REPORT ON RECONNAISSANCE ROCK,
STREAM SAMPLING AND GEOLOGICAL MAPPING
ON THE
AYACO RECONNAISSANCE LICENCE
GHANA, WEST AFRICA
FOR
COLUMBIA RIVER RESOURCES INC.
BY
CME & COMPANY
SEPTEMBER 30, 1999
SUMMARY
The 306.99 sq. kilometer Ayaco Reconnaissance License is located in the
northeastern portion of the Sefwi-Bibiani Belt in the Brong Ahafo and Ashanti
Regions of Ghana. It lies on-strike to the northeast of highly prospective
ground held by Normandy LaSource and Moydow Mines International Ltd., where
recent drilling has indicated an estimated resource in excess of 1 million
ounces gold. This resource is associated with major northeast-southwest trending
shears.
Reconnaissance mapping indicates the presence of greywackes and argillites in
the west with silicified metabasalts (greenstones) in the south. These
lithologies belong to the Birimian Supergroup. In the north and west, the
Birimian is flanked by granite gneiss, which is tentatively believed to be older
than the Birimian. In the west, sandstones of the Voltaian Supergroup
unconformably overlie the Birimian. Northeast-southwest trending shears, known
to control gold mineralization to the southwest of the concession, are present.
The shears form the tectonic contact between granites, greenstones and
metasediments and represent late-stage Birimian activity. These faults do not
cut the Voltaian sediments.
A total of 138 stream sediment samples were collected and analyzed by the Bulk
Leach Extractable Gold (BLEG) method. At the majority of sample locations, both
active and trap samples were collected. The maximum values obtained are 856.2
ppb Au in the active sediment samples and 1,407.6 ppb Au in the trap samples. At
several localities, the anomalous response from the active sediment exceeded the
value of the trap site. This suggests the presence of very fine disseminated
gold in the license area in addition to coarser grained gold, which ordinarily
concentrates at trap localities.
The metabasalts have a higher gold signature than the Birimian and Voltain
sediments. Geostatistical evaluation has also revealed a strong spatial
association with an east-west trending shear. This shear separates metabasalts
from sediments in the south of the concession. These anomalies suggest the
presence of an auriferous system that may be related, in part, to brittle
fracturing within metabasalts along the shear. Additional shearing and
structural preparation for migrating auriferous fluids within the metabasalt
should not be overlooked.
The Ayaco Reconnaissance License is highly prospective. Detailed exploration
over the metabasalt and shears in the southern portion is strongly advised. The
cost of this work, entailing soil geochemistry, geological mapping, rock
sampling, and report preparation is estimated at US$295,000 and should be
completed in approximately three months.
ii
TABLE OF CONTENTS
SUMMARY II
1.0 INTRODUCTION 1
2.0 LOCATION, ACCESS, TITLE AND PHYSIOGRAPHIC SETTING 1
2.1 LOCATION 1
2.2 ACCESS 1
2.3 TITLE 4
2.4 PHYSIOGRAPHIC SETTING 4
3.0 PREVIOUS WORK 4
4.0 REGIONAL GEOLOGICAL AND ECONOMIC SETTING 5
4.1 REGIONAL GEOLOGY 5
4.2 REGIONAL MINERALIZATION 8
4.2.1 BOUNDARY FAULT ENVIRONMENT 8
4.2.2 INTRABASINAL ENVIRONMENT 9
4.3 ECONOMIC SETTING 10
5.0 RECONNAISSANCE EXPLORATION PROGRAM 11
5.1 PROPERTY GEOLOGY 11
5.2 ROCK SAMPLING 13
5.3 STREAM GEOCHEMISTRY 14
5.3.1 RESULTS 14
6.0 CONCLUSIONS 16
7.0 RECOMMENDATIONS 16
8.0 REFERENCES 18
LIST OF TABLES
page
1 Active Stream Sediment Samples: Selected Results 14
2 Trap Stream Sediment Samples: Selected Results 15
3 Active vs. Trap Samples: Results 15
4 Recommended Work Program 17
LIST OF FIGURES
page
1 General Location Map; Ghana, West Africa (1:22,000,000) 2
2 Location and Access Map; Ghana, West Africa (1:333,333) 3
3 Regional Geology; Ayaco Licence Area (1:2,000,000) 6
4 Regional Geology and Concession Location (1:2,000,000) 7
5 Property Geology (1:50,000) map pocket
6 Stream Geochemistry: Location and Results (1:50,000) map pocket
LIST OF APPENDICES
Volume
I List of Abbreviations and Conversion Factors I
IIa Certificates of Analysis: Rock Samples I
iii
IIb Certificates of Analysis: Stream Sediment Samples I
III Rock Sample Descriptions I
IVa Methodology - Stream Sediment Samples Descriptions I
IVb Stream Sediment Sample Descriptions I
V Geostatistical Evaluation I
iv
1.0 INTRODUCTION
This report summarizes the results of the Reconnaissance Exploration Program
carried out on the Ayaco Reconnaissance License in the Brong Ahafo and Ashanti
Regions of Ghana, at the request of Mr. Bob Ferguson, President of Columbia
River Resources Inc.
The Reconnaissance Exploration Program commenced June 11, 1999 and ended July
20, 1999; with the objective of defining the presence of a possible gold system
in the Ayaco license area. Work included stream sediment sampling using the bulk
leach extractable gold method (BLEG), reconnaissance geological mapping and rock
sampling.
A list of abbreviations and conversion factors used in the report is presented
in Appendix I.
2.0 LOCATION, ACCESS, TITLE AND PHYSIOGRAPHIC SETTING
2.1 LOCATION
The Ayaco Reconnaissance License covers an area of 306.99 sq. kilometers and is
located in both the Brong Ahafo and Ashanti Regions of Ghana (Figures 1 and 2).
The license area is 380 kilometers northwest of Accra and 20 kilometers east of
Sunyam.
The license area is comprised of an eastern and western block which are
separated by the Yaya and Mankrang Forest Reserves in the north and south,
respectively. Exploration is currently prohibited in the forest reserves. The
western block lies within latitude 7(degrees)15' and 7(degrees)25'N and
longitude 2(degrees)10' and 2(degrees)03'W, while the eastern part lies within
latitude 7(degrees)20' and 7(degrees)30'N and longitude 2(degrees)05' and
1(degree)55'W. The licence area is located on topographic Field Sheets 0703D2
and 0702C1.
Larger towns and villages in the license include Asuakwa, Mankranho, Subenso,
Krofofrom and Dagyamen in the western block, and New Takyiman, Tanaso,
Mankranso, Eserentitia, Nyinatase and Adugyansu in the eastern block.
2.2 ACCESS
Access to the western block is either via the paved Kumasi-Sunyani-Kyeraa road,
or by way of the paved Kumasi-Takyiman road to the east. A well-maintained road
from Kyeraa, which passes through the southern end of the Yaya Forest Reserve,
and connects Eserentitia with Afrantwo on the Kumasi-Takyiman road, links the
two roads. Several maintained dirt logging tracks cross the entire area and are
accessible by four wheel drive vehicles during the dry season. Access within the
license area during the two rainy seasons is difficult. Foot access is afforded
by an extensive network of footpaths that connect the
1
LOCATION MAP
LOCATION AND ACCESS MAP
hamlets and cultivated fields in the area.
2.3 TITLE
Ayaco (Ghana) Ltd. currently holds a 90% interest in the Ayaco license; the
remaining 10% interest is held by the Government of Ghana. On September 27,
1999, Columbia River Resources Inc. signed a letter of intent with Ayaco (Ghana)
Ltd. to acquire 99% of Ayaco's interest in the Ayaco Reconnaissance License.
Ownership, summarized above, represents no legal opinion of CME, as this is
beyond the scope of this report.
2.4 PHYSIOGRAPHIC SETTING
The license area lies within an equatorial setting and experiences two rainy
seasons. The earlier rainy season occurs between June and early August, and
there is a later season from October to November. Average annual rainfall is
approximately 1,400 millimeters. Temperatures range between 22(degrees) and
30(degrees)C.
Low, thick bush and open canopy trees are found in the western block while the
eastern area is characterized by open grassy tracts with isolated trees and
bush. Secondary forest is found in the Yaya and Mankrang Forest Reserves. The
Forestry Department has carried out a program of reforestation over large
tracts.
Topography is generally gently undulating. Some areas are characterized by
moderate to steeply sloping ridges, with elevations ranging between 273 and 423
meters.
The license is drained by the Tano River. Tributaries to the Tano include the
Mankrang, Srani, Subri, Bisi, Ejuriansu, Nsuta and Bomina Rivers. Second and
third order tributaries are dendritic. The Tano and its main tributaries flow
northeast-southwest, with the exception of the Bisi, Ejuriansu and Srani Rivers
in the south. These three rivers flow northwest-southeast. Tributaries to the
main drainages mainly flow northwest-southeast.
Cocoa is the main cash crop, in addition to subsistence farming of maize,
cassava, yams, and cocoyams
3.0 PREVIOUS WORK
Little evidence of aritisanal mining activity has been observed within the Ayaco
license area. This may simply be the result of unsuccessful exploration
techniques of native miners. Little or no evidence of native or European
workings exists. Once again, this is probably not the result of the absence of
gold in the area, but unsuccessful exploration efforts.
4
4.0 REGIONAL GEOLOGICAL AND ECONOMIC SETTING
4.1 REGIONAL GEOLOGY
The regional geology of western Ghana is comprised of thick sequences of steeply
dipping metasediments, alternating with metavolcanic units of Proterozoic age
(~2200-2300 Ma). These sequences extend along strike for approximately 200
kilometers in a number of northeasterly trending belts, including the 30 to 60
kilometer wide Sefwi-Bibiani Belt.
The Ayaco Reconnaissance License lies within the Sefwi-Bibiani Belt in
southwestern Ghana. The Sefwi-Bibiani Belt is the second most significant
gold-bearing belt in Ghana after the Ashanti Belt to the east. The belt hosts a
major northeast trending regional structure with a strike length in excess of
200 kilometers, and is comprised of a sequence of Birimian upper greenschist to
amphibolite facies metamorphic rocks and locally foliated metasedimentary with
minor metavolcanic rocks.
A detailed description of the geology of Ghana is discussed by Kesse (1985).
Structural and lithological evolution is discussed by Eisenlohr (1989), Leube
and Hirdes (1986) and Leube et. al. (1990). The geological evolution of the
Sefwi-Bibiani Belt commenced with stabilization of the crust followed by an
episode of rifting and incipient ocean floor spreading. The rifting gave rise to
the formation of tectonically active basins and micro-plates. Along the margins
of plates, volcanic island arc complexes formed. Volcaniclastics associated with
the island arc complexes, along with sediments derived from uplift and erosion
of the craton margins fed the basins,
This was followed by a compressive episode (the Eburnean orogeny) in which the
island arc and basinal assemblages were deformed. Under the compressional
regime, the basinal sediments were folded and the island arc assemblages
migrated along major thrust faults. Continued deformation gave rise to major
wrench faults, which occurred preferentially at the margins of the volcanic
belts and basinal sediments.
The Eburnean Orogeny gave rise to a series of northeast trending linear volcanic
belts (greenstone belts) and resulted in the intense deformation of basinal
sediments. These sediments and associated volcanics collectively form the
Birimian Supergroup. The orogeny is associated with several phases of tectonic
activity, not all of which were compressive. Periods of extension in the Sefwi
Basin are tentatively related to renewed "hot spot" activity, and led to
incipient sea floor spreading and the formation of deep-seated faults which are
located within the basinal metasediments. These faults trend northeast-southwest
and are similar in genesis and characteristics to the Asankrangwa Fault in the
Kumasi Basin. The faults have a strike extent exceeding 200 kilometers and
control the location of many granitoids in the basin.
Syn- and post-tectonic granitoids intruded both the metasediments and
metavolcanics of the Birimian Supergroup as a result of the Eburnean Orogeny.
The granitoids can be broadly grouped into two types; Basin and Belt types.
Basin granitoids intrude the metasedimentary basins whereas Belt type intrude
the volcanic and volcanosedimentary assemblages.
5
REGIONAL GEOLOGY SOUTHWESTERN GHANA MAP
REGIONAL GEOLOGY AND CONCESSION LOCATIONS MAP
Uplift and erosion, prior to the final stages of deformation, resulted in the
deposition of intracratonic sediments; the Tarkwaian Supergroup, which
unconformably overlie the Birimian.
4.2 REGIONAL MINERALIZATION
Mineralization in Ghana can be divided into two groups based on spatial
associations. The first group lies close to boundary faults that separate
greenstone belts from basinal sediments; the second is found within the
intrabasinal assemblage.
Mineralization is tentatively believed to be 5 to 30 million years younger than
the ages of corresponding granitoid emplacement. The age of mineralization is
broadly coincident with intrusion of Basin granites and was coeval with regional
deformation and metamorphism.
4.2.1 BOUNDARY FAULT ENVIRONMENT
For over a century, mineralization associated with belt-basin faults was the
target for both local prospectors and foreign exploration companies; and has
proven to be a primary exploration target due to the presence of coarse, visible
gold. Deposits of this type in Ghana include Obuasi, Prestea, Bogosu, Konongo
and Bibiani. There are a number of commonly observed associations with gold
mineralization which include:
o located on, or close, to the lithological contact between greenstones
and metasediments;
o spatially related to deep-seated, high-angle wrench faults, which have
a strike extent exceeding 100 kilometers. Cross-cutting
northwest-southeast trending faults have also exerted an influence on
the location of gold remobilized from the main zones;
o native gold is hosted by quartz veins, which may possess an en-echelon
character. Grade-width characteristics persist virtually unchanged to
depths exceeding one kilometre. The veins are mainly concordant with
the regional foliation but locally cross-cutting the foliation;
o disseminated sulphides in the wallrock are common;
o several generations of quartz veining are common and gold is seemingly
associated with the final phase;
o mineralization is spatially associated with graphitic phyllite and
manganiferous sediments;
8
o mineralogy is simple with a strong positive correlation between gold
and arsenopyrite. Accessory minerals include
pyrite-chalcopyrite-pyrrhotite-bornite;
o strong silicification is common, accompanied by sericite and carbonate
alteration. Tourmaline may also be present; and,
o granitoids may or may not be spatially associated with mineralization.
4.2.2 INTRABASINAL ENVIRONMENT
Mineralization associated with intrabasinal sediments has received less
exploration attention, however, the significance of these deposits is now being
recognized. The Kumasi Basin, the northern area of the Sefwi-Bibiani Belt, and
the southern area of the Ashanti Belt best represent this style of
mineralization. This style of mineralization has also been found to occur in the
basin north of the Sefwi-Bibiani Belt and south of the Ashanti Belt. Two
different associations are recognized in this style of mineralization:
SEDIMENTARY ASSOCIATION
o disseminated mineralization, hosted by graphitic and manganiferous
argillite and tuffaceous phyllite, with a strike extent exceeding 1,000
meters and a width in excess of 30 meters;
o a direct association with intrabasinal faults; the Asankrangwa Fault is
the prime example; and,
o mineralogy is simple with disseminated pyrite-arsenopyrite with
subordinate chalcopyrite. Silicification is common.
INTRABASINAL GRANITOID ASSOCIATION
Mineralization associated with granitoids within the intrabasinal environment is
represented by the Bokitisi Mine at Ayanfuri, between Bogosu and Dunkwa. The
following characteristics are present:
o the granitoids are related to major intrabasinal shears;
o pervasive sericitic alteration accompanied by silicification is common;
o mineralogy is simple with gold-pyrite accompanied by subordinate
pyrrhotite-chalcopyrite. Minor tellurides are also reported;
o grade drops sharply to background level at the country rock contact.
The thermal aureole is some 10's of meters wide and is associated with
pyrite - carbonate alteration.
9
At Ayaco, mineralization occurs along the boundary/contact between rocks of the
Birimian Supergroup and granitoids. Mineralization is hosted in metasediments
and metavolcanics of the Birimian.
4.3 ECONOMIC SETTING
The Ayaco Reconnaissance License is located in the northeastern portion of the
Sefwi-Bibiani Belt. Other gold mines and prospects in the Sefwi-Bibiani belt
include the Bibiani Mine to the south, where current reserves are estimated to
be approximately 56,000 kilograms of gold and production has been 37,000 to
53,000 kilograms gold (CME, 1997). In addition, the Sewum, Tokosea, Ntubia and
Aniuri Mines also occur within this belt. Structurally controlled quartz veins
ranging in thickness from 1 to 8 meters along shear zones of several kilometers
are the hosts to the ore zones at Aniuri. An evaluation of seven deposits has
indicated a reserve base of 2.4 million tonnes grading 5.42 g/t gold (CME,
1997). This includes both open pit "heap leachable" oxides and underground
accessible sulphide targets. Annual production for 1994 was 871 kg of gold with
plans to increase to 2426 kg gold per year. The Ntubia Mine produced between
1912 and 1939, a recorded 38,667 tonnes of crushed ore yielding 581,257 g of
fine gold grading on average 15.1 g/t gold (Junner, 1973).
Southwest of Ayaco, are the license areas belonging to Moydow Mines
International Ltd. and Normandy LaSource and Rank Mining Ltd. (Figure 4). Rank
Mining is owned through a joint venture agreement between Moydow and Normandy.
Six zones have been identified on the Ntotoroso License, which is owned by Rank
Mining Ltd., and represents the northeast continuation of Normandy's Kenyase
deposit. As of 1999, current resources at Ntotoroso, were estimated to be over
800,000 ounces of gold (Moydow, 1999) for two of the zones, with follow-up
studies to occur in the other four zones. Of the 800,000 ounces, 700,000 ounces
grading 2.5 g/t Au occur in a granodiorite. At Ntotoroso, gold mineralization
occurs at both the immediate thrust contact with the underlying lower Birimian
metasediments and along parallel shears developed entirely within batholiths at
distances up to 2 kilometers from the thrust contact.
Immediately north and southwest of the Ntotoroso License, initial soil sampling
in licences held by Normandy revealed gold anomalies over a strike length of 40
kilometers. Subsequent drilling by Normandy to mid-1998 outlined a resource
estimated at 4.35 million ounces of gold, largely in deposits at Yamfo, Kenyase
and Subenso (Normandy, 1999). Currently, the existing resources are estimated at
6 million ounces (Normandy, 1999), with potential to increase the resource
between known mineralized zones. These deposits are located along the contact
zone between the granodiorite and metasediments, where gold is associated with
the sheared margin between granites and metasediments.
Also to the southwest of the Ayaco license is the Centenary Deposit, where
resources have been estimated to be at 1.1 million ounces gold (Mbendi, 1999).
10
5.0 RECONNAISSANCE EXPLORATION PROGRAM
The Reconnaissance Exploration Program commenced June 11, 1999 and ended July
20, 1999. The objectives of the program were to define the presence of a gold
system in the Ayaco license area.
The Reconnaissance Exploration Program included the following:
o reconnaissance geological mapping and rock sampling of the Ayaco
license area (19 samples), and
o stream sediment sampling (138 samples).
5.1 PROPERTY GEOLOGY
The Ayaco license is underlain primarily by Birimian metasediments and
metavolcanics. In more detail, the following lithologies underlie the Ayaco
license area:
o Fine- to medium-grained, flat-lying sandstones in the northeast of the
property. These belong to the late Precambrian to early Paleozoic
Voltaian Supergroup.
o Metavolcanics, volcaniclastics and sediments of the early Proterozoic
Birimian Supergroup. The metavolcanics and volcaniclastics form part of
the Sefwi-Bibiani Belt.
o Granite gneiss crops out in the middle and north of the license.
VOLTAIAN SANDSTONE
Voltaian sandstone crops out in the northeast portion of the license, and is
coincident with topographic highs which range from 394 to 423 meters. The
sandstone is exposed on ridge tops and in stream channels around New Takyiman
and Tanoso. The rock is fine to medium grained, grey-brown, friable and consists
of more than 90% quartz with minor feldspar.
The strike is mainly northeast-southwest with a very gentle dip to the
southeast. Fracture planes strike between 160(degrees) and 170(degrees)with sub-
vertical dips to the west.
BIRIMIAN METASEDIMENTS.
GREYWACKE
The greywacke is interbedded with argillite and is exposed in the southwest of
the license along the Tano, Subri and Adei Rivers near the village of Tanom. It
also crops out on a road cut at Subenso. At Locality 1, the greywacke is exposed
in the Tano River where it is massive, competent, fresh and undeformed, showing
little foliation. It is greenish-grey with abundant red-brown ferruginous spots
after iron bearing carbonate, probably siderite.
11
The rock consists of grey and blue quartz, up to 5 millimeters in diameter, with
minor fragmental cherty material embedded in a fine- to medium-grained matrix.
Euhedral post-tectonic pyrite is locally observed with a width up to 4
millimeters.
Argillite beds in the greywacke are found at Locality 2 (Figure 5). The
argillite is foliated and dark greyish-green with a well developed amorphous
black mineral, tentatively identified as secondary chloritoid, occurring on
fracture planes. The lithology is best observed in the Tano and Subri Rivers
near Tanom.
ARGILLITE The type locality is found 2 kilometers west of Krofofrom village in
the southwest of the area (Locality 3; Figure 5). Here, the argillite is close
to basaltic lavas that mark the southwest portion of the Sefwi-Bibiani Belt. The
argillite is light-green, fine-grained, foliated, and is commonly intensely
sheared and silicified.
BIRIMIAN METAVOLCANICS
BASALT
Although basaltic float is common on hills and in drainages close to Twabidi
village, exposure is scarce. Basalt crops out in the Subri River near Santaso
village (Locality 5; Figure 5). Additional exposure is found outside the
concession boundary at Sraneano and Subenso, in the southeast of Field Sheet
0703D2.
At Locality 5 (Figure 5), the basaltic rock is fine- to medium-grained and light
green. It is intensely silicified and possesses a shear foliation. Remnant
phenocrysts of plagioclase and amphibole are observed. Near Twabidi village,
float from a road cut consists of a dark green fine grained basalt. At Sraneano
and Subenso the rock is intensely foliated and sheared with intense
silicification and quartz veining.
RHYOLITE
Abundant rhyolite float and subcrop of rhyolite is identified on hills and in
drainages close to Nyinatase and Adugyansu villages in the southeast corner of
the property. The rhyolite occurs immediately above a basaltic flow and
indicates bimodal activity through differentiation of a hypabyssal source.
In hand specimen, the rock is aphanitic, pale-grey and may be intensely sheared
and silicified (Locality 6; Figure 5).
GRANITE GNEISS
Granite gneiss is exposed outside the concession, within a quarry at Locality 7
(Figure 5), within the Yaya Forest Reserve along the Kyeraa-Takyiman road. It is
also found near Mfronte village, along the feeder road from Kyeraa to Afrantwo
through the forest reserve. Within the concession, the presence of granite
gneiss is inferred through float in drainage channels and from waterwell spoil
at Santaso village (Locality 4; Figure 5).
At Locality 7, the biotite-muscovite granite gneiss is intruded by pegmatites
several meters wide. These pegmatites are cut by later aplite dykes. At Asuakwa
village, northeast of Kyeraa, weathered granitoid of dioritic composition is
exposed. Due to the paucity
12
of exposure, relationship between the dioritic body and granite gneiss could not
be determined. The intense deformation leading to formation of the granite
gneiss strongly suggests formation before deposition and subsequent deformation
of the Birimian Supergroup.
STRUCTURE AND ALTERATION
Although there is less than one percent exposure in the Ayaco license area, the
probable presence of faults and shears was inferred through intensely sheared
rocks and their spatial association to linear drainage patterns. Faulting in the
Ayaco license has similarities with the basin-boundary environment where brittle
deformation of metabasalts along the boundary of the basin results in the
formation of preferential sites for gold emplacement. The dominant fault trends
northeast-southwest, following the Tano River with an offset along the Mankrang
River. The fault exceeds a strike extent of 40 kilometers of which 7 kilometers
are contained within the Ayaco license.
Three sets of strike-slip faults are tentatively identified and these post-date
the Tano-Mankrang fault. The first group consists of three north to northeast
trending shears that cut the main shear with left-lateral (sinistral)
displacement. One of the set forms the tectonic boundary between basalt and
granitoid (granite gneiss) in the eastern portion of the license. Measured
foliation within the area is consistent with the shear direction. The second set
trends northwest-southeast and feathers out in the northern part of the
argillaceous lithology. This shear brings greywacke into tectonic contact with
the argillite. In the east, this shear separates rhyolite from granitoids
(granite gneiss). The third fault trends approximately east-west and separates
basalt from rhyolite in the east and cuts the basalt in the central part of the
license.
At the fault contact between the greenstones and granite-volcaniclastics,
silicification is common, with locally developed medium-grained pyrite.
The dominant fabric in the concession area is a northeast striking, moderate to
subvertical foliation that is sub-parallel to bedding. Locally developed
sub-horizontal intersection lineations and minor fold axes are also present.
5.2 ROCK SAMPLING
Although the concession is not covered by close canopy forest, exposure is very
poor and mainly restricted to spot exposures along road cuts and some drainage
channels. Nineteen (19) samples were collected, and the location of samples is
shown in Figure 6. Due to the paucity of outcrop exposures, rock samples were
unable to be obtained on or close to the east-west trending shear associated
with the highly anomalous BLEG drainage samples in the south of the concession.
The samples were sent to Transworld Laboratories, Tarkwa, Ghana for gold
determination by fire assay. Certificates of analysis are presented in Appendix
IIa. Sample descriptions for all samples can be found in Appendix III.
All samples returned results that were below, or close to, the level of
analytical detection (0.01 ppm Au).
13
5.3 STREAM GEOCHEMISTRY
One hundred and thirty-eight (138) active and trap samples were collected over
an area of 307 sq. kilometres with an average density of one sample in 4.5 sq.
kilometres. A description of the methodology used in the collection of samples
can be found in Appendix IVa.
The location of samples was determined using a Global Positioning System (GPS)
unit. Sample locations are shown in Figure 6. Each sample site was described
according to stream width, sediment color and composition, bedload composition
and site solid geology; and sample descriptions can be found in Appendix IVb.
Samples were submitted to Transworld Laboratories, Tarkwa, Ghana, for BLEG
determination. Certificates of analysis are presented in Appendix IIb.
5.3.1 RESULTS
All results were geostatistically evaluated using 'PPLOT' software. A
description of the data processing and development of applicable Log histograms
and probability plots can be found in Appendis V. Applicable Log histograms and
probability plots are also presented in Appendix V.
ACTIVE SEDIMENT SAMPLES
Sixty-four (64) active sediment samples were collected, with samples returning
gold values ranging from (less than) 0.03 to 856.2 ppb Au. Geostatistical
evaluation defined the presence of three populations. The upper population can
be considered entirely anomalous with seven values exceeding the theoretical
threshold of 32 ppb Au. Samples that returned values greater then the threshold
are presented in Table 1.
Table 1: Active Stream Sediment Samples: ANOMALOUS RESULTS
SAMPLE NUMBER Au ppb
AY-26 856.2*
AY-29 247.9*
AY-42 62.3
AY-45 32*
AY-46 142.2
AY-48 135.3
AY-50 57.5
* - average value
The lower population, with a threshold of 4 ppb Au, is tentatively related to
sediments in the license. The second, higher population has a threshold of 10
ppb Au and is related to subcrop of basalt in the south of the license. Highly
anomalous values show a spatial association with an east-west trending shear,
which forms the contact between Birimian metabasalts and sediments.
14
TRAP SEDIMENT SAMPLES
Seventy-four (74) trap samples were collected, with samples returning gold
values ranging from (less than) 0.03 to 1,407.6 ppb Au. Geostatistical
evaluation defined the presence of four populations. The upper population can be
considered entirely anomalous with eight values exceeding the theoretical
threshold of 45 ppb Au. Samples that returned values greater then the threshold
are presented in Table 2.
Table 2: Trap Stream Sediment Samples: ANOMALOUS RESULTS
SAMPLE NUMBER AU PPB
AY-27 1,407.6*
AY-37 47.6
AY-43 159.4*
AY-47 179.0
AY-49 785.1*
AY-59 234.5*
AY-130 50.2
AY-138 120.0
* - average value
The cause of the lower population is uncertain and could be an artifact of the
analytical method. The second population is tentatively related to the presence
of metasediments, and has a threshold of 4.5 ppb Au. This is slightly higher
than the threshold of the active sediments, a situation that is to be expected.
The third population, with a threshold of 15 ppb Au is, in similarity with the
active drainage results, spatially related to metabasalts. The upper population
is entirely anomalous and shows a spatial relationship between the Birimian
metabasalts and sediments.
In several localities, the results obtained from the active sediment samples are
higher than the corresponding trap value from the same area (Table 3). This is
suggestive hydromorphic dispersion of gold in the active sediment, which may
indicate the presence of a source of finely disseminated gold.
Table 3: Active vs. Trap Samples: RESULTS
SAMPLE PAIR RESULT (AU PPB)
ACTIVE TRAP
AY14(A); AY15(T) 4.6 2.7
AY50(A); AY51(T) 57.5 12.9*
AY54(A); AY55(T) 9.8 6.3
AY76(A); AY77(T) 0.8 (less than)0.3
AY86(A); AY87(T) 4.9 0.8
AY96(A); AY97(T) 6.4 0.6
AY100(A); AY101(T) 5.3 4.4
AY132(A); AY133(T) 24.3 15.6
AY136(A); AY137(T) 2.9 (less than)0.3
15
6.0 CONCLUSIONS
There are several factors that indicate and support the highly prospective
nature of the Ayaco Reconnaissance License. Firstly, the Ayaco license area lies
along strike northeast-southwest trending Sefwi-Bibiani Belt; host to a major
new gold belt which has been identified in western Ghana. Also present in this
belt, and to the immediate southwest of Ayaco are the estimated >1 million ounce
resource of the Ntotoroso License and Yamfo, Kenyase and Subenso Deposits, and
the 1.1 million ounce resource of the Centenary Deposit.
Geologically, the Ayaco license area is in a setting similar to that for the
aforementioned deposits and licenses. The Ayaco license area overlies Birimian
metasediments, metavolcanics and granodiorites cut by a northeast-southwest
trending shear zone.
Results from reconnaissance stream sediment sampling returned encouraging
values, especially in the southern portion of the license where high values in
active and trap sediment samples appear to follow the northwest-southeast trend
of the Sefwi-Bibiani Belt. Geostatistical evaluation of the results demonstrated
a spatial association between basalt, and particularly the tectonic contacts
between the basalt and adjacent metasediments. Also indicated by the
geostatistical evaluation was the association between anomalous gold and late
stage east-west shearing in the south of the permit. Although the stream
sediment results reflect a lithological-structural association, the response
given by both the active and trap sediments testifies to the presence of a
gold-bearing system. This lithological-structural association has also been
identified in other deposit within the belt.
7.0 RECOMMENDATIONS
The basalt, and tectonic contacts between the basalt and metasediments should be
further investigated through a program of soil geochemistry. A soil grid over
the most prospective ground will have a line spacing of 200 metres with
collection of soil samples along lines at 50 metre intervals. Lines will be
oriented north-south to optimize the intersection of both lithological
boundaries and faults in the license. The northern part of the area, up to and
including the Tano River Fault, will be investigated through extension of the
southern grid lines at a separation of 400 metres. Sample separation will be 50
metres. Tie-lines will be used to control the accuracy of the grid.
Samples will be collected from a depth between 0.4 and 0.5 metres. In areas with
alluvial cover, the depth may be extended; or hand augering may be implemented.
This situation is not expected in the southern grid but may develop especially
along the margins of the Tano River. Each soil site will be described n
according to practice established by CME (Ghana). Standards and blanks will be
randomly inserted to test for laboratory precision and contamination.
16
Samples will be dried disaggregated and sieved to -80# under the direct
supervision of CME at their sample processing laboratory in Accra Ghana. The
- -80# fraction will be homogenised and riffle-split to provide a 100g sample
which will be sent to ACME Analytical Laboratories Ltd. in Vancouver, Canada for
gold and multielement ICP analysis.
The recommended work program is shown in Table 4.
Table 4: Recommended Work Program
ITEM LENGTH (KM) SAMPLES
Baselines 10
Tie-lines 20.5
Cross-lines (200 m) 270 5,400
Cross-lines (400 m) 50 1,000
All lines will be leveled using hand-held inclinometer. In addition, a
geological map will be produced at a scale of 1:10,000.
The total cost of sample collection is estimated at US$125,000. The estimated
cost for sample preparation and analyses, including precision control and
airfreight, is US$120,000. Report preparation and production is estimated at
US$50,000. The total estimated cost is US$295,000.
Respectfully Submitted,
CME & Company
September 30, 1999
17
8.0 REFERENCES
Cahen, L., Snelling, N.J., Delhal, J. and Vail, J.R.
1984. Geochronology and evolution of Africa; Carendon Press, Oxford, 512p.
CME
1997. Report on Phase III Geology, Soil and Rock Geochemistry, Trenching
and IP Survey on the Antubia-Afere Concession, Ghana, West Africa for
Proxpex Mining Inc., October 31, 1997, 47p.
Eisenlohr, B.N.
1989. The structural geology of the Birimian and Tarkwain rocks of
southwest Ghana; Tech. Coop. Proj., 80.2040.6, Ghana, 66p.
Junner, N.R.
1973. Gold in the Gold Coast; Gold Coast Geological Survey, Memoir 4, 67p.
Kesse, G.
1985. The mineral and rock resources in Ghana; Balkema, Rotterdam- Boston,
610p.
Leube, A. and Hirdes, W.
1986. The Birimian Supergroup of Ghana: depositional environment,
structural development and conceptual model of an early Proterozoic
suite; Tech. Coop. Proj., 80.2040.6, Ghana, 259p.
Leube, A, Hirdes, W., Mauer, R. and Kesse, G.
1990. The early Proterozoic Birimian Supergroup of Ghana and some aspects
of its associated gold mineralization; Precambrian Research, v.46,
p.139-165
Mbendi
1999. Website; www.mbendi.co.za
Moydow Mines International Ltd.
1999. Company website; www.moydow.com
Normandy Mining Ltd.
1999. Annual Report
18
APPENDIX I
LIST OF ABBREVIATIONS
AND CONVERSION FACTORS
ABBREVIATIONS AND SYMBOLS
As arsenic
aspy arsenopyrite
Au gold
Az azimuth
CA core axis
cm centimetre
cpy chalcopyrite
cu.cm cubic centimre
cu.m cubic metre
cu.yd cubic yard
eqAg equivalent silver
eqAu equivalent gold
ft foot
g gram
g/cu.m grams per cubic metre
g/t grams per metric ton
kg kilogram
kg/t kilograms per metric ton
km kilometre
lb Pound avoidupois
m metre
l litre
mi mile
mm millimetre
n number of items in a statistical array
po pyrrhotite
py pyrite
oz troy ounces
oz/cu.yd troy ounces per cubic yard
oz/T troy ounces per short ton
ppb parts per billion
ppm parts per million
sq.km square kilometre
sq.mi square mile
T short ton
t metric ton (tonne)
tpd short tons per day
t/d metric tons per day
yd yard
$US United States dollars
x statistical mean
% percent
+
- - plus or minus
o degree
ARGS Annual Report of the Geological Society
GGS AR Annual Report (Gold Coast Geological Society)