Establising a high-frequency standard reference sequence stratigraphy, sea-level curve, and biostratigraphy for Morrowan strata of the Lower Absaroka I time slice based upon the Bird Spring Formation, Arrow Canyon, Nevada
For the same reasons which prompted its ratification in 1990 as the Global Stratotype Section and Point for the Mid-Carboniferous boundary, namely, section completeness, abundant fossils, and excellent exposure, the Morrowan Arrow Canyon Bird Spring strata is recommended as a candidate standard sequence stratigraphic reference for the Morrowan portion of the Lower Absaroka I supersequence. The stratigraphic architecture of Morrowan strata in Arrow Canyon was largely controlled by high-amplitude (100-m), high-frequency sea-level changes. Outcrop data and facies stacking patterns define 59 fifth-order fundamental cycles. These fundamental cycles stack into ten third-order sequences with an average duration of 320 ka. Changes in both cycle thickness and fundamental cycle type indicate that the second-order sea-level curve of Golonka and Keissling for the Lower Absaroka Ia supersequence should be modified to reflect rising sea-level from the Mid-Carboniferous boundary with maximum flooding conditions ~120 to 135 meters above the Mid-Carboniferous boundary, followed by falling sea-level to ~6 meters below the Morrowan-Atokan boundary in Arrow Canyon. Additionally, cycle diagnostic conodonts and foraminifera permit correlation of selected third-order sequences to basins containing time-equivalent strata.
College and Department
Physical and Mathematical Sciences; Geological Sciences
BYU ScholarsArchive Citation
Briggs, Kristen Phelps, "Establising a high-frequency standard reference sequence stratigraphy, sea-level curve, and biostratigraphy for Morrowan strata of the Lower Absaroka I time slice based upon the Bird Spring Formation, Arrow Canyon, Nevada" (2005). Theses and Dissertations. 301.
cycle, sequence, second-order, sea level, Morrowan, Arrow Canyon, third-order, Bird Spring Formation, stratigraphy