Sierra Mojada ProjectThe Sierra Mojada project lies within a historical high grade silver, lead, zinc mining district discovered in 1879. The main zone of mineralization found at Sierra Mojada extends over 6 kilometers in an east-west direction along the base of the Sierra Mojada Range. Over 54 historical mine shafts lie along this strike, mining to depths in-excess of 200 meters.
The geology is composed of a well preserved Cretaceous carbonate platform typical of a marine transgression deposited on top of Jurassic 'San Marcos' Red Bed conglomerates. The main zone of mineralization is hosted along the Sierra Mojada fault which lies at the base of the Sierra Mojada Massif and cross cuts the rock package in an east-west direction.
The mineralization at Sierra Mojada has strong analogies with a number of different deposit styles which includes; Carbonate Replacement Deposits (CRD), Irish-type deposits, and possibly Mississippi Valley Type (MVT). Although an intrusive system has yet to be found, elevated copper, molybdenum, arsenic, and mercury in the area all point to a likely intrusive source.
A second step in the forming of the main zone at Sierra Mojada has seen supergene processes re-mobilize and re-constitute the original sulphide mineralization as oxides into the current 'manto' deposit style we see today. This cyclical leaching over a long period of time has in particular mobilized the silver and zinc in the system and re-deposited them into the fracture and cavern (karst) systems developed along the Sierra Mojada fault zone. The different solubility of these metals has resulted in a crude "zoning" within the ore body, creating zones that are "silver rich", and "zinc rich".
The mineralization can be broken out into three main zones;
"Shallow Silver Zone" - Is a near surface silver oxide zone (+/- zinc & lead) hosted along the Sierra Mojada fault system. Previous drilling defined a mineralized body over 2km in length which averages between 30m - 90m thick, and up to 200m in width. A 43-101 Technical Report on the Shallow Silver Zone released April 20, 2011 can be found on www.sedar.com.
"Red Zinc Zone" - Is an extensive zinc oxide "manto" composed mainly of the zinc silicate "hemimorphite" sits at a deeper level to the Shallow Silver Zone. The main body of the Red Zinc Zone dips at approximately 10 degrees to the east and has a known strike length of just over 2.5 km and a thickness of up 50m. It is strongly controlled by the Sierra Mojada fault and dolomite beds, which are thought to represent a favorable host rock for the remobilized zinc. Based on over 90,000m of drilling, a NI 43-101 report from Pincock, Allen & Holt was completed in January 2010 and can be found on www.sedar.com. It outlines that the Red Zinc Zone is one of the largest undeveloped zinc oxide finds in the world. On April 26, 2011, a report on the Red Zinc was produced by JDS Engineering Oxide Zinc Resource
"White Zinc Zone" - Commonly underlies the Red Zinc zone but on several occurrences lies adjacent, possibly due to structural displacement. Mineralogically the White Zinc Zone differs from the Red Zinc Zone with much higher concentration of the zinc carbonate "smithsonite". The White Zinc Zone can be seen in the widespread underground workings in area but has never been drilled, and suggests a significant upside to zinc mineralization at Sierra Mojada.
Other styles of mineralization also seen at Sierra Mojada include;
- Structurally controlled, sulphide-dominated lead-silver mineralization occurring along select segments of the Sierra Mojada Fault Zone principally along a north-dipping erosional unconformity in the area.
- Copper-lead-silver mineralization on locally mineralized shallow, north-dipping structures throughout the area.
- Disseminated copper mineralization within the deeper "red bed" sandstones and siliclastics. The potential for significant tonnages within this lower part of the Sierra Mojada stratigraphic package awaits verification in the near future.