Hello Peter
I am frustrated about Yamba too Peter, very frustrated, but this game is only part geology and part psychology. The market already believes in Snap Lake, not so much because Winspear proved up a deposit, but because DeBeers thought it was good enough to bid on. That gave it legitimacy in the eyes of the serious players.
We (I) have always argued strongly that SUF needs free market resources, especially here in Canada. Of late, the media has adopted that concept (none blood diamonds) in reference to DeBeers aggressive expansion into free market deposits.
While this is an educated gamble by CJ, logic seems to suggest that the odds are in the range of at least 50/50. There is no doubt that there are pipes at Yamba, but so far the odds per drill hole have been lower than that. If CJ can boost SUF's share price with a hit at McKay, and a hit will go a long way towards doing that, then raising capital for other initiatives like Yamba will require much much smaller share dilutions and I am all for that.
I am not sure if everyone has a clear graphic picture of just how close Snap Lake is to SUF's claims so I have attached the following two links to give a clearer picture.
After looking at these two maps, you can appreciate the logic of taking a shot at this hole.
Finally, as a follow-up to my discussion with Teevee about borehole kimberlite exploration, I have included some research below in that area that might also be of interest. Once CJ has dropped his drill hole and hopefully hit one or more dikes, he will still have the option of using borehole geophysics to try to give an indication of the extent of what is down there, which should help lend some wings to any discovery news.
Like I have said for years, the market likes 1st world discovery stories, and this one has blue sky written all over it. It's not a pipe, not even a small one, but a hit confirming WSP's data tells the market the dike is extensive, that it probably keeps on going, probably has grade continuity and $300+ value per tonne continuity.
The market will give SUF at least what WSP had $5/s because at the very least, DeBeers, in the market's eyes will be an immediate potential buyer of those claims without SUF spending another cent.
winspear.com
winspear.com
Snap Lake Diamond Discovery, Camsell Lake Project, NWT
Walter Melnyk, Winspear Resources Ltd., Vancouver
Winspear Resources Ltd. and its partners in several joint venture projects throughout the Slave province have spent approximately $25 million on diamond exploration since 1992. During this period, Winspear has been involved in the discovery of three kimberlite pipes, all of which are diamond bearing but uneconomic. During on-going exploration on the Camsell Lake property, a gently dipping, diamond bearing kimberlite dyke was discovered in the Snap Lake area. In 1998, processing of a mini-bulk sample of this dyke resulted in the recovery of gem quality diamonds. In light of this discovery, a major exploration program is planned for 1999 designed to evaluate the economic potential of this kimberlitic body.
The Camsell Lake property covers approximately 277,000 acres and is controlled by a joint venture between Winspear Resources Ltd.(67.76%; operator) and Aber Resources Ltd. (32.24%). Approximately $11.0 million has been spent on the property to date.
The property is underlain by a suite of Archean aged metavolcanic, metasedimentary and intrusive rocks. The metavolcanic and metasedimentary rocks are part of the Yellowknife Supergroup, which includes intermediate volcanics and associated turbidites, mudstones and siltstones. This supracrustal sequence is intruded by a younger Archean suite of granite, granodiorite with lesser granitic gneiss and migmatite. All rocks are intruded by north-northwest and, less commonly, northeast trending Proterozoic aged diabase dykes.Since 1992, the Camsell Lake property has been subject to several episodes of basal till sampling, geophysical surveying, terrain analysis, and drilling. Two small, diamondiferous pipes were discovered near the eastern property boundary in 1994, and since then, numerous geophysical and indicator mineral anomalies have been evaluated. Continued exploration on the Camsell Lake property has established Snap Lake as a distinct focus of activity. Drilling has identified the presence of a continuous, uniform, gently dipping hypabyssal kimberlite dyke on the northwest shore of Snap Lake. A total of 79 holes have intersected the kimberlite dyke in the northwest peninsula area and these have determined an average thickness of 2.5 metres for this body which strikes north-south, and dips 12° east. Step-out holes have intersected the dyke along an east-west dimension of 2,200 metres, and a north-south dimension of 1,350 metres. Drilling along the south and southeast shores of Snap Lake early in 1998 also intersected hypabyssal kimberlite and kimberlite breccia dykes from 0.5 to 5.0 metres thick. The dyke intersections were found to occur in three clusters over 2.2 km long northeast-southwest trend. A 199.7 tonne mini-bulk sample was extracted from two pits on the northwest peninsula and processed at the Diavik plant in Yellowknife. A total of 226.7 carats of diamonds were recovered representing a grade of 1.14 carats per dry tonne. Twenty-one diamonds weighed more than 1 carat, and the three largest stones, all of gem quality, weighed 10.87, 8.43, and 6.03 carats.
The diamonds were valued at US$301 per carat, implying a value of US$343 per dry tonne of kimberlite. The portion of the NW peninsula underlain by the kimberlite dyke was drill tested on a grid basis during a summer drilling program in 1998. The results of this program permitted MRDI Canada - a division of H.A. Simons Ltd. to define an estimated quantity of approximately 1,348,000 tonnes of kimberlite in this area. Of this total, approximately 670,000 tonnes is considered to be potentially open-pittable. Based on widely spaced intersections to date, there is significant tonnage potential of kimberlite in the NW dyke system.
Characteristics of the NW dyke as defined by the drill program on the peninsula offer optimism that more regularly spaced drilling on the down-dip portion under Snap Lake as planned for this winter season can reasonably be expected to add significantly to its defined tonnage.
***
aseg.org.au
Australian Society of Exploration Geophysicists
Victorian Branch
The DeBeers Airborne Multispectral Scanner
Mike Hussey, Stockdale Prospecting Limited.
De Beers' geologists started research into Spectral Geology when they began utilising digital imagery acquired from satellites in 1981. This resulted in the discovery that kimberlites may be identified from infrared reflectance features. Routine use of field spectrometers soon followed.
Comparison of field spectral study results with airborne image data indicated that there was potential to detect and delineate kimberlites from the air but no suitable operational air or spaceborne remote sensing systems were going to be developed prior to 2000. De Beers therefore decided to finance development themselves.
After a feasibly study it was decided that an Australian consortium could design and build this instrument. Construction commenced during 1994 and the Airborne Multispectral Scanner (AMS) was completed in 1996. After delivery, an extensive program of testing over kimberlite occurrences in Australia and Southern Africa was completed. This program proved that the data produced by the AMS, when processed with the De Beers' proprietary software, could be used to detect and delineate kimberlites. Since 1996 the AMS has been used extensively in De Beers exploration programs worldwide.
mountainprovince.com
NEWS RELEASE
May 18, 2000
TSE:MPV
NASDAQ:MPVI
DE BEERS/MONOPROS DISCOVERS NEW KIMBERLITE BODY ON MOUNTAIN PROVINCE MINING'S AK CLAIMS
Mountain Province Mining Inc., (the Company) is pleased to announce that it has received from its contractor, Monopros Limited (Monopros), a wholly-owned subsidiary of De Beers Consolidated Mines Limited (De Beers), results of the spring drilling program. A new kimberlite body has been discovered in a lake approximately nine km northeast of Kennady Lake and three km southwest of the Faraday kimberlite. In addition, the south lobe of the Hearne pipe has increased in size and on the north shore of MZ Lake, in the central part of the AK claims, new kimberlite intersections in drill holes indicate that either sill or dyke like bodies are present. The Company's AK claims are located in the Northwest Territories of Canada.
The spring exploration drilling program started in early March and ended this past week. A total of 23 drill holes were drilled into 19 targets (mainly EM highs and mag lows), most of which underlie lakes. Eight of the drill holes intersected kimberlite. A new kimberlite body which has been named Kelvin, was discovered in a lake located approximately nine km northeast of Kennady Lake, which contains the Gahcho Kue diamondiferous kimberlites, and three km southwest of the diamondiferous Faraday body. One drill hole in the north-south direction intersected 40 meters of kimberlite horizontally projected, while another hole in approximately the east-west direction intersected 23 meters of kimberlite horizontally projected. A third hole drilled failed to intersect kimberlite. The shape and dimensions of the Kelvin kimberlite are difficult to determine from the three holes completed. A 3.3 meter thick kimberlite dyke at a depth of 31 meters was discovered approximately 200 meters south of the Kelvin body in the same lake.
Further work in this area will consist of analysis of all the drill results, acid dissolution of the drill core for microdiamond recovery, till sampling and possible drilling of additional targets this summer.
During the 1999 winter program kimberlite dykes were discovered in MZ Lake located in the central part of the AK claims, approximately 20 km northwest of Kennady Lake. A large number of indicator minerals, mainly garnets, have been recovered on the western edge of the lake and as far west as the border of the AK claims (approximately 20 km to the west). A land based target on the north shore of MZ Lake, located approximately 300 meters to the northwest of the previously located kimberlite dyke intersections, was drilled with a vertical hole to a depth of 35 meters. Five kimberlite stringers with the largest two having thicknesses of 0.40 and 0.70 meters were intersected, as well as a 1.70 meter thick intersection of what may be a sill (an approximately horizontal lying kimberlite body). Additional work, which may include ground penetrating radar (GPR), will be required to define the extent and morphology of these bodies.
A delineation hole in the southern lobe of the Hearne kimberlite in Kennady Lake was drilled to determine the previously poorly defined southeastern limits of this lobe. The drill hole intersected 40 meters of kimberlite, extending the body some 30 meters horizontally beyond the previous estimated contact. This extension could increase the resource size estimate of the Hearne kimberlite by approximately 350,000 tonnes.
The Company is very pleased with the discovery of the Kelvin and MZ kimberlites since they confirm that additional kimberlites exist outside of the Kennady Lake cluster, and that the De Beers/Monopros team has refined the exploration techniques necessary for locating these bodies. We look forward to the exploration activities this coming summer. There are at least eight areas on the AK claims that contain kimberlitic indicator minerals with as yet undiscovered sources, the search for which will be ongoing.
Mr. Richard Molyneux, President and CEO of De Beers Canada stated: "We believe there is strong evidence for additional kimberlite occurrences on the AK claim as confirmed by these latest discoveries. Exploration will continue during this summer and the next winter seasons with the objective of locating additional bodies as quickly as possible. Several indicator mineral trains have been identified with as yet undiscovered sources".
De Beers is currently in the middle of a study investigating both open pit and underground mining options for the Kennady Lake bodies, as well as less conventional alternative mining methods. The results of the study are expected around August.
The AK and CJ claims, located in the Northwest Territories of Canada, are held 90% by Mountain Province Mining, Inc., and 10% by Camphor Ventures (VSE:CFV). As reported in the press release on March 7, 1997, Mountain Province Mining, Inc. and its partners have entered into a joint venture agreement with Monopros, under which Monopros has the right to earn up to a 60% interest in the AK and CJ properties.
On Behalf of the Board of
Mountain Province Mining, Inc.
Jan W. Vandersande
Jan W. Vandersande, Ph.D.
President
***
mgls.org
BOREHOLE GEOPHYSICAL SIGNATURES OF KIMBERLITES IN CANADA
C.J. Mwenifumbo, P.G. Killeen and B.E. ElliottGeological Survey of Canada, 601 Booth St., Ottawa CANADA K1A 0E8
ABSTRACT
Multiparameter borehole geophysical measurements were conducted at one kimberlite pipe in Saskatchewan and at four pipes in the Kirkland Lake area in Ontario to obtain in situ physical rock property data in kimberlites and their host rocks. The measurements included natural gamma-ray spectrometry, magnetic susceptibility, resistivity/conductivity, induced polarization, spectral gamma gamma (density and heavy element indicator), temperature, borehole 3-component magnetometer and seismic P-wave velocity.
Most of the geophysical measurements show anomalous values within the kimberlite pipes compared to the host rocks. These geophysical parameters, however, vary considerably within individual kimberlite pipes and between the different pipes, primarily due to the different facies and source material of kimberlite intrusions. Density, magnetic susceptibility and P-wave velocity logs indicate higher values in kimberlite compared to the overlying sediments at the Fort à la Corne kimberlite pipe in Saskatchewan.
Crossplots for measurements of conductivity, magnetic susceptibility, gamma-ray activity and spectral gamma gamma ratio (SGGR) in the kimberlites indicate several distinctly different subpopulations of kimberlitic material that represent different eruptive phases of kimberlite in the Fort à la Corne pipe. There are no relationships between the various geophysical parameters except for the magnetic susceptibility and conductivity that are positively correlated. The geophysical signature of the C14 kimberlite pipe in the Kirkland Lake area of Ontario is different from that of the Fort à la Corne pipe that comprises of kimberlite with crater facies pyroclastics. Most of the geophysical variables from the C14 pipe are moderately to highly correlated. The C14 pipe consists of diatreme and hypabyssal facies kimberlites that have distinct geophysical signatures. The diatreme facies kimberlites are characterized by lower density, resistivity, gamma-ray activity and magnetic susceptibility than the hypabyssal facies kimberlites. Crossplots and two-dimensional kernel density distribution analysis reveal several clusters that correspond to the different kimberlite units.
INTRODUCTION
Over the past few years, a wide range of ground and airborne geophysical surveys have been conducted in the search for kimberlite pipes in Canada. Most of these surveys have been mainly airborne and ground magnetics (Brummer et al., 1992, Lehnert-Thiel et al., 1992; Reed and Sinclair, 1991), electromagnetics (Reed and Sinclair, 1991), and to a lesser extent seismic (Richardson et la., 1995) and gravity (Lehnert-Thiel et al, 1992). Although some laboratory physical property data on Canadian kimberlites exist (e.g. Katsube et al., 1992) there is a lack of in situ data to aid in quantitative interpretation of airborne or ground geophysical surveys. Having these data would help to plan, interpret and understand many geophysical surveys.
The Geological Survey of Canada (GSC) is currently making an inventory of in situ physical property data, using borehole geophysics, for a variety of mineral deposit types including kimberlites in Canada. The main objectives are:
1. to compile information on the physical properties of kimberlite pipes and their host rocks,
2. to develop a database of geophysical signatures of the different kimberlites,
3. to determine the responses of different logging tools that may be used to delineate and explore kimberlites.
A compilation of kimberlite geophysical signatures will provide standards for comparing geophysical data and for evaluating new borehole exploration technology designed to find new kimberlites in Canada. The in situ physical property data will also support the design of new generations of geophysical exploration equipment and survey techniques.
Fort à la Corne Kimberlite Pipe, Saskatchewan
Geology and Geophysical Logs
A 242-m deep HQ-size borehole (100 mm diameter) was drilled on pipe 169 at the Fort à la Corne kimberlite field near Smeaton, Saskatchewan, specifically for geological and borehole geophysical investigations by the Geological Survey of Canada. The hole intersected 100 m of Quaternary sediments, 40 m of Cretaceous shales and siltstones interbedded with kimberlite, 80 metres of kimberlite with minor layers of shales and sandstone, 20 m of Mannville sandstone, and 2 m of kimberlite. The kimberlite intersected in this hole belong to the crater facies and consists of fluvial, reworked kimberlite; lapilli tuff-dominated kimberlite; olivine crystal tuff-dominated kimberlite and wave-reworked kimberlite (Kjarsgaard et al., 1995). Kjarsgaard et al. (1995) also identified several kimberlite eruptive phases in this intersection.
Borehole geophysical data were acquired in this hole to determine the geophysical characteristics of the kimberlite and its host rocks. Because the borehole showed signs of collapsing, it was cased with 2-inch plastic pipe which restricted the use of galvanic electrical methods. However, seven different logging tools were run in the hole inside the PVC pipe. Nuclear, electromagnetic and magnetic measurements can all "see" through the plastic pipe. The geophysical logs acquired included natural gamma-ray spectrometry, magnetic susceptibility, inductive conductivity, spectral gamma gamma (density and the spectral gamma-gamma ratio (SGGR) - a heavy element indicator), temperature, three-component magnetometer and sonic P-wave velocity. The sonic P-wave velocity was measured using a surface energy source and downhole recording with an array of twelve hydrophones (Hunter and Burns, 1991).
Figure 1 shows five of the borehole geophysical variables measured; natural gamma-ray, magnetic susceptibility, electrical conductivity, density and acoustic P-wave velocity. Density, magnetic susceptibility and seismic P-wave velocity show distinctly higher values in kimberlite than in the Quaternary or Cretaceous sedimentary units. This suggests that gravity, magnetic and seismic methods can be successfully applied in exploration for this type of kimberlite pipe (Lehnert-Thiel et al., 1992, Richardson et al., 1995). Although the conductivity of the kimberlite is generally high, that of the overlying Cretaceous shales and siltstones is equally high, making this type of kimberlite a difficult target to find using surface and airborne electrical prospecting techniques. The gamma-ray signature is highly variable in the kimberlite and is similar to that observed in overlying and interbedded Cretaceous shales, siltstones and sandstones. The gamma-ray data alone, therefore, do not characterize this kimberlite.
Data Summaries and Univariate Distributions
Figure 2 shows a brief statistical summary of the distribution of four geophysical variables in the form of box and whisker plots for the four main Cretaceous lithological units intersected in the Smeaton borehole. The boxes are bounded by the 25th (Lower Hinge) and 75th (Upper Hinge) percentiles, i.e. 50% of the data have values in the boxes. The notch locates the median (50th percentile) and its 95% confidence bounds. The whiskers, lines drawn from the lower and upper hinges, represent data within 1.5*IQR from the hinges , (i.e. between - 1.5*IQR and + 1.5*IQR, for the lower and upper hinges, respectively) where IQR is the interquartile range or box length. The statistical summary of the data is also given in Table 1.
The distribution of magnetic susceptibility (Fig. 2A) shows that more than 50 percent of the kimberlite data are distinctly higher (>103µSI) than those observed in the three sedimentary rock units. The magnetic susceptibilities of the siltstone, shale and sandstone are low and fall mostly between 102 and 103 µSI, with the sandstone having the lowest values. The density of the kimberlite (Fig. 2B) is also distinctly higher than that of the Cretaceous sedimentary rocks. The siltstones have the lowest densities and are distinct from the shale and sandstone whose density distributions overlap and lie between the siltstones and kimberlites. The natural gamma-ray data (Fig. 2C) show the distribution of kimberlite overlapping that of the shale and sandstone which indicates that these three rock types cannot be readily differentiated based solely on gamma-ray data. The gamma-ray activity in the siltstone is much higher than in the other three rock types. Kimberlite has a wide range of conductivities (Fig. 2D and table 1), varying from 2.5 to >600 milliSiemen/metre. The median values for the shale and siltstone that overlies the kimberlite are higher than that of the kimberlite.
Table 1: Summary Statistics for Fort à la Corne Borehole
Variable Lithology Min Max Mean 25th percentile Median 50th percentile 75th percentile
Magnetic Susceptibility (µSI)
Shale 224 1126 588 447 563 631
Siltstone 93 2787 547 200 324 646
Sandstone 112 722 305 200 251 355
Kimberlite 500 83176 18653 1995 6031 31622
Density (g/cm")
Shale 1.69 2.57 2.09 1.95 2.05 2.20
Siltstone 1.20 2.19 1.65 1.53 1.60 1.80
Sandstone 1.37 2.80 2.19 2.00 2.10 2.30
Kimberlite 2.21 2.81 2.52 2.40 2.54 2.59
Natural Gamma-Ray (cps)
Shale 46 117 82.3 73 83 92
Siltstone 97 204 158.9 145 165 178
Sandstone 22 120 68.7 49 72 84
Kimberlite 53 181 86.7 53 99 115
Conductivity (milliSiemen/m)
Shale 66.9 311.7 204.2 77.6 144.5 223.9
Siltstone 156.6 240.2 194.0 173.8 190.5 218.8
Sandstone 46.5 115.7 79.4 69.2 79.4 83.2
Kimberlite 2.5 624.2 87.4 25.1 39.8 125.9
The box and whisker plots presented above provide the summary statistics of the distribution of the data sets but do not show the modality of the data. Histograms, however, provide better distribution statistics than the box-and-whisker plots. Histograms in figure 3 show the distribution of natural gamma-ray, electrical conductivity, magnetic susceptibility and density in the kimberlite. Also included in the figures are the box-and-whiskers plots. The gamma-ray (Fig. 3A) and electrical conductivity (Fig. 3C) data show a bimodal distribution. This bimodal distribution indicates that the central tendency and variance of these data is poorly represented in the summary statistics. The data should be treated as having two distinct populations.
The magnetic susceptibility data (Fig. 3B) show a multimodal distribution with a wide range of values (see Table 1). The density data (Fig. 3D) show a slightly skewed, unimodal distribution with a narrow range indicating a fairly homogeneous density distribution.
Two Dimensional Distributions
Crossplots of conductivity, susceptibility, gamma-ray and spectral gamma-gamma ratio (SGGR) measurements in the kimberlite are presented in figures 4 to 8 as scatter plots (A) and two-dimensional density distribution plots (contour map (B) and perspective view (C) of the kernel density estimate). The kernel density estimate shows areas where data are most concentrated on these bivariate plots and provides a way of recognizing subpopulations in a given data set (Mwenifumbo, 1993). The crossplots of these data were made to explore trends, clusters and patterns in the data that are of interest in interpreting compositional and physical property changes in the kimberlite.
Gamma-Ray versus Magnetic Susceptibility. The scatter plot (Fig 4A) shows four fuzzy clusters or clumps of data :- (i) high gamma, high susceptibility; (ii) high gamma, low susceptibility; (iii) low gamma, high susceptibility; and (vi) low gamma, low susceptibility. The contour map and perspective view of the kernel density estimate, however, show these clusters to be relatively distinct. Within the low gamma, low susceptibility cluster, there are two distinct minor clusters. Most of the data are, however, concentrated in the high gamma, low susceptibility cluster. Since changes in magnetic susceptibility relate to variations in ferromagnetic minerals such as magnetite and ilmenite, and gamma-ray activity to variations in concentrations of radioelements such as potassium, the observed clusters may correlate to compositional changes in the kimberlite. These clusters may indicate different phases of kimberlite intrusions/eruptions.
Gamma-Ray versus Conductivity. The contour map and perspective view of the kernel density estimate (Fig. 5B, C) show five distinct clusters:- ( i) high gamma, high conductivity; (ii) high gamma, low conductivity; (iii) low gamma, high conductivity; (vi) medium gamma, low conductivity and (v) low gamma, low conductivity. This two-dimensional density distribution is fairly similar to that observed for the gamma-ray versus magnetic susceptibility plots because conductivity and magnetic susceptibility are highly correlated (see crossplot in Fig.6).
Magnetic Susceptibility versus Conductivity. The perspective view and contour map of the kernel density estimate show three clusters (Fig 6B, C). The data are plotted on a log-log scale. There is a strong, positive, correlation between magnetic susceptibility and conductivity (correlation coefficient, r=0.74) and the clusters lie approximately along the regression line (Fig 6B). This relationship is unusual for most kimberlite pipes. Generally high conductivities are associated with low susceptibilities as a result of alteration of magnetic minerals to non-magnetic minerals. The conductive, altered or weathered kimberlite, consists of abundant clays known as yellow ground (Macnae, 1979). Pipe 169, at the Fort à la Corne kimberlite field, is believed to be a reworked and altered pipe consisting of crater facies (eruptive) kimberlite (Kjarsgaard et al., 1995) where higher susceptibilities are a result of secondary magnetite enrichment.
SGGR versus Magnetic Susceptibility. From the scatter plot (Fig 7A) there is no apparent relationship between the two data sets and any clustering of the data is unclear. The kernel density estimate (Fig 7B, C), however, clearly shows three distinct clusters. The SGGR maps variations in the effective atomic number of the intersected lithology and hence reflects changes in the whole rock chemistry. The two-dimensional density distribution indicates three mineralogically different groups of kimberlite. The high magnetic susceptibility, low SGGR cluster is fairly tight whereas the low magnetic susceptibility, high SGGR is more dispersed along the magnetic susceptibility dimension. This broad, diffuse cluster represents two subpopulations that were identified on the magnetic susceptibility versus gamma-ray crossplots (Fig. 4).
SGGR versus Conductivity. There is again no apparent no relationship between SGGR and conductivity (Fig 8A). Three distinct clusters are, however, recognized on the kernel density distribution. The similarity between the cross plots in Figure 7 and 8 is due to the high, positive correlation between magnetic susceptibility and conductivity.
Both gamma-ray and electrical conductivity data show bimodal distribution in the kimberlite which indicates two distinct populations. The magnetic susceptibility values are fairly heterogeneous and show a multimodal distribution. However, when these data sets are crossplotted as discussed above (see Fig. 5) five distinct clusters emerge: (i) low gamma, low conductivity; (ii) medium gamma, low conductivity; (iii) low gamma, high conductivity; (vi) high gamma, high conductivity; and (v) high gamma, low conductivity, which likely represent different phases of the kimberlite eruptions. The five units identified from the kernel density estimate (KDE) are indicated in figure 1. Most of these units correspond to the kimberlite eruptions identified by Kjarsgaard et al. (1995). It should be noted that the identification of these five units by borehole geophysical methods was done before the geological examination of the drill core.
Second half to follow.
Regards |
