Provenance of Neoproterozoic and lower Paleozoic siliciclastic rocks of the central Ross orogen, Antarctica: Detrital record of rift-, passive-, and active-margin sedimentation
Siliciclastic rocks in the Transantarctic Mountains record the tectonic transformation from a Neoproterozoic rift-margin setting to a passive-margin and ultimately to an active early Paleozoic orogenic setting along the paleo-Pacific margin of East Antarctica. New U-Pb detrital-zircon ages constrain...
| Published in: | Geological Society of America Bulletin |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
Association of Engineering Geologists
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| Subjects: | |
| Online Access: | http://hdl.handle.net/1885/86302 https://doi.org/10.1130/B25347.1 |
| Summary: | Siliciclastic rocks in the Transantarctic Mountains record the tectonic transformation from a Neoproterozoic rift-margin setting to a passive-margin and ultimately to an active early Paleozoic orogenic setting along the paleo-Pacific margin of East Antarctica. New U-Pb detrital-zircon ages constrain both the depositional age and sedimentary provenance of these strata. In the central Transantarctic Mountains, mature quartz arenites of the late Neoproterozoic Beardmore Group contain Archean and Proterozoic zircons, reflecting distal input from the adjacent East Antarctic shield, Mesoproterozoic igneous provinces, and Grenville-age parts of East Gondwana. Similarly, basal sandstones of the Lower Cambrian Shackleton Limestone (lower Byrd Group) contain zircons reflecting a dominantly cratonic shield source; the autochthonous Shackleton was deposited during early Ross orogenesis, yet its basal sandstone indicates that the inner shelf was locally quiescent. Detrital zircons from the Koettlitz Group in southern Victoria Land show a similar age signature and constrain its depositional age to be ≤670 Ma. Significant populations (up to 22%) of ca. 1.4 Ga zircons in these Neoproterozoic and Lower Cambrian sandstone deposits suggest a unique source of Mesoproterozoic igneous material in the East Antarctic craton; comparison with the trans-Laurentian igneous province of this age suggests paleogeographic linkage between East Antarctica and Laurentia prior to ca. 1.0 Ga. In strong contrast, detrital zircons from upper Byrd Group sandstones are dominated by young components derived from proximal igneous and metamorphic rocks of the emerging Ross orogen. Zircon ages restrict deposition of this syn- to late-orogenic succession to ≤520 Ma (Early Cambrian or younger). Sandstone samples in the Pensacola Mountains are dominated by Grenville and Pan-African zircon ages, suggesting a source in western Dronning Maud Land equivalents of the East African orogen. When integrated with stratigraphic relationships, the detrital-zircon age ... |
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