Hello Valuepro
***OFF TOPIC***
Yes, apparently any change in density, an object, grave, paleochannel, kimberlite pipe, dike, etc. shows up rather nicely. I saw an image of the Crater of Diamonds pipe in Arkasas several years ago, when Texas Star was trying to prove its economics. You would not believe how beautifully it stood out. I have tried for the past several years to find that image on the net again, unfortunately without success.
On a separate note, Russett suggested a few days ago that Winspear had some unique geochemistry. Apparently RT had suggested that G11 and G12 garnets were key in some way in detecting this unique type of kimberlite.
That set me to digging and in the course of doing that, I came across a number of extremely interesting papers both on diamond geochemistry and other related exploration subjects. For all those who may be lurking, if technical stuff turns you off, now's the time to surf on by because some of these papers (abstracts) can be a little hard to follow, but what they have to say is facinating if you take the time to try to understand.
I won't post them all today as it would be overwhelming, but a few each day for a while should make interesting reading if you are into it. A number are particularly applicable to SUF's NWT claims.
On the matter of Winspear's geochemistry, I could find virtually nothing on the Internet. A few snippets here and there but no papers submitted at any conferences, no NRC studies, etc., etc. Frankly, I find that highly unusual, as virtually every other player up here has had their discoveries documented in one way or another.
There was one article (promtional) that discussed Snap Lake's almost complete lack of Pyropes which also noted that it produced quite a number of Chromites sourced from the diamond stability field, however, that isn't all that unusual. Argyle (a lamproite) and a number of other well known pipes have similar geochemical profiles. However, neither that article, nor any paper I could find made any reference what so ever to G11's or G12's. In fact Winspear's old news releases and their exploration history outlined on their web site talks about having in the early days of exploration, traced G10 pyropes up to Snap Lake. It seems as though the standard geochemical rules applied at least in those days (two years ago).
There is one abstract that discusses in some detail the current theory (with mounting evidence) that the Slave Craton is not only accreted (most of the earth's crust is), but that portions are made up of two distinct layered terranes, the upper older terrane being highly depleted peridotite and probably being the source of the highly subcalcic G10's and the lower newer terrane believed to be subducted oceanic basalt/seafloor and likely being the source of the high sodium eclogitic garnets. As you read that abstract and others, you might begin to draw some conclusions about Snap Lake's geochemistry, ore grade and stone values.
Here is the WSP article and its link, along with a few others. By the by, check the links, because a number of these have very good graphics.
Winspear Resources Ltd.
Anything But Average
· Introduction
· Above Average Diamonds
· Extraordinary Deposit
· Exploration Expenditures
· Diamondex Resources Ltd.
· Conclusion
Introduction
A diamond is a diamond by any other name — or is it? According to officials at Winspear Resources Ltd. the kimberlites and diamonds at their NWT Snap Lake project are not your ordinary kind. They say, in fact, that these finds differ significantly from most others in the world.
Above Average Diamonds
For one thing, the averages from the samples are anything but average in size or quality. In 1998, company officials announced that "Analyses from two one-hundred tonne kimberlite samples returned an average grade of 1.14 carats/tonne with an average value of US$301/carat. These are the richest ‘per carat' values ever reported from a kimberlite." The samples yielded 25 diamonds weighing more than one carat, including the three largest which weighed 6.04, 8.42 and 10.82 carats.
In July of this year, Winspear announced that 10,708.08 carats of diamonds valued at US$104.96 per carat were discovered from 5,985.7 dry tonnes of kimberlite obtained from the Snap Lake project on their Camsell Lake property.
Officials announced the finding of nine stones which exceeded 10.8 carats in weight and were classified as "specials." To date the largest reported diamond is 14.07 carats and according to company reports, 103 stones are classified as +3 carat diamonds. Winspear cites DeBeers as saying that many mines in the world average stones of .4 to .5 carats, but that stones larger than one carat are rarer, with only about 400,000 are produced annually.
Extraordinary Deposit
Not only are Snap Lake's diamonds extraordinary, but the deposit itself is also unusual in several respects. For one thing, its intrusive form is rare. Company officials report that dykes are gently inward-dipping and appear to have a common centre.
The kimberlites, too, are highly irregular. In fact the dykes differ from the ordinary in thickness, in volatiles and in indicator materials. Whereas the usual kimberlite dykes average a metre in thickness and are vertical, Snap Lake's dykes exceed two metres in thickness, are relatively flat-lying, and the kimberlites appear to be low in mantle volatiles. The seems to be consistent with their non-explosive hypabyssal character.
Another anomaly is the kimberlite's indicator mineral abundance, which is low. Company officials report that, although most G10 pyrope garnets rarely exceed 12 per cent chromium, a significant number of Snap Lake's pyrope garnets have chromium contents between 12 per cent and 17 per cent. Also, they contain an unusual distribution of rare-earth elements, all of which suggest that these kimberlites originated from as deep as 300 kilometres within the mantle, significantly deeper than most economic kimberlites known in either South Africa or Siberia.
"While only a small portion of pyropes from Snap Lake kimberlites have classic G10 compositions," say company officials, "a surprising large number of chromites (>20 per cent) have compositions consistent with their having formed within the diamond stability field of the earth's interior."
So maybe a diamond is a diamond by any other name, but Snap Lake's diamonds are without question very extraordinary.
Exploration Expenditures
Since Winspear commenced diamond exploration in the Slave Province of the Northwest Territories in 1982, $20 million has been expended on exploration. Of this, $12.5 million was expended on the Camsell Lake project alone, eight million of which was Winspear's share. Camsell Lake is a joint venture owned by Aber Resources Ltd. and Winspear (operator and 67.7 per cent owner).
Diamondex Resources Ltd.
Winspear recently created a new exploration vehicle called Diamondex Resources Ltd. (DSP.V). This move, they say, enables Winspear to focus on the Snap Lake Project with a view to completing its pre-feasibility stage by the year 2000. Planning is now underway for future programs in the Snap Lake area.
Conclusion
Winspear is headquartered in Vancouver, BC. and lists on the Vancouver Stock Exchange under the symbol WSP. In 1998 Winspear traded in excess of 177 million shares on the Vancouver Stock Exchange and its share price fluctuated between a low of $0.46 to its year end close at $4.85. Today it's share price remains strong, peaking at $5.25 in May, and remaining above $4.00 in mid-July.
The company estimates that over the next five years, "projected diamonds sales from the NWT will contribute approximately 10 per cent of the world's supply." Much of that portion will of course will be cut by Snap Lake's diamonds.
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Created by
Shirley Collingridge, Wordsmith
collingridge@sk.sympatico.ca
Last modified: October 8, 1999
URL:http://www3.sk.sympatico.ca/collingr/winspear.html
www3.sk.sympatico.ca
***
Journal of Petrology, Volume 40, Issue 5: May 1999.
Cr-Pyrope Garnets in the Lithospheric Mantle. I.
Compositional Systematics and Relations to Tectonic Setting
W. L. GRIFFIN1,2, N. I. FISHER1,3, J. FRIEDMAN4, C. G. RYAN1,2 AND S. Y. O'REILLY1</AUTHGRP
1ARC NATIONAL KEY CENTRE FOR GEOCHEMICAL EVOLUTION AND METALLOGENY OF CONTINENTS, DEPARTMENT OF EARTH AND PLANETARY SCIENCES, MACQUARIE UNIVERSITY, NSW 2109, AUSTRALIA
2CSIRO EXPLORATION AND MINING, PO BOX 136, NORTH RYDE, NSW 2113, AUSTRALIA
3CSIRO MATHEMATICAL AND INFORMATION SCIENCES, LOCKED BAG 17, NORTH RYDE, NSW 1670, AUSTRALIA
4DEPARTMENT OF STATISTICS, STANFORD UNIVERSITY, STANFORD, CA 91045, USA
Chrome-pyrope garnet is a minor but widespread phase in ultramafic rocks of the continental lithosphere; its complex chemistry preserves a record of events related to fluid movements in the mantle, including melt extraction and metasomatism. We have examined the major-element and trace-element composition of >12 600 Cr-pyrope (Cr2O3 > 1 wt %) xenocrysts in volcanic rocks to evaluate their compositional ranges and interelement relationships.
Samples have been divided into three major groups (Archon, >= 2·5 Ga; Proton, 2·5-1 Ga; Tecton, <1 Ga) depending on the age of the last major tectonothermal event in the crust penetrated by the host volcanic rock. Relative depths of garnets within each sample have been determined by measurement of Nickel Temperature (TNi). Mn, Ni and Zn contents of Cr-pyrope garnets are controlled by T-dependent partitioning between garnet and mantle olivine. The expected correlation of mg-number with T is largely masked by effects of bulk composition and crystal chemistry. The Cr content of garnet is a primary indicator of the degree of depletion of the host rock; Fe, Y, Ti and Ga show negative correlations with Cr, suggesting that all have been removed as part of the primary depletion process. In garnets with TNi < 1200°C, the average degree of depletion as measured by these elements decreases from Archon to Proton to Tecton. High-temperature metasomatism, reflecting the introduction of asthenospheric melts, produces strong positive correlations between Fe, Zr, Ti, Y and Ga, and leads to `refertilization' of previously depleted rocks.
The prominent Ca-Cr correlation (`lherzolite trend') seen in garnets from clinopyroxene-bearing rocks is controlled primarily by the Cr/Al of the host rock, and Ca shows a strong negative association with Mg. The position and slope of the lherzolite trend vary with temperature and tectonic setting, suggesting that the P/T ratio exerts a control on Ca/Cr in lherzolite garnets. Garnets with less Ca than the lherzolite trend (`subcalcic garnets') are largely confined to Archon suites, where they typically are concentrated in the 130-180 km depth range. The few subcalcic garnets from Proton suites typically are lower in Cr and occur at shallower depths (100-120 km). Subcalcic garnets are absent in Tecton suites analysed in this work. The complexity of the geochemical relationships illustrated here, and their variation with temperature and tectonic setting, suggests that it is possible to define meaningful compositional populations of garnets, which can be used to map the stratigraphy and structure of the lithospheric mantle.
Keywords: Cr-pyrope garnet;mantle;lithosphere; trace elements; kimberlite; lamproite; tectonothermal age
Pages 679-704
***
Kimberlite Indicator Minerals in Till, Central Slave Province, Northwest Territories
sts.gsc.nrcan.gc.ca
***
KIMBERLITE INDICATOR MINERALS
Several minerals, when found in glacial sediments, are useful indicators of the presence of kimberlite, and to a certain extent, in evaluation of the diamond potential of kimberlite. These minerals are far more abundant in kimberlite than diamond, survive glacial transport, and are visually and chemically distinct. Cr-pyrope (purple colour, kelyphite rims), eclogitic garnet (orange-red), Cr-diopside (pale to emerald green), Mg-ilmenite (black, conchoidal fracture), chromite (reddish-black, irregular to octahedral crystal shape), and olivine (pale yellow-green) are the most commonly used kimberlite indicator minerals in drift prospecting, although in rare cases, diamond is abundant enough to be its own indicator. Kimberlite indicator minerals are recovered from the medium to very coarse sand-sized fraction of glacial sediments, and analyzed by electron microprobe to confirm their identification. For this study, indicator minerals were picked from the 0.25-0.5 mm, 0.5-1.0 mm, and 1.0 to 2.0 mm non-ferromagnetic heavy mineral concentrates of 10 to 20 kg glacial sediment samples and analyzed at the GSC using a four spectrometer Cameca SX50 electron microprobe.
Mg-ilmenite
Mg-ilmenite Ilmenite occurs in many of the Archean rocks in the Kirkland Lake area as well as in kimberlite. Kimberlitic ilmenites can be distinguished from other ilmenites by their high MgO content, typically containing >4 wt.%. Ilmenites from the A4, B30, C14 and Diamond Lake kimberlites (red dots) contain 4 to 15 wt.% MgO, and are low in Cr2O3, most grains contain <1 wt.% Cr2O3. Glacial sediments (blue dots) contain kimberlitic ilmenite as well as ilmenite form other sources. Each kimberlite has a distinct Cr2O3 versus MgO signature that is mimicked by the glacial sediments and kimberlite boulders collected down-ice, as shown in the Cr2O3 versus MgO plots. For example, one 25 kg kimberlite boulder found 3 km southeast of the Diamond Lake pipe, has a similar Cr2O3 versus MgO signature indicating it was derived from the Diamond Lake pipe.
Garnet
Cr-pyrope Subcalcic harzburgitic garnets are associated with diamondiferous kimberlites. They can be differentiated from other lherzolitic, harzburgitic or dunitic garnets by plotting CaO versus Cr2O3. The diagonal line separating lherzolitic and harzburgitic garnets is the 85% line defined by Gurney (1984). Garnets that fall below the 85% line, i.e. low-Ca Cr-pyropes, are "subcalcic" or G10 garnets derived from harzburgite. The high chrome content gives these garnets a distinct lilac purple colour. The vertical line separates Cr-poor, orange-red garnets having <2 wt. % Cr2O3 from the purple peridotitic garnets. Garnets from the A4, B30, C14 and Diamond Lake kimberlites (red dots) are mostly G9 (lherzolitic), and only a few are subcalcic-G10 garnets. Garnets in the glacial sediments (blue dots), in general, have similar compositions to those in the kimberlites. The low abundance of G10 garnets in the kimberlites and glacial sediments is consistent with the low diamond grades of these pipes.
Chromite
Chromite associated with diamonds has a high Cr2O3 content (>60 wt. %) and moderate to high level (12-16 wt.%) of MgO. The compositions of chromites from the A4, B30, C14 and Diamond Lake kimberlites represent a "poor" chromite population with only a few chromite xenocrysts approaching the diamond inclusion field. This is consistent with the trace quantities of diamonds found in these pipes. Chromite grains in glacial sediments show similar compositions to those from the kimberlites, suggesting many of the grains are from kimberlite.
Cr-diopside
Cr-diopside Cr-rich (>0.5 wt.% Cr2O3) diopside is easily identified by its distinctive green colour. It indicates the presence of kimberlite but provides little information on the presence of diamonds in the kimberlite. Cr-diopsides in the Kirkland Lake area occur in ultramafic rocks as well as kimberlites, although only kimberlites contain very Cr-rich (>1.5 wt.% Cr2O3) diopsides. The B30, A4, C14 and Diamond Lake kimberlites contain pale green (0.5 wt.% Cr2O3) to bright green (1.0 to 4.0 wt.% Cr2O3) Cr-diopside. The presence of Cr-diopside is not a useful kimberlite indicator on its own, because of the ubiquitous distribution of Cr-diopside grains in glacial sediments across the Kirkland Lake region and the difficulty in distinguishing between Cr-diopsides from kimberlite and those from other rocks.
olivine
Mg-ilmenite
Pyrope
Distribution of Mg-ilmenite grains in overburden drill holes south of the Diamond Lake kimberlite.
sts.gsc.nrcan.gc.ca
***
Geological Survey of Canada Open File 3228
Searching for diamonds in Canada
Edited by A.N. LeCheminant, D.G. Richardson, R.N.W. DiLabio and K.A. Richardson1996 Available at the GSC Bookstore
Table of Contents
Foreword
A.N. Lecheminant, D.G. Richardson, R.N.W. DiLabio and K.A. Richardson
Part 1: Geology, petrology and geotectonic controls
Introduction
A.N. Lecheminant and B.A. Kjarsgaard
Precambrian Shield of Canada
Archean cratons
J.A. Percival
Paleoproterozoic Orogenic Belts
M.R. St-Onge and S. B. Lucas.
The Mesoproterozoic Grenville orogen
A. Davidson
Kimberlites and methods used for their study
Kimberlites
B.A. Kjarsgaard
Isotopic age determinations of kimberlites and related rocks: Methods and applications
W.J. Davis, R.R. Parrish, J.C. Roddick, and L.M. Heaman
Fossils from diamondiferous kimberlites at Lac de Gras,
N.W.T.: Age and paleogeography
W.W. Nassichuk and D.J. McIntyre
Tools of investigation: The electron microprobe and scanning electron microscope
J.A.R. Stirling and G.J. Pringle
Slave Province kimberlites, N.W.T.
B.A. Kjarsgaard
Somerset Island kimberlite field, District of Frankin , N.W.T.
B.A. Kjarsgaard
Prairie kimberlites
B.A. Kjarsgaard
Kimberlites in the vicinity of Kirkland Lake and Lake Temiscaming, Ontario and Quebec
D.J. Schulze
Lamproites and other alkaline rocks
Lamproites
T.D. Peterson.
The relation of diamond-bearing rocks to other alkaline rocks
K L Currie
Diatreme breccias in the Cordillera
O.J. Ijewliw and J. Pell
Ultrapotassic rocks of the Dubawnt Supergroup, District of Keewatin
T. D. Peterson and A.N. LeCheminant
The diamondiferous Akluilâk lamprophyre dike, Gibson Lake area, N.W.T.
N.D. MacRae, A.E. Armitage, A.R. Miller, J.C. Roddick, A.L. Jones, and M.P. Mudry.
Lamproite dykes of southeast Baffin Island
D.D. Hogarth and T. D. Peterson
Sweet Grass minettes, Alberta
B.A. Kjarsgaard and W.J. Davis
Superior Province lamprophyres
R. A. Stern
Alnoïtes and related rocks, Monteregian Hills alkaline igneous province, Quebec
J. H. Bédard and A.N. LeCheminant
Lamprophyric dykes in Labrador. Summary of occurrences and their significance to diamond exploration
B. Ryan
Xenoliths and xenocrysts
Ultramafic xenoliths and xenocrysts in kimberlite and alnoïtes: Windows to the upper mantle
D.J. Schulze
Geochronological and pathogenetic studies of lower crustal xenoliths entrained in kimberlites and alkaline rocks
W.J. Davis and D. Moser
Insights on minette emplacement and the lithosphere underlying the southwest Grenville Province of Quebec at 1.08 Ga
L. Corriveau, D. Morin, M. Tellier, Y. Amelin, and O. van Breemen
Fossils as indicators of thermal alteration associated with kimberlites
A. D. McCracken, D. K. Armstrong, and D.C. McGregor
Thermal data from petrographic analysis of organic matter in kimberlite pipes, Lac de Gras, N.W.T.
L.D. Stasiuk and W.W. Nassichuk.
Geotectonic controls
Thermal evolution of the lithosphere in the central Slave Province: Implications for diamond genesis
P.H. Thompson, A.S. Judge, and T.J. Lewis
Mafic magnetism, mantle roots, and kimberlites in the Slave craton
A.N. Lecheminant, L.M. Herman, O. van Breemen, R.E. Ernst, W.R.A. Baragar and K.L. Buchan
Other diamond host rocks
Diamonds associated with ultramafic complexes and derived placers
A.N. Lecheminant and J. H. Bédard
Diamonds in ultrahigh-pressure metamorphic rocks
R.G. Berman
Impact diamonds
R.A.F. Grieve and V. L. Masaitis
Part 2: Diamond exploration in glaciated terrain
Introduction
R.N.W. DiLabio
Kimberlite indicator minerals in glacial deposits, Lac de Gras area, N.W.T.
B.C. Ward, L.A. Dredge, D.E. Kerr, and I.M. Kjarsgaard
Morphology and kelyphite preservation on glacially transported pyrope grains
L.A. Dredge, B.C. Ward, and D.E. Kerr.
Kimberlite indicator mineral and soil geochemical reconnaissance of the Canadian Prairie region
R.G. Garrett and L.H. Thorleifson
Geochemistry and indicator mineralogy of drift over kimberlite, Kirkland Lake, Ontario
M.B. McClenaghan
Biogeochemical studies of kimberlites
C.E. Dunn and M.B. McClenaghan
Part 3: Geophysical exploration and Geographic Information System (GIS) applications
Introduction
K.A. Richardson
The National Aeromagnetic Data Base
P. Keating, J. Tod, and R. Dumont
Kimberlites and aeromagnetics
P. Keating
Geophysical characteristics of Canadian kimberlites
C.J. Mwenifumbo, J.A.M. Hunter, and P.G. Killeen
Physical characteristics of Canadian kimberlites
T.J. Kasube and B.A. Kjarsgaard
Geophysical measurements for lithospheric parameters
A.G. Jones, D.W. Eaton, D. White, M. Bostock, M. Mareschal, and J.F. Cassidy
Seismic reflection survey of a kimberlite intrusion in the Fort à la Corne District, Saskatchewan
D. J. Gendzwill and S.D. Matieshin
Application of thermal imagery from LANDSAT data to locate kimberlites, Lac de Gras area, District of Mackenzic, N.W.T.
A.N. Rencz, C. Bowie and B.C. Ward
GIS activities related to diamond research and exploration, Lac de Gras area, District of Mackenzie, N.W.T.
C. Bowie, B.A. Kjarsgaard, H.J. Broome, and A.N. Rencz.
Appendix A: Contributors Names and Addresses
Foreword
A.N. Lecheminant, D.G. Richardson, R.N.W. DiLabio, and K.A. Richardson
Diamonds! "The Great Canadian Diamond Rush" north of Yellowknife (McNellis, 1993) revives for this generation a sense of the excitement and dreams of the Klondikers of the last century. Until recently, most Canadians thought of diamonds only as exotic and treasured jewels, appreciated for their rarity and brilliance, but of little direct economic interest to Canada. Prospective areas of the Canadian Shield were largely ignored, even though for almost thirty years geologists have known that diamond deposits are closely associated with the old stable nuclei of continents (cratons). Diamonds originate in the Earth's mantle at depths >150 km and most are stored in distinctive source rocks that make up part of the stable mantle root beneath Archean (> 2500 million years old) and Proterozoic (2500 to 570 million years old) cratons. The two most important diamond source rocks are peridotite and eclogite, and each rock type contains a characteristic suite of minerals that are key indicators for diamond exploration. Primary diamond deposits occur where kimberlite and lamproite magmas erupted, since these deep-seated magmas provide a medium to sample diamond-bearing source rocks and transport diamonds and associated indicator minerals to surface. Economic diamond-producing gelds occur on most Archean cratons worldwide, with the notable exception of Archean cratons in Canada, such as the Superior, Slave and Nain provinces. However, intense exploration activity throughout Canada, since the late 1980s, has located numerous diamond-bearing kimberlite in the Slave Province near Lac de Gras, north of Yellowknife, and additional kimberlites have been discovered in Alberta, Saskatchewan, Manitoba, Ontario, and Quebec.
Surprisingly, before the 1990s, diamonds were almost absent from Canadian folklore and mineral history. Jacques Cartier's men mined "diamonds" at the mouth of Rivière du Cap-Rouge in 1541, but their treasure turned out to be worthless quartz. This episode gave Quebec's Cap Diamant its name, and the story survives in the saying "faux comme des diamants du Canada". Early this century, reports by officers of the Geological Survey of Canada suggested microdiamonds were recovered from chromitite lenses in the Tulameen complex, British Columbia Camsell, 1911) and from chromite ore mined at Black Lake, Quebec (Dresser, 1913).
Although the Tulameen "microdiamonds" were later shown to be synthetic periclase formed by laboratory heating of the rock samples, recent work in Morocco, Spain, and Tibet has documented the association of diamonds with similar mechanically emplaced untramafic rocks (Davies et al., 1993; Baio et al., 1993).
J.J. Brummer (1978) culled meagre data from a wide range of source's to provide a remarkably comprehensive overview of the early history of "Diamonds in Canada". He noted that W.H. Hobbs (1899) first raised the possibility of diamond sources in Canada, based on discoveries of diamonds in glacial drift south of the Great Lakes. Although a 33 carat alluvial diamond was discovered near Peterborough, Ontario before 1920, and some finds were reported in Saskatchewan and Quebec in the late 1940s and early 1950s, significant diamond exploration did not begin in Canada until the 1960s, when indicator mineral surveys were conducted in Ontario by mining companies, the Ontario Department of Mines and the Geological Survey of Canada. Satterly (1949) recognized the first Canadian kimberlites in Michaud Township, north of Kirkland Lake and, by the late 1960s, several other kimberlites and a few diamonds had been discovered. The history of recent diamond discoveries in Canada has yet to be written, but many of he most enthusiastic extortionists, active over more than 25 years, now find themselves drawn to the Barrenlands near LaC de Gras, hoping to be among the first to bring Canadian diamonds to world markets.
Discovery of world-class diamond deposits depends on determined mineral exploration aided by a reliable and comprehensive geological database. Papers in this volume provide a snapshot of the spectrum of geoscience information available to assist diamond exploration in Canada. Maps provide elegant and ready access to data acquired and interpreted by the Geological Survey of Canada (GSC), Provincial Surveys, and University-based researchers. Mapping by the GSC now integrates traditional geological, geophysical, geochemical, and surficial surveys with specialized Geographic Information System (GlS) techniques, several of which have important applications to diamond exploration. This volume provides background for several of the national databases maintained by the GSC, as well as summaries of specific areas of diamond-related research and short reviews of GSC research relevant to diamond exploration. Readers seeking further information are encouraged to contact the authors, whose addresses are listed at the end of the volume. In addition, the GSC has published a bulletin that reviews the use of various indicator minerals and mineral assemblages as important aids in diamond exploration in Canada (Fipke et al., 1995).
Reports contained in this volume were submitted during the period December 1994-June 1995, and have been reviewed by GSC staff, but have not undergone rigorous scientific review. Thanks are extended to the many scientists who contributed to this volume, and to OJ. Ijewliw, R. Lacroix, D. Paul, S. Scully, M. Sigouin, K. Venance and T. West, all of the GSC, for assistance with figure production. W.C. Morgan undertook the technical editing. Preliminary corrections, compilation and layout were completed by A. Anand with assistance from N. Devine, C. Bélanger, L. O'Neill and C. Plant (all of the GSC). Printing of this volume was funded by the GSC's Mineral Resources and Continental Geoscience divisions.
Sadly, two scientist who contributed to this volume died in 1995. On February 23, Chris Roddick died in a skiing accident in Vermont, tragically cutting short a scientific career in isotope geoscience characterized by imagination, enthusiasm, and curiosity. His contribution to the Geochronology Laboratory of the GSC is commemorated in the introduction to the 1995 Radiogenic Age and Isotope Studies report ( Parrish, 1996). Chris leaves a rich legacy and is deeply missed. Marianne Mareschal, a leading scientist in Canada's LITHOPROBE project, passed away on July 11, 1995, after a long and courageous struggle with cancer. She was a member of the organizing committee for the Precambrian conference in Montreal and a dedication to her is published in the Program and Abstracts volume for Precambrian '95'.
Her kindness and energy touched all whom she met and she will be missed by many. Most of all, her direction and vision in combining seismic and electromagnetic experiments for the study of cratonic root:, which was her last major research effort, will bear fruit for many years to come. A foundation, established in her name, will be used to provide a student bursary in geophysics at the École Polytechnique de Montréal. Contributions should be forwarded to: Fonds Marianne Mareschal, Départment de génie minéral, École Polytechnique de Montréal, Montréal, CP 6079, Succ "centre ville" Montréal H3C 3A7, Canada.
References
Bai, W.-J., Zhou, M.-F., and Robinson, P.T.
1993: Possibly diamond-bearing mantle peritonitis and coliform chromiums in the Luobusa and Donqiao ophiolites, Tibet,
Canadian Journal of Earth Sciences, v. 30, p. 1650-1659.
Brummer, J.J.
1978: Diamonds in Canada.
Canadian Mining and Metallurgical Bulletin, October, 1978, p. 64-79.
Camsell C.
1911: A new diamond locality in the Tulameen district British Columbia;
Economic Geology, v. 6, p. 604-611.
Davies G.R., Nixon, P.H., Pearson, D.G., and Obata M.
1993: Tectonic implications of graphitized diamonds from the Ronda peridotite massif, southern Spain;
Geology, v. 21, p. 471-474.
Dresser, J.A.
1913: Preliminary report on the serpentine and associated rock of southern Quebec;
Canadian Department of Mines, Memoir 22, p. 82-84.
Fipke, C.E., Gurney, JJ., and Moore, R.O.
1995: Diamond exploration techniques emphasizing indicator mineral geochemistry and Canadian examples;
Geological Survey of Canada Bulletin 423, 86 p.
Hobbs W.H.
1899: The diamonds fields of the Great Lakes;
Journal of Geology, v.7, p. 375-388.
McNellis M.
1993: The Great Canadian Diamond Rush;
The Financial Post Magazine, October 1993, p. 18-36.
Parrish, R.R.
1996: Radiogenic Age and Isotopic Studies: Report 9 - Introduction; in Radiogenic Age and Isotopie Studies: Report 9.,
Geological Survey of Canada Current Research 1995-F, p. v-vi.
Satterly, J.
1949: Geology of the Michaud Township; Ontario
Departnent of Mines. Annual Report v. LVII, part IV, 1948.
SI post capacity won't accommodate the rest, so I have cut the paper here and will post the rest in another message in a few minutes.
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