Abstract Detail

Paleobotanical Section

Cleveland, Claire [1], Hildebrand, Terri [2], MacLean, Johnny [3], Hargrave, Jennifer [4].

Insights into Late Quaternary Paleoenvironment of Northwestern Arizona.

Tufa is a soft, porous deposit of calcite, aragonite, or ikaite that forms in sub-aerial, alkaline, cool-water regimes frequently associated with proximal sources of calcitic limestone. Due to the nature and process of deposition, these deposits offer the potential to serve as sedimentary signatures of hydrology, climate, ecology, and biodiversity in areas that otherwise may lack such historic archives. This study investigated a previously undocumented tufa site located in the northwestern corner of Arizona using research methods that included field surveys and mapping, x-ray diffraction, thin section analysis, and fossil identification. Exposed beneath a Mojave Desert biome currently dominated by shrub and cacti diversity, the wedge-shaped tufa deposit revealed a distinctly different past. Through mapping and stratigraphic correlation, our results suggested the age of the deposit is late Pleistocene to early Holocene, concurrent with numerous documented lacustrine deposits that occur in the Basin and Range Province. X-ray diffraction and petromicrographs confirmed nearly pure calcitic tufa morphology indicative of a springhead, possibly related to a currently active, albeit distant, local spring. Associated leaf, bark, and root molds were identified as deciduous woody species closely resembling Betula occidentalis and may include coniferous species as well. In addition, a dense understory of tubular fossils suggestive of Equisetum sp. (scouring rush), Typha sp. (cattail), and Juncus/Spircus sp. (rushes) all support a diverse environment distinct from that observed today. In addition, a gastropod fossil and what may represent impressions of lignified xylem cells were recently discovered in petromicrograhs and these are currently under investigation. As research continues on the northwestern Arizona site, we anticipate refinement of our results will provide a more complete description of this unique paleoenvironment, particularly its correlation with similar tufa sites in the Basin and Range. Furthermore, our study may provide insights into southwestern desert ecological patterns and processes observed today.

Broader Impacts:

1 - 246 S 800 W, Cedar City, UT, 84720, USA
2 - Southern Utah University, Biology, 351 W University Boulevard, Center for Health & Molecular Sciences 213, Cedar City, UT, 84720, USA
3 - Southern Utah University, Physical Sciences, 351 W University Boulevard, Cedar City, UT, 84720, United States
4 - Southern Utah University, 351 W University Boulevard, Cedar City, UT, 84720, United States

Keywords:
paleoenvironment
tufa deposit
desert biome
fossil.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PPB003
Abstract ID:303
Candidate for Awards:None