SEDIMENTOLOGY AND STRATIGRAPHY OF HIGH-LATITUDE, SHELF-EDGE AND SLOPE, GLACIGENIC DEPOSITS FROM THE LATE PALEOZOIC ICE AGE IN THE TEPUEL BASIN, PATAGONIA, ARGENTINA

The Late Paleozoic Ice Age (LPIA) was the longest lived ice age of the Phanerozoic lasting ~87 million years. The emerging view of the LPIA is that of multiple, small ice sheets that advanced and retreated with alternating glacial and nonglacial cycles across polar and mid-latitude regions of Gondwana. The size, timing, and number of ice sheets are still debated. Much of the near-field record of this ice age is derived from composite records obtained from widely-spaced outcrops across Gondwana with the South Polar record coming mainly from Antarctica, which contains only a Permian record. Therefore, our understanding of the LPIA is incomplete. What is needed is a complete, polar archive from a glaciomarine setting, which preserves a high-fidelity stratal record. The Tepuel Basin (Patagonia, Argentina) is ideal for such a study as it contains a 5000+ m thick Carboniferous to Middle Permian record deposited in a shallow to deep marine, rapidly subsiding, tectonically active basin located within the South Polar Circle throughout much of the LPIA. We studied strata deposited in glacially-influenced outer shelf, shelf-slope break, and basinal slope settings and identified large-scale synsedimentary thrust-faulted diamictites and lonestone-bearing sandstones; coarsening-upward, lonestone-bearing mudstone to wave-rippled cross-laminated successions lacking hummocky cross-stratification; deformed sandstones containing large load structures (T/L= 10x100 m); large (T/L= 10x100 m) slide and slump blocks; and thick (100+ m thick) fossil-bearing mudrock successions. These deposits are interpreted as glacially-shoved ice-proximal deposits; wave-dominated shoreface deposits shielded from winter storms by the occurrence of sea ice; seismically deformed sandstones; mass-transport complexes deposited on the basinal slope; and thick slope and basinal muds. These deposits provide an unparalleled view of a tectonically active basin within the South Polar Circle.