DIOS EXPLORATION reports a significant field work discovery: a hydrothermal-magmatic breccia pipe, ROBINO, was found and yields up to 37grams gold per ton, 14 grams silver per ton with bismuth and molybdenum association, highest value ever discovered on the property, some 3.5 kilometers from main Heberto gold showing, a major breakthrough in exploring and understanding DIOS'AU33 road accessible gold property, James Bay, QC.
The HEBERTO gold showing returned up to 5.18 g/t gold /5 meters (true width) in channel sampling and is composed of disseminated pyrite along small quartz-sericite stringers in a quartz diorite. This showing is coincidental with a weak 1 kilometer long north-south induced polarization conductor near the margin of a sub-circular magnetic anomaly, itself enclosed within a low magnetic one.
ROBINO shows the same structure orientation as Heberto and an anomalous gold content (0.1 to 37.6 g/t gold). It has a 30 m x 40 m sub-circular outcrop surface expression, is open to the northwest and coincidental with an ovoid 400 m x 250 m low magnetic anomaly (characteristic of magnetite destruction associated to alteration).
The ROBINO breccia pipe shows different facies including a CORE BRECCIA, surrounded by a MICROBRECCIA intruding a fractured-altered (sericite-silica) granodiorite. The system is intruded by mafic ring-dykes and dykes. Laterally, ROBINO goes from mineralized quartz-sericite stockworks to breccias, possibly hinting the same lateral set-up for Heberto (the presence of a nearby mineralized breccia at Heberto also).
CORE BRECCIA: 10-20% interstitial rock flour matrix with 1-2% pyrite and 80-90% subangular tonalite fragments
MICROBRECCIA: 5-7% well-rounded clasts (fragments) in tonalitic matrix
Another hydrothermal breccia (Mitsumis) was also observed 5 km east of Heberto (biotite-quartz-pyrite stockworks, locally anomalous gold (up to 0.5 g/t gold) in quartz diorites like Heberto.
GOOD INDICATORS OF A LARGE MINERALIZED SYSTEM are the presence of concentric structures associated with mineralized brittle ones and magmatic-hydrothermal breccia pipes (both suggestive of buried magmatic domes), the juxtaposition of alterations halos, the significant regional gold in till train, and the anomalous gold background in the fractured intrusive rocks. The Heberto area geological environment suggests a structurally-controlled oxidized (IRG) intrusion-related gold system.
Exploration will focus on drilling the Heberto targets and neighbouring hydrothermal-magmatic breccia pipes. Top priority-targets include:
1- Heberto target, 1 km-long I.P. chargeability anomaly, quartz-sericite-pyrite stockworks possibly grading into breccia;
1a- North Heberto sub-circular low magnetic anomaly corresponding to altered zone under small lake along Heberto structure;
1b-South Heberto sub-circular low magnetic anomaly corresponding to altered zone under small lake along Heberto structure;
2-Robino hydrothermal-magmatic breccia coincidental with a well-defined ovoid low magnetic anomaly;
3-Mitsumis hydrothermal breccia pipe coincidental with a low magnetic anomaly.
4-Other possible breccia pipe magnetic targets along lineaments.
In Archean geological context, such gold systems are generally associated with small high-level stock with calc-alkaline (to alkaline) volcanism and breccia formation. Such magmatic-hydrothermal environment includes structures in the brittle rocks overlying batholitic system that focus magma ascent and fluid flow into narrow apex regions (or cupolas) (Tosdal and Richards, 2001, Richards 2011). Shallow crustal magma emplacement may cause doming in the cover rocks, with dilational fault zones providing high-permeability pathways for fluids and magma ascent. Cylindrical shapes of many porphyry stocks may have arisen first as breccia pipes or diatremes bored out by rapidly escaping volatiles, only later to be back-filled with porphyritic magma (stocks and dykes). Such high-permeability pathways are likely to have thermally weaken the wall-rocks and promote further fracturing and channeling for metals.
This press release was prepared par M.J. Girard, M.Sc.Geo, 43-101 QP.