Aspects of a Suture Zone.
The Mariner Glacier Area, Antarctica

German-Italian Collaborative Research in Antarctica. Polar Issue No. 9

Ed.: Franz Tessensohn; Carlo Alberti Ricci

2003. 444 pages, 135 figures, 40 tables, 8 plates, 1 map, 17x24cm, 1050 g
Language: English

(Geologisches Jahrbuch Reihe B, Band B 85)

ISBN 978-3-510-95915-0, paperback, price: 76.00 €

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Summary top ↑

This volume contains the results of joint work of German and Italian geologists in North Victoria Land, Antarctica, carried out during several expeditions.

The Mariner Glacier area is part of the Early Paleozoic Ross orogen which is exposed in the present Transantarctic Mountains over a length of at least 3000 km. In this particular area, a Paleozoic continent/ocean suture is exposed providing evidence for the plate tectonic setting at the Gondwana margin in the Ordovician.

It is common understanding that there exist two major types of orogens: one formed by continent/continent collision after the closure of an ocean at the end of a Wilson cycle; the other one formed by subduction accretion at an active continental margin. There are many examples for the first type like the Alps, Himalayas or Caledonides, but usually but one example for the second type, the Cordilleras of America.

Therefore it is of great interest that the Paleozoic Ross Orogen has many features in common with the Cenozoic Andes, i.e. a well developed magmatic arc as well as relics of an adjacent oceanic plate and the lack of a second continental plate.

The suture in North Victoria Land separates an inboard granitic arc, hosted in low-pressure, high-temperature metamorphic rocks of the cratonic Wilson "Terrane", from two outboard low-grade terranes of mainly oceanic character (Bowers and Robertson Bay Terranes). Intrusive and metamorphic ages in the Wilson "Terrane" are at of around 500 Ma, the Bowers and Robertson Bay Terranes contain Cambrian to early Ordovician fossils.

The suture is characterized by
* a small belt of medium-pressure metamorphic rocks and high pressure eclogites;
* the amputation of the continental margin as demonstrated by partly sheared arc granites now close to the suture;
* a system of thrusts carrying the three major tectonic units outwards, the inboard units on top of the outboard ones;
* lenses of ultramafic rocks in the form of cumulates, layered gabbros, serpentinites and eclogites lined up along the main suture fault.

All these features provide evidence for a cratonward-dipping subduction system. The study of this suture zone has provided evidence that an ocean/continent boundary existed along the Paleozoic active margin of Gondwana similar to the present-day one along the Andes. If one considers other orogens of intermediate age along this active margin of Gondwana and the later continental fragments of Australia, Antarctica, and South America it appears that there is evidence for a continuous, though episodic, subduction from the early Paleozoic to the present, with shifting positions along the margin.

The onshore geology thus indicates the persistence of a Paleo-Pacific ocean adjacent to Gondwana far beyond the time directly derived from the marine magnetic anomalies.

Contents top ↑

Marco Meccheri, Piero C. Pertusati & Franz Tessensohn: Expanatory
Notes to the Geological and Structural Map of the Area between the
Aviator Glacier and Victory Mountains, Northern Victoria Land,
Franz Tessensohn & Bruno Lombardo: Compilation of Radiometric Ages for
the Mariner Glacier Area, North Victoria Land, Antarctica
Gianni Capponi, Georg Kleinschmidt, Piero C. Pertusati, Carlo Alberto
Ricci & Franz Tessensohn: Terrane Relationships in the Mariner Glacier
Area of Northern Victoria Land, Antarctica
Thomas Flöttmann: The Kyanite Wall Shear Zone - Evidence for a
Mid-Crustal Ductile Detachment Zone at the South-Central Wilson
Terrane Margin, Antarctica
Marco Scambelluri, Bruno Messiga, Riccardo Vannucci & Igor Maria
Villa: Petrology, Geochemistry and Geochronology of the Dessent Unit
(Northern Victoria Land, Antarctica): Some Constraints on its
Evolutionary History
Daniele Castelli, Giacomo Oggiano, Franco Talarico, Elena Belluso &
Fabrizio Colombo: Mineral Chemistry and Petrology of the Wilson
Terrane Metamorphics from Retreat Hills to Lady Newnes Bay, Northern
Victoria Land, Antarctica
Grazia Vita-Scaillet & Bruno Lombardo: Biotite K/Ar Ages of
Metamorphic Rocks of the Retreat Hills, Meander Glacier and
Mountaineer Range, Northern Victoria Land, Antarctica Raffaele Casnedi
& Andrea di Giulio: Sandstone Petrography of the Bowers Supergroup and
Robertson Bay Group (Mariner Glacier Area, Antarctica): Preliminary
Report and Remarks on the Paleotectonics
Giovanni Capponi, Rodolfo Carosi, Marco Meccheri & Giacomo Oggiano:
Strain Analysis in the Millen Range of Northern Victoria Land,
Giovanna Giorgetti & Isabella Memmi: A Study of Phyllosilicates in
Metapelites to Determine Metamorphic Conditions in the Bowers Terrane,
Robertson Bay Terrane and "Millen Schist" in the Millen Range of
Northern Victoria Land, Antarctica
Friedhelm Henjes-Kunst & Hans Kreuzer: Mid-Paleozoic Igneous Activity
in Northern Victoria Land, Antarctica: Implications of New
Geochnological Data
Carlo Alberto Ricci & Franz Tessensohn: The Lanterman-Mariner Suture:
Antarctic Evidence for Active Margin Tectonics in Paleozoic Gondwana
Heinz Jordan, Peter Müller, Franz Tessensohn & Detlef Damaske: The
Cenozoic Meander Intrusives of No Ridge and Cape King and their
Tectonic Setting
Ingrid Hornig & Gerhard Wörner: Cenozoic Volcanics from Coulman
Island, Mandible Cirque, Malta Plateau and Navigator Nunatak, Victoria
Land, Antarctica
Pietro Armienti, Lorella Francalanci, Patrizia Landi & Grazia
Vita-Scaillet: Age and Geochemistry of Volcanic Rocks from Daniell
Peninsula and Coulman Island, Hallett Volcanic Province, Antarctica