A multi-proxy approach to determine Antarctic terrestrial palaeoclimate during the Late Cretaceous and Early Tertiary

Abstract

Fossil wood is abundant throughout the Cretaceous and Tertiary sequences of the northern Antarctic Peninsula region. The fossil wood represents the remains of the vegetation that once grew at the southern high palaeolatitudes at 59-628S through the general decline in climate, from the Late Cretaceous global warmth through to the mid-Eocene cool period prior to the onset of glaciation. This study draws on the largest dataset ever compiled of Antarctic conifer and angiosperm woods in order to derive clearer insights into the palaeoclimate. Parameters including mean annual temperature, mean annual range in temperature, cold month mean, warm month mean, mean annual precipitation are recorded. The fossil wood assemblages have been analysed using anatomical (physiognomic) characteristics to determine the palaeoclimate variables from the Coniacian-Campanian to the middle Eocene. These results are compared with data derived from Coexistence Analysis of the fossil floras (composed of leaves, wood and palynomorphs) and published data based on leaf physiognomic characters. These studies indicate a relatively warm and wet Late Cretaceous that becomes drier and cooler in the Early Paleocene and subsequently returns to warmer, wetter conditions by the latest Early Paleocene. During the Eocene the climate becomes relatively cool and dry once again. The discrepancies obtained from these two methods coupled with other published data are discussed in the context of the fluctuations in the temperatures of the surrounding oceans and global patterns of climate change. D

Hydrothermal alteration and isotopic variations of igneous rocks in Barton Peninsula, King George Island, Antarctica

“…It is necessary, however, to consider paleoclimate data to estimate the isotope composition of meteoric water when the alteration took place. The mean annual temperature of King George Island during the Middle Eocene was generally between 12 o C and 13.3 o C (Poole et al, 2005), much higher than the present average -2.8 o C (Ferron et al, 2004). Thus, this suggests that the isotopic composition of meteoric water during the alteration process would have not been so low as that of the present time.…”

Snapshot of cooling and drying before onset of Antarctic Glaciation

“…Dallai and Burgess (2011) (Ivany et al, 2011). Fossil wood from the James Ross Basin and South Shetland find diverse mid-Eocene assemblages (Poole et al, 2005), with species similar those found on Seymour Island mid-Eocene sections (Askin, 1997). The pollen records from Seymour Island (La Meseta Formation) reveal a decline in plant diversity from the mid-late Eocene (Askin, 1997) with a loss of varied Nothofagus brassii group species (Chen, 2000).…”

100 Million Years of Antarctic Climate Evolution: Evidence from Fossil Plants

“…After the peak warmth of the mid-Late Cretaceous, climate appears to have cooled globally during the latest part of the Cretaceous, as seen also in the Antarctic fossil wood record (Francis and Poole, 2002;Poole et al, 2005). However, warm climates returned to the high latitudes during the Paleocene and early Eocene, as is reflected in fossil plants.…”