Carbon isotope signals, especially when recorded in multiple localities, are often interpreted as perturbations to the global carbon cycle. However, sometimes local processes can distort or overprint these global signals. Here I investigate whether paleoenvironmental changes affected the expression of the Cambrian SPICE event across several Appalachian sections.

Using localities in Virginia and Maryland, I documented three new occurrences of the SPICE event and carefully logged their sedimentological and fossil trends. We noticed that the SPICE event did not seem to correlate with known regional sea-level changes, but fossil patterns might. Two of the sections experienced a dramatic shallowing near the beginning of the SPICE and remained shallow throughout the rest of the section, and thin section point count data shows a decrease in fossil material that parallels this trend. In another section, however, sea level drops but deepens again towards the end of SPICE. Fossils are more abundant before and after the sea-level low. 

Many SPICE sections from Laurentia have quartz sand within them that is thought to reflect this regional sea-level regression. An interesting finding from our study was that in our particular basin, quartz sand deposition seems to be asynchronous, appearing in each section at different times due to basin geometry.

Look out for this paper coming soon!