Detrital zircon age from the glacial and littoral deposit, Northern Victoria Land, Antarctica: Implications for the timing of magmatic activity of the Ross Orogeny on the Gondwana continental margin

Abstract

The Transantarctic Mountains across the central Antarctic continent are the Ross orogenic belt formed by westward subduction of the Paleo-Pacific underneath the East Gondwana active continent margin in the early Paleozoic. The sedimentary, deformation and metamorphism, and granitic magmatic intrusion in this stage represent the process of the Ross Orogeny. Due to the significant difference in age among the three elements mentioned above, there is no precise time defined on the Ross Orogeny. In this paper, detrital zircon U-Pb dating of gravel and sand samples from moraines and coastal sediments in the Inexpressible Island of Northern Victoria Land was carried out. The ages of four samples with different gravel diameters range from 2443 to 323 Ma and are mainly concentrated between 530~450 Ma, with a peak age of~485 Ma. Most of the zircons show oscillatory zoning in CL images and have Th/U ratios great than 0.1 (mainly>0.4), with REE characteristics indicating a magmatic origin. Therefore, these ages reflect the timing of magmatic activity in the provenance of the loose sediment samples. The age composition of detrital zircons is consistent with the age of magmatic intrusion, intracontinental deformation and depositional stratigraphy in the surrounding areas, suggesting that the magmatic activity in the Northern Victoria Land and its surrounding areas might have lasted up to 450 Ma in the intracontinental deformation stage, which may represent the end time of the Ross Orogeny. These results provide a new constraint for the tectonic evolution of the Ross Orogeny on the Gondwana continental margin.

Keywords

• ross orogeny
• detrital zircon
• subglacial geology
• northern victoria land
• antarctica