INSIGHTS INTO THE LATE QUATERNARY PALEOENVIRONMENT OF NORTHWESTERN ARIZONA

摘要

Because of the nature and process of precipitation, tufa deposits offer the potential to serve as sedimentary signatures of hydrology, climate, ecology, and biodiversity in areas otherwise lacking such historic archives. This study investigated a previously undocumented tufa site located in northwestern Arizona. Field mapping, X-ray diffraction, and thin-section analyses revealed a wedge-shaped deposit of nearly pure calcitic tufa. Leaf and bark molds were identified as closely resembling water birch (Betula occidentalis) and conifer species as well. A dense understory of tubular fossils suggestive of horsetails (Equisetum) and other wetland species were also found. Biotic content, lack of ikaite, and proximity to pluvial lake systems strongly correlate the deposit's age with numerous lacustrine deposits in the region and possibly extend the lake system to the south.