INVESTIGATING THE RELATIONSHIP OF MINERAL AND ORGANIC PHASES IN THE STROMATOLITIC FABRICS OF THE KNOX GROUP, NW GA

Stromatolitic fabrics are commonly associated with black chert deposits in Proterozoic peritidal environments. These chert deposits are interpreted to be early diagenetic and commonly contain well-preserved microfossils; however, chert deposition changed as silica-utilizing organisms evolved, and it is unclear whether similar deposits exist from the Cambrian. Stromatolites within the Copper Ridge Dolomite of the late-Cambrian Knox Group were recently collected near Chatsworth, Georgia. These stromatolites, which have only been briefly mentioned in previous literature in Georgia, are associated with large, discontinuous black chert nodules and the stromatolite fabrics include individual layers of black chert. Many of these samples have gently convex, wavy laminae. Columnar and cumulate fabrics are preserved in the samples that appear to be dolomite rich. However, unlike older samples, the chert in the Copper Ridge Dolomite does not preserve good examples of individual microfossils. Petrographic analysis suggests that preserved microfossils were altered during diagenesis. The research presented here investigates the mineralogy of these stromatolites in detail and attempts to establish a paragenetic sequence for the mineral phases preserved in these samples based on petrographic and geochemical techniques.