MIDDLE TRIASSIC PALEOSOLS AND PALEOCLIMATE OF ANTARCTICA

The Lashly Formation in the Allan Hills of southern Victoria Land, Ant arctica, is now at a latitude of 76 degrees S and during the Middle Tr iassic was at least 70 degrees S, The combined evidence of fossil root s 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 Eur ope, Silt infiltration structures around root traces and in cracks wit hin the paleosols are evidence for a seasonally snowy climate, but the re is no evidence of ice wedges or other permafrost features in the pa leosols, Other evidence of climatic seasonality includes well-defined growth rings in fossil wood, and abscission scars at the base of fossi l leaves, Diverse broadleaf plants, and noncalcareous paleosols, indic ate a humid climate with mean annual precipitation of about 1200 mm, S uch a wet climate is anomalous for the interior of the supercontinent of Pangea, and such a warm and mildly seasonal climate is anomalous fo r such high latitudes. This paleoclimatic anomaly may be a lingering e ffect of global greenhouse initiated at the Permian-Triassic boundary, Paleoclimatic variables calculated here may be useful for recalibrati ng global paleoclimatic models for the middle Triassic.