Mostrar 55 resultados

As part of a multidisciplinary team led by Grant Zazula (then a Ph.D. student at Simon Fraser University; later a palaeontologist with the Government of Yukon) and Duane Froese (Professor, University of Alberta), Dr. Paul Sanborn examined a set of buried paleosols (fossil soils) preserved in frozen sediments exposed by placer mining in the spring of 2004.

The findings were published in:
Zazula, G.D., D.G. Froese, S.A. Elias, S. Kuzmina, C. La Farge, A.V. Reyes, P.T. Sanborn, C.E. Schweger, C.A.S. Smith, and R.W. Mathewes. 2006. Vegetation buried under Dawson tephra (25,300 14C yr BP) and locally diverse late Pleistocene paleoenvironments of Goldbottom Creek, Yukon, Canada. Palaeogeography, Palaeoclimatology, Palaeoecology 242: 253–286. https://doi.org/10.1016/j.palaeo.2006.06.005

The eastern flank of the Mackenzie Mountains has a complex history of multiple glaciations by both the Laurentide and Cordilleran ice sheets, recorded in thick sequences of glacial sediments that were documented at 3 locations (Katherine Creek, Little Bear River, Inlin Brook) by:
Duk-Rodkin, A., R.W. Barendregt, C. Tarnocai, and F.M. Phillips. 1996. Late Tertiary to late Quaternary record in the Mackenzie Mountains, Northwest Territories, Canada: stratigraphy, paleosols, paleomagnetism, and chlorine-36. Canadian Journal of Earth Sciences 33 (6): 875-895. https://doi.org/10.1139/e96-066

Of the 3 sites, the exposure on Inlin Brook, a tributary of the Keele River, was the least well-documented, so in summer 2004 Dr. Paul Sanborn joined a field party of the Geological Survey of Canada (GSC) based at Tulita, NWT, and was given helicopter support to visit Inlin Brook (August 5-8). A brief visit was also made to the Little Bear River site.

On August 9-10, Sanborn joined Alejandra Duk-Rodkin (GSC) and Rene Barendregt (U Lethbridge) in helicopter-assisted field work at sites in the Franklin Mountains and elsewhere east of the Mackenzie River.

The Lost Chicken Mine, a placer gold mine in eastern Alaska, approximately 120 km west of Dawson City, Yukon, is an important fossil locality for the late Pliocene (approximately 2.5 – 3.0 million years ago). A comprehensive account of the stratigraphy and paleontology of this site was given by:
Matthews, J.V., Jr., J.A. Westgate, L. Ovenden, L.D. Carter, and T. Fouch. 2003. Stratigraphy, fossils, and age of sediments at the upper pit of the Lost Chicken gold mine: new information on the late Pliocene environment of east central Alaska. Quaternary Research 60: 9-18. https://doi.org/10.1016/S0033-5894(03)00087-5

Dr. Paul Sanborn visited the site on July 20, 2004, as part of a group led by Duane Froese (Professor, University of Alberta). The group concentrated on a single exposure (~ 2 m thick) straddling the Lost Chicken tephra, a volcanic ash bed (2.9 ± 0.4 myr) which is a major stratigraphic marker at the site. Sanborn described, photographed, and sampled this exposure, and obtained a basic set of characterization data. Intact samples were collected but thin sections were never produced.