K-Ar and Rb-Sr dating of collected rocks from the Priestley Formation, Bowers/Wilson and Bowers/Robertson Bay Terrane boundaries in the Preistley and Mariner Glacier areas, North Victoria Land

One of the best exposed geological cross sections of the Antarctic continent occurs in the northern sector of the Transantarctic Mountains along the west coast of the Ross Sea in North Victoria Land. Geological investigations of the region reveal a cross section of a late Precambrian-Palaeozoic mobile orogenic belt, segmented into distinctive 'terranes' and further disrupted by Cretaceous-Cenozoic break up tectonics of Gondwanaland in the Ross Sea region. Field sampling for K-Ar and Rb-Sr geochronological studies in the Priestley and Mariner Glacier areas was undertaken during the first half of the 1990/91 Italiantartide Expedition at Terra Nova Bay Station, Antarctica, as part of a regional 1: 250,000 geological mapping programme in North Victoria Land. Some 320 samples were collected. A sequence of samples from the Priestley Formation in the upper Priestley Glacier was collected for K-Ar and Rb-Sr dating of early regional metamorphism (late Precambrian and/or early Palaeozoic) in the Wilson Terrane basement. Possible correlatives at higher metamorphic grade were collected for similar work in the upper Boomerang and lower Preistley Glaciers (Preistley Schists) and on the coast around Terra Nova Bay. Samples were also collected from the Bowers/Wilson and Bowers/Robertson Bay Terrane boundaries in the Mariner Glacier region, especially in the Mountaineer and Millen Ranges. Rocks from the Bowers and Robertson Bay Groups are in the intervening Millen Schists and may help to identify the timing of fault movement at the terrane boundaries and hence their amalgamation.