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Crater Mountain Project
Introduction
Crater Mountain is an advanced exploration project located in the Papua New Guinea Highlands approximately 50 kms southwest of Goroka and the sealed Highlands Highway which links Goroka to the port at Lae. Despite this relative proximity to a major populated centre and infrastructure the Crater Mountain area is rugged and remote with access from Goroka only by helicopter and small fixed wing aircraft. Previous exploration has been hampered by this poor access and the presence of volcanic ash deposits which obscure much of the prospective geology.
The project comprises three contiguous Exploration Licences [ EL 1115, EL 1353 and EL 1384] which have a combined area of approximately 428 square kilometres. Anomaly has entered into a joint venture with AIM-listed Triple Plate Junction plc (TPJ) and its minority partners whereby it will assume operatership and earn a minimum seventy percent holding in the project. A fully operational base camp with sleeping, office, storage, power and telecommunication facilities has been constructed at the Nevera Prospect.
Regional Geology and Mineralisation Potential
The Crater Mountain geology is structurally complex with all the hallmarks of a large mineralised system. It is highly prospective for world class multi-million ounce epithermal gold deposits and related base metal deposits. The geology is dominated by the Crater Mountain volcanic complex, one of a series of stratovolcanoes situated in the PNG thrust belt along the leading edge of the Australian Continental Plate. The volcanic complex is underlain by Cretaceous to Lower Tertiary aged marine sediments and includes two large craters over one kilometre in diameter, approximately thirty small vents along with hot springs and associated sub-volcanic intrusives spread over more than 200 square kilometres.
The volcanic complex was emplaced during two separate phases of volcanism. The older and more voluminous volcanic activity took place in the early Pliocene to early Pleistocene and is characterised by andesitic rocks ranging from porphyritic andesite lavas and agglomerates to volcanic breccia, tuffs and dioritic intrusive rocks. The latter volcanic phase is Holocene to Recent in age and is generally basaltic in composition with flows, scoria and ash fall deposits along with lahar flows which fill valleys in the older volcanics.
Mineralization is widespread within hydrothermal systems associated with the first phase of volcanism. The mineralisation systems have the potential to host world-class porphyry copper-gold and epithermal gold deposits in addition to related base metal deposits. In addition to widespread surface mineralisation all seventeen holes drilled to date contain evidence of alteration and mineralisation with two containing intervals of over 100 metres grading in excess of 1.40 g/t Au.
Previous Exploration
More than 30 years of exploration work by major and junior mining companies has provided an excellent data base to support new approaches to unlocking the mineralisation at Crater Mountain. Exploration began in 1970’s when Kennecott and later CRA explored the area for porphyry copper. While little attention was paid to the gold potential, the Nevera and Nimi Prospects were defined by anomalous base metals and gold anomalies. In the 1980’s Esso, City Resources and Highlands Gold explored the area for epithermal gold mineralisation leading to the delineation of the Awanita Prospect.
Macmin conducted a soil sampling program in 1995 which outlined zones of anomalous gold with a strike length in excess of 1,500 m and up to 600 m wide on the west flank of a dissected plateau in the northern part of the Nevera Prospect. BHP Minerals farmed into the project in 1995, conducting a program of gridding, geological mapping, geochemical sampling, petrographic sampling and a ground magnetic survey. The petrographic study suggested that the Nevera Prospect represents the top of a telescoped porphyry Cu-Au system. BHP drilled 3 holes at the Nevara Prospect with NEV 2 containing a 115m interval averaging 1.83 g/t Au ending in mineralisation. In 1998 BHP’s worldwide restructuring resulted in withdrawal from exploration in PNG and the Crater Mountain JV.
Macmin subsequently drilled a further 4 holes at the Nevara Prospect with the best intersection being 24m grading 6.55g/t Au. The project was joint ventured to Celtic Minerals and later to Triple Plate Junction plc who have been conducting field exploration since October 2004. TPJ drilled a further 10 holes at Nevera with the best intersection being 158 metres at 1.40 g/t Au.
TPJ concentrated exploration on the Nevera prospect with a conceptual target of epithermal gold associated with the margins of the Nevera diatreme but it was later realised that there was an unrecognised structural control on the mineralisation complicating the diatreme margin model.
In March 2007 Macmin confirmed that TPJ and Celtic Minerals had earned a 75% interest in the joint venture after expenditure of $C4 million. TPJ elected to seek a farm out and Anomaly farmed into the project.
Prospects
Nevera
Nevera is the most advanced of the prospects at Crater Mountain and all 17 holes drilled to date have been at Nevera. Alteration and mineralisation at the Nevera Prospect are hosted in Cretaceous-aged basement sediments, the overlying Crater Mountain andesitic volcanics and a dacitic diatreme dome complex which intrudes the sediments and volcanics at the intersection of a major NE-trending transfer structure [the Nevera Fault ] and a number of NW-orientated structures.
The diatreme-dome complex is approximately 700m x 1200m in dimensions and associated with geochemical anomalies along its east, west and north margins which each individually have similar dimensions to the combined A, B and Link zones at the Wafi River deposit some 100 Kilometres to the north east. Mineralisation at Wafi River (total resource 72.2 Mt @ 2.72 g/t gold) is associated with the margins of a diatreme complex where intersected by NE trending structures and thus serves as a model for mineralisation at Nevera.
It is proposed that mineralised magmatic fluids from depth have migrated up the diatreme margins and along the Nevera fault and mixed with descending ground waters forming an early phase of low-grade gold–copper mineralisation in pyrite quartz veins and a later stage of carbonate-base metal-gold mineralisation. Sulphide mineralisation at Nevera is associated with intense silica, argillic and carbonate alteration concentrated along structures. Most of the drilling was aimed at testing the Nevera Fault and diatreme margins. Better drill intersections included ;
115 metres at 1.83 g/t Au 24 metres at 6.55 g/t Au 25.5 metres at 2.36 g/t Au
158 metres at 1.40 g/t Au 19 metres at 1.30 g/t Au 13.9 metres at 1.97 g/t Au
Significantly a zone of intense hematite alteration approximately 500 x 500 metres in extent and up to 30 metres thick [“the hematite cap”] has been identified overlying the dacite diatreme but to the west of the main area of drilling and apparently not related to the Nevera fault. A number of highly mineralised trenches have been excavated in this area, including ;
48 metres at 10.20 g/t Au, 26.5 metres at 6.27 g/t Au , 35 metres at 3.10 g/t Au
54 metres at 1.21 g/t Au, 20 metres at 1.10 g/t Au
Local artisinal miners are mining high grade supergene gold from narrow quartz-hematite-manganese veins and reportedly producing up to 4 kg of gold per week. This zone has not been adequately drill tested and is an obvious target for initial drilling.
Nevera South, South West and West Anomalies
Several prospects have been identified near the main Nevera prospect. The Nevera Southwest Prospect about 2.5 kms southwest of Nevera has significant lead [up to 13.2%], zinc [up to 33.31%], silver [up to 453 g/t Au] and anomalous gold [up to 0.6 g/t] values collected from rock float. Trenching by TPJ returned significant silver and base metal values including ;
6m at 0.25 g/t Au, 163 g/t Ag, 9.74 %Pb, 12.43 Zn
6m at 0.50 g/t Au, 225 g/t Ag, 3.02 %Pb, 7.56 Zn
4m at 0.17 g/t Au, 298 g/t Ag, 1.33 %Pb, 0.70 Zn
The last drill hole [NEV17] drilled by TPJ was drilled at this site but failed to intersect any significant mineralisation. It was concluded the hole had been collared in the hanging wall and orientated parrallel to the mineralised zone.
The Nevera West Prospect is defined by a northwest trending zone of arsenic in soil with erratic but anomalous lead, zinc and gold values. At Nevera South, 2 to 3 kilometres south of the main drilled area, pan concentrate stream values of 2.56 g/t gold and 86.3 g/t silver were collected but there has been no follow up.
Nimi Prospect
The Nimi Prospect is located approximately 10 kms southwest of Nevera in a similar geological setting characterised by basement sediments, Crater Mountain volcanics and a diorite intrusive approximately one kilometre in diameter located in the eastern part of the area. The prospect was located by stream sediment and rock chip sampling but has never been drilled. Rock chip sample values are highly anomalous in gold [up to 7.10 g/t], silver [up to 1,060 g/t], copper [up to 1.3%], lead [up to 6.4%] and zinc [up to 15.65%].
Mineralisation and alteration is controlled by two main structural trends [NNW and ENE] characterised by broad zones of chlorite and clay chlorite alteration containing zones of fracturing associated with intense sericite-silica-clay-pyrite alteration. Alteration is concentrated at the intersection of the two zones and most of the mineralised rock chip samples were collected from this area. Mineralisation is dominated by pyrite with subordinate amounts of galena, sphalerite, chalcopyrite and chalcocite. Gold mineralisation is hosted in breccias and shear hosted quartz-carbonate (calcite and rhodocrosite) – gold - base metal veins. Within individual outcrops, gold mineralisation is confined to discrete 1-50 cm fault-fracture zones and appears to broadly correlate with base metal mineralisation.
Masi Creek
Masi Creek is located approximately 3 km due east of the main Nevera Prospect in a similar geological setting consisting of basement sediments and a volcanic pile intruded by several distinct phases of felsic to intermediate intrusives with porphyry copper style alteration and mineralization present. Disseminated and fracture controlled pyrite and chalcocite mineralization is extensive within the altered intrusives and contact zones of the different intrusive phases.
The prospect area appears to be centred on the intersection of NW and SW structural corridors with the intrusives located within a possible graben along the NW structural trend. Anomalous sample returns included stream sediment assays of 0.905, 0.706, 0.190, and 0.156 g/t gold and rock chip assays up to 2.81 g/t gold, 3.25% zinc and 11.2 g/t silver. The prospect has never been drilled.
Awaunita
The Awaunita prospect is located 8 km due east of the Nevera prospect. The geology of the prospect is defined by an extensively argillised diorite stock consisting of three individual bodies intruding overlying volcanics and sediments. The area was initially defined by three panned concentrate samples from the headwaters of a single drainage which assayed 430 ppm, 255 ppm and 180 ppm respectively. Gold assay results from follow up programs returned low level gold with occasional elevated base metal and pathfinder geochemistry. There has been little recent exploration in the area and the prospect has never been drilled.
Conclusion
Previous exploration at Crater Mountain has been conducted by a number of different companies aimed at different commodities using a variety of different geological models. Anomaly Resources is conducting three simultaneous initial exploration programs on the Crater Mountain tenements ahead of a comprehensive drilling program. The current exploration includes;
1. Compilation and re-evaluation of all regional exploration data combined with the acquisition of remote sensing data and detailed aerial photography. Structural and alteration mapping will be conducted along with in-fill regional sampling in order to develop an integrated overview of the entire mineralisation system.
2. Detailed re-appraisal including further trenching, soil and rock geochemistry along with ground geophysical surveys of all known prospects and mineralized areas prior to initial drill testing.
3. Detailed exploration of the Nevera prospect involving structural mapping, alteration mapping and ground geophysics [IP and ground magnetics] and the development of a three D computerised model prior to further drilling. Drilling will be conducted at targets generated by this work along with the known but untested targets such as the hematite cap and the Nevera South-West silver-base metal mineralisation.
Crater Mountain is an advanced exploration project located in the Papua New Guinea Highlands approximately 50 kms southwest of Goroka and the sealed Highlands Highway which links Goroka to the port at Lae. Despite this relative proximity to a major populated centre and infrastructure the Crater Mountain area is rugged and remote with access from Goroka only by helicopter and small fixed wing aircraft. Previous exploration has been hampered by this poor access and the presence of volcanic ash deposits which obscure much of the prospective geology.
The project comprises three contiguous Exploration Licences [ EL 1115, EL 1353 and EL 1384] which have a combined area of approximately 428 square kilometres. Anomaly has entered into a joint venture with AIM-listed Triple Plate Junction plc (TPJ) and its minority partners whereby it will assume operatership and earn a minimum seventy percent holding in the project. A fully operational base camp with sleeping, office, storage, power and telecommunication facilities has been constructed at the Nevera Prospect.
Regional Geology and Mineralisation Potential
The Crater Mountain geology is structurally complex with all the hallmarks of a large mineralised system. It is highly prospective for world class multi-million ounce epithermal gold deposits and related base metal deposits. The geology is dominated by the Crater Mountain volcanic complex, one of a series of stratovolcanoes situated in the PNG thrust belt along the leading edge of the Australian Continental Plate. The volcanic complex is underlain by Cretaceous to Lower Tertiary aged marine sediments and includes two large craters over one kilometre in diameter, approximately thirty small vents along with hot springs and associated sub-volcanic intrusives spread over more than 200 square kilometres.
The volcanic complex was emplaced during two separate phases of volcanism. The older and more voluminous volcanic activity took place in the early Pliocene to early Pleistocene and is characterised by andesitic rocks ranging from porphyritic andesite lavas and agglomerates to volcanic breccia, tuffs and dioritic intrusive rocks. The latter volcanic phase is Holocene to Recent in age and is generally basaltic in composition with flows, scoria and ash fall deposits along with lahar flows which fill valleys in the older volcanics.
Mineralization is widespread within hydrothermal systems associated with the first phase of volcanism. The mineralisation systems have the potential to host world-class porphyry copper-gold and epithermal gold deposits in addition to related base metal deposits. In addition to widespread surface mineralisation all seventeen holes drilled to date contain evidence of alteration and mineralisation with two containing intervals of over 100 metres grading in excess of 1.40 g/t Au.
Previous Exploration
More than 30 years of exploration work by major and junior mining companies has provided an excellent data base to support new approaches to unlocking the mineralisation at Crater Mountain. Exploration began in 1970’s when Kennecott and later CRA explored the area for porphyry copper. While little attention was paid to the gold potential, the Nevera and Nimi Prospects were defined by anomalous base metals and gold anomalies. In the 1980’s Esso, City Resources and Highlands Gold explored the area for epithermal gold mineralisation leading to the delineation of the Awanita Prospect.
Macmin conducted a soil sampling program in 1995 which outlined zones of anomalous gold with a strike length in excess of 1,500 m and up to 600 m wide on the west flank of a dissected plateau in the northern part of the Nevera Prospect. BHP Minerals farmed into the project in 1995, conducting a program of gridding, geological mapping, geochemical sampling, petrographic sampling and a ground magnetic survey. The petrographic study suggested that the Nevera Prospect represents the top of a telescoped porphyry Cu-Au system. BHP drilled 3 holes at the Nevara Prospect with NEV 2 containing a 115m interval averaging 1.83 g/t Au ending in mineralisation. In 1998 BHP’s worldwide restructuring resulted in withdrawal from exploration in PNG and the Crater Mountain JV.
Macmin subsequently drilled a further 4 holes at the Nevara Prospect with the best intersection being 24m grading 6.55g/t Au. The project was joint ventured to Celtic Minerals and later to Triple Plate Junction plc who have been conducting field exploration since October 2004. TPJ drilled a further 10 holes at Nevera with the best intersection being 158 metres at 1.40 g/t Au.
TPJ concentrated exploration on the Nevera prospect with a conceptual target of epithermal gold associated with the margins of the Nevera diatreme but it was later realised that there was an unrecognised structural control on the mineralisation complicating the diatreme margin model.
In March 2007 Macmin confirmed that TPJ and Celtic Minerals had earned a 75% interest in the joint venture after expenditure of $C4 million. TPJ elected to seek a farm out and Anomaly farmed into the project.
Prospects
Nevera
Nevera is the most advanced of the prospects at Crater Mountain and all 17 holes drilled to date have been at Nevera. Alteration and mineralisation at the Nevera Prospect are hosted in Cretaceous-aged basement sediments, the overlying Crater Mountain andesitic volcanics and a dacitic diatreme dome complex which intrudes the sediments and volcanics at the intersection of a major NE-trending transfer structure [the Nevera Fault ] and a number of NW-orientated structures.
The diatreme-dome complex is approximately 700m x 1200m in dimensions and associated with geochemical anomalies along its east, west and north margins which each individually have similar dimensions to the combined A, B and Link zones at the Wafi River deposit some 100 Kilometres to the north east. Mineralisation at Wafi River (total resource 72.2 Mt @ 2.72 g/t gold) is associated with the margins of a diatreme complex where intersected by NE trending structures and thus serves as a model for mineralisation at Nevera.
It is proposed that mineralised magmatic fluids from depth have migrated up the diatreme margins and along the Nevera fault and mixed with descending ground waters forming an early phase of low-grade gold–copper mineralisation in pyrite quartz veins and a later stage of carbonate-base metal-gold mineralisation. Sulphide mineralisation at Nevera is associated with intense silica, argillic and carbonate alteration concentrated along structures. Most of the drilling was aimed at testing the Nevera Fault and diatreme margins. Better drill intersections included ;
115 metres at 1.83 g/t Au 24 metres at 6.55 g/t Au 25.5 metres at 2.36 g/t Au
158 metres at 1.40 g/t Au 19 metres at 1.30 g/t Au 13.9 metres at 1.97 g/t Au
Significantly a zone of intense hematite alteration approximately 500 x 500 metres in extent and up to 30 metres thick [“the hematite cap”] has been identified overlying the dacite diatreme but to the west of the main area of drilling and apparently not related to the Nevera fault. A number of highly mineralised trenches have been excavated in this area, including ;
48 metres at 10.20 g/t Au, 26.5 metres at 6.27 g/t Au , 35 metres at 3.10 g/t Au
54 metres at 1.21 g/t Au, 20 metres at 1.10 g/t Au
Local artisinal miners are mining high grade supergene gold from narrow quartz-hematite-manganese veins and reportedly producing up to 4 kg of gold per week. This zone has not been adequately drill tested and is an obvious target for initial drilling.
Nevera South, South West and West Anomalies
Several prospects have been identified near the main Nevera prospect. The Nevera Southwest Prospect about 2.5 kms southwest of Nevera has significant lead [up to 13.2%], zinc [up to 33.31%], silver [up to 453 g/t Au] and anomalous gold [up to 0.6 g/t] values collected from rock float. Trenching by TPJ returned significant silver and base metal values including ;
6m at 0.25 g/t Au, 163 g/t Ag, 9.74 %Pb, 12.43 Zn
6m at 0.50 g/t Au, 225 g/t Ag, 3.02 %Pb, 7.56 Zn
4m at 0.17 g/t Au, 298 g/t Ag, 1.33 %Pb, 0.70 Zn
The last drill hole [NEV17] drilled by TPJ was drilled at this site but failed to intersect any significant mineralisation. It was concluded the hole had been collared in the hanging wall and orientated parrallel to the mineralised zone.
The Nevera West Prospect is defined by a northwest trending zone of arsenic in soil with erratic but anomalous lead, zinc and gold values. At Nevera South, 2 to 3 kilometres south of the main drilled area, pan concentrate stream values of 2.56 g/t gold and 86.3 g/t silver were collected but there has been no follow up.
Nimi Prospect
The Nimi Prospect is located approximately 10 kms southwest of Nevera in a similar geological setting characterised by basement sediments, Crater Mountain volcanics and a diorite intrusive approximately one kilometre in diameter located in the eastern part of the area. The prospect was located by stream sediment and rock chip sampling but has never been drilled. Rock chip sample values are highly anomalous in gold [up to 7.10 g/t], silver [up to 1,060 g/t], copper [up to 1.3%], lead [up to 6.4%] and zinc [up to 15.65%].
Mineralisation and alteration is controlled by two main structural trends [NNW and ENE] characterised by broad zones of chlorite and clay chlorite alteration containing zones of fracturing associated with intense sericite-silica-clay-pyrite alteration. Alteration is concentrated at the intersection of the two zones and most of the mineralised rock chip samples were collected from this area. Mineralisation is dominated by pyrite with subordinate amounts of galena, sphalerite, chalcopyrite and chalcocite. Gold mineralisation is hosted in breccias and shear hosted quartz-carbonate (calcite and rhodocrosite) – gold - base metal veins. Within individual outcrops, gold mineralisation is confined to discrete 1-50 cm fault-fracture zones and appears to broadly correlate with base metal mineralisation.
Masi Creek
Masi Creek is located approximately 3 km due east of the main Nevera Prospect in a similar geological setting consisting of basement sediments and a volcanic pile intruded by several distinct phases of felsic to intermediate intrusives with porphyry copper style alteration and mineralization present. Disseminated and fracture controlled pyrite and chalcocite mineralization is extensive within the altered intrusives and contact zones of the different intrusive phases.
The prospect area appears to be centred on the intersection of NW and SW structural corridors with the intrusives located within a possible graben along the NW structural trend. Anomalous sample returns included stream sediment assays of 0.905, 0.706, 0.190, and 0.156 g/t gold and rock chip assays up to 2.81 g/t gold, 3.25% zinc and 11.2 g/t silver. The prospect has never been drilled.
Awaunita
The Awaunita prospect is located 8 km due east of the Nevera prospect. The geology of the prospect is defined by an extensively argillised diorite stock consisting of three individual bodies intruding overlying volcanics and sediments. The area was initially defined by three panned concentrate samples from the headwaters of a single drainage which assayed 430 ppm, 255 ppm and 180 ppm respectively. Gold assay results from follow up programs returned low level gold with occasional elevated base metal and pathfinder geochemistry. There has been little recent exploration in the area and the prospect has never been drilled.
Conclusion
Previous exploration at Crater Mountain has been conducted by a number of different companies aimed at different commodities using a variety of different geological models. Anomaly Resources is conducting three simultaneous initial exploration programs on the Crater Mountain tenements ahead of a comprehensive drilling program. The current exploration includes;
1. Compilation and re-evaluation of all regional exploration data combined with the acquisition of remote sensing data and detailed aerial photography. Structural and alteration mapping will be conducted along with in-fill regional sampling in order to develop an integrated overview of the entire mineralisation system.
2. Detailed re-appraisal including further trenching, soil and rock geochemistry along with ground geophysical surveys of all known prospects and mineralized areas prior to initial drill testing.
3. Detailed exploration of the Nevera prospect involving structural mapping, alteration mapping and ground geophysics [IP and ground magnetics] and the development of a three D computerised model prior to further drilling. Drilling will be conducted at targets generated by this work along with the known but untested targets such as the hematite cap and the Nevera South-West silver-base metal mineralisation.
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