Paper No. 4
Presentation Time: 2:30 PM
COLES HILL, CHATHAM, VIRGINIA URANIUM DEPOSIT
The Coles Hill uranium deposit is located east of U.S. Highway 29 between Gretna and Chatham in Pittsylvania County, Virginia. A resource of 110 million pounds U3O8 at a grade of 0.025% is reported from the deposit. The epigenetic deposit lies within the Paleozoic Smith River Allochthon Synclinorium and is hosted by the Ordovician Leatherwood Granite. Mineralization within the granite is localized within a strongly deformed zone proximal to the fault contacts (Chatham Fault) between the granite and sedimentary rocks of the Triassic Danville Basin. Deformation in the host granite is complex and likely records the reactivation of a Paleozoic thrust/transpressional fault during Mesozoic normal faulting. An early ductile deformation is represented by overturned isoclinal folds, with an axial planar foliation striking N30E, dipping 45SE. These structures are overprinted by mylonites of uncertain age and brittle fractures that may be related to the Mesozoic normal faulting. Several working hypotheses are being considered for the origin of the mineralization. These include hydrotheremal activity asssociated with waning stages of Leatherwood magmatism, magmatic and/or hydrothermal activity associated with Paleozoic faulting, and mineralization by fluids derived from the adjacent Triassic Basin.