T286 Evolution of Rocky Mountain Basins—Ancestral Rocky Mountains through the Laramide

Wednesday, 7 November 2018
1:30 PM - 5:30 PM
Sagamore Ballroom 7

HIGH-RESOLUTION MAGNETOSTRATIGRAPHY OF THE K-PG BOUNDARY INTERVAL, CORRAL BLUFFS, DENVER BASIN, COLORADO (USA)

Paper number: T286-10
Program: Technical Sessions
Time: 3:35 PM – 3:50 PM

Authors

Abstract

The Cretaceous-Paleogene (K-Pg) boundary interval represents one of the most significant periods of biological turnover in Earth history. The Laramide synorgenic sediments within the Denver Basin preserve one of the most continuous records of the K-Pg boundary interval in North America. However, poor exposure in much of the Denver Basin makes it difficult to correlate outcrops via surface exposure. In order to relate localities across the basin, previous studies have relied upon chronostratigraphic methods such as magnetostratigraphy. It is possible to relate contemporaneous outcrops using the patterns of paleomagnetic reversals corresponding to the Geomagnetic Polarity Timescale (GPTS). Most of the aforementioned magnetostratigraphic studies have been focused in the northern portion of the basin. Here we present a high-resolution magnetostratigraphy of 13 lithostratigraphic sections spanning the K-Pg boundary interval at Corral Bluffs located east of Colorado Springs. Fossil localities from Corral Bluffs have yielded limited dinosaur remains, mammal fossils assigned to the Puercan North America Land Mammal age, and numerous fossil leaf localities. Our paleomagnetic analysis has identified clear polarity reversal boundaries from Chron 30N to Chron 28N across the sections. The total thicknesses of C29R, C29N, and C28R have been determined and the K-Pg boundary has been identified in three of the sections based on palynological analysis. It is now possible to place the fossil localities at Corral Bluffs within the broader basin-wide chronostratigraphic framework and evaluate them in the context of K-Pg boundary extinction and recovery.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-320593

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