Southern high-latitude terrestrial climate change during the Palaeocene–Eocene derived from a marine pollen record (ODP Site 1172, East Tasman Plateau)

Abstract

Abstract. Reconstructing the early Palaeogene climate dynamics of terrestrial settings in the high southern latitudes is important to assess the role of high-latitude physical and biogeochemical processes in the global climate system. However, whereas a number of high-quality Palaeogene climate records has become available for the marine realm of the high southern latitudes over the recent past, the long-term evolution of coeval terrestrial climates and ecosystems is yet poorly known. We here explore the climate and vegetation dynamics on Tasmania from the middle Palaeocene to the early Eocene (60.7–54.2 Ma) based on a sporomorph record from Ocean Drilling Program (ODP) Site 1172 on the East Tasman Plateau. Our results show that three distinctly different vegetation types thrived on Tasmania under a high-precipitation regime during the middle Palaeocene to early Eocene, with each type representing different temperature conditions: (i) warm-temperate forests dominated by gymnosperms that were dominant during the middle and late Palaeocene (excluding the middle/late Palaeocene transition); (ii) cool-temperate forests dominated by southern beech (Nothofagus) and araucarians that transiently prevailed across the middle/late Palaeocene transition interval (~ 59.5 to ~ 59.0 Ma); and (iii) paratropical forests rich in ferns that were established during and in the wake of the Palaeocene–Eocene Thermal Maximum (PETM). The transient establishment of cool-temperate forests lacking any frost-sensitive elements (i.e. palms and cycads) across the middle/late Palaeocene transition interval indicates markedly cooler conditions, with the occurrence of frosts in winter, on Tasmania during that time. The integration of our sporomorph data with previously published TEX86-based sea-surface temperatures from ODP Site 1172 documents that the vegetation dynamics on Tasmania were closely linked with the temperature evolution in the Tasman sector of the Southwest Pacific region. Moreover, the comparison of our season-specific climate estimates for the sporomorph assemblages from ODP Site 1172 with the TEX86L- and TEX86H-based temperature data suggests a warm bias of both calibrations for the early Palaeogene of the high southern latitudes.

Surface-circulation change in the southwest Pacific Ocean across the Middle Eocene Climatic Optimum: inferences from dinoflagellate cysts and biomarker paleothermometry

“…Model simulations for the modern system indicate that a wind-driven strengthening and further southward extent of the EAC are expected under conditions of enhanced global warmth, as part of intensification of the southern midlatitude circulation (Cai et al, 2005). Similarly, SST anomaly reconstructions over the peak interglacial Marine Isotope Stage 5e (∼ 125 ka) indicate intensification of the EAC to offshore Tasmania (Cortese et al, 2013). Possibly a similar atmospheric and oceanographic response to global warming occurred during MECO.…”

Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

“…S. prominatus, closely related to pollen of the extant mangrove palm Nypa, is important for regional correlations as its first consistent appearance seems to be contemporaneous with the PETM on both sides of the Tasmanian Gateway (Contreras et al, 2014). Nypa is a thermophilic genus and requires mean annual temperatures above ∼ 22 • C (Utescher and Mosbrugger, 2015).…”

“…Both marine (Bijl et al, 2009;Hollis et al, 2009) and terrestrial (Carpenter et al, 2012;Contreras et al, 2014;Macphail et al, 1994) temperature proxy records suggest that the midlatitude to high-latitude southwest Pacific was extremely warm (25-35 • C) during the warmest intervals of the late Paleocene, Paleocene-Eocene Thermal Maximum (PETM; 56 Ma) and early Eocene, yielding a substantial mismatch between proxy data and climate-model output for this region that is yet unresolved (Hollis et al, 2012). The anomalously high temperatures may have partly resulted from large-scale tectonic changes such as the opening of the Tasmanian Gateway, and it has been hypothesized that this gateway played an important role in diverting ocean currents and influencing climate on a regional scale (Bijl et al, 2013a;Sijp et al, 2016Sijp et al, , 2014Sijp et al, , 2011 and beyond (e.g., Kennett, 1977).…”

Record of Early to Middle Eocene paleoenvironmental changes from lignite mines, western India

“…The Early Eocene sections from Tasmania, Tanzania, Africa and Egypt have exhibited a tropical mangrove forest domination (Contreras et al, 2014). Similarly, the Early Eocene sections of the Cambay and Barmer basins in India also indicate an overall domination of mangrove vegetation (Arecaceae, Bombacaceae groups; refer to Figs.…”