COMPILED GEOLOGIC MAP OF THE WESTERN PORTION OF THE HENDERSON 100K

The North Carolina Geological Survey (NCGS) has finalized the digital compilation of the bedrock geologic map of the western portion of the Henderson 1:100,000-scale Quadrangle. The map area, consisting of 8.25 1:24K scale quadrangles, incorporates geologic data collected by the USGS, NCGS, and academic researchers. Partial funding for the compilation work and for some of the detailed geologic mapping was provided by the STATEMAP and EDMAP components of the National Cooperative Geologic Mapping Program.

Geologically, the map area includes a small portion of the Hyco shear zone, the terrane bounding fault between the Milton and Carolina terranes. The majority of the map area is underlain by the Carolina terrane which includes the major lithotectonic elements of the Hyco and Albemarle arcs with the intervening Aaron Formation. The Hyco arc is composed of metamorphosed felsic to mafic volcanics, volcaniclastic-sedimentary, and intrusive igneous rocks. The Albemarle arc lithologies in the map area include the Roxboro pluton, the Goshen gabbro and a felsic porphyry. The northeastern edge of the map area includes the Vance County pluton which hosts the historic Hamme Tungsten district. The Aaron Formation, interpreted to have been deposited after the magmatism of the Hyco arc but before Albemarle arc magmatism, is being re-evaluated after Aaron Formation rocks in Chatham County yielded detrital zircons ages that link parts of the Aaron Formation to the Albemarle arc. Pending detrital zircon analysis from the Aaron Formation in the map area continues the investigation into this problem. The southeast portion of the map area is underlain by Triassic-aged sedimentary rocks belonging to the Durham sub-basin of the Deep River Triassic basin and are intruded by Jurassic diabase sills.

During the compilation efforts, line work from multiple legacy sources was utilized and adjusted based on new field observations, edge-matched with adjacent quadrangles, and verified through targeted foot and vehicle traverses. Edge-match issues between detailed data in the Henderson 100K and contacts in the South Boston 100K were identified. Further compilation efforts in the southern segment of the South Boston 100K may be needed to create a seamless transition from the South Boston to Henderson 100K maps.