DOCSLIB.ORG

Geochemistry and REE Minerals of Nepheline Syenites from The

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

American Mineralogist, Volume 70, pages 1087-1 100, 1985 Geochemistryand REE mineralsof nephelinesyenites from the Motzfeldt Centre,South Greenland A. P. JoNrsr Diuisionof Geologicaland Planetary Sciences CalifurniaInstitute of Technology,Pasadena, California 91125 .rNp L. M. LensrN GrsnlandsGeologiske U ndersogelse @sterVoldgade 10, DK-1350,Copenhagen, Denmark Abctract Whole-rock analysesincluding the REE are given for nineteensamples from four of the six overlappingnepheline syenite intrusions which constitutethe Proterozoic(- 1310ma) Motz- feldt Centre. Larvikite margins of one unit (SM5) are apparently related to the nepheline syenites by early fractionation of Ol + Pl followed by fractionation of Ol + Pl + Cpx t Amph at current levels of exposure.Positive Eu-anomaliesin the larvikites might be 875r/865r explained by large-scaleincorporation of earlier Pl-rich cumulates.Low initial ratios imply a mantle source,and the most basic magma was a late alkali gabbro giant dike with plagioclasemegacrysts. REE- and incompatibleelement-rich peralkaline lujavrites with large negativeEu-anomalies are late stageproducts of extremefractionation. Electron probe analysesof REE in eudialyteconfirm this mineral as the major host to Zr and REE in the lujavrites. Other REE-bearingminerals in the nephelinesyenites are Ca-Na{e-Ti-Zr-Nb- silicatesof the rinkite-mssandrite and l6venite series,with up to 22 wt.% RE-oxides;some may be related to metasomaticfluids which had geochemicalsignatures similar to the lujav- rites. Introduction sphene.Electron probe analysesincluding the REE in sev- discussed. The Motzfeldt Centre is the older of four major centers eral of theseminerals are reportedand becausea of igneousactivity which make up the Igaliko Complexof The Motdeldt Centre is especiallyinteresting was developed. nephelinesyenites (Emeleus and Harry, 1970).It is situated late stage peralkaline magma, lujavrite, bulk of silica- at the eastern end of the Proterozoic alkaline igneous This provides a link between the and the un- Gardar Province of southern Greenland (Emeleus and undersaturatedsyenite plutons in the Gardar (Ferguson,1964, Upton, 1976).The Motzfeldt Centre has a determined usual peralkalineIlimaussaq Intrusion that Rb/Sr (whole-rock)age of 1310+31 ma and an initial 1970;Bailey et al., 1981;Sorenson, 1969). We suggest 8?5r/865rratio near 0.702 (Blaxland et al., 1978).The incorporation of earlier feldspar-richcumulates in addition played im- MotzfeldtCentre covers an areaof approximately350 km2 to extensivecrystal fractionation could have an and is well exposedas a steeply dissectedand glaciated portant role in the overall petrogenesisof the syenites. 2000 m plateau. The mineralogy of the mafic silicatesto- getherwith a briefoutlineofthe geologyhas been given by Geology Jones(1984). The Motzfeldt Centre was formed by a seriesof overlap- In this paper we present new whole-rock geochemical ping intrusions emplacedby a combination of block stop- data for major and trace elementsincluding the rare earth ing and 5-10 km radius ring fractures.The country rock is elements(REE). In particular the REE are contained in a mostly gneiss,known as Julianehib granite (Allart, 1973) variety of minerals,some of which show evidenceof meta- and a sequenceof supracrustalrocks including metasedi- somatism. These minerals are principally eudialyte and ments, agglomerates and lavas collectively called the alkali-zircono-silicates of the rinkite-mssandrite and Eriksfiord Formation (Emeleusand Upton, 1976).Meta- livenite series,and to a lesserextent, apatite, zircon and somatizedand alteredrelics of the supracrustalrocks form large founderedraftlike xenoliths within the syenitesand measure up to several kilometers in length and a few I Current address, School of Geological Sciences,Kingston hundred meters in thickness.Adjacent lavas in the supra- Polytechnic, Penrhyn Road, Kingston Upon Thames, England crustal volcanic rocks, including the altered xenoliths, KTl 2EE. range from alkali basalts to phonolites and are possibly 0003-004x/85/l l 12-1087$02.00 1087 JONESAND LARSEN:NEPHELINE SYENI?ES FROM THE MOTZFELDT CENTRE Fig. l. Geology of the Motzfeldt Centre and location of samples used for whole-rock analysesin this study. Map after Jones (1984) with revised eastward extension to the major E-W fault after Tukiainen et al (1984). AGGD is alkali gabbro giant dike; EM : East Motzfeldt : syenites; NM North Motzfeldt syenites. Ornamentation, solid : supracrustal rocks. NQ : North Q6roq Centre (Chambers, 1976),SQ : South Q6roq Centre (Stephenson,1976). related to the Motzfeldt Centre itself (Jones, 1980). The structurally high levels. Pegmatites are sometimes associ- center is cut by a major transcurrent E-W fault (The ated with contacts between xenoliths and host syenites. Flink's Dal Fault, Emeleus and Harry, 1970) which was Several pegmatites, microsyenite sills and altered limonite- shown to have a left lateral displacementof severalkilome- rich shear zones in the center are enriched in radioactive ters (Jones, 1980) measured as 6 km to the east of the minerals (Tukiainen et al., 1984). inland lake, Moztfeldt So (Tukiainen et al., 1984).The Geo- The simplified geological map in Figure 1 shows the logical Survey of Greenland is currently engaged in de- location of analyzed whole-rock samples (XRF) selected for tailed investigations of several syenites and of radioactive additional REE determination by Instrumental Neutron mineralization in and around the center. There are six Activation Analysis (INAA). The XRF analyses were ob- major syenite units, prefixed "SM" and numbered I to 6 in tained by Jones (1980) from which the following summary order of intrusion as indicated on the summary geological is largely extracted. The ranges of zoned mafic minerals, map in Figure 1. Future refinements to the geological especially Fe/(Fe + Mg) and Na/(Na + Ca) in pyroxene, boundaries of the syenite units are unlikely to affect the are related to the calculated normative differentiation index major conclusions of this paper, but might provide answers (D.L) of the host rock. The D.L was calculated after Thorn- to some of the outstanding problems. A unit of late-stage ton and Tuttle (1960) with the addition of normative lujavrites (SM6) and a sub-unit of cancrinite-rich roof-zone acmite (NaFe3Si2O6), which is important in the more frac- syenites (HY) were recognized subsequent to the work of tionated syenites.Whole rock P and Ti decreasewith in- Emeleus and Harry (1970) by Jones (1980). Unequivocal creasing D.I. and increasing Fe/Mg, consistent with p€tro- time relationships between units SM5 and SM6 have not graphic textures which indicate early crystallization ofapa. been established, since they are separated by the Flink's tite and Ti-magnetite. Many of the syenites show cumulus Dal Fault. The center is cut by a regional swarm of ENE- textures in thin section and classic mineral banding, al- trending trachytic dikes and a prominent alkali gabbro though rare, does occur in the center (Emeleus and Harry, giant dike (AGGD) intruded in similar orientation. A few 1970; Jones, 1980). Mineral compositions show normal near-vertical carbonatitic and ultrabasic breccia pipes up zoning and combined trends which are the expectod conse- to 200 m across also cut the center, but are not shown on quences of crystallization from increasingly fractionated oy- Figure 1. The minor intrusions remain an attractive goal enite magmas. In addition to continuous zonation, the for future study and it is not known how they relate to the mafic minerals also show discontinuous zonation of the syenites.Thin discontinuous fluorite- and calcite-rich veins type pyroxene-amphibole-pyroxene (Jones, 1984). Bulk are found sporadically throughout the center and may pro- feldspar probe analyses are difficult to obtain because of vide clues to late stage metasomatic processesseen in some perthitic textures and show a wide range in Ca-poor com- JONESAND LARSEN:NEPHELINE SYENITES FROM THE MOTZFELDT CENTRE 1089 dike relatedto the marginsof unit SM5 (SM5{')contains well defined plagioclasecores with irregular outlines and lamellar twinning abruptly terminatedby mantlesof crypt- operthitic alkali feldspar.Three reconnaissancemicroprobe analysesof the plagioclaseshow a range in composition from Ab.rAnrrOr, to AbroAnrrOr,n and are plotted in the feldspar ternary in Figure 2. Similar, though slightly lesscalcic plagioclasecores (<An2o) occur in chilled facies of augitesyenite from Ilimaussaq(Larsen, 1981). The bulk composition of the larvikite ring dike provides the best estimateof a basic magma availableat Motzfeldt that was directly associatedwith the syenites(Table 2). However,the most basicrocks in the center,apart from the little studied carbonateplugs, are representedby the late AGGD (Fig. l). The AGGD carries abundant plagioclasemegacrysts (-Anruor.) and is similar to a Ti-rich alkali basalt in Ab 0r composition,with about 47 wt.VoSiO, and l4%o nephel- ine (Ne)in the CIPW norm at Fe3lFe2:0.1 (Jones,1980). Fig. 2. Feldspar compositions (Ca Na-K). Symbols: solid tdangles : plagioclase cores in larvikites of SM5; open triangles : rims and normal feldspar from larvikitic syenites of SM5; open Analytical procedure circles : feldspar from nepheline syenites of SM5; hexagon X-ray onalyses(XRF) (AGGD) : plagioclase megacryst from alkali gabbro giant dike. fluorescence Ruled areas are loci of feldspar (including plagioclase relics) from Originalrock samples,typically 0.5 to 2.0kg in sizedepending chilled facies of augite
Recommended publications
  • Minor Elements in Magnetic Concentrates from the Syenite-Shonkinite Province, Southern Asir, Kingdom of Saudi Arabia

    Minor Elements in Magnetic Concentrates from the Syenite-Shonkinite Province, Southern Asir, Kingdom of Saudi Arabia

    DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Minor elements in Magnetic concentrates from the Syenite-Shonkinite Province, Southern Asir, Kingdom of Saudi Arabia I/ I/ I/ I/ W. C. Overstreet, G. W. Day, Theodore Botinelly, and George Van Trump, Jr. Open-File Report 87 r Report prepared by the U.S. Geological Survey in cooperation with the Deputy Ministry for Mineral Resources, Saudi Arabia This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature, I/ USGS, Retired 2/ USGS, Denver, CO 1987 CONTENTS ABSTRACT............................................................ 1 ACKNOWLEDGMENT...................................................... 1 INTRODUCTION........................................................ 1 Areas covered and previous work................................ 1 Syenite plutons........................................... 3 Jabal Fayfa and Jabal Bani Malik..................... 3 Pluton southeast of Suq al Ithnayn................... 3 Shonkinite pluton at Jabal Atwid..................... 3 Mineral potential......................................... 3 Purpose of present investigation............................... 3 PROCEDURES.......................................................... 10 Collection and preparation of detrital magnetite............... 10 Mineralogical analyses......................................... 10 Semiquantitative spectrographic analyses....................... 11 Method...................................................
  • National Treasure of Global Significance. Dimension-Stone Deposits in Larvikite, Oslo Igneous Province, Norway

    National Treasure of Global Significance. Dimension-Stone Deposits in Larvikite, Oslo Igneous Province, Norway

    National treasure of global significance. Dimension-stone deposits in larvikite, Oslo igneous province, Norway Tom Heldal1, Idunn Kjølle2, Gurli B. Meyer1 and Sven Dahlgren3 1Geological Survey of Norway (NGU), 7491 Trondheim, Norway. 2Directorate of mining, 7491 Trondheim, Norway. 3Geological advisor, Buskerud, Telemark and Vestfold, Fylkeshuset, 3126 Tønsberg, Norway. E-mail: [email protected] Larvikite has for more than a hundred years been appreciated as one of the world’s most attractive dimension stones, and at present, its production and use is more extensive than ever. The main reason for the continuous success of larvikite on the world market is the blue iridescence displayed on polished surfaces, which is caused by optical interference in microscopic lamellae within the ternary feldspars. The larvikite complex consists of different intrusions, defining several ring- shaped structures, emplaced during a period of approximately five million years. Following this pattern, several commercial subtypes of larvikite, characterised by their colour and iridescence, have been mapped. Four of these subtypes are being exploited at the present time and define the most important reserves in the short run. Some other subtypes are less attractive in the present market situation, but may provide an interesting potential for the future. However, the industrial value of the larvikite also depends on other geological features, such as various types of dykes, faults and fractures, ductile deformation zones, late-stage magmatic and hydrothermal alteration and deep weathering. When combining the distribution pattern of such features with the map of the larvikite subtypes, it is possible to delineate various types of larvikite deposit that are considered to have commercial value in the short or long term.
  • The Permo-Carboniferous Oslo Rift Through Six Stages and 65 Million Years

    The Permo-Carboniferous Oslo Rift Through Six Stages and 65 Million Years

    52 by Bjørn T. Larsen1, Snorre Olaussen2, Bjørn Sundvoll3, and Michel Heeremans4 The Permo-Carboniferous Oslo Rift through six stages and 65 million years 1 Det Norske Oljeselskp ASA, Norway. E-mail: [email protected] 2 Eni Norge AS. E-mail: [email protected] 3 NHM, UiO. E-mail: [email protected] 4 Inst. for Geofag, UiO. E-mail: [email protected] The Oslo Rift is the northernmost part of the Rotliegen- des basin system in Europe. The rift was formed by lithospheric stretching north of the Tornquist fault sys- tem and is related tectonically and in time to the last phase of the Variscan orogeny. The main graben form- ing period in the Oslo Region began in Late Carbonif- erous, culminating some 20–30 Ma later with extensive volcanism and rifting, and later with uplift and emplacement of major batholiths. It ended with a final termination of intrusions in the Early Triassic, some 65 Ma after the tectonic and magmatic onset. We divide the geological development of the rift into six stages. Sediments, even with marine incursions occur exclusively during the forerunner to rifting. The mag- matic products in the Oslo Rift vary in composition and are unevenly distributed through the six stages along the length of the structure. Introduction The Oslo Palaeorift (Figure 1) contributed to the onset of a pro- longed period of extensional faulting and volcanism in NW Europe, which lasted throughout the Late Palaeozoic and the Mesozoic eras. Widespread rifting and magmatism developed north of the foreland of the Variscan Orogen during the latest Carboniferous and contin- ued in some of the areas, like the Oslo Rift, all through the Permian period.
  • Summary of the Mineral Information Package for the Khanneshin Carbonatite Area of Interest

    Summary of the Mineral Information Package for the Khanneshin Carbonatite Area of Interest

    Chapter 21A. Summary of the Mineral Information Package for the Khanneshin Carbonatite Area of Interest Contribution by Robert D. Tucker, Harvey E. Belkin, Klaus J. Schulz, Stephen G. Peters, and Kim P. Buttleman Abstract The Khanneshin carbonatite is a deeply dissected igneous complex of Quaternary age that rises approximately 700 meters above the flat-lying Neogene sediments of the Registan Desert, Helmand Province, Afghanistan. The complex consists almost exclusively of carbonate-rich intrusive and extrusive igneous rocks, crudely circular in outline, with only three small hypabyssal plugs of leucite phonolite and leucitite outcropping in the southeastern part of the complex. The complex is broadly divisible into a central intrusive vent (or massif), approximately 4 kilometers in diameter, consisting of coarse-grained sövite and brecciated and agglomeratic barite-ankerite alvikite; a thin marginal zone (less than 1 kilometer wide) of outwardly dipping (5°–45°). Neogene sedimentary strata; and a peripheral apron of volcanic and volcaniclastic strata extending another 3–5 kilometers away from the central intrusive massif. Small satellitic intrusions of biotite-calcite carbonatite, no larger than 400 meters in diameter, crop out on the southern and southeastern margin of the central intrusive massif. In the 1970s several teams of Soviet geologists identified prospective areas of interest for uranium, phosphorus, and light rare earth element (LREE) mineralization in four regions of the carbonatite complex. High uranium concentrations are reported in two regions; the greatest concentrations are confined to silicified shear zones in sandy clay approximately 1.1 kilometers southwest of the peripheral part of the central vent. An area of phosphorus enrichment, primarily occurring in apatite, is present in coarse-grained agglomeratic alvikite, with abundant fenite xenoliths, approximately 750 meters south of the periphery of the central vent.
  • Feldspar and Nepheline Syenite 2016

    Feldspar and Nepheline Syenite 2016

    2016 Minerals Yearbook FELDSPAR AND NEPHELINE SYENITE [ADVANCE RELEASE] U.S. Department of the Interior January 2020 U.S. Geological Survey Feldspar and Nepheline Syenite By Arnold O. Tanner Domestic survey data and tables were prepared by Raymond I. Eldridge III, statistical assistant. In 2016, feldspar production in the United States was representing 46% of the 2016 production tonnages listed in estimated to be 470,000 metric tons (t) valued at $33.1 million, tables 1 and 2. an almost 10% decrease in quantity and a 11% decrease in Feldspar was mined in six States (table 3). North Carolina value compared with 2015 (table 1). Exports of feldspar in 2016 was by far the leading producer State; the remaining five were, decreased by 61% to 5,890 t, valued at $1.5 million, and imports in descending order of estimated output, Virginia, California, of feldspar decreased by 69% to 36,900 t, valued at $3.4 million. Idaho, Oklahoma, and South Dakota. Production was from Imports of nepheline syenite (predominantly from Canada) 10 mines and beneficiating facilities—4 in North Carolina, 2 in increased by 27% to about 572,000 t valued at $73 million. California, and 1 in each of the 4 remaining States (table 3). World production of feldspar in 2016 was 23.4 million metric I-Minerals Inc. continued the mine permitting process for tons (Mt) (tables 1, 7). its Helmer-Bovill project in north-central Idaho; the mine Feldspars, which constitute about 60% of the earth’s crust, would produce potassium feldspar, halloysite, kaolin, and are anhydrous aluminosilicate minerals of two main groupings: quartz.
  • Graveyard Geology

    Graveyard Geology

    GRAVEYARD GEOLOGY A Guide to Rocks in Graveyards and Cemeteries Wendy Kirk Department of Earth Sciences, David Cook University College London & Aldersbrook Geological Society London Geodiversity Partnership Introduction Walk around graveyards and cemeteries (in this case, those of London and the southeast of England) and it becomes apparent that, prior to the latter part of the twentieth century, many memorials were made out of just a few different rock types. These were chosen for reasons of appearance, cost, workability and ease of transport to the cemetery, as well as for resistance to weathering and dependence on local regulations. In the last few decades, a range of different, interesting and beautiful stones have appeared, many brought in from abroad, enhancing the diversity of materials used. The intention of this guide is to help a non-specialist identify the main rock types, to recognize some of the varieties and to know where some of these might have come from. Graveyards are a wonderful resource for those with an interest in geology at any level, wildlife, plants, history or sculpture. We hope you gain as much pleasure as we have done. First things first A useful place to start is to be able to distinguish between igneous, sedimentary and metamorphic rocks. Igneous rocks form from melted rock called magma. If this erupts at the surface, it is called lava. It cools and crystallizes quickly, so the grains are too small to see even with a hand lens (magnifying glass). If the lava erupt explosively to form a spray, the cooled fragments are known as volcanic ash.
  • Controls on Syenite-Hosted Gold Mineralization in the Western Timmins Camp

    Controls on Syenite-Hosted Gold Mineralization in the Western Timmins Camp

    Western University Scholarship@Western Electronic Thesis and Dissertation Repository 11-24-2014 12:00 AM Controls on Syenite-Hosted Gold Mineralization in the Western Timmins Camp Robert A. Campbell The University of Western Ontario Supervisor Bob Linnen The University of Western Ontario Graduate Program in Geology A thesis submitted in partial fulfillment of the equirr ements for the degree in Master of Science © Robert A. Campbell 2014 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Geology Commons Recommended Citation Campbell, Robert A., "Controls on Syenite-Hosted Gold Mineralization in the Western Timmins Camp" (2014). Electronic Thesis and Dissertation Repository. 2636. https://ir.lib.uwo.ca/etd/2636 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Controls on Syenite-Hosted Gold Mineralization in the Western Timmins Camp (Thesis format: Monograph) by Randy Campbell Graduate Program in Earth Sciences A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science The School of Graduate and Postdoctoral Studies The University of Western Ontario London, Ontario, Canada © Randy Campbell 2014 ABSTRACT The Abitibi granite-greenstone belt has long been known for its’ world-class Archean lode gold deposits. While a spatial relationship between felsic intrusions and gold deposits has been noted for some time, it is not clear whether porphyries are genetically related to gold mineralization or just provided a brittle host for unrelated mineralization.
  • Petrology of Nepheline Syenite Pegmatites in the Oslo Rift, Norway: Zr and Ti Mineral Assemblages in Miaskitic and Agpaitic Pegmatites in the Larvik Plutonic Complex

    Petrology of Nepheline Syenite Pegmatites in the Oslo Rift, Norway: Zr and Ti Mineral Assemblages in Miaskitic and Agpaitic Pegmatites in the Larvik Plutonic Complex

    MINERALOGIA, 44, No 3-4: 61-98, (2013) DOI: 10.2478/mipo-2013-0007 www.Mineralogia.pl MINERALOGICAL SOCIETY OF POLAND POLSKIE TOWARZYSTWO MINERALOGICZNE __________________________________________________________________________________________________________________________ Original paper Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: Zr and Ti mineral assemblages in miaskitic and agpaitic pegmatites in the Larvik Plutonic Complex Tom ANDERSEN1*, Muriel ERAMBERT1, Alf Olav LARSEN2, Rune S. SELBEKK3 1 Department of Geosciences, University of Oslo, PO Box 1047 Blindern, N-0316 Oslo Norway; e-mail: [email protected] 2 Statoil ASA, Hydroveien 67, N-3908 Porsgrunn, Norway 3 Natural History Museum, University of Oslo, Sars gate 1, N-0562 Oslo, Norway * Corresponding author Received: December, 2010 Received in revised form: May 15, 2012 Accepted: June 1, 2012 Available online: November 5, 2012 Abstract. Agpaitic nepheline syenites have complex, Na-Ca-Zr-Ti minerals as the main hosts for zirconium and titanium, rather than zircon and titanite, which are characteristic for miaskitic rocks. The transition from a miaskitic to an agpaitic crystallization regime in silica-undersaturated magma has traditionally been related to increasing peralkalinity of the magma, but halogen and water contents are also important parameters. The Larvik Plutonic Complex (LPC) in the Permian Oslo Rift, Norway consists of intrusions of hypersolvus monzonite (larvikite), nepheline monzonite (lardalite) and nepheline syenite. Pegmatites ranging in composition from miaskitic syenite with or without nepheline to mildly agpaitic nepheline syenite are the latest products of magmatic differentiation in the complex. The pegmatites can be grouped in (at least) four distinct suites from their magmatic Ti and Zr silicate mineral assemblages.
  • Geology of the Saline County Xenolith and Surrounding Area

    Geology of the Saline County Xenolith and Surrounding Area

    A.G.E.S. Brochure Series 005 State of Arkansas Arkansas Geological Survey Bekki White, State Geologist Geology of the Saline County Xenolith and surrounding area By J. Michael Howard Illustrations and photos by Angela Chandler _______________________________________________________ _______________________________________________________ Xenolith – “ a foreign inclusion in an igneous rock.” Glossary of Geology American Geological Institute 1987 (from the Greek words Xenos, meaning guest or stranger, and Lithos, meaning stone.) _______________________________________________________ _______________________________________________________ Introduction Located in Saline County, Arkansas, at the south edge of the community of Bauxite, this natural outcrop of nepheline syenite contains several geologically interesting features, including a xenolith. Sloping west, the outcrop encompasses about one-quarter acre near the center of section 21, Township 2 South, Range 14 West. In early 1990, the Aluminum Company of America (ALCOA) donated the outcrop along with approximately five surrounding acres of land to the Arkansas Geological Commission so that the site can be preserved for educational purposes. Outcrop of nepheline syenite at xenolith locality. History of the site The outcrop and its geologic features were first described by J. Francis Williams in 1891 in The Igneous Rocks of Arkansas, Arkansas Geological Survey Annual Report for 1890, Volume II. Williams discussed the outcrop and xenolith in some detail and included a sketch of the xenolith (see title page). However, for many years the outcrop location remained unknown to most scientists. In the late 2 1960’s employees in the mining division of ALCOA, suspecting that the site was on their property, began a concerted search. Soon afterward the outcrop was rediscovered and was visited by a staff member of the Arkansas Geological Commission, who in turn told Dr.
  • Rhyolite and Trachyte Formation at Lake City Caldera: Insight from Quantitative Textural and Geochemical Analyses

    Rhyolite and Trachyte Formation at Lake City Caldera: Insight from Quantitative Textural and Geochemical Analyses

    Michigan Technological University Digital Commons @ Michigan Tech Dissertations, Master's Theses and Master's Reports 2016 Rhyolite and Trachyte Formation at Lake City Caldera: Insight from Quantitative Textural and Geochemical Analyses Jordan Lubbers Michigan Technological University, [email protected] Copyright 2016 Jordan Lubbers Recommended Citation Lubbers, Jordan, "Rhyolite and Trachyte Formation at Lake City Caldera: Insight from Quantitative Textural and Geochemical Analyses", Open Access Master's Thesis, Michigan Technological University, 2016. https://doi.org/10.37099/mtu.dc.etdr/99 Follow this and additional works at: https://digitalcommons.mtu.edu/etdr Part of the Geochemistry Commons, and the Geology Commons RHYOLITE AND TRACHYTE FORMATION AT LAKE CITY CALDERA: INSIGHT FROM QUANTITATIVE TEXTURAL AND GEOCHEMICAL ANALYSES By Jordan E. Lubbers A THESIS Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE In Geology MICHIGAN TECHNOLOGICAL UNIVERSITY 2016 © 2016 Jordan E. Lubbers This thesis has been approved in partial fulfillment of the requirements for the Degree of MASTER OF SCIENCE in Geology. Geological and Mining Engineering and Sciences ThesisDepartment Advisor: ofChad Deering Committee Member: Olivier Bachmann Committee Member: William Rose Department Chair: John Gierke Table of Contents Acknowledgements ................................................................................................................................................. 6 Abstract ......................................................................................................................................................................
  • FELDSPAR and NEPHELINE SYENITE by Michael J

    FELDSPAR and NEPHELINE SYENITE by Michael J

    FELDSPAR AND NEPHELINE SYENITE By Michael J. Potter Domestic survey data and tables were prepared by Hoa P. Phamdang, statistical assistant, and the world production table was prepared by Glenn J. Wallace, international data coordinator. Feldspars are the Earth’s most abundant mineral group, The value of total feldspar sold or used in table 4 is higher than estimated to constitute 60% of the earth’s crust (Kauffman and the feldspar production value shown in tables 1 and 2. The sold Van Dyk, 1994). They are aluminum silicate minerals that or used value represents the final marketed feldspar product. contain varying proportions of calcium, potassium, and sodium. The unit value of $65.27 per metric ton for the “pottery and Nepheline syenite is a light-colored, silica-deficient feldspathic miscellaneous” category in table 4 is less than the price range rock made up mostly of sodium and potassium feldspars and for ceramic-grade feldspar in table 5. However, the latter is nepheline; although not mined in the United States in 2002, it was stated by the publisher to be intended to serve only as a guide. imported from Canada for use in the glass and ceramic industries. World Review.—Canada.—Avalon Ventures Ltd. continued work on its high-lithium feldspar Separation Rapids project Feldspar in Kenora, Ontario. Project engineering and feasibility study work focused on process flowsheet design and transportation In glassmaking, alumina from feldspar improves product studies. To further evaluate a new dry process flowsheet, a 5-t hardness, durability, and resistance to chemical corrosion. In ore sample was collected for shipment to a test milling facility.
  • Oregon Geologic Digital Compilation Rules for Lithology Merge Information Entry

    Oregon Geologic Digital Compilation Rules for Lithology Merge Information Entry

    State of Oregon Department of Geology and Mineral Industries Vicki S. McConnell, State Geologist OREGON GEOLOGIC DIGITAL COMPILATION RULES FOR LITHOLOGY MERGE INFORMATION ENTRY G E O L O G Y F A N O D T N M I E N M E T R R A A L P I E N D D U N S O T G R E I R E S O 1937 2006 Revisions: Feburary 2, 2005 January 1, 2006 NOTICE The Oregon Department of Geology and Mineral Industries is publishing this paper because the infor- mation furthers the mission of the Department. To facilitate timely distribution of the information, this report is published as received from the authors and has not been edited to our usual standards. Oregon Department of Geology and Mineral Industries Oregon Geologic Digital Compilation Published in conformance with ORS 516.030 For copies of this publication or other information about Oregon’s geology and natural resources, contact: Nature of the Northwest Information Center 800 NE Oregon Street #5 Portland, Oregon 97232 (971) 673-1555 http://www.naturenw.org Oregon Department of Geology and Mineral Industries - Oregon Geologic Digital Compilation i RULES FOR LITHOLOGY MERGE INFORMATION ENTRY The lithology merge unit contains 5 parts, separated by periods: Major characteristic.Lithology.Layering.Crystals/Grains.Engineering Lithology Merge Unit label (Lith_Mrg_U field in GIS polygon file): major_characteristic.LITHOLOGY.Layering.Crystals/Grains.Engineering major characteristic - lower case, places the unit into a general category .LITHOLOGY - in upper case, generally the compositional/common chemical lithologic name(s)