Paper No. 26
Presentation Time: 1:30 PM-5:30 PM
LITHOLOGY, PHYSICAL SEDIMENTARY STRUCTURES, AND TRACE FOSSILS OF THE PINELOG FORMATION, AND THEIR APPLICATIONS TO MAPPING IN THE BLUE RIDGE PROVINCE OF GEORGIA
The Pinelog Formation Quartzite is a low-grade metamorphosed quartz arenite that crops out near Jasper, Georgia. Its lithology, physical sedimentary structures, and trace fossils indicate that its sediments were initially deposited in a shallow, near-shore marine environment. The presence of trace fossils (Skolithos, Aulichnites) has been previously documented; however, this discovery was not examined in detail and the full implications of these fossils remained unresolved. Furthermore, despite information about the original depositional environment of the Pinelog Formation, its age and occurrence have not been clearly defined. Previous work has placed the Pinelog in the Precambrian, but vertically oriented trace fossils indicate the Pinelog is at least Cambrian in age. Samples of bedding and fossil burrows were collected from two different outcrops and burrow dimensions measured. These burrows are compared with examples of trace fossils from similar formations to determine if their classifications were appropriate. The mineral composition of each sample was analysed through thin-section point counts and mineral proportions were compared with quartzite formations from the Ocoee’s Snowbird Group and the Chilhowee Group to better determine the lithologic affinity of the Pinelog Formation. Locations of samples and associated features were mapped using ESRI’s ArcGIS software, which was used to aid in the prediction of other, previously unknown outcrops and determine the extent of features within each individual outcrop. Geospatial analyses revealed limited overlap between occurrences of bedding and trace fossils, suggesting significant bioturbation by burrowing organisms, which may have removed physical sedimentary structures in places. Such high amounts of bioturbation are more characteristic of the early Paleozoic, rather than the Precambrian, thus adding more circumstantial evidence supporting a Paleozoic origin for the Pinelog Formation.