Neogene and Quaternary quantitative palynostratigraphy and paleoclimatology from sections in Yukon and adjacent Northwest Territories and Alaska

Abstract

A quantitative pollen and spore zonation for the Neogene and Quaternary of Yukon, western Northwest Territories and central and northern Alaska has been assembled from seven sections and one borehole. The palynological spectra from 163 samples from these sections were grouped and averaged within the groups to produce twenty-one composite spectra that depict the long-term pattern of vegetation change. The oldest record included in the study is estimated to be within the late Early Miocene (ca. 18.3 Ma) and the record extends to the late Quaternary. Pollen and spores are grouped and summed by environmental tolerances and physiognomy of the modern families and genera of plants to which they are related. Using these groups, pollen and spore ratios are drawn to track environmental parameters - temperature, forest canopy cover, and paludification of the study sites. Biostratigraphic and paleoecological patterns are explained in terms of known changes in global climate and the climatic effects of regional tectonics. Six assemblage zones and five subzones are proposed to describe the palynological succession.

Pliocene palaeoceanography of the Arctic Ocean and subarctic seas

“…Superimposed on the long-term cooling since the Mid-Miocene (e.g. White et al 1997White et al , 1999Bezrukova et al 1999;Demske et al 2000), distinct excursions to warmer climates structured this relatively short geological epoch in the Arctic region (Matthews & Ovenden 1990;Brigham-Grette & Carter 1992;Cronin et al 1993;Funder et al 2001;Elias et al 2006). A relatively warm Early Pliocene with small-scale glaciations was succeeded by a progressive intensification in the Mid-Pliocene, leading to the build-up of large ice sheets in North America and Eurasia (e.g.…”

Phylogeny, biogeography, and diversification of barn owls (Aves: Strigiformes)

“…A considerable change in both climate and environment during in this time (e.g. Bezrukova et al ., ; White et al ., ; Demske, Mohr & Oberhansli, ). Indeed, during the warmer period of the Miocene, an early representative of this eastern branch reached Alaska and founded a lineage that spread all the way to Patagonia.…”

A new whitefish from the early Quaternary of Bluefish Basin, Yukon Territory, Canada, and its paleoenvironmental implications

“…The palynology at the base of unit 3 indicates a shrub-tundra environment, with conditions similar to those today at or near the tree line. White et al (1999) noted that boreal forest and tundra floristic elements were in place in the region by 2.3 Ma and pine was becoming scarce. Fission-track and paleomagnetic data (Froese et al 2000;Westgate et al 2003) reinforce that pine was abundant in the region until *3 Ma and seems to be largely absent by the early Pleistocene.…”