|Zinco Mining Corporation is the 100% owner of 8 exploration and 2 exploitation concessions (Jalisco MS Project) in Sierra Madre del Sur in western Jalisco State (UTM zone 13; 500,000E; 2,240,000N). The project is located approximately 45 km southeast of Puerto Vallarta. (Figure 1). Talpa de Allende the nearest centre for supplies and lodging, is located to the east of the project and the State capital of Guadalajara is approximately 155 km east of Talpa de Allende.
The Jalisco MS Project covers 527.5 km2 (Table 2) and cover a major part of the historic Cuale MS District. Elevations within the project area range between 300 m and 2,400 m and access is through a network of dirt roads from either Puerto Vallarta or Talpa de Allende (Figure 2).
Table 2; List of mining concessions comprising the Company's Jalisco VMS Project.
Figure 2: Map of Jalisco MS Project concessions. Zinco concession boundaries in blue and third part concessions in magenta.
Silver rich MS mineralization was discovered in the Cuale District in the early 19ths century. The first production dates back to 1823. By 1873 seven mines were in operation, but were closed down in 1900 due to declining silver price. Several companies attempted to reopen the mines during the first half of the 20th century. Subsidiaries of Industrias Peñoles operated several MS deposits within and adjacent to the Jalisco MS project between the 1960s and 1980s with flotation recovery plants in at least two locations (Cuale and El Rubi). The Cuale plant was operated for 13 years at a maximum capacity of 2,500 tonnes per day. Industrias Peñoles operations included exploitation of five deposits within Jalisco MS Project area and the reserve information is listed in Table 3.
Table 3; Reserve information* from past producing mines within the Jalisco MS Project.
The Desmoronado area was drilled in 1975 and in 1989. Following the latest drilling Industrias Peñoles calculated mineral resources for the San Rafael and San Pedro mineralization's (Table 4),
Table 4; Estimated mineral resources* in the Desmoronado area.
Historic resource estimate by Minas de Tapalpa S.A. de C.V. for the America mineralization in the Aranjuez area that is located within a third party concession (Table 5),
Table 5; Estimated mineral resources* in the Aranjuez area.
Between 1984 and 1986, the International Cooperation Agency and Metal Mining Agency of Japan and the Servicio Geologico Mexicano completed regional geologic mapping, stream sediment geochemistry, geophysics and diamond drilling programs for volcanogenic MS mineralization over a 40 by 50 km area in western Jalisco State including the Cuale District. The stream sediment samples defined contiguous polymetallic geochemical anomalies that extend beyond the known mines and workings in Cuale, Bramador, Desmoronado, El Rubi, Aranjuez and La Mina areas.
During the 1990s Cominco (since merged with Teck) held concessions and explored the Bramador area.
The Jalisco MS Project covers part of the Guerrero Terrane that is composed of a complex island-arc assemblage of Jurassic age that was accreted onto the North American continent in Late Cretaceous. It can be divided into five sub-terranes and is host to more than 150 MS deposits in western and central Mexico.
In the east (Aranjuez, El Rubi, Desmoronado), andesitic rocks are far more abundant with rhyolite flows and tuffs. There are less intrusive domes, sills and dykes than in the west. At Cuale, argillite layers are discontinuous or mixed with rhyolite breccia which implies a rather active volcanic environment.
Argillite is typically less than 10 m thick and discontinuous, or mixed with rhyolite breccia at Cuale (shallow-water depositional environment) and increase in thickness towards the east (more than 400 m Bramador and more than 1 km at Aranjuez) suggesting increasing deposition debt to the east.
The large Puerto Vallarta Batholith, (alkali feldspar granite and biotite granite, two mica granites, and granodiorites and tonalites) is located to the west with apothosis of the batholith intruding the volcano-sedimentary sequence.
The volcano-sedimentary sequence is displaced by Tertiary age, northwest trending faults
Figure 4: General geological map of the Jalisco MS Project. Zinco concession boundaries in blue and third part concessions in magenta.
The most important alteration in the host rock is silicification, sericitizatiion, kaolinization, chloritization, propylization, amphibolization and oxidation which makes it typical hydrothermal.
Calculation of lithogeochemical alteration patterns using the multi-element Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) suggest marked differences in alteration within the Cuale area. The data suggest more intense alteration at San Juan and Jesus Maria than at Naricero.
Mineralization is presently poorly exposed within the project area. Historically it is described as fine grained in lenses with gangue of calcite, quartz and possible anhydrite that are parallel to structures and discordant to the volcano-sedimentary stratigraphy. It has been divided into three types:
Samples from the 2008 drilling found MS mineralization replacing volcanic spherulites and lithophysae which suggest a post volcano-sedimentary origin of the mineralization.
There are indications there are two phases of pyrite mineralization.
Brecciated mineralization is found locally on both sides of the MS lenses with xenoliths of host rocks (andesite and tuffs), quartz, pyrite-chalcopyrite and sphalerite-galena in a pyrite matrix.
The oxidized (limonite-iron oxide) zones in the Bramador area carry gold and silver. The sulphide mineralization in this area is galena-sphalerite-argentite (silver sulphide) in a gangue of silica-clay-pyrite-arsenopyrite (arsenic-iron sulphide) and barite.
Analytical data from the 2008 drilling have identified a separate silver mineralization event that either is superimposed on or spatially separate from the MS mineralization.
The mineralization displays several features and textures typical of hydrothermal deposition. However, resolving the genesis of the mineralization is complicated by multiple phases and it is preliminary to state the genesis of the various phases from the available information.
Following acquisition of the initial concessions in the Cuale District the Company completed follow-up stream sediment sample survey of most of the anomalous zones established by the earlier work.
Geological mapping was completed in the period 2002-2007 by the Company and the University of BC Mineral Deposits Research Unit. This work concluded that the geological environment is shallow water with characteristics similar to districts that host volcanogenic MS deposits.
The Company completed a 1,859 line km helicopter airborne EM, radiometric and magnetic survey to identify bedrock conductors reflecting buried MS mineralization. Resistivity mapping from the survey identified several areas of black shale (resistivity lows). The surveys also identified 320 bedrock conductors within the black shales that might reflect MS mineralization. Inversion and 3-D modeling of the airborne magnetic data implies that the Cuale District is underlain by a pipe-like intrusion centered below Descubriadora Mountain in the Aranjuez Area. Similar magnetic anomalies were also identified in the Bramador and Desmoronado areas thought to reflect subvolcanic intrusions and diatremes.
A B-horizon soil geochemistry survey was completed to assist in prioritization of the geophysical and stream sediment geochemical anomalies for drilling. The soil survey covered less than 50% of the conductors identified by the airborne survey and about 75% of the resistivity lows identified as black shales.
In 2008 the Company completed 4,751.2 m of RC drilling in 33 holes in the Cuale area on the Naricero, Jesus Maria, San Juan and Grandeza zones.
In 2009, the Company completed grid-based rock sampling over several different target types on the Almatea concession. Additional compilation of the historic data on the entire Project area has recently been completed (including the drill holes at Aranjuez, Cuatro Minas and Bramador).
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