doi:10.1016/j.gr.2007.05.003
Copyright © 2007 International Association for Gondwana Research Published by Elsevier B.V.
Detrital zircons from upper Permian and lower Triassic Victoria Group sandstones, Shackleton Glacier region, Antarctica: Evidence for multiple sources along the Gondwana plate margin
References and further reading may be available for this article. To view references and further reading you must
purchase this article.
D.H. Elliota, 
, 
and C.M. Fanningb
aDepartment of Geological Sciences and Byrd Polar Research Center, The Ohio State University, Columbus, OH 43210, USA
bResearch School of Earth Sciences, Australian National University, Canberra, ACT 2000, Australia
Received 14 June 2006;
accepted 1 May 2007.
Available online 10 May 2007.
Abstract
In the central Transantarctic Mountains region, siliciclastic strata of the Permian–Triassic Victoria Group (Beacon Supergroup), the Gondwana sequence in Antarctica, have both cratonic and magmatic arc provenance. Volcaniclastic strata occur in the upper part of the Permian Buckley Formation, whereas the Triassic Fremouw and Falla formations are more quartzose. Two sandstones in the upper Buckley and one near the base of the Fremouw, and immediately above the Permo-Triassic boundary, in the Shackleton Glacier region have yielded detrital zircon U/Pb SHRIMP age populations with clear evidence for a contemporaneous source. The stratigraphically lowest sample, about 70 m below the top of the Buckley Formation, is dominated by zoned igneous zircons of late Permian age. The sample from near the top of the Buckley Formation, about 40 m below the Permo-Triassic boundary, predominantly has zoned igneous zircons with the principal age peak again late Permian but with subordinate Devonian and Cambrian age peaks. The third sandstone from just above the Permo-Triassic boundary yielded zircons mainly of Neoproterozoic to Cambrian age. These results indicate a Permian–Triassic magmatic source existed during upper Buckley time, which is consistent with paleocurrent indicators of flow from the West Antarctic flank of the Permian–Triassic foreland basin, the inferred plate margin (Panthalassan) flank. The Devonian source is attributed to the Ford granodiorite suite in Marie Byrd Land, West Antarctica. Because Beacon strata cover the Cambrian Ross orogen and extend onto older basement, the Cambrian and Upper Proterozoic zircons are interpreted to be reworked from sandstones (Ordovician, Devonian, Early Permian in age) exposed in the Permian–Triassic Gondwanide orogen as a result of uplift of a fold and thrust belt by late Permian time.
Keywords: Zircon; geochronology; Beacon; Antarctica; Permian–Triassic
Fig. 1. Location map for Devonian to Triassic Beacon Supergroup strata in the Transantarctic Mountains, Antarctica. EM: Ellsworth Mountains; MBL: Marie Byrd Land; TI: Thurston Island.
Fig. 2. Beacon Supergroup stratigraphy (Taylor and Victoria Groups) in the Transantarctic Mountains. Star on the central Transantarctic Mountains column marks the location of analyzed samples. See Collinson et al. (1994) for details of stratigraphy.
Fig. 3. Locality and simplified geologic map of the Shackleton Glacier region. (Note: orientation reversed from Fig. 1).
Fig. 4. Simplified stratigraphic columns for the upper Buckley Formation and lower Fremouw Formation in the Shackleton Glacier area. (see Fig. 3 for locations).
Fig. 5. Representative cathodoluminescence (CL) images for zircons analyzed from samples: a. 96-35-2; b. 96-36-1; c. 96-36-4. Note: areas analyzed are labeled with spot analysis numbers as in Tables 1, 2 and 3.
Fig. 6. U–Pb zircon age probability plot for sample 35-2, Layman Peak.
Fig. 7. U–Pb zircon age probability plot for sample 36-1, Collinson Ridge.
Fig. 8. U–Pb zircon age probability plot for sample 36-4, Collinson Ridge.
Fig. 9. Gondwana reconstruction for the Antarctic sector, showing the inferred locations of orogenic belts, generalized distribution of dated plutonic rocks and orthogneisses, inferred extent of the Beacon Supergroup sedimentary basins, and the inferred Gondwana orogen structural front. All reconstructions have problems reconciling the geology, continental blocks, and space issues; this is exemplified by Tasmania which, in terms of its geology, should lie along the boundary between the Early and mid Paleozoic orogenic belts. CHP: Challenger Plateau, Lord Howe Rise, and New Zealand Paleozoic and older basement rocks; CP: Campbell Plateau, Chatham Rise, and New Zealand Paleozoic margin strata. Reconstruction modified from Fig. 1 of Elliot and Fleming (2004).
Fig. 10. Schematic cross-section through the central Transantarctic Mountains for the late Permian to earliest Triassic, showing the Beacon foreland (Middle Permian to Late Triassic) and older (Devonian and intracratonic Early Permian) basins with respect to the inferred fold and thrust belt and magmatic arc of the Gondwana active margin.
Table 1.
Summary of SHRIMP U–Pb zircon results for sample 96-35-2
Notes: 1. Uncertainties given at the one σ level.
2. Error in FC1 Reference zircon calibration was 0.82% for the analytical session. (not included in above errors but required when comparing 206 Pb/238 U data from different mounts).
3. f206% denotes the percentage of 206 Pb that is common Pb.
4. For areas older than 
800 Ma correction for common Pb made using the measured 204Pb/206Pb ratio.
5. For areas younger than 800 Ma correction for common Pb made using the measured 238 U/206 Pb and 207Pb/206 Pb ratios following Tera and Wasserburg (1972) as outlined in Williams (1998).
6. For % disc, 0% denotes a concordant analysis.
Pb
indicates radiogenic Pb.
Table 2.
Summary of SHRIMP U–Pb zircon results for sample 96-36-1
Notes : 1. Uncertainties given at the one σ level.
2. Error in FC1 Reference zircon calibration was 0.59% for the analytical session. (not included in above errors but required when comparing 206 Pb/238 U data from different mounts).
3. f206 % denotes the percentage of 206 Pb that is common Pb.
4. For areas older than 800 Ma correction for common Pb made using the measured 204 Pb/206 Pb ratio.
5. For areas younger than 800 Ma correction for common Pb made using the measured 238 U/206 Pb and 207Pb/206 Pb ratios following Tera and Wasserburg (1972) as outlined in Williams (1998).
6. For % disc, 0% denotes a concordant analysis.
Pb indicates radiogenic Pb.
Table 3.
Summary of SHRIMP U–Pb zircon results for sample 96-36-4
Notes : 1. Uncertainties given at the one σ level.
2. Error in FC1 Reference zircon calibration was 0.59% for the analytical session. (not included in above errors but required when comparing 206 Pb/238 U data from different mounts).
3. f206 % denotes the percentage of 206 Pb that is common Pb.
4. For areas older than 800 Ma correction for common Pb made using the measured 204Pb/206Pb ratio.
5. For areas younger than 800 Ma correction for common Pb made using the measured 238U/206Pb and 207Pb/206 Pb ratios following Tera and Wasserburg (1972) as outlined in Williams (1998).
6. For % disc, 0% denotes a concordant analysis.
Pb indicates radiogenic Pb.
Corresponding author. Tel.: +1 614 292 5076; fax: +1 614 292 7688.
Abstract
Purchase PDF (1769 K)
E-mail Article
Add to my Quick Links
Cited By in Scopus (1)
Purchase PDF (2671 K)
