Northeastern Section - 53rd Annual Meeting - 2018

Paper No. 14-6
Presentation Time: 3:25 PM

EVALUATING GEOCHEMICAL SIGNATURES AND TECTONIC IMPLICATIONS OF CALCITE VEINS WITHIN THE CHAMPLAIN VALLEY, VT


ROBBINS, Liesel, Sue, Geology, Middlebury College, 276 McCardell Bicentennial Hall, Middlebury, VT 03755 and AMIDON, William H., Geology Department, Middlebury College, Middlebury, VT 05753

U-Pb dating of calcite veins in faults and fractures of the Champlain Valley has returned surprisingly young ages ranging from the Cretaceous to the Mio-Pliocene. This work is part of a larger body of evidence suggesting post-rift rejuvenation of eastern North America. However, it remains unclear whether all the veins record primary fracturing events or whether some may result from recrystallization events. This study thus focuses on trace elemental mapping of calcite veins using LA-ICMPS to identify distinct domains of calcite growth. Specifically, trace elemental mapping is used as a tool to analyze U-Pb dated calcite vein samples to ascertain and characterize different generations of calcite based on geochemical and textural differences in the calcite compositions. Trace element mapping will compare Ca, U, Pb, Sr, Mg, Fe, Yb and other trace element concentrations within 20 calcite vein samples, comparing the maps of geochemical signatures with data on successful laser shot placement for U-Pb dating. This should help to define vein characteristics that are suitable for this dating method and potentially distinguish different generations of brittle deformation within the Champlain Valley.