Initiation of Jurassic Ferrar Group Magmatism in North Victoria Land, Antarctica: - stratigraphic age, composition and depositional environment of volcaniclastic and epiclastic sediments of the Beacon Supergroup

The aim of this multidisciplinary project including igneous petrology, sedimentology, paleozoology and paleobotany is to reconstruct the chronology of events preceding the eruption of thick Jurassic plateau lavas (183 Ma, Ferrar Large Igneous Province) in North Victoria Land, Antarctica. The investigations focus on Triassic to Lower Jurassic siliciclastic and volcaniclastic rocks of the Beacon Supergroup directly underlying the Ferrar lavas. The results will lead to a new concept of the initiation of magmatism in the Ferrar Large Igneous Province and will improve our understanding of early Gondwana break-up.

The Field work was carried out during the 9th German North Victoria Land Expedition (GANOVEX IX) 2005/2006, which was operated by the Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover. Representative outcrops of the up to 300 m thick succession of siliciclastic and volcaniclastic rocks were documented in the southern part of North Victoria Land (Eisenhower Range, Deep Freeze Range, Mesa Range, southern Rennick Glacier, Outback Nunataks). Across that area, the onset of deposition on top of a regional erosional surface is characterized by a succession of quartzose fluvial sandstones and subordinate conglomerates, called Section Peak Formation (SPF). Fine grained carbonaceous horizons and coal layers are locally interbedded. The upper part of the sedimentary sequence is represented by a succession of fine grained, typically ripple cross-laminated tuffaceous sandstones and siltstones, and minor mudstones. This unit, which has not been described before, is referred to as Shafer Peak Formation (SHF). It may be interpreted as the lithological equivalent of parts of the Hanson Formation in the Central Transantarctic Mountains. Preliminary data suggests a Triassic to Lower Jurassic age for the SPF, and a Lower Jurassic age for the SHF. Clastic products of mafic volcanic eruptions are intercalated in the upper sedimentary succession (SHF). They are laterally not continuous and vary from chaotic breccias over lapilli- and block-bearing tuffs to ash- and small lapilli-sized lumps and angular fragments. They can be interpreted as proximal to distal products of local hydroclastic eruptions, which are related to early shallow Ferrar sill intrusions into wet sediments. Due to the local and stratigraphically repetitive nature of these eruptions, they should be referred to as Exposure Hill Type "events" rather than a stratigraphic "Formation". The first pillow lavas and/or lava flows that cover the clastic/volcaniclastic succession, are of variable composition and thus of local origin as well. They are locally overlain by thin sediments including fossiliferous lake sediments. Only the following volcanic eruptions produced the homogeneous plateau basaltic lava flows of the Ferrar Group.


Priestley Glacier (lower left, here ~1000 m) and Shafer Peak (~3600 m), North Victoria Land. The Triassic to Lower Jurassic sedimentary succession is exposed at the cliff beneath the summit of Shafer Peak.


Left: Triassic seed fern frond Dicroidium, scale 1 cm. Middle: Jurassic bennettitalean frond Otozamites, scale 1 cm. Right: Compilation of Triassic and Jurassic pollen and spores from the Beacon Super Group, scale 50 µm.

Applicants

Prof. Dr. Lothar Viereck-Götte (Jena, Igneous Petrology)
Prof. Dr. Reinhard Gaupp (Jena, Sedimentology)
Prof. Dr. Jörg W. Schneider (Freiberg, Paleozoology)
Prof. Dr. Hans Kerp (Münster, Paleobotany)

Scientists

Prof. Dr. Lothar Viereck-Götte, Jena, Project Leader Igneous Petrology
Dr. Michael Abratis, Jena, Igneous Petrology
Prof. Dr. Reinhard Gaupp, Jena, Project Leader Sedimentology
Dr. Robert Schöner, Jena, Sedimentology
Dipl.-Geol. Martin Elsner, Jena, PhD Student Sedimentology
Prof. Dr. Jörg W. Schneider, Freiberg, Project Leader Paleozoology
Prof. Dr. Hans Kerp, Münster, Project Leader Paleobotany
Dipl.-Geol. Benjamin Bomfleur, Münster, PhD student Paleobotany

Research area

North Victoria Land

Publications

Bomfleur B, Schneider J, Schöner R, Viereck-Goette L, Kerp H, 2011. Fossil sites in the continental Victoria and Ferrar groups (Triassic-Jurassic) of north Victoria Land, Antarctica. Polarforschung, 80, 88-99.

Schöner R, Bomfleur B, Schneider J, Viereck-Goette L, 2011. A systematic description of the Triassic to Lower Jurassic Section Peak Formation in north Victoria Land (Antarctica). Polarforschung, 80, 71-87.

Schöner R, Viereck-Götte L, Schneider J, Bomfleur B, 2007. Triassic-Jurassic sediments and multiple volcanic events in North Victoria Land, Antarctica: A revised stratigraphic model. In: Cooper AK, Raymond CR (eds.), Antarctica: A Keystone in a Changing World. Online Proceedings of the 10th ISAES, USGS Open-File Report 2007-1047, Short Research Paper, 102: 1-5. doi: 10.31333/of2007-1047.srp102.

Viereck-Goette L, Schöner R, Bomfleur B, Schneider J, 2007. Multiple shallow level sill intrusions coupled with hydromagmatic explosive eruptions marked the initial phase of Ferrar Magmatism in North Victoria Land, Antarctica. In: Cooper AK Raymond CR (eds.), Antarctica: A Keystone in a Changing World. Online Proceedings of the 10th ISAES: USGS Open-File Report 2007-1047, Short Research Paper, 104: 1-5. doi: 10.31333/of2007-1047.srp104.

Homepage

Sedimentology group see http://www.igw.uni-jena.de/ahgeol/start.html

Research funding organisation

German Research Foundation (DFG)

Project numbers: VI 215/6, GA 457/11+13, SCHN 408/11+13, KE 584/12
Funding period: 09/2005-09/2008