--> Abstract: Neoproterozoic Paleogeography and Paleoclimate Implications from the Red Pine Shale, Uinta Mountains, Utah; #90063 (2007)

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Neoproterozoic Paleogeography and Paleoclimate Implications from the Red Pine Shale, Uinta Mountains, Utah

 

Myer, Caroline A.1, Carol M. Dehler1 (1) Utah State University, Logan, UT

 

The Red Pine Shale, Uinta Mountain Group, (625 to >1200 m thick) is an organic-rich sedimentary succession that indicates a south-trending marine deltaic system in the Uinta Mountain area of Utah at ~750 Ma. C-isotope record indicates a fluctuating carbon cycle and possibly changes in regional climate.

 

Six measured sections have been described (type section in northwestern part of range and Hades section in southwestern part of range) for facies analysis and were sampled for C-isotope and TOC analyses, and sandstone petrography. Five facies have been identified including: shale facies (distal prodelta), slump-fold facies (distal to proximal prodelta), concretion facies (distal to proximal prodelta), shale-and-sandstone facies (distal delta front), and sandstone facies (proximal delta front to delta plain). Concretions contain vase-shaped microfossils, which are used for correlation and the ~750 Ma age constraint.

 

Measured sections in the Hades area were correlated using marker beds and facies intervals. Correlations show a thinning of sandstone bodies southward, suggesting a delta system feeding the basin from the north. Correlations also indicate a minimum measured composite thickness of 880m, and a minimum mapped thickness of >1200m (basal contact not exposed). The type section is ~625m thick, the lower contact with the underlying formation of Hades Pass quartzite is seemingly gradational, and the upper contact is erosional. Correlation between the north and south flank allow a composite section that is about 1505m thick. This overall composite section shows several cycles of delta progradation.

 

Initial C-isotope values from the overall composite section range from -28.93 to -16.91 PDB (~3 to 20 m sample spacing) and display anomalies that have potential to be used as fingerprints for local and regional correlation, as well as potential climate proxies.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California