REFINING THE SEQUENCE STRATIGRAPHY OF THE UNION FURNACE SECTION, PA: BUILDING A FRAMEWORK FOR HIGH RESOLUTION GEOCHEMISTRY

The Upper Ordovician Union Furnace section spans the Sandbian-Katian boundary, an interval of Earth’s history with proposed climatic cooling and changes to the global carbon cycle. These interpretations are based, in part, on geochemical datasets, one of which was generated from the Union Furnace section (stable carbon). The Union Furnace section also contains a detailed record of sea level change and a diverse assemblage of carbonate depositional facies. By building on previous sedimentological and sequence stratigraphic work for the Union Furnace section, we hope to establish a detailed framework for the interpretation of high-resolution (sub-meter) geochemical datasets. To accomplish this, we created a detailed measured section for 220 m of the Union Furnace exposure that includes the Loysburg, Hatter, Snyder, Linden Hall, Nealmont, Salona and lower Coburn Formations. We collected samples for petrographic, microfossil, and geochemical analysis. Unfortunately, the ~30 limestone samples dissolved for conodonts had yields insufficient for geochemical work (~5 elements/2 kg).

Based on our field observations, targeted petrographic work, and the foundation established by previous workers we were able to describe and characterize nine carbonate facies associations that represent a range of environments from peritidal to basinal and have applied those facies associations to our measured section. Now that the broad sedimentological framework has been further refined, our next step is to identify and characterize small, sub-meter scale cycles and generate high-resolution bulk carbonate carbon isotopic records for those cycles. Our hope is that those records will allow us to further explore potential relationships between geochemical trends, sea level, and environment.