Collaborative Research: Permian-Triassic Basin History of Southern Victoria Land and the Darwin Mountains

Summary of Project and Data Collected

This is a collaborative sedimentological (John Isbell, University of
Wisconsin-Milwaukee) , palynological (Rosemary Askin, Ohio State University),
and paleomagnetic (Anne Grunow , Ohio State University) study of Permian and
Lower Triassic strata in southern Victoria Land (SVL) and the Darwin Glacier
region (DM) of Antarctica. Results of the study are constraining the
paleoenvironmental, tectonic, biotic, and paleogeographic histories of southern
Pangea and providing a polar view of the world during an icehouse to greenhouse
transition. Results of the work are now appearing in the literature. Samples
and data are currently stored at the University of Wisconsin-Milwaukee
(sedimentologic and stratigraphic) and the Ohio State University (palynologic
and paleomagnetic). All samples will be transferred to the Antarctic Rock
Repository at the Ohio State University.

Background of Project:

Upper Paleozoic and Lower Mesozoic rocks in southern Victoria Land (SVL) and
the Darwin Glacier (DM) regions of Antarctica were deposited during Pangea's
drift across the south pole. Based on present plate reconstructions, SVL and
DM were located higher than 75 S from 320 to 210 Ma. Despite the putative high
latitude position, SVL and DM sedimentary successions record a change from
Lower Permian glacial deposits, to Permian fluvial coal measures, to Lower
Triassic non-carbonaceous fluvial deposits, and finally to Middle and Upper
Triassic fluvial coal measures, with well-developed vegetation during much of
this time. Present climatic simulations suggest seasonal climatic extremes
within Pangea's polar interior. Discrepancies between the geological evidence
and the climate simulations need to be resolved, and may be magnified by
incomplete understanding of the timing and extent of glaciation; the influence
of paleotopography, large lakes, and river systems at the time of deposition;
as well as by incomplete documentation of paleoenvironmental conditions.
Furthermore, Late Permian and Triassic mean pole positions for Gondwanaland are
not tightly constrained. Paleomagnetic signatures will be recovered from
Permian and Triassic petrified wood, silicified peat, and coal, which were
cemented during early diagenesis (preliminary results indicate stable remanent
magnetization). Palynological analyses will provide time control for the
succession.

Objectives of the study:
1) determining the late Paleozoic glacial/deglaciation history of SVL and DM,

2) relating the glacial record of this region with that of other Gondwana areas
to produce a summary of late Paleozoic glaciation for the Earth.

3) testing the hypothesis that Gondwana glaciation was a major factor driving
other Earth systems during the Carboniferous and Permian,

4) documenting the Permian record in DG and SVL as a means to better understand
the change from glacial to nonglacial conditions,

5) documenting the Permian post-glacial record in DG and SVL as a means to
better understand the formation and environments of high latitude fluvial
coal-bearing deposits,

6) documenting Triassic lithofacies as a means to better understand high
latitudebconditions during the Early to Middle Triassic 'coal gap' interval,

7) providing a well-constrained stratigraphic framework for the Permian to
lower Triassic succession,

8) testing the diachronous and inversion tectonic models for the Panthalassan
Margin of southwestern Pangea, and

9) constructing better paleogeographic models for Gondwana by obtaining new
Gondwana reference poles for the Permian and Triassic

Antarctica Field work for the study was conducted during the 2000-01 season in
the Darwin Glacier region, and during 2001-02 in southern Victoria Land.

Sites Visited 2000-01:

A) Darwin Mountains and Byrd Glacier region of Antarctica:
1) Coliseum Ridge - 5 sites (Dev. Hatherton Sandstone, Permian Darwin Formation
and Misthound Coal Measures)
2) Haskell Ridge (Permian Darwin Formation and Misthound Coal Measures)
3) Roadend Nunatak (Dev. Hatherton Sandstone, Permian Darwin Formation)
4) Haven Mountain (Dev. Hatherton Sandstone, Permian Darwin Formation and
Misthound Coal Measures)
5) Mt. Ellis -2 sites (Permian Misthound Coal Measures and Ellis Formation)
6) Mt. Henderson (Permian Misthound)
7) Wallabies Nunataks (Dev. Hatherton Sandstone, Permian Pagoda Formation)

B) Southern Victoria Land
1) Mt. Metschel - 2 sites (Permian Metschel Tillite and Weller Coal Measures)
2) Mt. Richie (Dev. Aztec Siltstone, Permian Metschel Tillite and Weller Coal
Measures)
3) Alligator Peak - 2 sites (Dev. Aztec Siltstone, Permian Metschel Tillite and
Weller Coal Measures)

Sites Visited 2001-02:

A) Southern Victoria Land
1) Portal Mountain - 2 sites (Permian Weller Coal Measures, Triassic Feather
and
Lashly Formations)
2) Mt. Crean, (Permian Weller Coal Measures, Triassic Feather Formation)
3) Kennar Valley - 2 sites (Permian Metschel Tillite and Weller Coal Measures)
4) Aztec Mountain - 2 sites (Dev. Aztec Siltstone, Permian Metschel Tillite and
Weller Coal Measures)
5) Maya Mountain -2 sites (Dev. Aztec Siltstone, Permian Metschel Tillite and
Weller Coal Measures)
6) Mt. Fleming (Permian Weller Coal Measures)
7) Mt. Robison - 2 sites (Permian Weller Coal Measures, Triassic Feather and
Lashly Formations)
8) Allan Hills - 2 sites Permian Weller Coal Measures, Triassic Feather and
Lashly Formations)

Stratigraphic and Sedimentologic Data stored at UWM:
Data collected in the field and lab for this project include
1) Graphic logs of outcrop exposures
2) Photo mosaics and other detailed photos of rock features
3) Facies descriptions
4) Facies maps
5) Maps of sediment body geometries
6) Grain size (lateral and vertical within sediment bodies)
7) Unit thickness and lateral extent
8) Sedimentary structures
9) Paleocurrent orientations and paleoslope maps
10) Description of sediment contacts (unit contacts, and unconformities)
11) Petrographic modal analysis of sandstones