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2002 Denver Annual Meeting (October 27-30, 2002)

Paper No. 9
Presentation Time: 10:30 AM

THE STRUCTURAL AND STRATIGRAPHIC CONTROL ON SEDIMENT-HOSTED GOLD MINERALIZATION AT THE SALAMÓN GOLD DEPOSIT (LEÓN, N OF SPAIN)


ALONSO, Juan L.1, BARBA, Pedro2, CABRERA, Ramón3, CRESPO, José L.3, FADÓN, Oscar2, MARCOS, Alberto1, MORO, Candelas2 and VILLA, Elisa1, (1)Departamento de Geología, Universidad de Oviedo, Arias de Velasco s/n, Oviedo, 33005, Spain, (2)Departamento de Geología, Universidad de Salamanca, Plaza de la Merced s/n, Salamanca, 37008, Spain, (3)SIEMCALSA, Incas 5, Valladolid, 47008, Spain, jlcrespo@siemcalsa.com

The Salamón micron gold deposit is located in N Spain within the Cantabrian Zone, a more external part of the Iberian Massif. It is hosted in U. Carboniferous limestone and shales adjacent to the León Fault, a major, steep, E-W trending regional structure of more than 100 km length. Many small, historic, epithermal deposits, important for gold and other elements (As, Sb, Hg, Cu, etc.) are found along this fault.

In Salamón East, the outcropping altered and mineralized structure is 10-20 m wide, some 400-500 m long and has been followed by drilling to a depth of 250 m. The best DDH intercept, 22.20 m @ 20.50 g/t Au is consistently mineralized over the ~22 meters. This mineralization is located along the faulted contact between two, Upper Carboniferous units: the top of the Bachende Limestones (late Kashirian-Podolian; Moscovian) and mainly the base of the Dueñas unit (Podolian-Myachkovian; latest Moscovian). Both formations were deposited in calm, subtidal environments. The Bachende Limestone is a massive, bioclastic and algal bound carbonate; the Dueñas unit consists of terrigenous coarsening-upward sequences, mainly formed by marly carbonoceus silstones, interbedded with bioclastic and algal bound limestones.

The Salamón deposit is located, more precisely, at the intersection of the regional León Fault and the important, NE trending, local, Salamón Fault; both are deep seated, thrust-related structures of latest Moscovian age. In connection with the Salamón Fault, a brittle shear zone with sinistral-slip faults of Riedel type was developed, that was reactivated in the N-S shortening of the Cantabrian Zone, after Stephanian B time. The Salamón deposit is found along the southern end of this shear zone, localized along the fault contact between the contrasting lithologies of the Bachende and Dueñas units. Some 35 drill holes suggest a resource, open to depth and laterally, of < 0.5 Mtm @ 7.8 g/t.

Session No. 63

T7. Diverse Origins of Sedimentary Rock-Hosted Disseminated Gold Deposits: A Global Perspective
Monday, 28 October 2002: 8:00 AM-12:00 PM
Geological Society of America Abstracts with Programs. Vol. 34, No. 6, September 2002, p.141
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