Summary:
Regional Geology
The Pani Project is located within the Tertiary magmatic arc of North Sulawesi. This magmatic arc consists of preTertiary basement metamorphics and granitic intrusions unconformably overlain by late Tertiary volcanic and related sedimentary rocks. These consist of Oligo-Miocene submarine volcanics and sediments and late Miocene-Pliocene subaerial volcanics. Plio-Pleistocene rhyodacitic to andesitic volcanics punctuate this stratigraphic package forming caldera dome complexes, dyke swarms and diatremes.
Local Geology and Mineralisation
The Pani Gold Project licence areas overlie the Plio-Pleistocene, rhyodacitic Pani Volcanic Complex (PVC) that sits within a large circular feature interpreted to be a caldera of 25 km in diameter. Basement rocks compose the Eocene Tinombo Formation oceanic basalts to the north and younger Miocene granodiorite batholiths to the south and underneath the PVC. Much of the PVC is made of a series of flow-dome complexes and un-subdivided pyroclastic rocks. Stratigraphic correlation within the PVC is problematic due to the repetition of pyroclastic rocks, lava flows and flowdome complexes of the very same composition. There are several dome complexes (Ilota, Paceda, Tomula) recognised within the PVC but only the Baganite Dome hosts major, bulk epithermal gold mineralisation. The Baganite Dome consists of the following main lithostratigraphic units:
• Lapilli tuff,
• Baganite Dome, massive porphyritic rhyodacite,
• Baganite Dome, flow-banded rhyodacite,
• Baganite Dome, -related rhyodacite breccias,
• Pani Volcanic Complex, rhyodacitic host-rocks to the Baganite Dome.
A Geological Matrix Analysis (GMA) has confirmed previously reported observations that mineralisation is a low sulphidation epithermal mineralisation. Gold Mineralisation is associated with quartz ± pyrite ± goethite veins, silica alteration and goethite alteration and the tenor of the gold mineralisation increases as the silica alteration and frequency of veining or veinlets increase.
Local structures identified from field mapping are dominated by fractures, normal and strike slip faults with dominant orientations of ENE-WSW and NNE-SSW to N-S. These structures are moderate to steeply dipping to the west and appear to be a control on the mineralisation.
Alteration zones at Pani are differentiated based on descriptive mineralogy assemblages. There are 5 types recognised: undefined alteration/surface weathered (UA), clay ± chlorite (CYCH), clay ± silica (CYSI), silica ± chlorite (SICH) and silica ± clay (SICY). Mineralisation is associated with silica dominated alteration.
Gold mineralisation is associated with open space oxide - sulphide fracture fillings, stockwork veins, and narrow mosaic hydrothermal breccia within the dominantly silica altered host rock.
Silver domains were separated from gold domains. Silver mineralisation has no correlation, uncovered to date, with any geological parameters. It is assumed that silver deposited at lower temperature than gold in the periphery of the gold mineralisation.
Dimensions
The mineralisation at Pani sits between the surface and approximately 500 m below the surface. It is roughly circular in plan with a diameter of approximately 1,000 m and is contained within an intrusive rhyodacite dome complex (‘Baganite Dome’).