Aspects of a suture zone - the Mariner Glacier Area, Antarctica

This volume presents findings from collaborative research by German and Italian geologists in North Victoria Land, Antarctica, conducted during multiple expeditions. The Mariner Glacier area is part of the Early Paleozoic Ross orogen, which stretches over 3000 km in the Transantarctic Mountains. Here, a Paleozoic continent/ocean suture reveals insights into the plate tectonic framework at the Gondwana margin during the Ordovician period. Generally, two main types of orogens are recognized: those formed by continent/continent collisions and those resulting from subduction accretion at active margins. While many examples exist for the former, such as the Alps and Himalayas, the Ross Orogen shares characteristics with the Cenozoic Andes, including a developed magmatic arc and remnants of an adjacent oceanic plate. The North Victoria Land suture delineates an inboard granitic arc from two outboard low-grade oceanic terranes. Key geological features include medium-pressure metamorphic rocks, high-pressure eclogites, and a system of thrusts that transport tectonic units outward. These observations suggest a cratonward-dipping subduction system, indicating a historical ocean/continent boundary along Gondwana's active margin. Evidence points to a continuous, albeit episodic, subduction from the early Paleozoic to the present, highlighting the persistence of a Paleo-Pacific ocean adjacent to Gondwana.