Stackebrandt, W.

Thiedig, F.

English

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Polarforschung 60 (2): 99-100, 1990 (erschienen 1992)8. Agmatites, Basaltic Intrusions and YoungerDeformations in the "Berliner Mauer", CapeSibbald, Aviator Glacier Tongue, North VictoriaLand, AntarcticaBy Friedhelm Thiedig* and Werner Stackebrandt**The southern part of the Mountaineer Range fonns a dissected, high plateau between Parker and Aviatar glaciers.The highest peak is approximately 2330 m above sea level. For this peak we propese the name .BrandenburgcrSpitze" (Brandenburg Peak)', To the south, the plateau drops down to the Aviatar Glacier, in a nearly vertical,about 1200 m high bluff with some spectacular icefalls. For this bluff the name "Berliner Mauer" (Berlin Wall)'is proposed; for a srnall, tower-like detached rock at Cape Sibbald we propose the name "Checkpoint Charlie'".During several helicopter landings we were able to climb down to the foot of this big bluff to collect samples.The main rock types in the upper part of the bluff are granites of the Granite Harbour Intrusives, whereas thelower part consists of Aviaror Agmarites. After BERTHELSEN (1961) agmatite describes metamorphic brecciasand breccia-like rocks where the fragments are more basic than the "groundmass", The first report of the agmatitesby GANOVEX-TEAM (1987), only viewed from the helicopter, mentioned .xlark igneous and partly metamorphicmaterial which is floating in a matrix of light coloured granite". However, the fragments of all parts of the bluffwhich we could observe consist of different types of migmatic gneisses. Darker parts are enriched in biotite, Nogabbro 01' other basic rocks could be recognized in the agmatite. The generation of the agmatites and the intrusionof granites belong to the late Ross cycle (500-480 Ma).The "Berliner Mauer" is penetratcd by many younger mafic dikes and sills of a post-Ross event, presumable ofMesozoic 01' Cenozoic age. The strike of the dikes is SW-NE 01' SSW -NNE, in accordance with the axes of theRoss Sea Rift System (TESSENSOHN & WÖRNER 1991, HINZ & KRISTOFFERSEN 1987), The sills dipwith 10- 30° to the WSW and W, The basaltic veins are tectonically displaced by faults running SW-NE to SSW-l\TNE, This youngest structural event seems to be part of the young uplift of the Transantarctic Mountains andthe graben formation in the Ross Sea.We want to thank our field guide Robert Stecher and pilot Bemd Kirstein for their assistance to reach the bluffsafely. We are greatly indebted to F Tessensohn and G, Kleinschmidt for the possibility to do our Antarctic studiesin a very historical time, The project was financially supported by the Deutsche Forschungsgemeinschaft (DFG),Re f c r e n c c sBe r t hel s c n , A. (1961): Structural classification of gneisses as uscd in team werk in SW Grecnland.- In: Sorcnsen, H. (ed.), Symposium onmigmatite nomenclaturc.. Rep. Int. Geol. Congr., 21. Sess., Norden 1960, XXVI, Suppl. Vol.: 69-71, Berlinske Boktryggeri, Copenhagen.GA N 0 V E X - Te a m (1987): Geological map of North Victoria Land. Antarctica. I : 500,000 - Explanarory Notes.. Geol. Jb. B 66: 7-79.Hin z, K. & Kr ist 0 ff er sen Y. (1987): Antarctica. Recent advances in the understanding of the continental Shclf.. Geol. Jb. E37: 3-54.Te s s e n s 0 h n , F. & W ö r n er, G. (1991): The Ross Sea Rift System (Antarctica) - structure. evolution and analogues.. In: Thomson, M.R.A.,Crame, J.A. & Thomson, J.W. (eds.), Geological evolution of Antarctica.. Cantbridge University Press: 27-277, Carnbridge.*' Prof. Dr. Friedhelm Thiedig, Gcol-Paläont. Institut, Universität MÜnster, Correnssrraße 24, D-4400 MÜnster, FRG.*'*' Dr. Wemer Stackebrandt, Landesamt für Geowissenschaften und Rohstoffe Brandenburg. Stahnsdorfer Damm 77, D-O-1532 Kleinmachnow, FRG.# proposed names are up to now not official.99100Fig. 1: SE comcr of Mountaincer Range (Cape Sibbald) with Aviator Glacier and Aviator Icc Tonguc. 111emore than1200 m high bluff of ,.Berliner Mauer" is visible in the shadow 10 thc lcft.Abb. 1: SÜdost-Ecke der Mauntaineer Range am Cape Sibbald. Aviator-Glctscher im Vordergrund. Die Über 1.200 mhohe Wand der ..Berliner Mauer" ist links im Schatten sichtbar.Fig. 2: Eastern part ofthe lowcr "Berliner Mauer" with basaltic dikes and sills. crossout by norrnal Faults.The height ofthe visible patt of this bluff is abour 300 m.Abb. 2: Ausschnitt aus der dem unteren östlichen Teil der "Berliner Mauer" mit basaltischen Gängen und Lagergängen.die VOll Abschiebungen versetzt werden. Die Höhe des abgebildeten Teils der Wand ist etwa 300 1l1.

8. Agmatites, Basaltic Intrusions and Younger Deformations in the Berliner Mauer, Cape Sibbald, Aviator Glacier Tongue, North Victoria Land, Antarctica

8. Agmatites, Basaltic Intrusions and Younger Deformations in the Berliner Mauer, Cape Sibbald, Aviator Glacier Tongue, North Victoria Land, Antarctica

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