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Article Dans Une Revue Geology Année : 2021

Ice-crystal traces imply ephemeral freezing in early Permian equatorial Pangea

Résumé

Abstract Delicate impressions in lacustrine strata of the lower Permian (lower Cisuralian) Usclas Formation record ephemeral freezing in equatorial Pangea. These sediments accumulated in the paleoequatorial and intramontane Lodève Basin (southern Massif Central, France) during peak icehouse conditions of the Late Paleozoic Ice Age. Experimental replication of these features supports the interpretation that they are ice-crystal molds. Evidence for films of ice in marginal-lacustrine sediment at such low latitudes and inferred low to moderate altitudes (1–2 km) calls for a reevaluation of climate conditions in eastern equatorial Pangea. Ephemeral freezing implies either cold tropical temperatures (~5 °C cooler than the Last Glacial Maximum) and/or lapse rates that exceeded those of the Last Glacial Maximum. Extreme continentality of the Lodève Basin would have amplified seasonality, albeit the climatic forcing(s) necessary to have promoted cold temperatures in equatorial Pangea remain enigmatic.

Domaines

Climatologie
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Origine : Publication financée par une institution

Dates et versions

hal-03414901 , version 1 (09-12-2021)

Identifiants

Citer

Lily Pfeifer, Brooke Birkett, Jean van den Driessche, Stéphane Pochat, Gerilyn Soreghan. Ice-crystal traces imply ephemeral freezing in early Permian equatorial Pangea. Geology, 2021, 49 (11), pp.1397-1401. ⟨10.1130/G49011.1⟩. ⟨hal-03414901⟩
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