Age and composition of Antarctic sub-glacial bedrock reflected by detrital zircons, erratics, and recycled microfossils in the Ellsworth Land–Antarctic Peninsula–Weddell Sea–Dronning Maud Land sector (240°E–0°–015°E)
TL;DR: In this article, the authors present four new analyses (U-Pb age, T DM C, eHf, and rock type) of detrital zircons from Neogene turbidites as proxies of Antarctic bedrock.
About: This article is published in Gondwana Research.The article was published on 2013-01-01. It has received 35 citations till now. The article focuses on the topics: Provenance & Detritus (geology).
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TL;DR: The high-grade terranes of southern India are made up of four main tectonic units; from north to south these are a) the Salem Block, b) the Madurai Block, c) the Trivandrum Block, and d) the Nagercoil Block as discussed by the authors.
245 citations
TL;DR: A compilation of ~120,000 detrital zircon uranium-lead ages from global sedimentary deposits as a proxy to track the spatial distribution of continental magmatic arc systems from the Cryogenian period to the present demonstrates a direct relationship between global arc activity and major climate shifts.
Abstract: Variations in continental volcanic arc emissions have the potential to control atmospheric carbon dioxide (CO2) levels and climate change on multimillion-year time scales. Here we present a compilation of ~120,000 detrital zircon uranium-lead (U-Pb) ages from global sedimentary deposits as a proxy to track the spatial distribution of continental magmatic arc systems from the Cryogenian period to the present. These data demonstrate a direct relationship between global arc activity and major climate shifts: Widespread continental arcs correspond with prominent early Paleozoic and Mesozoic greenhouse climates, whereas reduced continental arc activity corresponds with icehouse climates of the Cryogenian, Late Ordovician, late Paleozoic, and Cenozoic. This persistent coupled behavior provides evidence that continental volcanic outgassing drove long-term shifts in atmospheric CO2 levels over the past ~720 million years.
236 citations
TL;DR: In a recent paper as discussed by the authors, the authors investigated the role of Antarctica in the formation of the Neoproterozoic supercontinent Rodinia and found that Rodinia was formed by a collisional orogeny in the East Antarctic Craton.
Abstract: The Antarctic rock record spans some 3.5 billion years of history, and has made important contributions to our understanding of how Earth’s continents assemble and disperse through time. Correlations between Antarctica and other southern continents were critical to the concept of Gondwana, the Palaeozoic supercontinent used to support early arguments for continental drift, while evidence for Proterozoic connections between Antarctica and North America led to the ‘SWEAT’ configuration (linking SW USA to East Antarctica) for an early Neoproterozoic supercontinent known as Rodinia. Antarctica also contains relicts of an older Palaeoto Mesoproterozoic supercontinent known as Nuna, along with several Archaean fragments that belonged to one or more ‘supercratons’ in Neoarchaean times. It thus seems likely that Antarctica contains remnants of most, if not all, of Earth’s supercontinents, and Antarctic research continues to provide insights into their palaeogeography and geological evolution. One area of research is the latest Neoproterozoic–Mesozoic active margin of Gondwana, preserved in Antarctica as the Ross Orogen and a number of outboard terranes that now form West Antarctica. Major episodes of magmatism, deformation and metamorphism along this palaeo-Pacific margin at 590–500 and 300–230 Ma can be linked to reduced convergence along the internal collisional orogens that formed Gondwana and Pangaea, respectively; indicating that accretionary systems are sensitive to changes in the global plate tectonic budget. Other research has focused on Grenville-age (c. 1.0 Ga) and PanAfrican (c. 0.5 Ga) metamorphism in the East Antarctic Craton. These global-scale events record the amalgamation of Rodinia and Gondwana, respectively. Three coastal segments of Grenville-age metamorphism in the Indian Ocean sector of Antarctica are each linked to the c. 1.0 Ga collision between older cratons but are separated by two regions of pervasive Pan-African metamorphism ascribed to Neoproterozoic ocean closure. The tectonic setting of these events is poorly constrained given the sparse exposure, deep erosion level and likelihood that younger metamorphic events have reactivated older structures. The projection of these orogens under the ice is also controversial, but it is likely that at least one of the Pan-African orogens links up with the Shackleton Range on the palaeo-Pacific margin of the craton. Sedimentary detritus and glacial erratics at the edge of the ice sheet provide evidence for the c. 1.0 and 0.5 Ga orogenesis in the continental interior, while geophysical data reveal prominent geological boundaries under the ice, but there are insufficient data to trace these features to exposed structures of known age. Until we can resolve the subglacial geometry and tectonic setting of the c. 0.5 and 1.0 Ga metamorphism, there will be no consensus on the configuration of Rodinia, or the size and shape of the continents that existed immediately before and after this supercontinent. Given this uncertainty, it is premature to speculate on the role of Antarctica in earlier supercontinents, but it is likely that Antarctica will continue to provide important constraints when our attention shifts to these
120 citations
Cites background from "Age and composition of Antarctic su..."
...Further constraints on the presence and age of orogenic belts within the East Antarctic Craton are provided by detrital zircons eroded from the Antarctic interior and deposited at the continental margins (e.g. Goodge & Fanning 2010; Veevers & Saeed 2011, 2013)....
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...…there have been attempts to couple regional variations in the U–Pb age and Hf isotope composition of these zircons with glacial drainage patterns to identify discrete basement provinces (e.g. Veevers et al. 2008; Veevers & Saeed 2011, 2013), these spatial constraints are qualitative at best....
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TL;DR: In this article, U-Pb and Lu-Hf isotopic analyses of different sedimentary sequences of the Ventania System, an old Paleozoic orogenic belt exposed in the southern region of the Rio de la Plata Craton in the province of Buenos Aires, Argentina, provide new evidence for the understanding of the tectonic evolution of the western sector of the Gondwanides mountain belt.
65 citations
TL;DR: In this paper, an analysis of detrital zircons from Permian sandstones at those two localities demonstrate a slowly changing zircon age-probability distribution for four samples from the lower part of the sequence, with an abrupt change for the upper Buckley Formation sandstone.
53 citations
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TL;DR: In this paper, the concentrations of 26 trace elements have been determined for zircons from a wide range of different rock types and reveal distinctive elemental abundances and chondrite-normalised trace element patterns for specific rock types.
Abstract: Trace element abundances in igneous zircons, as determined by electron microprobe and laser-ablation microprobe ICPMS analysis, are shown to be sensitive to source rock type and crystallisation environment. The concentrations of 26 trace elements have been determined for zircons from a wide range of different rock types and reveal distinctive elemental abundances and chondrite-normalised trace element patterns for specific rock types. There is a general trend of increasing trace element abundance in zircons from ultramafic through mafic to granitic rocks. The average content of REE is typically less than 50 ppm in kimberlitic zircons, up to 600–700 ppm in carbonatitic and lamproitic zircons and 2,000 ppm in zircons from mafic rocks, and can reach per cent levels in zircons from granitoids and pegmatites. Relatively flat chondrite-normalised REE patterns with chondrite-normalised Yb/Sm ratios from 3 to 30 characterise zircons from kimberlites and carbonatites, but Yb/Sm is commonly over 100 in zircons from pegmatites. Th/U ratios typically range from 0.1 to 1, but can be 100–1000 in zircons from some carbonatites and nepheline syenite pegmatites. The geochemical signatures characteristic of zircon from some rock types can be recognised in bivariate discriminant diagrams, but multivariate statistical analysis is essential for the discrimination of zircons from most rock types. Classification trees based on recursive partitioning techniques provide a rapid means of relating parent rock type to zircon trace element analysis; zircons from many rock types can be discriminated at confidence levels of 75% or more. These trees allow recognition of the provenance of detrital zircons from heavy mineral concentrates, and significantly enhance the usefulness of zircon in regional crustal studies and as an indicator mineral in mineral exploration.
1,660 citations
TL;DR: In this article, the authors estimate that East Antarctica is close to a balanced mass budget, but large losses of ice occur in the narrow outlet channels of West Antarctic glaciers and at the northern tip of the Antarctic peninsula.
Abstract: Observed estimates of ice losses in Antarctica combined with regional modelling of ice accumulation in the interior suggest that East Antarctica is close to a balanced mass budget, but large losses of ice occur in the narrow outlet channels of West Antarctic glaciers and at the northern tip of the Antarctic peninsula.
952 citations
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01 Jan 1999TL;DR: In this article, the authors present a bibliography for Antarctica's glacial history Bibliography index. But they focus on the geomorphology and relief-forming processes of Antarctica.
Abstract: 1. Antarctica's environment 2. Geological history of Antarctica 3. Continental shelf geomorphology and relief-forming processes 4. Sedimentology 5. Continental margin evolution 6. Antarctica's glacial history Bibliography Index.
501 citations