodymium (Nd) isotopic data to reconstruct short high-resolution records of deep-water circulation across the PETM. These records are derived by reductively leaching sediments from seven globally distributed sites to reconstruct past deep-ocean circulation across the PETM. The Nd data for the leachates are interpreted to be consistent with previous studies that have used fish teeth Nd isotopes and benthic foraminiferal δ13C to constrain regions of convection. There is some evidence from combining Nd isotope and δ13C records that the three major ocean basins may not have had substantial exchanges of deep waters. If the isotopic data are interpreted within this framework, then the observed pattern may be explained if the strength of overturning in each basin varied distinctly over the PETM, resulting in differences in deep-water aging gradients between basins. Results are consistent with published interpretations from proxy data and model simulations that suggest modulation of overturning circulation had an important role for initiation and recovery of the ocean–atmosphere system associated with the PETM.
Publisher: Frontiers Media SA
Date: 14-04-2021
DOI: 10.3389/FENVS.2021.610115
Abstract: Marine systems across the globe are experiencing myriad pressures with consequences for their health, management and the industries and communities that depend on them. Critical to improved management of our oceans and coasts is effective education and communication that ultimately leads to improved societal value of the world’s oceans. In Australia, the national scientific research agency, CSIRO, operates critical national research infrastructure such as the Marine National Facility (MNF), which also plays an important role in marine education, training and communication. The MNF Outreach Program seeks to strategically engage the community in marine science, identifying audience segments and developing programs, activities and content to meet their specific information needs. The program is structured around three specific audience segments: Purpose Seekers, Nurturers and Lifelong Learners. With both at-sea and shore-based activities and programs including the Indigenous Time at Sea Scholarship, CAPSTAN sea-training, Educator on Board, Floating Classroom, live ship-to-shore crosses and media and social media programming, the MNF Outreach program delivers meaningful engagement through experiential learning opportunities, rather than simply addressing knowledge deficits. As marine issues are varied and complex, marine communication and education approaches must be equally multifaceted, and a successful outreach program will have a spectrum of activities of varying resource intensity (such as cost, time and appropriately skilled personnel) which are matched to clear target audience segments. With increasing recognition of the importance of science communication in informing science literacy and policy, publicly funded national research facilities have an essential role to play by shifting from traditional research-only roles to also provide for targeted education and outreach.
Publisher: Springer Science and Business Media LLC
Date: 10-08-2016
DOI: 10.1038/NATURE19065
Abstract: African climate is generally considered to have evolved towards progressively drier conditions over the past few million years, with increased variability as glacial-interglacial change intensified worldwide. Palaeoclimate records derived mainly from northern Africa exhibit a 100,000-year (eccentricity) cycle overprinted on a pronounced 20,000-year (precession) beat, driven by orbital forcing of summer insolation, global ice volume and long-lived atmospheric greenhouse gases. Here we present a 1.3-million-year-long climate history from the Lake Malawi basin (10°-14° S in eastern Africa), which displays strong 100,000-year (eccentricity) cycles of temperature and rainfall following the Mid-Pleistocene Transition around 900,000 years ago. Interglacial periods were relatively warm and moist, while ice ages were cool and dry. The Malawi record shows limited evidence for precessional variability, which we attribute to the opposing effects of austral summer insolation and the temporal/spatial pattern of sea surface temperature in the Indian Ocean. The temperature history of the Malawi basin, at least for the past 500,000 years, strongly resembles past changes in atmospheric carbon dioxide and terrigenous dust flux in the tropical Pacific Ocean, but not in global ice volume. Climate in this sector of eastern Africa (unlike northern Africa) evolved from a predominantly arid environment with high-frequency variability to generally wetter conditions with more prolonged wet and dry intervals.
Publisher: Geological Society of America
Date: 28-02-2019
DOI: 10.1130/G45904.1
Publisher: Springer Science and Business Media LLC
Date: 16-06-2021
No related grants have been discovered for April Abbott.