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1
LIST OF CONTENTS
Page
.
Executive Summary 3
Location and Access 4
Geophysics 4
Mineral Occurrences (Historical data) 5
P...
2
List of Figures
Page
Figure 1. Location Map 10
Figure 2. Gold Geochemistry Summary map 11
Figure 3. Mineral Occurrence S...
3
Executive Summary
The Prospecting Licence (C-68) located in the Cuyuni Mining District No. 4 as shown on
Terra Surveys T...
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C 68 Report

  1. 1. 1 LIST OF CONTENTS Page . Executive Summary 3 Location and Access 4 Geophysics 4 Mineral Occurrences (Historical data) 5 PL Mineralisation 5 Regional Geology 6-7 C-68 Area Geology 7-8 Structure and relative age 8 Comments & Conclusions 9 References 19
  2. 2. 2 List of Figures Page Figure 1. Location Map 10 Figure 2. Gold Geochemistry Summary map 11 Figure 3. Mineral Occurrence Summary Map. 12 Figure 4. Geological Summary Map 13 Figure 5. Geological Summary Map 14 Figure 6. Geological Summary Map 15 Figure 8. Aeromagnetic Map 16 Figure7. Structural Summary Map showing outcrop location 17 Figure 9. Topographic Map 18
  3. 3. 3 Executive Summary The Prospecting Licence (C-68) located in the Cuyuni Mining District No. 4 as shown on Terra Surveys Topographic Map 18SW, as shown in fig 10 and enclosing an area of approximately 10194 acres of the Ekabago River. The potential of the area for gold is very good. The PL is presently under mining license by C B & R Mining Enterprises. Active gold extraction is presently undertaken by land dredging, using excavators on mining concesions bordering this PL. The PL area is located in the upper drainage portion of the Ekabago River that drains in the Puruni River,and close to the mouth of the Waikuri River that drains into the Cuyuni River, approximately 150 km due west of the city of Georgetown . Based on information from surface mapping in the areas of the soil geochemical anomalies suggest the majority of the alluvial gold and gold anomaly areas located to the north/west of this, see fig 3, PL are likely related to zones of weakly mineralized, structurally deformed, lithological contact between mafic and felsic volcanic or intrusive rocks which interlayer with more extensive packages of sedimentary formations. A portion (perhaps the majority) of the gold mineralization may have been derived from quartz lode type occurrences in lithologically controlled shear structures. The geology of the area consists of Lower Proterozoic Mazaruni Supergroup (greenstone belts) consisting of meta-sediments and meta-volcanic rocks, intruded by Younger Granites. Unconformably overlying these rocks is the Roraima Formation, a generally flat lying series of conglomerates, sandstones, shales and with minor interbedded volcanics. All of these rocks (greenstones, granites, and post-orogenic sedimentary series), are intruded by doleritic and gabbroic dikes and sills (the Younger Basic Intrusive Suite), see fig 4-6.
  4. 4. 4 Location and Access The PL area can be accessed by 4WD vehicle or Bedford truck via a logging and mining road from Bartica, crossing the Mazaruni at Itaballi,from Itaballi the journey by truck/pick up is approximately 5-6 hours to the PL . Bartica is accessed from Georgetown via speed boat from Parika, or by road via the Georgetown-Linden Highway crossing the Essequibo River at the Shirima crossing, see fig 1. Geophysics The first systematic geophysical survey in Guyana was an aeromagnetic survey flown by Aero Services Corporation, funded by the United Nations in 1963. The survey used a set of N-S flight lines at a spacing of approximately 1.6 to 2.4 km, and a height of 300m. In 1971- 72 additional areas in Guyana were flown by Terra Surveys, funded by the Canadian Commonwealth Bureau, and older data was incorporated in a set of 1:200,000 scale map. These sheets were then re-issued with an interpretation by Tyl & Reford of Terra Surveys Ltd in 1973. In 1994 aeromagnetic data covering Guyana was converted to digital form by Gtech Ltd, a commercial group attached to the University of Leeds in the UK as part of the “South American Magnetic Mapping Project” (SAMMP). A relief-shaded map compiled recently (Heesterman 2004) from this data. It should be noted that this data has not been reduced to the pole. The aeromagnetic data shows distinct areas with magnetic highs, or abrupt magnetic gradients,see fig 7. The Quartzstone mountains, which trend north-south, directly to the west of the study locations (excluding Wiamu) show elevated geophysics results to the immediate background geophysics. `
  5. 5. 5 Mineral Occurrences Historical Data Historically the plains underlain by granitic saprolite in the area has been a good source of gold. However recent sampling from this area has not determined a significant source of gold in the granitic saprolite, which is now exposed. It is therefore suggested that historical extraction of gold has derived from alluvial material deposited on the bed rock which has subsequently been removed and processed for gold. The alluvial material is most likely to be derived from lode structures and schistose rocks observed and from the hill ranges. It is therefore seen as an important exercise to study the hill range of the area for primary mineralization. The Quartzstone – Aremu Batholith which within the PL area is associated with the extensive surface gold workings along the contact zone with the country rock. Gold occurs in the contact zone, marginal granite and gold bearing quartz veins, which are usually associated with shear zones (Annual Report, 1964) PL Mineralisation From data on the mining activities bordering the PL, gold is found to be present in quartz veins and quartz rich lodes and well foliated saprolitic schist which in general all strike north-south throughout the area. The gold bearing quartz veins are usually associated with a black mineral (tourmaline?). Active extraction of gold from saprolite and quartz material in areas bordering the PL area is presently undertaken by small and medium scale miner. In some areas saprolite and quartz is being crushed and washed. One notably anomalous area is located within the PL area with Au assay values up to 212 ppb, see fig 2, however it should be noted that approximately sixty percent (60%) of the PL area have subjected to geochemical sampling, as shown in fig 2, with no information on soil sampling. Mineralized quartz was located at two locations within the PL, as shown in fig 8.Alluvial mineralization and Gold anomaly is located south-eastern part of the concession and just north east , as shown in fig 3.
  6. 6. 6 Regional Geology Two major lithological sequences, the Bartica Assemblage and the Barama – Mazaruni Supergroup Greenstone sequences, underlie the northwestern area of Guyana. Basement – the Kanuku complex is considered to be part of the Archean basement. It consists of paragneisses and migmatites, granulites (Kanuku Mts.) and granite gneisses. Greenstones - The Barama and Mazaruni groups have been classically considered as part of the Guiana Shield’s widespread Birrimian Age Greenstone Belts (2.2 G.a). The Barama group outcrops in the northwestern region of Guyana, close to the border with Venezuela. It consists of a predominantly sedimentary sequence with locally developed Mn rich chert layers (Mathews Ridge deposit) interbeded with volcano sedimentary packages. It is bounded to the west by the predominantly volcanic Mazaruni group (El Callao in Venezuela stratigraphy). The contacts between The Mazaruni group, the Barama Group and the gneissic basement sequences have not been well defined. Generalized descriptions by Gibbs and Barron, made at Waikuri, suggest a typical Archean greenstone sequence, with ultramafics rocks in the lower part, andesitic and felsic volcanics in the central part and sediments in the upper part. All the above sequences were deformed during the Trans Amazonian Event (2.1-1.9 Ga.). Older Basic Rocks – this is a distinct group, also of Birrimian age, and is described as intruding the Barama –Mazaruni greenstones. These are deformed and metamorphosed to the same degree as the host sequences (Heesterman 2001).
  7. 7. 7 The Bartica assemblage is a gneissic terrain, occurring in the Cuyuni River Region, composed of various ortho / paragneisses with amphibolites, metamorphosed to the amphibolite facies. Locally it reached the granulite facies. These rocks are believed (Gibbs and Barron) to be reworked Barama-Mazaruni units during the Trans Amazonian event (1.95 to 2.2 Ga). Other authors believe the Bartica assemblage is another basement portion of Archean age Of similar age, but clearly late, are the so-called Younger Granites. These are generally small individual intrusions forming large complexes of granitic terrain. Their composition varies from granitic to dacitic. Gibbs and Barrow describe the Aurora Complex, as composed of three rock types: tonalites, granodiorites and leucogranites. They are unfoliated and display saussuritization (sericite + epidote), and sometimes are sheared by later events. The above rocks are intruded by sills and dikes and overlain by flat lying, undeformed volcanics, probably, of the middle Proterozoic age. These could be related to the 1.8 Ga Uatuma event, and correlate to the Kuyuwini volcanics, mapped originally in the southern portion of Guyana. C-67 Area Geology Generally, the geology of this area is very similar to that seen in other parts of the greenstone belts of Guyana, with the oldest rocks consisting of the Mazaruni Supergroup, as shown in fig 4-6. The local geology is presented in terms of the Landsat interpretation, geophysical features and limited information from geological mapping in thick laterite terrain and scarce outcrop exposure along grids lines and riverbeds. Given the scarcity of outcrops, information is more often derived from mapping float and saprolite. Differential recessive weathering of soft rocks and positive relief from more resistant (fresher) rock types can create the false impression of an abundance of the latter units in the field. All sulphides at surface are readily weathered, except where they are dispersed in competent metacherts or siliceous volcanic rocks. This differential weathering feature in the presence of sulphides and/or alteration zones and/or permeable structures, can however locally enhance exposure via the development of deep erosional cuts at surface.
  8. 8. 8 In several areas in Northern Brazil this is noticed and an interesting example is the Amapari skarn deposit, located in Amapá state. In Guyana the mineralized zone is deeply weathered to as much as 140m while the adjacent rock units are generally only weakly weathered and oxidized to depths of 20 to 60 meters. Greenstone Belts: These areas was identified using Landsat interpretation, the greenstone sequence is the predominant rock type, and is characterized by a weak, but persistent, bedding or foliation generally trending NNW-SSE. Because of the weak contrast in the Landsat imagery of the bedding/foliation, it was not possible to determine the internal structure of the units or to separate it into predominantly volcanic or sedimentary units. Only a few resistive ridges were clearly identified and interpreted to consist of either massive volcanics, sandstones, chert or BIF. Structure and relative age A study of lineaments from stereoscopic examination of air photos was modified using aeromagnetic and field data to identify major structures. Where all different data types coincide, the probability that the structure is significant is higher. A similar process was used to define major lithological boundaries. Historically very few faults have been mapped in the field, mainly as softer faulted material rarely survives as outcrop. Airphoto interpretation suggests that many linear features can be traced between photographs over long distances. At least some of these must be faults with significant movement, and others are first and second order fracture systems related to primary movement. Some of the larger lineaments thought to be faults and fractures are shown in Figures 8. A number of main lineament directions can be recognised. Age relationships of some of these can be interpreted from the way that they control the geology and mineralisation, but in many cases these structures may be long lived, and have been re-activated several times.
  9. 9. 9 Comments & Conclusions Based on the body of data on this concession, further exploration activity which entails detailed soil and geological mapping is required to accurately define the grade and type of mineralisation,however from the mining activities that bordering this PL and the mineralized quartz located within the concession it can be assumed that gold mineralization is hosted in quartz veins and quartz rich lodes in this PL also. Therefore it is suggested that further work to better understand the geology in this concession should be undertaken as there may be a significant source of primary gold.
  10. 10. 10 Fig1, Location map
  11. 11. 11 Figure 2, Gold Geochemistry Summary map
  12. 12. 12 Figure 3, Mineral Occurrence Summary map
  13. 13. 13 Figure 4, Geological Summary Map
  14. 14. 14 Figure 5, Geological Summary Map
  15. 15. 15 Figure 6, Geological Summary Map
  16. 16. 16 Figure 7, Aeromagnetic map
  17. 17. 17 Figure 8, Structural Summary Map showing outcrop location
  18. 18. 18 Figure 9, Topographic Map
  19. 19. 19 REFERENCES : Bishop DW. 1936. Quartzstone-Wiamu area. Cuyuni River. Preliminary report Annual Report of Geological Services Department, British Guiana. 1964. Special geological problems. Granite studies: Quartzstone – Aremu, Rupa, Kopang. 33-35 Learmont J W. 1954. Area vbetween Aremu and Quartzstone Rivers, Cuyuni Rivers. Annual Report on the Geological Survey Department for the Year 1954 (British Guiana Geological Survey). 42-43, 88-89 Lloyd JW. 1958, Area North-west of Quartzstone Landing, Cuyuni River. Annual Report on the Geological Survey Department for the Year 1958 (British Guiana Geological Survey). 42-43

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