Middle Triassic paleosols and paleoclimate of Antarctica



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Retallack, G.J. and Alonso-Zarza, Ana María (1998) Middle Triassic paleosols and paleoclimate of Antarctica. Journal of sedimentary research, 68 (1). pp. 169-184. ISSN 1527-1404

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Official URL: http://jsedres.geoscienceworld.org/


The Lashly Formation in the Allan Hills of southern Victoria
Land, Antarctica, is now at a latitude of 768S and during the
Middle Triassic was at least 708S. The combined evidence of fossil roots
and soils indicates a paleoclimate unusual for such a high latitude.
Temperate paleotemperature is indicated by roots, logs, and leaves of
woody plants and the degree of chemical weathering and clay formation
within the paleosols. Paleosols of the Lashly Formation are more
like soils of southern Sweden than those of either Finland or southern
Europe. Silt infiltration structures around root traces and in cracks
within the paleosols are evidence for a seasonally snowy climate, but
there is no evidence of ice wedges or other permafrost features in the
paleosols. Other evidence of climatic seasonality includes well-defined
growth rings in fossil wood, and abscission scars at the base of fossil
leaves. Diverse broadleaf plants, and noncalcareous paleosols, indicate
a humid climate with mean annual precipitation of about 1200 mm.
Such a wet climate is anomalous for the interior of the supercontinent
of Pangea, and such a warm and mildly seasonal climate is anomalous
for such high latitudes. This paleoclimatic anomaly may be a lingering
effect of global greenhouse initiated at the Permian–Triassic boundary.
Paleoclimatic variables calculated here may be useful for recalibrating
global paleoclimatic models for the middle Triassic

Item Type:Article
Uncontrolled Keywords:Paleosols, Paleoclimate, Antarctica
Subjects:Sciences > Geology > Stratigraphic geology
Sciences > Geology > Paleontology
ID Code:25328
Deposited On:08 May 2014 12:02
Last Modified:08 May 2014 12:02

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