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Abstract

The Jarlsbergian unconformity at the Late Proterozoic-Early Cambrian boundary, is expressed in the Hecla Hoek Succession of South Spitsbergen as a regional low-angle unconformity, the result of folding and subsequent erosion of the Late Precambrian Jarlsbergian Basin deposits. The unconformity pre-dates the Bonnia-Olenellus trilobite zone; the sedimentary hiatus covers the lowest Cambrian Fallotaspis and Nevadella trilobite zones, and a closer undefined uppermost part of the Late Proterozoic. There are no Varangian (latest Proterozoic) tillites present in south Spitsbergen at the top of the Late Proterozoic metasediment column which is represented by the Gashamna Formation phyllites and associated rocks.

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Authors and Affiliations

Krzysztof Birkenmajer
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Abstract

There are two important unconformities in the Calypsostranda Group (late Palaeogene) at Bellsund, Spitsbergen. The first one is the basal angular unconformity of the Skilvika Formation against folded and planated Proterozoic metasediments: the author provides evidence for its primary sedimentary character. The second one is an intraformational erosional disconformity/discontinuity expressed by rapid replacement of coal-bearing terrestrial strata (Skilvika Formation) by shallow-marine strata (Renarddodden Formation).

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Authors and Affiliations

Krzysztof Birkenmajer
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Abstract

Stacks of the Pleistocene tills and associated airfall/slopewash/colluvial sediment abound on East African Mountains but few localities exist where thick deposits of middle to Late Pleistocene age can be studied to bedrock with topography the main soil-forming agent over <0.8 Ma. Two tills form the main structure of the catena, the oldest buried in the crest, backslope and footslope of the deposit, the youngest forming the crest and upper backslope, with massive colluvial infill forming a still younger sediment mass superposed on older sediment in the lower backslope, footslope and toeslope, the latter all radiocarbon dated to within the last glaciation (Liki on Mt. Kenya; Weichselian in Europe, Wisconsin in North America). The moraine stack, first identified by J.W. Gregory in the late 19th century, as belonging to the ‘Older Glaciation’ (Illinoian in North America; Teleki on Mt. Kenya), is much older than originally thought with tills and other paraglacial sediment extending to saprolitic bedrock, paleomagnetic assessment and relative weathering indices placing the mass in the Brunhes Chron. These results demonstrate that despite erosion and weathering, paleosols in toposequences near the margins of successive glaciations retain properties allowing reconstruction of environmental changes over long periods of time.
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Authors and Affiliations

William C. Mahaney
1
Ronald G.V. Hancock
2

  1. Quaternary Surveys, 26 Thornhill Ave., Thornhill, Ontario, Canada, L4J1J4 and Department of Geography, York University, 4700 Keele St. N. York, Ontario, Canada, M3J 1P3
  2. Department of Anthropology, McMaster University, Hamilton, Ontario, Canada, L8S 4K1

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