Caractérisation géophysique et géochimique du système hydrologique et rôle de la Faille Chatham dans l’écoulement de nappe, gisement d’uranium de Coles Hill, Virginie, USA Caracterización geofísica y geoquímica del sistema de agua subterránea y rol de la Falla de Chatham en el movimiento del agua subterránea en el depósito de uranio de Coles Hill, Virginia, EEUU 地下水系统的地球物理和地球化学特征以及Chatham断裂对地下水运动的影响---以美国弗吉尼亚州Coles山铀矿为例 Caracterização geofísica e geoquímica do sistema hidrogeológico e o papel da Falha Chatham no escoamento da água subterrânea no jazigo de urânio Coles Hill, Virgínia, EUA

Gannon, John P.; Burbey, Thomas J.; Bodnar, R. J.; Aylor, Joseph

Caractérisation géophysique et géochimique du système hydrologique et rôle de la Faille Chatham dans l’écoulement de nappe, gisement d’uranium de Coles Hill, Virginie, USA Caracterización geofísica y geoquímica del sistema de agua subterránea y rol de la Falla de Chatham en el movimiento del agua subterránea en el depósito de uranio de Coles Hill, Virginia, EEUU 地下水系统的地球物理和地球化学特征以及Chatham断裂对地下水运动的影响---以美国弗吉尼亚州Coles山铀矿为例 Caracterização geofísica e geoquímica do sistema hidrogeológico e o papel da Falha Chatham no escoamento da água subterrânea no jazigo de urânio Coles Hill, Virgínia, EUA | Geophysical and geochemical characterization of the groundwater system and the role of Chatham Fault in groundwater movement at the Coles Hill uranium deposit, Virginia, USA

2012

Gannon, John P. | Burbey, Thomas J. | Bodnar, R. J. | Aylor, Joseph

The largest undeveloped uranium deposit in the United States, at Coles Hill, is located in the Piedmont region of Pittsylvania County, south-central Virginia, and is hosted in crystalline rocks that are adjacent to and immediately west of Chatham Fault, which separates these crystalline rocks from the metasedimentary rocks of the Danville Triassic Basin (in the east). Groundwater at the site flows through a complex network of interconnected fractures controlled by the geology and structural setting. The role of Chatham Fault in near-surface (<≈200 m) groundwater flow is examined using electrical resistivity profiling, borehole logging, a pumping test, groundwater age dating and water chemistry to determine if the fault represents a permeability barrier or conduit for groundwater flow. The volumetric flow per unit width flowing eastward across the fault is estimated at 0.069–0.17 m2/day. Geochemical data indicate that groundwater in the granitic crystalline rocks represents a mixture of modern and old water, while the Triassic basin contains a possible deeper and older source of water. In regions with shallow water tables, mine dewatering during operation presents significant mining costs. The study’s results yield important information concerning the effect that Chatham Fault would have on groundwater flow during Coles Hill mining operations.

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