Abstract Kennecott Minerals Company (KMC) operates a 15,000-ton-per-day open-pit gold mine located approximately 5 miles east of the town of Ridgeway, and 25 miles north of Columbia, South Carolina (Figure 1). The Ridgeway gold mine is one of four gold mines which were put in production in South Carolina in the 1980’s. It is currently the only operating gold mine in the Eastern United States. The Ridgeway mine produces gold bullion from two bulk-mineable, open-pit deposits located one mile apart. Low-grade oxide and sulfide ore produced from the siliceous deposits is blasted and hauled to a central mill complex. Ore is milled to minus 200 mesh, and gold is extracted by a carbon-in-pulp, electrowinning process. The mine operates 24 hours a day, and employs over 100 people. The mine began producing gold in December 1988 and total developed in order to achieve an ultimate production goal of 1.5 million ounces of gold bullion by the year 2000. The North Pit is 2,000 feet long, 1,400 feet wide, and 320 feet deep. The South Pit is 2,600 feet long, 1,500 feet wide, and 360 feet deep. The South Pit is being mined at full scale, and is expected to be mined out by June 1996. Activity in the North Pit is currently focused on the stripping of oxide ore and waste at the 420-440 level along the northern half of the pit. Future development plans for the North Pit include deepening the pit from the 120 elevation to -40 elevation. This paper

Abstract Renewed gold exploration in the Carolina slate belt of North and South Carolina that led to the discovery of the Ridgeway gold mine (#5 on Figure 1) by Amselco (now Kennecott) began at about the same time as the last Geological Society of America field trip to focus on southeastern metal deposits. That trip occurred in the fall of 1980 as part of the national GSA meeting in Atlanta, Georgia (Bell, Carpenter, and Feiss, 1980). On that trip at stop 8, Henry Bell described abundant hydrothermal alteration similar to the Haile and Brewer mines in an area with no known gold mines. He noted that auger cuttings from a hole drilled by the South Carolina Geological Survey in the 1960’s near stop 8 at Mount Rehovah church contained 0.06 ppm gold and 220 ppm copper in the upper 9 feet of rock and 10 ppm molybdenum from 30-40 feet. Because the values decreased with depth, the gold was attributed to surface enrichment (Bell, 1976). Samples collected by Bell (1976) of small drainage basins in the region contained up to 1000 ppm tin in heavy mineral concentrates that were also anomalous in gold, boron, lanthanum, niobium, beryllium, and copper (Figure 16 of Bell, Carpenter, and Feiss, 1980). Bell et al. (1980) stated “Geochemical data suggest that this region is on the periphery of an area having many of the ore-bearing characteristics of the Haile and Brewer mines” Stop 8 was only hundred’s of feet west of the present site of the

Abstract The Cadia district of New South Wales contains four alkalic porphyry Au-Cu deposits (Cadia East, Ridgeway, Cadia Hill, and Cadia Quarry) and two Cu-Au-Fe skarn prospects (Big Cadia and Little Cadia), with a total of ~50 Moz Au and ~9.5 Mt Cu (reserves, resources, and past production). The ore deposits are hosted by volcaniclastic rocks of the Weemalla Formation and Forest Reefs Volcanics, which were deposited in a submarine basin on the flanks of the Macquarie Arc during the Middle to Late Ordovician. Alkalic magmatism occurred during the Benambran orogeny in the Late Ordovician to early Silurian, resulting in the emplacement of monzonite intrusive complexes and the formation of porphyry Au-Cu mineralization. Ridgeway formed synchronous with the first compressive peak of deformation and is characterized by an intrusion-centered quartz-magnetite-bornite-chalcopyrite-Au vein stockwork associated with calc-potassic alteration localized around the apex of the pencil-like Ridgeway intrusive complex. The volcanic-hosted giant Cadia East deposit and the intrusion-hosted Cadia Hill and Cadia Quarry deposits formed during a period of relaxation after the first compressive peak of the Benambran orogeny and are characterized by sheeted quartz-sulfide-carbonate vein arrays associated with subtle potassic, calc-potassic, and propylitic alteration halos.

Abstract Calcic pedocomplexes in the Siluro-Devonian Old Red Sandstone (ORS) of the Anglo-Welsh Basin (UK) have traditionally been interpreted as paleosols developed in dryland depositional environments. Their recognition has been used to indicate a range of controls, including climate, landscape stability, sedimentation rate, soil residence time, and proximity to alluvial channels (the pedofacies concept). A study of the Devonian Ridgeway Conglomerate Formation (RCF) in Pembrokeshire, southwest Wales, has, however challenged some of these notions, recognizing that many calcretes were not developed in soil horizons. The RCF was deposited as part of a dryland alluvial fan and axial fluvial valley complex. Regionally, structural blocks and basins were defined by a series of extensional faults, with the RCF being deposited in a half-graben as a hanging-wall alluvial fan. The RCF is heterolithic, comprising conglomerates, sandstones, and mudstones that reflect differences in processes, suggesting sheetfloods, low-relief lateral accretion, and cohesive debris flows across the alluvial fan. Pedogenic calcretes are common in all areas of the fan and axial fluvial zone. In mudstone and sandstone-grade lithofacies they comprise common horizonated nodules and subhorizontal crystallaria sheets in association with pedogenic indicators such as drab haloes, desiccation cracks, and ped textures. Also observed are both horizontal and vertical root traces, some of which have been the focus of micrite nodule growth (rhizogenic calcretes). Wedge-shaped peds are absent. Pedogenic profiles display upward-increasing percentages of nodules, and may be capped by blocky, massive calcrete and laminated micrite that developed in small ponded areas. In gravel-grade lithofacies, the pedogenic expression is different, and comprises carbonate-coated clasts with pendant and pore-occluding calcrete fabrics. Pedogenic calcretes are best developed in proximal areas of the fan, possibly on terraces adjacent to fan-channel entrenchment zones (the pedofacies concept). Proximal fan areas may also have had increased soil residence times due to reduced sedimentation rates compared to distal fan and axial fluvial valley zones. In distal fan and axial alluvial zones, thin layerbound micritic groundwater calcretes are common, typically being sharp based with upper surfaces comprising vertical and cylindrical nodules that possibly developed in the capillary-fringe zone. Inclined heterolithic bedsets, the deposits of laterally accreted ephemeral channels also commonly contain layer-bound micritic calcretes, again interpreted as having a groundwater origin. Lake-margin calcretes comprising centimeter-thick, laminated micrite, represent possible calcretized matgrounds in fan-toe, ephemeral ponds. The identification of common non-pedogenic calcretes in the RCF begs the question: how much of the ORS calcretes are similarly non-pedogenic in nature? Our analysis may act as a cautionary check for subsurface work where carbonate horizons in alluvial suites are being modelled solely in accordance with the pedofacies concept.

Abstract The Haile gold mine is located in southern Lancaster County, South Carolina, near the town of Kershaw. Gold was discovered at the site in 1827, and four periods of mining have yielded 360,000 ounces of gold. The mine is located between the past producing Ridgeway and Brewer mines that, when all are combined, constitute a significant amount of historical gold production in the southeastern United States. These mines are hosted within Neoproterozoic to lower Cambrian Carolina terrane rocks and are dominated by volcanic and epiclastic units that have experienced greenschist facies metamorphism. Saprolitic weathering is present in the near-surface portions of the deposit and is locally covered by Cretaceous-aged Coastal Plain sediments. The gold mineralization at the Haile mine is hosted within silicified meta-sediments containing fine-grained disseminated pyrite and pyrrhotite and is a replacement type-epithermal deposit. Re-Os ages from molybdenite associated with the mineralization indicate that the deposit formed shortly after major, arc-related volcanic activity. Haile currently has a measured and indicated resource of 4.03 million ounces at an average grade of 1.77 g/t Au with an additional inferred resource of 801,000 ounces at an average grade of 1.24 g/t Au. Included in the resource is a reserve of 2.02 million ounces of gold at an average grade of 2.06 g/t. Mine construction began in May 2015, and gold production is expected by the end of 2016. The construction cost is expected to be US$380 million. Ore will be extracted from eight open pits with mill extraction and the current mine life is 14 years.