STRATIGRAPHIC AND PETROLOGIC EXAMINATION OF METASEDIMENTARY ROCKS AT CHIMNEY MOUNTAIN, NEW YORK

During the summer of 2005, a new sequence of metasedimentary rocks was encountered during field study in the central Adirondacks at Chimney Mountain (Hamilton, County). The current investigation involves the stratigraphic (documentation of the distribution of rock layers and compositional variations between and within those layers), petrologic (mineralogy), geochemical characterization of this sequence of rocks. The level of preservation that exists in this sequence of rocks is remarkable. Typically, Adirondack metasedimentary rocks are so deformed and so highly altered due to the history of extreme heating and pressure, it is difficult to determine if the rock was once sediment. But, the rocks at Chimney Mountain contain what are believed to be primary sedimentary features such as bedding, channel structures, and possibly ripples.

Rock samples were collected and turned into thin sections. They are to be analyzed for mineral composition and abundance in each of the layers. The apparent metasedimentary sequence dominantly alternates between metasandstone and psammitic layers. The entire sequence may be several meters thick, and is completely exposed at the site. Further study may involve geochronology. The geochronologic study will provide information on the timing of the metamorphism and the age of the sedimentary source with analyses of zircon rims and cores respectively. Determination of the age range of sediments that make up this rock sequence may help to understand if these rocks are related to the erosion of ancient North America, ancient South America, or some other source currently unknown source.