Miocene glaciomarine sedimentation in the northern Antarctic Peninsula region: the stratigraphy and sedimentology of the Hobbs Glacier Formation, James Ross Island

Abstract

The onshore record of Cenozoic glaciation in the Antarctic Peninsula region is limited to a number of isolated localities on Alexander Island, the South Shetland Islands and in the James Ross Island area. In the James Ross Island area, Late Cretaceous sedimentary rocks are unconformably overlain by a unit of diamictites and tuffs, which occur at the base of the James Ross Island Volcanic Group. These rocks are here defined as the Hobbs Glacier Formation, and on the basis of palynological studies are assigned to a Miocene (?late Miocene) age. The diamictites are interpreted as representing glaciomarine sedimentation close to the grounding line of either a floating ice shelf or a grounded tidewater glacier in a marine basin. Provenance studies indicate that the glacier was flowing from the Antarctic Peninsula towards the southeast. Volcanic tuffs conformably overlie the diamictites and are interpreted as representing deposition in a periglacial delta front setting in either a marine or non-marine basin, away from direct glacial influence. The Hobbs Glacier Formation and overlying James Ross Island Volcanic Group help to enhance our understanding of the Neogene glacial chronology of West Antarctica.

Late Cenozoic Foraminifera from Diamictites of Cape Lamb, Vega Island, Antarctic Peninsula

“…Later, Gaździcki and Webb (1996) re-examined this microfauna, increased the number of taxa and added information on paleoenvironmental interpretations. microfossils and bryozoans were also found on James ross Island in diamictites of the late miocene hobbs Glacier Formation at hamilton Cape and rabot Point (Pirrie et al, 1997). This assemblage was detailed by Bertels-Psotka et al (2001) and Concheyro et al (2007).…”

“…Later, formal lithostratigraphic considerations were provided by Pirrie et al (1997) and Lirio et al (2003), and hence they proposed different interpretations for these deposits according to the different lithofacies.…”

Fossil proxies of near-shore sea surface temperatures and seasonality from the late Neogene Antarctic shelf

“…There is, however, evidence for periods of warmth (4.6 to 3. (Pirrie et al 1997;Smellie et al 2006;N vlt et al 2011), Larsemann Hills: (Webb 1974;Quilty et al 1990;McMinn and Harwood 1995), Vestfold Hills: (Colhoun et al 2010;Quilty et al 2000;Whitehead et al 2001;Whitehead et al 2004;Whitehead et al 2006b), Wright Valley: (Prentice et al 1993), McMurdo Sound: (Eggers 1979;Leckie and Webb 1979) Fig 3 Stratigraphic setting of late Neogene successions that yield shallow marine fossils.…”

Insight into the latest Messinian (5.7–5.2Ma) palaeoclimatic events from two deep-sea Atlantic Ocean ODP Sites

“…Evidence from Antarctica currently suffers from dating uncertainties, but terrestrial outcrops are available from this period. These are of great (Jonkers et al, 2002), (Pirrie et al, 1997) (Smellie et al, 2006), (Hambrey et al, 2008) (Smellie et al, 2008). In the Northern Hemisphere, in addition to long marine sequences recovered through ODP drilling (Jansen and Sjoholm, 1991) (Larsen et al, 1994),the best exposed outcrop repository of late Cenozoic glaciomarine rocks is the Yakataga Formation (Gulf of Alaska), which dates the earliest marine tidewater glacier incursions to no older than the late Miocene (Lagoe et al, 1993).…”