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

Abstract

14The West Antarctic Rift System is one of the largest continental rifts on Earth. Because it is obscured 15 by the West Antarctic Ice Sheet, its evolution is still poorly understood. Here we present the first low-16 temperature thermochronology data from eastern Marie Byrd Land, an area that stretches ~1000 km 17 along the rift system, in order to shed light on its development. Furthermore, we petrographically 18 analysed glacially transported detritus deposited in the marine realm, offshore Marie Byrd Land, to 19 augment the data available from the limited terrestrial exposures. Our data provide information about 20 the subglacial geology, and the tectonic and morphologic history of the rift system. Dominant 21 lithologies of coastal Marie Byrd Land are igneous rocks that intruded (presumably early Paleozoic) 22 low-grade meta-sedimentary rocks. No evidence was found for un-metamorphosed sedimentary rocks 23 exposed beneath the ice. According to the thermochronology data, rifting occurred in two episodes. 24

Multianalytical provenance analysis of Eastern Ross Sea LGM till sediments (Antarctica): Petrography, geochronology, and thermochronology detrital data

“…Spiegel et al . [] found an early Miocene AFT age population from Hobbs Coast glaciomarine sediment and they interpreted this age population as the result of an enhanced Neogene denudation, implying that uplift and relief formation in eastern Marie Byrd Land also started at about 20 Ma. Our samples record slightly an older age population, except for one sample (32–27 core) that has a similar age peak (P2 in Table ).…”

“…This similarity could imply that source rocks which experienced a ∼20 Ma exhumation event and provided detritus to offshore sites in the Eastern Ross Sea are located in a region involved in the uplift of Marie Byrd Land Dome, supporting the hypothesis of Spiegel et al . []. However, a volcanic source for apatites yielding this age cannot be excluded, since volcanoes of similar age are present in the central Marie Byrd Land [ LeMasurier and Rex , ].…”

“…[]; 9: Lisker and Olesch []; 10: Mukasa and Dalziel []; 11: Spiegel et al . []; 12: Richard et al . []; 13: Yakymchuk et al .…”

“…Spiegel et al . [] provide zircon fission track data (108–80 Ma), AFT (93–28 Ma), and apatite (U‐Th)/He (128–5 Ma) data for the Hobbs Coast and eastern Marie Byrd Land.…”

Geothermal heat flux in the Amundsen Sea sector of West Antarctica: New insights from temperature measurements, depth to the bottom of the magnetic source estimation, and thermal modeling

“…Narrow-mode rifting may have occurred in the Cenozoic, synchronous with oceanic spreading in the Adare Trough located in the Ross Sea Sector of the WARS between 48 and 24 Ma [Cande et al, 2000;Luyendyk et al, 2003;Davey et al, 2016]. MMR is the recently postulated Mount Murphey Rift [Spiegel et al, 2016]. Narrow Cenozoic rifts such as the Pine Island Rift however have not been clearly identified beneath the continental shelf of the Amundsen Sea [Jordan et al, 2017] and the Transantarctic Mountain Range, which separates East Antarctica (EA) from West Antarctica (WA).…”