Date of Award

Spring 2014

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Earth, Atmospheric, and Planetary Sciences

First Advisor

Kenneth Ridgway

Committee Member 1

Jonathan Harbor

Committee Member 2

Daniel Shepardson

Abstract

The sequence of sedimentary rocks at Acoma Pueblo, New Mexico, are important both in terms of their cultural significance for the Native people of Acoma Pueblo and the insight they provide into the long term geologic history of the Colorado Plateau. In this thesis we present the first stratigraphic and provenance analysis of the Mesozoic strata at Acoma Pueblo, New Mexico, based on field observations and detrital zircon U-Pb geochronology. Acoma Pueblo was located in the distal part (i.e. backbulge) of a foreland basin system during most of the Mesozoic. Acoma Pueblo has not been included in previous regional studies of the Colorado Plateau, which focused on proximal (i.e. foredeep) portions of the Cordilleran foreland basin system. However, field observations and detrital zircon U-Pb geochronology provide insight into how the sources of sediment for depositional environments at Acoma Pueblo changed throughout the Mid-Late Mesozoic as the Cordilleran foreland basin system evolved. The depositional environments of strata exposed at Acoma Pueblo, include aeolian dunes (Entrada Sandstone and Zuni Sandstone), lacustrine, fluvial playa (Morrison Formation), and shallow marine environments (Dakota Sandstone). Key provenance findings include: The end of sediment delivery from the East Mexico Magmatic Arc after Entrada time, an increase in Cordilleran Arc grains after Entrada time, an increase in Yavapai and Mazatzal age grains after Entrada time, and a more uniform distribution of zircon peak ages within the Dakota Sandstone. In addition to this western science geologic knowledge, this thesis also integrates the traditional cultural perspectives of a trained geologist who is a member of Acoma Pueblo. Thus, in describing/recognizing geologic formations we also draw on the cultural knowledge a tribal member has of the significance and value of the strata exposed at Acoma Pueblo.

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