Evidence for a marine incursion along the lower Colorado River corridor

摘要: Foraminiferal assemblages in the stratigraphically lower part of Bouse Formation Blythe basin (lower Colorado River corridor, western USA) indicate marine conditions, whereas upper lacustrine conditions and suggest presence a saline lake. Benthic foraminiferal are similar to lagoonal inner neritic biofacies modern Gulf California. Evidence suggesting change from includes highest occurrence planktic foraminifers at an elevation 123 m above sea level (asl), low diversity monospecific composed only Ammonia beccarii (between 110 126 asl), increase abundance A. specimens (above ∼110 increased number deformed tests ∼123 first appearance Chara (at ∼85 lowest reworked Cretaceous coccoliths m), decrease strontium isotopic values 70 120 δ 18 O 13 C seawater 100 asl). Planktic late Miocene age between 8.1 5.3 Ma for oldest southern basin. correlate with other sections proto–Gulf California that basal was deposited northern end this proto-gulf. After connection restricted or eliminated, flowed into basin, forming This lake supported assemblage until spilled Salton Trough became through-flowing river.