spe458-13 1st pgs page 255 255 The Geological Society of America Special Paper 458 2009 Petrographic and geochemical comparisons between the lower crystalline basement-derived section and the granite megablock and amphibolite megablock of the Eyreville B core, Chesapeake Bay impact structure, USA Gabrielle N. Townsend* Roger L. Gibson Impact Cratering Research Group, School of Geosciences, University of the Witwatersrand, P.O. WITS, Johannesburg 2050, South Africa J. Wright Horton Jr. U.S. Geological Survey, 926A National Center, Reston, Virginia 20192, USA Wolf Uwe Reimold Museum for Natural History–Leibniz Institute at the Humboldt University, Invalidenstrasse 43, 10115 Berlin, Germany, and Impact Cratering Research Group, School of Geosciences, University of the Witwatersrand, PO WITS, Johannesburg 2050, South Africa Ralf-Thomas Schmitt Museum for Natural History–Leibniz Institute at the Humboldt University, Invalidenstrasse 43, 10115 Berlin, Germany Katerina Bartosova Department of Geological Sciences, University of Vienna, Althanstrasse 14, Vienna A-1090, Austria ABSTRACT The Eyreville B core from the Chesapeake Bay impact structure, Virginia, USA, contains a lower basement-derived section (1551.19 m to 1766.32 m deep) and two megablocks of dominantly (1) amphibolite (1376.38 m to 1389.35 m deep) and (2) granite (1095.74 m to 1371.11 m deep), which are separated by an impac- tite succession. Metasedimentary rocks (muscovite-quartz-plagioclase-biotite- graphite ± fibrolite ± garnet ± tourmaline ± pyrite ± rutile ± pyrrhotite mica schist, hornblende-plagioclase-epidote-biotite-K-feldspar-quartz-titanite-calcite amphibolite, and vesuvianite-plagioclase-quartz-epidote calc-silicate rock) are domi- nant in the upper part of the lower basement-derived section, and they are intruded *gtown84@gmail.com Townsend, G.N., Gibson, R.L., Horton, J.W., Jr., Reimold, W.U., Schmitt, R.-T., and Bartosova, K., 2009, Petrographic and geochemical comparisons between the lower crystalline basement-derived section and the granite megablock and amphibolite megablock of the Eyreville B core, Chesapeake Bay impact structure, USA, in Gohn, G.S., Koeberl, C., Miller, K.G., and Reimold, W.U., eds., The ICDP-USGS Deep Drilling Project in the Chesapeake Bay Impact Structure: Results from the Eyreville Core Holes: Geological Society of America Special Paper 458, p. 255–XXX, doi: 10.1130/2009.2458(13). For permission to copy, contact editing@ geosociety.org. ©2009 The Geological Society of America. All rights reserved.