New Geochronological Age Constraint and Chemostratigraphy for Aptian Lacustrine Strata, Cedar Mountain Formation, Utah

Abstract The Early Cretaceous is an important time of transition in Earth history, marked by a succession oceanic anoxic events and carbon cycle perturbations that drove changes on land the ocean. need for more precise geochronologic constraints terrestrial sediments age record faunal floral transitions especially critical. Cedar Mountain Formation (CMF) continental lithostratigraphic unit hosts trove paleoclimate archives dinosaurian fossil localities. Determining timing deposition CMF strata has been ongoing effort many years. Here, we present new isotope chemostratigraphic data along with high‐precision radiometric ages to further constrain Ruby Ranch Member at unique locality referred as “Lake Carpenter,” where thick section dominantly lacustrine overlies fluvial‐overbank palustrine typical other outcrops. A bentonite bed near base provides one most yet determined within 115.92 ± 0.14 Ma via CA‐ID‐TIMS U‐Pb analysis zircons. trends indicate Lake Carpenter were deposited entirely late Aptian Stage. These provide step toward improving our understanding evolutionary events.