TORONTO, ONTARIO -- (Marketwired) -- 04/22/13 -- Lago Dourado Minerals Ltd. (TSX VENTURE: LDM), (the "Company") is pleased to provide an exploration update on its flagship 100%-owned Juruena Project located in Mato Grosso, Brazil. Three drill holes have now been completed at the previously untested Arrastro Hills porphyry-epithermal target. Assay results have been received for the first drill hole while alteration analyses (SWIR spectral analysis was conducted by the MDRU) from the first two drill holes and also grab samples across the Arrastro Hills target area have also been received and integrated with the soil sample data.
Forbes Gemmell, President & CEO, said, "The results from the initial drilling at Arrastro Hills and the SWIR study not only confirm the porphyry-epithermal geological model for Arrastro Hills but also provides us with a much better understanding of the zonation of the system. This zonation suggests that the Arrastro Hills South East target is the higher temperature part of the system which, in many porphyry systems, is located proximal to the porphyry centre. We look forward to drill testing this new target in the coming weeks."
The key takeaway points from the initial drill holes and the SWIR sample data are outlined below and a schematic with the key geochemical and geophysical data, alteration data and drill hole locations is provided in Figure A.
-- Geological logging, SWIR alteration analysis and assay results (where received) have confirmed that the Arrastro Hills alteration system represents a large porphyry intrusive complex as evidenced by the multiple intrusive types and zones of brecciation, the diversity and type of alteration minerals and the presence of disseminated sulfides. Most importantly, it has been confirmed that the underlying porphyry system is mineralized as evidenced by drill hole JRND065, the first hole drilled at Arrastro Hills, which intercepted 118m @ 3.0g/t Ag as well as anomalous levels of Pb and Zn. The presence of these co-incident mobile elements suggests the central part of Arrastro Hills, the focus of the first three drill holes, is an outflow area, either above or peripheral to the causative porphyry intrusive.-- An extensive alteration mineral study consisting of more than 230 samples was recently completed by the MDRU. The study suggested that the Arrastro Hills South East porphyry target area is the most prospective target based on the presence of phengite, which is characteristic of a higher temperature part of the system that may represent an exposed part of a porphyry system. The study also found a strong association between phengite and gold mineralization at known mineralized zones elsewhere at Juruena, including the Crentes, Tomate and Uiliam zones. The types of alteration minerals (predominantly K-rich muscovite) in the central part of the Arrastro Hills are typical of an outflow region above or peripheral to a mineralised porphyry intrusion. This conclusion is also consistent with the anomalous Ag-Pb-Zn intercepted in JRND065 from this same area.-- The initial three diamond drill holes from the central part of Arrastro Hills all intercepted a thick homogeneous pile of volcanic units (minimum thickness of at least 250 metres). The top part of the volcanic sequence is represented by a silica cap whilst at depth the volcanic rocks were strongly brecciated, fractured, intensely altered and contained a variable amount of sulfides, the product of circulating sulfide-rich fluids from the underlying intrusive units. The thickness of the volcanic pile is encouraging as it provides an ideal host rock environment to trap mineral rich fluids above a gold-rich mineralized intrusive. Drilling also intercepted multiple intrusive bodies of varying composition from felsic to mafic, confirming the underlying magmatic activity was long lasting and dynamic in nature, the type of geological setting that is required to form a porphyry type deposit.