Tectonomorphic evolution of Marie Byrd Land – Implications for Cenozoic rifting activity and onset of West Antarctic glaciation

• Published in: Global and Planetary Change
• Main Authors: Spiegel, Cornelia, Lindow, Julia, Kamp, Peter J.J., Meisel, Ove, Mukasa, Samuel, Lisker, Frank, Kuhn, Gerhard, Gohl, Karsten
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2016
• Subjects: Antarctic; Bellingshausen Sea; Byrd; Island Bay; Marie Byrd Land; Pine Island Bay; Pine Island Glacier; Ross Sea; West Antarctic Ice Sheet; Antarc*; Ice Sheet
• Online Access: https://oceanrep.geomar.de/id/eprint/44598/; https://oceanrep.geomar.de/id/eprint/44598/1/Spiegel.pdf; https://doi.org/10.1016/j.gloplacha.2016.08.013

Highlights • First fission track and (U-Th-Sm)/He data from eastern Marie Byrd Land • First direct dating of Cenozoic WARS activity outside the Ross Sea area • Structural model kinematically linking areas of extended crust within the WARS • Data on paleotopographic evolution providing boundary conditions for glaciation Abstract The West Antarctic Rift System is one of the largest continental rifts on Earth. Because it is obscured by the West Antarctic Ice Sheet, its evolution is still poorly understood. Here we present the first low-temperature thermochronology data from eastern Marie Byrd Land, an area that stretches ~ 1000 km along the rift system, in order to shed light on its development. Furthermore, we petrographically analysed glacially transported detritus deposited in the marine realm, offshore Marie Byrd Land, to augment the data available from the limited terrestrial exposures. Our data provide information about the subglacial geology, and the tectonic and morphologic history of the rift system. Dominant lithologies of coastal Marie Byrd Land are igneous rocks that intruded (presumably early Paleozoic) low-grade meta-sedimentary rocks. No evidence was found for un-metamorphosed sedimentary rocks exposed beneath the ice. According to the thermochronology data, rifting occurred in two episodes. The earlier occurred between ~ 100 and 60 Ma and led to widespread tectonic denudation and block faulting over large areas of Marie Byrd Land. The later episode started during the Early Oligocene and was confined to western Pine Island Bay area. This Oligocene tectonic activity may be linked kinematically to previously described rift structures reaching into Bellingshausen Sea and beneath Pine Island Glacier, all assumed to be of Cenozoic age. However, our data provide the first direct evidence for Cenozoic tectonic activity along the rift system outside the Ross Sea area. Furthermore, we tentatively suggest that uplift of the Marie Byrd Land dome only started at ~ 20 Ma; that is, nearly 10 Ma later than ...