Above Rocks Project: technical data
The Project: Rodinia Jamaica Limited (“Rodinia”), which is 100% owned by Carube Resources Inc of Canada, has a 100 percent interest in the Mt Royal Special Exclusive Prospecting License (SEPL) 552 and the Belvedere SEPL 550 which together are 104 km2. Together the Mt Royal and Belvedere SEPLs cover a significant portion of the Cretaceous Above rocks inlier ("ABI") located in east-central Jamaica (Map 1). It consists of Cretaceous rocks of the (a) Mt. Charles Formation, a sedimentary package likely formed during uplift prior to and during island arc formation (b) the Border Volcanic Group, erupted during arc volcanism. These rocks have been intruded by Cretaceous–Early Tertiary Above Rock Intrusions The most easterly portions of the SEPLs cross into the western edge of the Wagwater Belt which marks the limit of the ABI and is considered to be a normal fault, which may have been subjected to some recent (late Cenozoic) reverse movements.
Exploration work was first reported in the ABI at Jobs Hill in the 1860s; the actual work completed is unknown. Three adits and one shaft were completed at Allman Hill in the early 1900s, but no results were recorded. Again in the 1930s, Alcolex sunk three shafts and one adit at Jobs Hill.
Exploration employing relatively modern geochemical techniques began seriously in 1956 when Burrex Mines Ltd (“Burrex”) started collecting soil and sediment samples in the Above Rocks Inlier. This was continued by Noranda Exploration Co Ltd. (“Noranda”), Denison Mines Ltd (“Denison”) and Cominco Ltd (“Cominco”) through to 1971; trenching and core drilling was also part of these campaigns. From time to time, the Geological Survey of Jamaica would conduct in-stream sediment and bedrock sampling. A summary of above rocks exploration can be found in figure 1.
Exploration was again reinvigorated for the period from 1986 to 1994 due to anomalies found by the Canadian International Development Agency (“CIDA”) in their stream sediment sampling of the Cretaceous Inliers in Jamiaca; companies involved were Jam-Can Resources Inc (“Jam-Cam), Geofine (Jamaica) Limited and/or Geofine Exploration Consultants Ltd (“Geofine”), Noranda Exploration Co Ltd (“Noranda”), Denison Mines Ltd (“Denison”), Clarendon Mining Limited (“Clarendon”) , and BHP–Utah International Exploration Inc (“BHP”).
Geology and Mineralization
Regional Geology: Jamaica is a part of the Greater Antilles island arc system, situated on the northern Caribbean Plate margin, which is sliding eastward along the North American Plate. Hispaniola, Puerto Rico and Jamaica all lay on the northern margin of the Caribbean Plate. Most geologists believe that the three islands have similar stratigraphy and metallogeny, which opens the potential for porphyry Cu deposits in Jamaica similar to those in Puerto Rico and major gold deposits, such as Pueblo Viejo in the Dominican Republic. Jamaica is an emergent part of the Nicaraguan Rise, a broad, anticlinal, dominantly submerged belt of crustal thickening extending from Honduras to east of Jamaica.
Jamaica itself is comprised of three major groups of rocks:
The Cretaceous basement complex consists of volcanic, volcaniclastics and associated intrusive and coarse clastics. It is believed that the volcaniclastics represent an eroded island arc system. At the end of the Cretaceous period, the basement was uplifted, resulting in an unconformity making the Cretaceous-Tertiary boundary.
The Tertiary white and yellow limestones, unconformably overlying the Cretaceous basement complex and conformably overlying Cretaceous trough sediments, cover approximately 70% of the island. Intrusive activity was confined largely to the Cretaceous, Paleocene and Miocene, with major deformation occurring during the early Tertiary.
In areas where the limestone cover is breached, the older sedimentary, igneous and metamorphic rocks are exposed through windows known as inliers. There are seven major and twenty-one minor inliers on Jamaica. The three largest are the Blue Mountain the Central, and the Lucea Inliers. The Above Rocks Inlier is 30km by 11km and lies in eastern central Jamaica. It is bounded to the east by the Wagwater belt.
Above Rocks Inlier Geology: The Above Rocks Inlier, one of several Cretaceous inliers on the island. The inlier consists of the Above Rocks Intrusion and its metamorphosed host rocks, the Cretaceous Mt Charles Formation and Border Volcanic Group. The Mt Charles Formation, considered to be the oldest unit in the area, is found in contact with and as small roof pendants in the above rocks intrusions. It consists of blue or green-gray bedded siltstone sandstone and conglomerate. The Border Volcanic Group is comprised of andesitic volcaniclastics, lavas and conglomerates. The lavas are commonly porphyritic and exhibit flow-banding and some brecciation. These formations are cut by the Above Rocks Intrusion (Map 2) a somewhat heterogeneous body with rock types in the granodiorite–quartz monzonite composition range. Narrow granodiorite dykes, up to several hundred metres in length, have been found cutting the Intrusion and the Mt. Charles Formation.
The steeply dipping Wagwater Fault cuts the eastern extent of the Above Rocks inlier, separating it from the Paleocene–Eocene rift-basin volcanic rock and alluvial fan siliciclastic rock of the Wagwater Formation.
Above Rocks Inlier Mineralization and Alteration: Most deposits within the Above Rocks Inlier can be related to periods of compression and extension, fault movement, sub-volcanic intrusions and volcanic activity resulting from subduction, crustal thickening and the relative movement of different continental plates. Likely significant deposit types given the geological setting and results from previous exploration are:
Identified Mineralized Trends: Many of the mineral prospects in the Mt Royal and Belvedere properties (Map 3) are associated with structures (e.g., Jobs Hill—Wagwater fault) or intrusions (e.g., Allman Hill) of late Cretaceous–early Tertiary age. Copper and gold, and to a lesser extent silver and zinc, are the ore minerals that have been noted consistently throughout the Above Rocks Inlier.
At Glengoffe the mineralization is primarily disseminated pyrite, chalcopyrite, hematite, malachite and bornite within highly altered (quartz-sericite and quartz-Kspar-biotite) tonalite. The tonalite has been intruded into altered (quartz-sericite) granodiorites. Quartz-carbonate veins cutting pyrite siltstones are also present. One hundred and sixty eight metres of trenching on the tonalite at Glengoffe averaged 0.35% Cu.
Near Freetown, copper mineralization in the form of lenticular quartz veins bearing pyrite (1-5%), chalcopyrite and bornite can be present in shear zones cutting both volcanics and intrusives. In other cases it is simply pyrite, chalcopyrite, magnetite, hematite, disseminated and in fine fractures. There is a general absence of quartz veins although locally quartz veining and silicification in the form of fine sheeted quartz veins are present. The vein zones have E-W and NW-SE orientations. Anomalous molybdenum was noted in some weathered outcrop near Freetown.
Sue River North–Lucky River
Mineralization in this area appears to be related mainly to faulted and fractured Border Volcanics bordering Wagwater faults and showing quartz-epidote alteration. Pyrite veins of 2-4cm width and pebbly chalcopyrite compose the visible mineralization. Quartz-calcite-bornite-chalcocite veins are also present within both the volcanics and granodiorite. Copper values of the better mineralized samples generally exceed 0.5%; anomalous zinc and silver are present and gold to 6670 ppb has been recorded. The tectonized zones may exceed of 10 m in width.
Mineralization is typically magnetite skarn style replacement with associated chalcopyrite, now oxidized to goethite, malachite, brochantite, chrysocolla, azurite, cuprite, tessorite and neotocite. The oxide minerals may be in part due to secondary enrichment. Coarse-crystalline mesothermal quartz can be associated with the magnetite and chalcopyrite. The mineralization shows “quartz-magnetite-chalcopyrite centrally, grading outwards to ± molybdenum, then massive magnetite (± epidote) to magnetite chlorite, and then chlorite dominates, with a relatively sharp and sudden decrease in alteration intensity to barren granite”.
The “primary copper mineralization in the Stony River area [east part of Allman Hill area] appears to be associated with the granodiorite-sediment contact in all cases, and consists of lenses and veins of magnetite and copper minerals coating fractures and shears at N80E, with a buildup where this system intersects the granodiorite sediment contact zones”. The granodiorite rocks can be highly silicified. Both the veins and the silicified granodiorites commonly yield copper values in excess of 1%. Lead and zinc contents can also be anomalous.
Mineralization at Jobs Hill is complex. As observed by Tigers Realm geologists, it can be divided into three types: (1) malachite ± magnetite ± chalcocite filling fractured volcanic host rocks, (2) quartz-pyrite-chlorite filling breccia, and (3) malachite-neotocite ± manganese (oxide). Much of the malachite may be secondary. The mineralization that parallels a major shear zone marked by a slice of granodiorite can yield copper grades well over 1%; high grade veins of massive malachite can grade over 5%. Values of 500 ppb Au and up to 310 ppm Ag have been recorded from Jobs Hill grab samples, but the continuity and extent of precious metal mineralization is not clear
Kingsweston and Providence
Three styles of mineralization have been observed at Kingsweston and Providence: (1) malachite, chalcosite, hematite in shear zones (assays from a bulk sample yielded 0.24% Cu), (2) andesite hosting quartz veins and (3) disseminated sulphides within monzodiorite. Other than the results from the assayed bulk sample above no significant base or precious metal values have been encountered.
The high grade mineralization at Mount Friendship appears to be limited to fractured andesitic volcanic clasts. It consists mainly of malachite-brochantite ± chrysocolla ± pyrite ± hematite filling the fractures and coating the clasts. Sheared and weathered clasts of propylitically altered granodiorite are also mineralized. Copper grades for the most part exceed one percent.
HISTORIC EXPLORATION AT ABOVE ROCKS
The exploration history of the Above Rocks inlier is extensive involving at least 12 separate entities over an 80 year period on 9 separate anomalies, the companies involved and work completed is summarized in Figure 1.
Rodinia digitized most of the geochemical stream data available from the Geological Survey’s archives; much of the data was from a joint venture between BHP and Clarendon. Based on this analysis, a number of areas were identified that were anomalous in Au, Mo, Cu, Pb, Zn, Ag and Sb. Generally, these confirmed known prospects and together with the geology indicated that the area was prospective for “porphyry-type” and related deposits.
Stream and Soil Geochemistry: Geochemistry has been a primary means of delineating areas of potential mineralization in Jamaica. Results of surveys cannot always be located, but the following surveys delineated or defined mineralization:
Above Rocks: In 1986, CIDA conducted regional scale stream sediment sampling over Jamaica's Cretaceous inliers and numerous metallic anomalies were defined within the Above Rocks Inlier, including a broad Cu anomaly at 10 sample sites near Glengoffe, a Te-Sb anomaly at 2 sample sites near Jobs Hill, and an Au-Ag-Pb anomaly at 3 sample sites near Temple Hall–Mt Friendship. Chris Gleeson also analyzed the data and defined a broad Au anomaly that extends E–W across the Belvedere SEPL, and a broad Au anomaly centered east of the SEPLs that extends into the Temple Hall–Mt Friendship area.
Geophysics: Regional geophysical surveys have been completed over Jamaica and over the Above Rocks Inlier. Rodinia has reprocessed them: the two SEPLs herein lie along the NE edge of a complex magnetic high and the southern edge of a gravity high.
Local surveys over individual prospects are few, with only the magnetometer survey completed by Clarendon in 1994 being a systematic and meaningful survey. They completed two grids at Allman Hill, one 500 m by 350 m and the other 800 m by 2,000 m. The results appear to show values and patterns related to (i) underlying lithologies and (ii) structural trends; correlation with the surface geochemical patterns is limited, suggesting a near surface change in rock type. The magnetometer survey of Noranda's Allman Hill East Grid does not coincide closely with Noranda's copper in soils (Cu) for the same area. The Cu contours have a north-easterly trend within a broad triangle having its apex near the northwest corner of the grid. On the other hand, the magnetic contours, specifically in areas of elevated readings, seem to define broad areas (possibly subsurface intrusive bodies). The upper area of elevated readings forms a tilted U shape with the westerly limb projecting to a similar elevated area of Noranda's westerly grid where samples of altered sulphide-rich granodiorite gave values of 1.33 to 4.64% Cu during a due diligence property review.
Drilling: All exploration drilling pre-dates 1969. Twenty one cored drill holes totalling 1470 m and 24 augured holes ranging between 1.2 and 8.5 m in depth have been completed and recorded. Most drilling was completed at Jobs Hill and Allman Hill.
*Diamond drill holes (unless noted)
**Short (4– 28 ft) auger holes drilled to test for low-grade mineralization
paralleling a granodiorite dyke
Mining: There are records of at least 3 adits and 1 shaft completed for exploration purposes in the 1930’s the extent and repair of this development is currently unknown.
PLANNED EXPLORATION PROGRAMS
Strategy: Due to their close proximity and in many cases similar geology Carube intends to explore the Belvedere and Mt. Royal SEPLs under joint exploration programs. This will maximize the number of anomalies Carube will be able to investigate as well as mitigate costs associated with field activities. Past exploration has compiled abundant focused data on specific anomalies; Carube will use this data to determine relationships, and full extents, of (a) the more “localized styles of mineralization” (“LOCMs”), i.e. veins, mineralized shear zones, faults and skarns associated with both the edges of intrusions and fault zones and (b) “broader in dimension” porphyries (“BRODPs”) (copper ± gold ± molybdenum).
Action: Airborne magnetic and radiometric surveys with relatively close flight lines (spaced at 100 m) over the complete property is a priority. This should be of assistance to differentiating rock lithologies, contacts, faults, mineralized zones and various phases of granitic-type intrusions that will allow further definition of trenching and drill targets for the LOCMs and possible definition of intrusions that may host or be adjacent to porphyry type mineralization. Similarly in select areas (Figure 2, 3, 4) of the property geochemical soil sampling will be conducted on a broad scale for establishing trenching and drilling targets on LOCMs. This can, in combination with known geology and the magnetics and radiometrics, define different phases of intrusive bodies. Characterization of the intrusives would assist in targeting for porhphyry style mineralization and possibly lead to definition of a deposit. Soil samples for soil gas hydrocarbon analysis at a scale similar to the soil sampling (50 m x 200 m) may be useful for determining the location of buried porphyry deposits. Most mineralization, including the oblong shape of mineralized porphyries with their long axes parallel to structures, demands shorter intervals between soil samples at right angles to the N(N)W structural trend.