Through reconnaissance Chesapeake recognized the potential of a large, unexplored precious metal and polymetallic mining district located in western Veracruz state. In 2007, Chesapeake consolidated the Tatatila mining district totaling 25,523 hectares through purchase, joint venture and staking.
The Tatatila project is characterized by Cretaceous limestones and sedimentary rocks affected by multiphase intrusions of Tertiary granodiorites, quartz-diorites and granites which are interpreted as coalescing into a large underlying batholith. The metasomatic and hydrothermal activity has formed widespread skarn alteration zones with precious and base metals mineralization. The copper-gold mineralized skarn outcrops have been mapped over an area of 200 square kilometers. In two of the main central zones, the copper-gold contact controlled garnet skarns grade upward to gold-silver-copper retrograde skarn structures. Zonation is marked to the south passing from copper and gold skarns into silver rich and base metal mineralization.
The skarns are preferentially developed along intrusive-sediment contacts and include endoskarns developed within the intrusives themselves. Porphyry and epithermal-type mineralization have been found in the same areas. Skarn assemblages associated alteration includes garnet-magnetite, garnet-pyroxene-magnetite, hematite-magnetite-wollastonite, hematite-jasperoid and calcite-hematite-silica veins in the upper part of the system. The principal sulphides are pyrite and chalcopyrite.
Over thirty separate areas of skarn mineralization have been identified to date. Mapping and channel sampling have defined several individual bodies that outcrop over lengths of several hundred meters, widths up to 70 meters and in some areas, exposed depths of 50 to more than 250 vertical meters. Selected channel cuts from different mineralized skarn zones returned:
Prospect
Meters
Gold
g/t
Silver
g/t
Copper
%
Zinc
%
Cinco Señores
33
1.2
8.7
0.19
-
Santa Cruz
33
1.2
6.9
0.55
-
Carboneras
15
2.0
6.0
-
-
Melany
67
1.6
6.5
0.59
-
Melany
15
4.2
42.9
1.98
0.10
Boquillas
33
1.8
3.7
0.22
-
La Tuerta
18
1.3
7.9
0.88
-
La Perdida
21
3.8
3.6
0.17
-
Adai
18
1.1
9.0
0.95
-
Jenny
12
1.9
19.1
0.40
-
El Alto
9
1.7
13.8
0.64
-
Marmolina
13
0.2
46.2
0.86
7.91
Apart of the garnet-magnetite zones at the upper part of the skarn systems, structurally controlled mineralization exist in other prospects within the district. These mineralized structures consist of semi-tabular bodies of hematite-magnetite-wollastonite skarn, hematite-silica jasperoids, hematite-magnetite-marble breccias and brown calcite-hematite-silica veins in the uppermost parts of the zone. Precious metals mineralization has been found associated to all these prospects including La Perdida, Jenny and El Alto.
Chesapeake believes that the regional extent of the gold-copper skarn and favourable geological setting, provides an excellent opportunity to discover a significant polymetallic deposit in the Tatatila district. A mapping and sampling program is on-going in the district to prioritize targets for drilling. An airborne magnetic and electromagnetic survey is planned to define possibly new skarn developments and as well as extensions of existing prospects.
