Late Neogene Sirius Group strata in Reedy Valley, Antarctica: a multiple-resolution record of climate, ice-sheet and sea-level events

Late Neogene Sirius Group strata from Tillite Spur and Quartz Hills in the Reedy Glacier area, Antarctica, demonstrate the variability in Sirius Group facies and contrasts Sirius Group strata deposited at high and low palco-e levation, respectively. The Tillite Spur and Quartz Hills Formations (Plioc ene) are formally defined here. The Tillite Spur Formation type section cro ps out on the edge of the Wisconsin Plateau overlooking Tillite Spur. It co mprises 32 m of alternating coarse gray conglomerate and muddy olive-brown diamictites. The Quartz Hills Formation type section crops out above the we stern margin of Reedy Glacier in a pre-existing cirque towards the southern end of the Quartz Hills. It comprises c. 100 m of alternating massive diam ictites and rhythmically interbedded sandstone and laminated mudstones whic h were deposited close to sea level and subsequently rapidly uplifted (>500 m Myr(-1)) to their present elevation at c. 1500 m. Three orders of paleoc limatic variability are recorded in the Sirius Group strata from Reedy Vall ey: (1) recycled marine microfloras in glacial diamictites indicate interva ls of marine incursion into the Antarctic cratonic interior co-occurring wi th reductions in the East Antarctic ice sheet; (2) an advancing and retreat ing paleo-Reedy Glacier deposited a glacial/interglacial sequence alternati ng on a 10-100 kyr scale; (3) Centimeter and millimeter stratification in s trata of the Quartz Hills Formation record annual kyr scale variability.