292-11 Investigating Seasonal Shifts in Western Interior Basin (Utah) Climates During the Mid-Cretaceous

Session: New Advances in Mesozoic Paleontology, Stratigraphy, and Paleogeography of the Western Interior of North America (Part I)

Presenting Author:

Adam Moore

Authors:

Moore, Adam V.¹, Hyland, Ethan G.², Gates, Terry A.³, Zanno, Lindsay E.⁴, Burgener, Landon K.⁵r> (1) North Carolina State University, Marine, Earth & Atmospheric Sciences, Clayton, NC, USA, (2) North Carolina State University, Marine, Earth & Atmospheric Sciences, Raleigh, NC, USA, (3) North Carolina State University, Biological Sciences, Raleigh, NC, USA, (4) North Carolina Museum of Natural Sciences, Paleontology, Raleigh, NC, USA; North Carolina State University, Biological Sciences, Raleigh, NC, USA, (5) Brigham Young University, Geological Sciences, Provo, UT, USA,

Abstract:

Investigating seasonal temperature and precipitation paleoclimate trends associated with broader annual paleoclimate data is essential for understanding complete past temporal and spatial climate changes and their potential impacts on biodiversity. During the mid-Cretaceous, the upper Cedar Mountain, Naturita, and Straight Cliffs formations (~98-83 Ma) within a portion of the greater Western Interior Basin (WIB) in Utah, USA, underwent dynamic geological and environmental changes exacerbated, in part, by the regional transgression of the Western Interior Seaway (WIS) and continued uplift of the Sevier Orogeny. These formations capture terrestrial archives of the Cretaceous Thermal Maximum (KTM) and corresponding Ocean Anoxic Event 2 (OAE 2), as well as recorded regional dinosaur faunal turnover.

In order to more accurately determine the seasonal climatic shifts in these WIB formations, we examined B-horizon paleosol samples for geochemical (bulk) and carbonate clumped isotope (Δ₄₇) paleoclimate proxies through the utilization of a benchtop XRF and Dual Inlet Isotope Ratio Mass Spectrometry (DI-IRMS), respectively. Throughout these formations, the mean annual temperature (MAT) and mean annual precipitation (MAP) increased by ~4-8℃ and ~774-1,244 mm/yr, respectively, which indicates that the annual climate in Utah during the mid-Cretaceous was becoming warmer and wetter across the KTM. Seasonally, there was also an average decrease in the mean annual range in temperature (MART) of ~5℃, whereas summer extremes (temperatures during season of carbonate formation) increased by >15℃. This discrepancy is likely due to a shorter window in which carbonates formed as the MAP increased. Growing season precipitation (GSP) increased proportionally with MAP, and the ratio of GSP to MAP remained at ~75% over the studied interval. Furthermore, when examining samples of the same approximate age from multiple localities across a basinal transect, there are slight differences in the MAT, MART, GSP, and GSP/MAP values due to the proximity of the sample locality to the margin of the WIS. Overall, these data suggest that even though mid-Cretaceous Utah was becoming increasingly warm and wet (humid subtropical climate regime), seasonal climates in this region were becoming less extreme (MART) or remained approximately the same (GSP/MAP) through time.

Investigating Seasonal Shifts in Western Interior Basin (Utah) Climates During the Mid-Cretaceous

Description

Session Format: Oral

Presentation Date: 10/14/2026

Presentation Start Time: 10:30 AM

Presentation Room: CCC, Bluebird Ballroom 3A

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