Ultramafic rocks in the Haskard Highlands, Northern Shackleton Range: tracer of a Ross orogenic suture zone?

The Shackleton Range in Antarctica is an example for alpine-type ultramafic rocks occurring as lenses in high-grade gneisses. The lenses consist of garnet- and/or spinel-bearing peridotite and pyroxenite taken during the GEISHA expedition in 1987/1988 by W. Schubert in the Haskard Highlands. In olivine-bearing rocks, garnet testifies to high-pressure conditions – that were unrecognised in this area until recently. Generally, ultramafic rocks are valuable tracers of suture zones, such as palaeo-subduction and collision zones. If the high-pressure imprint in the Shackleton Range resulted from the Pan-African collisional event, the ultramafic rocks are very important to better understand the amalgamation of the Gondwana supercontinent, provided their pressure-temperature-time (PTt) evolution is known.

The general intention of this project is to unravel the PTt evolution of the Haskard Highland ultramafic, and closely associated mafic, rocks. The reconstruction of detailed PT paths was the prime task of the first year. Ongoing research is directed at geochronological and geochemical investigations of the ultramafic rocks and closely associated metabasites. Preliminary results imply that the Shackleton Range is one of the few examples of Pan-African eclogite-facies rocks in general; other examples are known from Mali (e. g. Jahn et al. 2001) and Zambia (e. g. John and Schenk 2003). Moreover, the study area is possibly the first example of eclogite-facies ultramafic rocks related to Pan-African collision (Schmädicke and Will 2006).

The continuation of the newly discovered suture zone within Antarctica and beyond remains unknown. Future research is needed to unravel (i) the nature of the protoliths and (ii) the time of protolith formation in order to put the Shackleton Range into the proper geodynamic framework.

Jahn B, Caby R, Monie P, 2001. Chemical Geology doi:10.1016/S0009-2541(01)00264-9. John T, Schenk V., 2003. Contributions to Mineralogy and Petrology 146: 174-191. Schmädicke E, Will T, 2006. Geology 34: 133-136.

Scientists

Prof. Dr. Esther Schmädicke
GeoZentrum Nordbayern
Universität Erlangen-Nürnberg

Prof. Dr. Wolfgang Schubert
Universität Würzburg

Dipl.-Geol. Tanja Romer
GeoZentrum Nordbayern
Universität Erlangen-Nürnberg

Research areas

Haskard Highlands, Northern Shackleton Range

Publications

Will T, Frimmel H, Zeh A, Le Roux, Schmädicke E, 2010. Tectonic and crustal evolution of the Shackleton Range, East Antarctica: Geochemical and isotope contraints. Precambrian Research 180: 85-112.

Romer T, Schmädicke E, Mezger K, 2009. Pan-African eclogite facies metamorphism of ultramafic rocks in the Shackleton Range, Antarctica. Journal of Metamorphic Geology 27: 335-347. DOI: 10.1111/j.1525-1314.2009.00820.x

Will TM, Zeh A, Gerdes A, Frimmel HE, Millar IL, Schmädicke E, 2009. Palaeoproterozoic to Palaeozoic magmatic and metamorphic events in the Shackleton Range, East Antarctica: Constraints from zircon and monazite dating, and implications for the amalgamation of Gondwana. Precambrian Research 172: 25-45.

Schmädicke E, Will T, 2006. First evidence of eclogite-facies metamorphism in the Shackleton Range, Antarctica: Tracer of a suture between East and West Gondwana? Geology 34: 133-136.

Schmädicke E, Will T, Schubert W, Frimmel HE, 2006. First evidence of eclogite-facies metamorphism in the Shackleton Range, Antarctica: Tracer of a suture between East- and West-Gondwana? 29th SCAR Meeting, Hobart, 9 – 19 July 2006, Abstract volume.

Homepage

Find more about Ultramafic rocks in the Haskard Highlands, Northern Shackleton Range at
http://www.gzn.uni-erlangen.de/krustendynamik/

Research funding organisation

German Research Foundation

Project number: SCHM 1038/8
Funding period: Since 2006