IRON, COPPER, AND ZINC ISOTOPIC CHARACTERIZATION OF BASE METAL DEPOSITS IN THE NEW JERSEY HIGHLANDS AND THE NEW YORK ADIRONDACKS

The extensive orogenic history recorded from Mesoproterozoic era to the Neoproterozoic era in the New Jersey Highlands and New York Adirondacks metamorphosed host rock and ore bodies of over 450 base metal deposits up to granulite facies. Ore deposits in the New Jersey Highlands reveal varying ore forming processes, including Sedimentary Exhalative (SEDEX) and Iron Oxide Apatite (IOA). Magnetite samples of varying host rock and ore body were taken from abandoned mines of the western and eastern New Jersey Highlands. The samples were then analyzed for δ⁵⁶Iron (Fe), δ⁶⁵Copper (Cu), δ⁶⁶Zinc (Zn) isotopes and trace elements. Magnetite from the NJ Highlands show a hydrothermal/magmatic emplacement with lower δ⁵⁶Fe average relative to SEDEX deposits in the Highlands. Samples from New York yield isotopic data that not only support deposit type but also show different redox conditions in a Grenville age back arc basin based on average δ⁵⁶Fe. δ⁶⁵Cu and δ⁶⁶Zn isotope and trace metal data support the variations in depositional environment and emplacement processes indicated by the fe isotopes. Together, stable isotope, trace element data, and field relationships reveal a metamorphosed hydrothermal and magmatic history of the New Jersey Highlands.