GEOLOGIC MAP OF THE SOUTHWEST PORTION OF THE HYCO SHEAR ZONE

The Hyco Shear Zone of North Carolina’s Piedmont region has been described as an Alleghanian ductile thrust zone separating the Ordovician Milton terrane to the west from the Neoproterozoic Carolina terrane to the east. Also located along this significant terrane boundary is the Churchland Plutonic Suite, whose previous age of ca. 282 Ma appears inconsistent with observations of ductile deformation along the shear zone. Our continuation of 1:50,000 scale bedrock mapping along the southwestern portion of the Hyco Shear Zone provides structural data and field observations that further illustrate the effect of ductile deformation along the shear zone. New zircon U-Pb age dates for the Churchland Plutonic Suite are coupled with this new mapping to better understand and constrain the timing of major plutonism occurring along the Hyco Shear Zone. Our mapping shows the southwestern continuation of ductile deformation features with right-lateral shear indicators, and a prevalence of heavy deformation. Variable texture and degrees of deformation within the Churchland Plutonic Suite also point to a multi-phase plutonic event occurring along the terrane boundary as a result of the Alleghanian Orogeny. Collectively, these data support the idea of a ductile thrust regime between the Carolina and Milton terranes and demonstrate how this relationship extends southwest along strike into the Central Piedmont Shear Zone.