FAULT-ASSOCIATED DOLOMITIZATION IN THE ONONDAGA LIMESTONE IN CENTRAL AND WESTERN NEW YORK

One process for the formation of dolomite is the alteration of primary calcium carbonates with Mg-rich fluids. Several studies (eg. Nurkhanuly et al. 2014) have found significant dolomitization of limestones along faults. Fault networks control the flow of hydrothermal fluids, therefore, the distribution and extent of dolomitization may be highly variable. Recent studies in central and western New York State have identified networks of fault zones. One of the more prominent fault zones that has long been identified is the Clarendon-Linden Fault which runs approximately N-S through Batavia, NY. A total of 26 samples from 11 different quarries running along a E-W transect that roughly parallels I-90 were analyzed for molar ratios of Ca and Mg by ICP-AES. Most samples are not in close proximity to fault zones. These samples show molar Mg percentages ranging from 1.97% to 2.86%, indicating low-Mg calcite. Those more closely associated with faults, in particular the Clarendon-Linden fault show molar Mg percentages of approximately 37%. While this is not pure dolomite, it indicates a significant degree of alteration of the native limestone. The significance of the alterations associated with the Clarendon-Linden fault zone is not known at this time.