INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
GRANITIC PEGMATITES AND THEIR MINERALS: A SECOND TRIBUTE TO PETR CERNÝ
GALLISKI M. A.; LONDON D.; NOVÁK M.; MARTIN R.
MINERALOGICAL ASSOC CANADA
Lugar: Toronto, Canada; Año: 2012 vol. 50 p. 1441 - 1444
Petr Cerný began his scientific carreer in the mid-1950s. From the beginning, he focused on granitic pegmatites in his home country, Czechoslovakia. He was particularly interested in granitic pegmatites enclosed in compositionally contrasting rocks, like serpentinites, which are common components of metamorphic complexes of the Moldanubian Zone. Two localities dominated his quest for answers, Drahonín (see below about the cover page) and especially Vě?ná, both localities situated about 40?50 km northwest of Brno, his birthplace. Beryllium-bearing minerals (bavenite, milarite, epididymite, eudidymite), cordierite, phosphates of the rare-earth elements, zircon and niobian rutile were the most common targets of his mineralogical studies, but he also studied the products of hydrothermal alteration, such as hydrotalcite and zeolites (e.g., thomsonite, harmotome, stilbite). Rather surprisingly, the topic of his M.S. thesis at Masaryk University in Brno was a study of secondary sulfates (e.g., halotrichite, melanterite, epsomite, slavíkite) from Smolník, a locality characterized by Fe ores in eastern Slovakia.After his arrival in Winnipeg in 1968, the granitic pegmatites of Manitoba, mainly at Bernic Lake (Tanco), as well as at Greer Lake (e.g., Annie Claim), Cross Lake, Shatford Lake (e.g., Huron Claim) and Red Cross Lake became targets of his focused investigations. And the focus is clearly an ongoing one, to judge from contributions in this issue. He studied, in cooperation with his colleagues and students, almost all minerals from the Tanco pegmatite, namely the (Nb,Ta,Ti) oxides (wodginite group, tantalite), phosphates (amblygonite?montebrasite, triphylite?lithiophilite), micas, and the aluminosilicates of lithium and their breakdown products. He regularly published results on the Tanco pegmatite as a running series in The Canadian Mineralogist, and thus contributed in an important way to the stature of this journal in the area of pegmatite research. This series culminated with part XVI, published in 2006, which really established the Tanco granitic pegmatite as the best studied example of a zoned granitic pegmatite in the world. The paper, by Andrew Stilling, Petr and Peter J. Vanstone, is really a landmark study because of the authors? description of the internal structure and their assessment of weighted bulk-compositions of the individual textural-paragenetic units, which led to a reconstructed composition of the pegmatite-forming magma.From the mid-1980s, Petr shifted his attention to other regions in Canada, e.g., Yellowknife, Northwest Territories, in the United States, and he also returned to central Europe, first to Czechoslovakia, in a pioneering study of feldspars using SIMS from the Vě?ná I pegmatite, and to pegmatites in the southern Alps, Austria. In early 1990s, after the Velvet Revolution, Petr significantly accelerated studies in his home country; he tackled classical localities such as beryl- and chrysoberyl-bearing pegmatites of Mar?íkov, northern Moravia, the Ro?ná lepidolite pegmatite, as well as other complex pegmatites (e.g., Dobrá Voda, Jihlava region, Nová Ves and Bli?ná near Český Krumlov). Along with a continuing study of granites and granitic pegmatites in Manitoba, he developed interests in Scandinavia, in particular in Sweden (e.g., Utö, Varuträsk) in the mid-1990s, then in Slovakia, and in the late 1990s, in Argentina. Along with the above-mentioned countries, he examined pegmatites and their minerals from Brazil, Africa (e.g., Zimbabwe, Uganda, Mozambique), Italy, France, Norway, Greenland, Russia, and Thailand, among others. Petr Černý is still active in the area of pegmatites from Manitoba. For example, his long-term quest to document the evolution of one of the world?s most highly fractionated suites, at Red Cross Lake, Manitoba, has now come to fruition in this issue.The scope of Petr?s research is very broad indeed. He tackles themes ranging from various regional studies, paragenetic and crystal-chemical mineralogy, and crystallography, to classical and isotopic geochemistry of granites and pegmatites. He is a world-class expert on many mineral groups occurring in granitic pegmatites, namely the oxides of Nb, Ta, Ti, W and Sn (columbite group, wodginite group, pyrochlore group, tapiolite group, rutile group, stibiotantalite group, ixiolite group, foordite?thoreaulite series), primary phosphates (amblygonite?montebrasite series, triphylite?lithiophilite series, graftonite group, phosphates of Y andthe rare-earth elements, Be-bearing phosphates) and silicates. He gives special attention to minerals of the cordierite group, beryl group, tourmaline group, milarite group, micas, feldspars, pollucite, zeolites and titanite, among others. Although not on a quest to describe new mineral species, he has participated in the description of 17 new minerals, mostly phosphates, oxides and silicates from granitic pegmatites: stibiobetafite, parabariomicrolite, bobfergusonite, foordite, rossmanite, rubicline, ferrowodginite, titanowodginite, ferrotitanowodginite, xenotime-(Yb), bederite, ercitite, monazite-(Sm), oftedahlite, manitobaite, aspedamite and billwiseite.Petr?s most cited papers are those about granitic pegmatites and their fertile granites, tectonic setting and source lithologies of granite?pegmatite systems, extreme geochemical fractionation as well as anatomy, internal structure and classification of granitic pegmatites. The impact of his productive career can be appreciated by the response of his peers to the idea of a thematic issue of The Canadian Mineralogist, first formulated on the occasion of the Fifth International Symposium on Granitic Pegmatites, held in 2011 in Mendoza, Argentina. The tribute was published as the August 2012 issue, a meaty 376-page collection of 20 pegmatite-related papers published under the title Granitic Pegmatites and their Minerals. But the response to the call for papers was so overwhelming that the organizers of the Festschrift had to contemplate a second celebratory issue, which is now before you.We are happy to present to the readership of this journal and to pegmatite afficionados around the world the second tribute to Petr Černý. It contains 23 contributions, which are organized under the following themes: Mineralogy and Crystal Chemistry, Mineral Assemblages and Evolution, Petrology, Geology and Granite?Pegmatite Relations, and Manitoba Pegmatites. The first theme, Mineralogy and Crystal Chemistry, includes descriptions of a new member of the sarcopside group, zavalíaite, (Mn2+,Fe2+,Mg)3 (PO4)2, from the La Empleada pegmatite, San Luis Province, Argentina by Frédéric Hatert and colleagues. Artur C. Bastos Neto et al. describe fluorine-rich xenotime from the world-class Madeira Nb?Ta?Sn deposit associated with the albite-enriched A-type granite at Pitinga, Amazonia, Brazil. The crystal chemistry of beryl from miarolitic pockets of granitic pegmatites at Elba, Italy, characterized by means of EMP and SIMS analyses, is described by Carlo Aurisicchio and colleagues.The second theme, Mineral Assemblages and Evolution, features detailed studies of various mineral assemblages, compositional evolution of minerals and hydrothermal alteration in granitic pegmatites including: bismuth-rich tellurium-bearing minerals in the El Quemado granitic pegmatite, Nevados de Palermo, Salta, Argentina by María Florencia Márquez-Zavalía and colleagues; mineralogical and mineral-chemical heterogeneity indicated by the distribution of accessory minerals in pegmatites of the Nine Mile pluton of the Wausau syenite complex, Marathon County, Wisconsin by Al U. Falster and colleagues; compositional and structural variations in columbite-group minerals from granitic pegmatites of the Brunswick and Oxford fields, Maine, related to F-poor and F-rich environments by Michael A. Wise and colleagues; genetic implications from mineralogy and geochemistry of phosphates and silicates in the Sapucaia pegmatite, Minas Gerais, Brazil by Maxime Baijot and colleagues; a case study of the garnet?phosphate buffer in peraluminous granitic magmas that gave rise to pegmatites in the Pocho district, Córdoba, Argentina by Fernando Colombo and colleagues; the internal structure, petrography and mineralogy of the Puentemocha beryl?phosphate granitic pegmatite, Salamanca, Spain by Encar Roda-Robles and colleagues; the mineralogy of spodumene pegmatites and related rocks in the tin?spodumene belt of North Carolina and South Carolina, USA by Sam E. Swanson; the replacement of quartz by ?kerolite? in graphic quartz?feldspar intergrowths from the Vě?ná I pegmatite, Czech Republic, as an expression of a complex desilication process related to episyenitization by Marek Dosbaba and Milan Novák; and corundum + tourmaline nodules related to hydrothermal alteration of spodumene in the Nanping no. 31 pegmatite dyke, Fujian Province, southeastern China by Can Rao and colleagues. The third theme , Petrology, Geology and Granite?Pegmatite Relations, provides several contributions to genesis of pegmatite, granite?pegmatite systems and relations among metamorphic and magmatic processes and granitic pegmatites including: radioactive abyssal granitic pegmatites from the Wollaston Domain, northern Saskatchewan, Canada in the Fraser Lakes area, with a look at mineral compositions and conditions of emplacement of radioactive abyssal granitic pegmatites and leucogranites; mineral compositions, metamorphic P?T?t path, and implications for the genesis of radioactive abyssal granitic pegmatites from medium- to low-pressure pelitic gneisses of Fraser Lakes Zone B, both by Christine L. McKechnie and colleagues; a comparison of the mineralogical and geochemical character and geological setting of Proterozoic REE-rich granitic pegmatites of the north-central and southwestern US by William B. (Skip) Simmons and colleagues; the mineralogy, classification, and tectonic setting of the granitic pegmatites of New York State, USA by Marian V. Lupulescu and colleagues; the intragranitic Potrerillos NYF pegmatites and their A-type host granites of the Las Chacras ? Potrerillos batholith, Sierra de San Luis, Argentina by Raúl Lira and colleagues, and the interrelationships among the emplacement of rare-element pegmatites, regional metamorphism and magmatism in the Moldanubian Domain of the Variscan Bohemian Massif, Czech Republic, by Jérémie Melleton and colleagues.The last theme concerns Manitoba Pegmatites. There are five contributions on granitic pegmatites from Manitoba, which have retained Petr Černý?s focused attention over the years. He has coauthored all five papers. The first is on radiogenic isotope systematics of the Tanco and Silverleaf granitic pegmatites, Winnipeg River pegmatite district, Manitoba, by Alfredo Camacho and colleagues. The next four papers deal with the highly fractionated and deformed leucogranite?pegmatite suite at Red Cross Lake, in fact one of the most strongly evolved granitic pegmatites in the world. The suite is described under the titles Geological setting (part I), Petrology of the leucogranites and pegmatites (part II), Description of shearing and mylonitization textures in the lepidolite pegmatites (part III), and Mineralogy (part IV), by Petr Černý and colleagues (parts I, II and IV) and William C. Brisbin and colleagues (part III).The cover illustration shows a chain of xenotime crystals (left), an acicular prism of zircon (center), and a syntactic alternation of zircon and xenotime (right), all three observed in the Drahonín granitic pegmatite. The illustration is taken from one of Petr?s earliest papers, published in 1956. The full title and reference: Oriented intergrowths of xenotime and zircon from Drahonín. Spisy přírodovědecké fakulty Masarykovy university, Brno 376, 293-306 (in Czech). Peter Gadas prepared the electronic file of the original figure, and Catherine Gibbard colorized it. Sincere thanks to Peter and Catherine for their contributions to the creation of this most relevant cover illustration, initially suggested by Milan Novák.As in the Preface of the first tribute to Petr Černý, published as the August 2012 issue of The Canadian Mineralogist, we thank all referees who accepted to scrutinize these contributions and to evaluate their relative merits, and who offered valuable suggestions for improvement. Enjoy!