PHOTOGRAMMETRY OF BIOHERM EXPRESSION AND ITS INFLUENCE ON PENNSYLVANIAN CYCLOSTRATIGRAPHY, PARADOX BASIN, UTAH
Paradox Formation bioherms range in size from 3 to 18 meters tall and 22 to 192 meters long. Average bioherm height is greatest in thickest cycles, however, the differential height relative to the containing bed is greatest within thin cycles. The predominant mound building biota (Chataetes and stromatolites) are laterally consistent within particular sequences, with some intervals dominated by Chaetetes and others by stromatolites. Bioherms containing Chaetetes are thicker than those without and stromatolitic bioherms are often longer with a lower amplitude. Bioherm occurrence appears to be distributed across the paleo-seafloor. Bioherm-generated paleobathymetry impacts overlying cycles via: 1) paleobathymetric highs formed by bioherms may serve as a nucleation site for later bioherms; and 2) bioherms from underlying sequences were causing progradational geometries in overlying units.
Sequences in the lower Paradox Formation cycles thicken up section, corresponding to an increase in apparent depositional duration. Thinner Barker Creek interval sequences reflect apparent durations between 100 – 350 ky, while thicker, overlying Akah intervals reflect longer durations from 200 ky to 1 My. Absent tuning, U-Pb and biostratigraphy suggest that Pennsylvanian sea level change is coherent across multiple locations across Laurasia, though local signals are also present.