T51 The Other Red Planet: Terrestrial Environments and Climates from the Permian and Triassic

Sunday, 25 September 2016
1:30 PM - 5:30 PM
Room 501

THE PERMIAN-TRIASSIC OF EASTERN COLORADO: REDBEDS, SLIME, SALT, DUNES, AND POSSIBLY AN EXTINCTION?

Paper number: T51-9
Program: Technical Sessions
Time: 3:30 PM – 3:45 PM

Authors

Abstract

The Lykins Formation and its equivalents in Colorado, a suite of redbeds and intercalated stromatolitic carbonates, are hypothesized to span the Permian-Triassic Boundary (PTB). To refine understanding of the age and depositional history of these strata, we logged sixteen reference sections through the Lykins and its equivalents, and here present a preliminary chemostratigraphy, detrital zircon geochronology, biostratigraphy and environmental framework for exposures along the Front Range and in southeastern Colorado.

Conodonts, together with other vertebrate, invertebrate, microfossil, and trace fossils, suggest a very shallow to emergent marine origin for the unit’s most substantial carbonates and intercalated gypsum-anhydrite members. Conodonts from the lower Lykins Formation indicate Middle Permian (Guadalupian) deposition for the lower portion of the Lykins. δ13C and 87Sr/86Sr stratigraphy through the unit is internally consistent with deposition of the Lykins across the PTB interval. Youngest concordant detrital zircons do not exclude deposition of the uppermost Lykins Formation during a portion of Early Triassic time. Detrital zircons from the uppermost Lykins and an overlying eolianite unit consist of a complex and highly diverse primary and multi-cycle grain population transported from eastern Laurentia. They include Appalachian, Grenvillian, and Gondwanan terrane signatures, and transport modes that include wind and water. Conodont alteration indices of 1 indicate the unit has a shallow burial history and is amenable to paleomagnetic inquiry. Considered together, these data help better frame the Lykins and its equivalents, providing a springboard for understanding their records of Permian-Triassic events.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-287701

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