C 62 Report
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Transcript of C 62 Report
1
LIST OF CONTENTS Page .
Introduction 3
Location and Access 3
Previous Work 4
Previous Work by the Geological Survey 4
Geophysics 5
Mineral Occurrences 6
C-62 Area Geology 7-8
Comments & Conclusions 8
References 19
2
List of Figures
Page
Figure 1. Location Map 9
Figure 2. Gold Geochemistry Summary map 10
Figure 3. Mineral Occurrence Summary Map. 11
Figure 4. Geological Summary Map 12
Figure 5. Geological Summary Map 13
Figure 6. Geological Summary Map. 14
Figure 7. Geological Summary Map 15
Figure 8. Geological Summary Map 16
Figure 9. Aeromagnetic Map 17
Figure 10. Topographic Map 18
3
Introduction
The Prospecting Licence (C-62) located in the Mazaruni Mining District No. 3 as shown
on Terra Surveys Topographic Map 35SW, as shown in fig 10 and enclosing an area of
approximately 10947 acres of the Hubana River. The potential of the area for gold
diamond and is very good.
The Kuribrong area where this concession is located have been subject to an
abundance of activity from small scale artisan prospecting up to large scale multi-phase
exploration programs initiated by Guyana Geology and Mines Commision.The entire
concession encompasses what is identified as Hubana Goldfied.
Several areas within the concession have been mined for gold and diamonds in the past by
pork Knockers, starting 1898.
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).
Location and Access
The concession (C-62) is located in the Potaro Mining District, approximately 180 km SW of
Georgetown, and comprises the catchments of the Hubana River. Access to the
Concession is either from Georgetown to Bartica via speed boat on the Essequibo River, or
by road from Georgetown to Linden (81 km) to the Sherima Ferry crossing (55 km). From
Bartica, the Issano Road leads to the Sherima Ferry Crossing (41 km) and then to Mile 72
(92 km). There is also a small dirt road that by-passes the crossing and connects the Issano
Road below the crossing. Continuing on the Issano Road from Mile 72 to Apanachi (46 km),
leads to an old trail that was rehabilitated for truck and 4-wheel drive access to Powis
Landing (19km).From Powis Landing on Kuribrong River,the concession can be access by
boat. Almost all basic supplies, such as fuel and food can be obtained in Bartica.
4
Previous Work
The area has a long history of localized, small-scale gold production, as far back as in
the 1930s and 1940s. The surrounding region of the Hubana River-Kuribrong River is
acknowledged for its gold production, whether it is from river dredging, land dredging or
land excavation. Historically and currently there has been an abundance of small to
medium scale gold and diamond operations. Gibbs (1971) reported that gold mining
activity was intense during the period 1898-1940.
Previous Work by the Geological Survey
Work began in the area with river traverses in 1875 (Gibbs, 1975). Throughout the late
1920’s and 1930’s numerous investigations were made by Connolly, Bracewell, Grantham
and Williams (Connolly and Bracewell 1928; Bracewell, 1944). These studies focused on
surficial deposits and prospecting for alluvial deposits of gold and diamonds, but their maps
also showed significant bedrock classification, and were the first to record the stratification
that has remained in use today. Reports detailed geographic relationship of bedrock
lithology to topography, surficial deposits and alluvial mineralisation. On a more regional
scale, Bateson, J.H., and Allderidge, M.G (1961) reported on the geology of the area
bounded by the Mazaruni, Kaburi, Waiamu, Hubana, and Kuribrong Rivers. They described
the major rock types and concluded with a stratigraphy unchanged from that discerned by
previous workers in the 1920’s. However, they provided further interpretation on the source
of gold mineralisation in the area and suggested that quartz veining accompanying intrusion
of granites (and diorites?) concentrated gold in bedrock.
5
Geophysics
The area is covered by a summary aeromagnetic data survey in digital form from the British
Geological Survey, and paper 1:200,000 scale aeromagnetic contour maps are available.
The simplest level of interpretation was used – studying visual patterns, correlating belts of
highs and lows and superimposing existing geological, topographic and aeromagnetic
maps, as well as previous interpretation maps by earlier workers.
The aeromagnetic data shows distinct areas with magnetic highs, or abrupt magnetic
gradients. Meta-basic rocks are often magnetic in hand-specimen, but also form distinct
topographic highs. Known areas of meta-basic rocks match well with the disturbed /
magnetic high areas, though this may be partly due to ground effects.
The Younger basic rocks surprisingly do not form distinct magnetic anomalies, though basic
rocks are normally magnetic, and known basic dykes form distinct topographic features.
Even reversed magnetised bodies are expected to reveal high gradients at the edges.
Known areas of Younger Granites correlate with magnetically quiet like Hubana the
concession area.
6
Mineral Occurrences
Gold
The central portion of the concession contains a number of known Alluvial mineralisation
and gold anomaly occurrences. Data is derived from a combination of the USGS MRDS
(Mineral Resources Database System), GGMC maps and reports and fieldwork. The
location of known mineral occurrences is shown in Figure 9. Digital data is divided into 2
files. The Guyana Mineralisation File is based on the original USGS MRDS, with improved
co-ordinates and updated information, and new mineral occurrences about which more than
minimal information is known. The Alluvial Minerals file is used for additional alluvial mineral
occurrences derived from spots marked on historical GGMC maps, or abandoned dredge
sites seen in the field for which additional information is not available. Many of the sites
shown in Figure 9 are derived from geological maps produced by Gibbs, et. al., 1971 & 1972
and a report by Gibbs (1973).
In the Kuribrong-Hubana area 14 gold mineral occurrences from the Guyana Mineralisation
file occur. A few of these are currently being mined on a small scale by “land dredges”.
Several areas in creeks headwaters may be related to primary mineralisation, or gold
derived from white sand basal gravels of which Hubana is one such creeks. At Lower
Hubana extensive pitting occurred over a one mile flat area. Almost continuous creek bed
excavations were worked along this creek flowing east 1.7miles from the Hubana Mouth.
Geology consists of high laterite capped hills of basic volcanics and meta-volcanics. Rocks
are reported to contain small quartz stringers and threads; larger veins were not seen.
Persistent fair values (50-100 eyes / battel) were seen in the region of basic volcanic south
of the creek.
.
7
C-62 Area Geology
The rock units are discussed in order of perceived age, oldest first. The discussion that
follows is summarized from Gibbs (1973 and 1975), Keats (1973), and Bracewell (1944).
These authors provide consistent summaries of the geology of the project area. Figure 8
and Enclosure 4 illustrate the distribution of different units in the area.
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 Lower Proterozoic
Mazaruni Supergroup, intruded by Younger Granites. In the western part of the area, these
rocks are uncomformably overlain by Roraima Formation, a generally flat lying, post-
orogenic series of conglomerates, sandstones, shales and volcanics. All these units are
intruded by Younger Basic Rocks.
Meta-Basic Rocks.
Meta-basic rocks consist of 1) metamorphosed gabbroic or doleritic dikes and 2) epidiorites
and amphibolites. One meta-basic gabbroic dike occurs in the project area, in the central
portion. It intrudes meta-volcanic rock and is offset by a northeast trending fault.
Amphibolites generally occur in contact zones around the larger Younger Granitoid
Intrusions. In general, these outcrops form low hills often capped by laterite duricrusts
Meta-volcanics.
Meta-volcanic rocks in the area have a varied composition, though most samples examined
petrologically were acid meta-volcanics. Bracewell (1944) reported that the rocks exist in a
belt that strikes NW across the Kuribrong area extending from the Hubana River mouth to
Embiparu Falls (about 5 km downstream in the Kuribrong River). This same belt appears on
the Gibbs et. al., (1971) maps. Gibbs (1975) noted pillowed exposures and water-lain tuffs
that supported a submarine origin for the volcanic rocks, as well as siliceous volcanics and
associated agglomerates that were probably once centres of volcanic eruption.
8
Meta-sediments
Bracewell (1944) described white sericite schists and green chlorite schists in the area
and suggested that these rocks were probably metamorphosed argillaceous
sedimentary beds. Gibbs (1975) described the series as grey graded greywackes and
shales, with ferruginous cherts
Comments & Conclusions
Based on the body of data in this concession, further exploration activity is warranted.
Mapping suggested that at least some of the gold was derived from superficial white
sand cover. Gold recent geochemistry data is in agreement with previously known gold
mineralisation areas,as shown in fig 3. This indicated that the stream sediment
samplying was done well.
Detail soil sampling and gological mapping is required to accurately define the grade
and type of mineralization but from the sampling and study undertaken it can be
suggested that gold mineralization is hosted in quartz veins and quartz rich lodes in this
area.Further work to better understand the geology in this concession should be
undertaken as there may be a significant source of primary gold, which resulted in
alluvial deposits seen in the concession.
9
Fig1, 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 7, Geological Summary Map
16
Figure 8, Geological Summary Map
17
Figure 9, Aeromagnetic map
18
Figure 10, Topographic Map
19
REFERENCES :
Cole, E.C., Heesterman, L.J.L. & Kemp, A.W. 2003. Kuribrong Project. A summary of geochemistry, geology and structure.Guyana Geology and Mines Commission, Geoservices Division Technical Report GS1/2003.
Gibbs, A.K. 1973. Notes to Accompany the Economic Geology map of the Potaro-Mazaruni District, Guyana.
Bateson, J.H., and Allderige, M.G., 1958, Geology of the area bounded by the Mazaruni, Kaburi, Kuribrong and Waiamu Rivers, GGMC unpublished report, maps P5/F2/8 and P5/F2/10, 17p.