Paper No. 5
Presentation Time: 9:00 AM-6:00 PM
SEDIMENTOLOGY AND CHEMICAL COMPOSITION OF THE SILURIAN BINNEWATER SANDSTONE, ULSTER COUNTY, NY
The Silurian Binnewater Sandstone (Sb), outcropping in Rosendale, N. Y., was studied in the field and in the laboratory using petrographic, sedimentological and X-Ray Fluorescence (XRF) techniques. The investigation focuses on the Taconic Highland, the probable source area for the sediments of the sandstone and the Acadian Orogeny, the major tectonic event affecting the sandstone and adjacent strata; it also considers provenance, sediment characteristics and diagenesis of the sandstone. Standard field tests including mineral identification, texture, degree of induration, and type of cementation were conducted. Primary sedimentary features, including asymmetrical ripple marks, interference ripple marks, low angle cross-bedding, and mud cracks were observed in the field. Sporadic distribution of ichnofaunal assemblages was very apparent in several horizons, suggesting a shallow marine to near shore, wave-dominated depositional setting. Shale of varying composition and color was observed interbedded in the sandstone. Laboratory work was carried out at York College on collected samples. The laboratory work included thin section analysis of samples from different outcrops in the study area which revealed minerals such as chert, plagioclase feldspars, microcline , muscovite, biotite, mono-and polycrystalline quartz. Among the heavy minerals, well-rounded tourmaline, zircon, rutile, and trace garnet were the dominant constituents. In situ XRF, (hand-held type), readings taken in the field recorded a relatively large concentration include Fe, K, Ca, Ti, and Mn; present in lower concentration are Cr, Ni, Cu, Zn, As, Rb, Sr, Zr, Ag, Ba, and Pb. These elements were cross potted, and the statistical correlation as well as ratios of key element-pairs were used to interpret provenance, maturity of sediments, environment of deposition, tectonic setting, and diagenesis. A mixed provenance, dominated by both reworked clastic and proximal source, was suggested by the chemical composition of the analyzed sandstone. Overall, the depositional environment of the Sb was dominated by deltaic to fluvio-deltaic, with occasional incursion of nearshore marine environment.