Oligocene and Pliocene interglacial events in the Antarctic Peninsula dated using strontium isotope stratigraphy

Abstract

Strontium isotope stratigraphy is used to date two interglacial-marine deposits in the Antarctic Peninsula region. On King George Island, interglacial pectinid-rich sediments in the Low Head Member of the Polonez Cove Formation give a strontium isotope stratigraphy age of 29.0 +0.7 0.6 to 29.8 +0.8 0.7 Ma (mid-Oligocene), which, in conjunction with previous K-Ar dating of volcanic rocks, indicates a glacial episode in the Antarctic Peninsula between middle Eocene (42.0 1.0 Ma) and mid-Oligocene time. In addition, an inter-glacial deposit (Pecten Conglomerate) from tectonically-elevated exposures on Cockburn Island is dated as Pliocene (3.5-5.3 Ma). Published data suggest these latter sediments were deposited under shallow marine conditions, which were warmer than those of present-day Antarctica.

Molecular evidence for genetic subdivision of Antarctic krill (Euphausia superba Dana) populations

“…This would mean that E. superba may have experienced remarkable demographic £uctuation over a period ranging between 16 000 and 324 000 years ago, from which the extant krill population is still recovering. Glaciological studies have reported signi¢cant £uctuations in the ice volume during the late Pliocene (which may be due to climate change) on a time-scale in the range of 23 000^400 000 years ago (Dingle et al 1997). Although the impact of these events on marine fauna remains speculative, the present data support the possibility of a link between climatic changes and biomass £uctuation of E. superba.…”

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

“…4.9 Ma for the CIF (Jonkers and Kelley 1998). Ages determined using mean Sr isotope ratios from Dingle et al (1997); based on Howarth and McArthur (1997) and Sr isotope ratios from bivalve shells ) suggest a depositional age of 4.7 (+0.6/ −1.2) and 4.66 (+0.17/−0.24) Ma respectively (Pirrie et al 2011). These ages are stratigraphically consistent with the 40 Ar/ 39 Ar age of the underlying volcanic rocks.…”

Geochemical Characteristics and Paleoenvironmental Signi cance of the Ordovician Paleokarst Reservoir in the Maigaiti Slope of Tarim Basin

“…Because of the unique nature of the Sr isotope, it is widely applied in such fields as marine stratigraphic dating (Dingle et al, 1997;Denison et al, 1998), global geological event comparisons (Crame et al, 1999;Jiang et al, 2001), diagenesis fluid research (Huang et al, 2004;Roger et al, 2004), and paleoclimatic and ancient marine environmental analyses (Huang et al, 2002;Shi et al, 2005;Liu and Ji 2008). However, the application of the Sr isotope in the study of paleokarst reservoirs is a new concept.…”