Revised Cambrian trilobite biostratigraphy of the northern Victoria Land, Antarctica

Abstract

Antarctica was located in East Gondwana during the Early Paleozoic. The Cambrian rocks in Antarctica are most exposed along the Transantarctic Mountains which runs along the eastern margin of the continent, and ends in the northern Victoria Land (NVL). The Cambrian sedimentary successions in NVL were formed in association with subduction of the paleo-Pacific plate under the Antarctic continent, and represented by an accretionary complex of sedimentary rocks in three tectonic terranes: the Wilson, Bowers and Robertson Bay terranes, from inboard to outboard. The Bowers Supergroup of the Bowers Terrane is well-known for containing Cambrian trilobites which can be used for biostratigraphic correlation. The original Cambrian stratigraphy of the Bowers Terrane was established on the basis of the trilobites collected from five localities (Fig. 1) during 1974/75 and 1981/82 expeditions by the New Zealand Antarctic Research Programme (NZARP). Of the five localities, Edlin Neve and Mariner Glacier represent the northwest and the southeast end points, and are only about 200 km apart (Fig. 1). Nevertheless, the Cambrian stratigraphy of the area were interpreted to show a remarkable lateral facies variation (Fig. 2). Korea Polar Research Institute carried out four expedition to the northern Victorian Land from 2012/2013 season to 2015/2016 season, with setting up field camps at Mariner Glacier and Reilly Ridge. A detailed biostratigraphic researches in the area has revealed that the thick Spurs Formation at Mariner Glacier is due to stratigraphic repetitions by tectonic folds, and the Paibian aspect of the Spurs Formation at Reilly Ridge was due to misidentifications of some taxa. As a result, the revised Cambrian stratigraphy of the Bowers Terrance has become to show less lateral facies variation than the original version (Fig. 3). The remaining issues of the area include 1) the unusually thicker Molar Formation at Houliston Glacier; 2) the unreliable age of the Eureka Formation which occurs only at Marine Glacier, and; 3) the lower boundary of the Spurs Formation at Mariner Glacier which was covered by snow (Fig. 3).