 | CABRAL, A. R., MOORE, J. M., MAPANI, B. S., KOUBOVA, M., SATTLER, C.- D. (2011) GEOCHEMICAL AND MINERALOGICAL CONSTRAINTS ON THE GENESIS OF THE OTJOSONDU FERROMANGANESE DEPOSIT, NAMIBIA: HYDROTHERMAL EXHALATIVE VERSUS HYDROGENETIC (INCLUDING SNOWBALL-EARTH) ORIGINS. South African Journal of Geology, 114 (1) 57-76 doi:10.2113/gssajg.114.1.57 | Journal (article/letter/editorial) | | CONSTRAINTS ON THE GENESIS OF THE OTJOSONDU FERROMANGANESE DEPOSIT, NAMIBIA: HYDROTHERMAL EXHALATIVE VERSUS...Department of Geology, University of Namibia, Private Bag 13301, Windhoek, Namibia e-mail: b.mapani@unam.na M...Africa ABSTRACT The stratigraphic position of the Otjosondu ferromanganese deposit in the Neoproterozoic Damara...the Swakop Group, as previously proposed. The Otjosondu ore comprises ferromanganese silicate-oxide assemblages...and manganese formations. The formation of the Otjosondu ferromanganese deposit is therefore unrelated |  | B HN, B., OKRUSCH, M., WOERMANN, E., LEHNERT, K., HOERNES, S. (1995) Metamorphic Evolution of Neoproterozoic Manganese Formations and their Country Rocks at Otjosondu, Namibia. Journal of Petrology, 36 (2) 463-496 doi:10.1093/petrology/36.2.463 | Journal (article/letter/editorial) | | depending on their paragenesis. They indicate very Namibia were subjected to high-^T-low-P metamorphism dur-...WORD& manganiferous sediments; Damara Orogeny; Namibia; formations. They are correlated with peak pressure...Manganese Formations and their Country Rocks at Otjosondu, Namibia JOURNAL OF PETROLOGY VOLUME :t(i NUMBER...and Miller (1983a) tentatively correlated the Otjosondu ores with the Chuos Formation, which bears glaciomarine...metallogenetic model (Buhn et al., 1992, 1993*). The Otjosondu Mn ore-bearing unit consists of at least two manganese |  | | Journal (article/letter/editorial) | | contain the mineral assemblage braunite-bixbyite-hollandite-hausmannite-jacobsite-vredenburgite where some... 1965) FEITKNECHTITE PYROCHROITE Mn(OH)2 HOLLANDITE BoR8016 i R=Mn 4+MAINLY, ALSO Mn 2+,Fe, Co (RICHMOND...manganesedeposits. Some escaped C• ,bA-{.A. IV•_ •ICOAND /HOLLANDITE,CORONADITE metamorphismand, but for somediageneticchanges...GRANT COUNTY, HOLLANDITE, CRYPTOMELANN (HEWETT AND FLEISCHER,1960) PSiLOMELANE, HOLLANDITE (HEWETT AND...AND FLEISCHER,196(• PSILOMELANE,HOLLANDITE NEW MEXICO HIDALGO COUNTY NEW MEXICO CRYPTOME LANE LUNA |  | | Journal (issue) | | ........................pg. 3 Actinolite from Namibia by Justin Zzyzx .................................we bring you eleven articles about locations in Namibia that do not receive much publicity. It is easy...legendary deposits such as Tsumeb, the Brandberg region and the Erongo Mountains. Alpine clefts, huge soda...Mountains, located in the southwestern part of central Namibia. The Gamsberg Mountain is the most important landmark...Fluorapatite Fluorapatite is quite rare from the region but can be found as complex, colorless crystals |  | | Journal (article/letter/editorial) | | depositsof Madhya Pradesh-Maharashtrabelt, India, Otjosondu, S.W. Africa and Mount Brandnuten,S. Norway are...oxidesof manganese suchashausmannite, bixbyite,hollandite andbraunite. The fieldrelationsdefinitely suggest...MANGANESE FORMATION OF OTJOSONDU, S.W. AFRICA The manganese ore deposits of Otjosondu,S.W. Africa havebeenshown...Precambrian--Siberia, Sagan-Zaba(near Lake Baikal), Baikal region, Ukraine. Cambrian-•Qussinsk, W. Siberia,Kazakhstan(Cambrianto...Gerais (Brazil), Ti•r• (French West Africa), Otjosondu (S.W. Africa), Madagascar,Simsi/5(Finland), Sierra |  | | Journal (article/letter/editorial) | | stability of both minerals is constrained in the region of low f CO2 . The paper reports data on the Fe–Si–O...First, Fig. 1 shows two subparallel lines in the region of high oxygen fugacity corresponding to the reactions...reactions (1), (8), and (5) and encompasses the region of log f O2 values at which braunite is stable...diagram, below the reaction lines 7 and 6. This region of relatively low log f O2 values corresponds to...previous diagram (Fig. 1), it corresponds to the region in the vicinity of reaction line 4. Because of |  | | Journal (article/letter/editorial) | | A NEW OCCURRENCE OF BARIUM-FELDSPAR AT OTJOSONDU, SOUTH-WEST AFRICA, AND AN THE X-RAY METHOD FOR DETERMINING...INrnolucrroN In a study of the manganeseores of Otjosondu, South-West Africa, de Villiers (1, p. 95) describedtwo...Cn5s)occur in rocks composed of braunite, garnet and hollandite. They were present in very small quantities and...hyalophane of composition Cnro, BARIUM-FELDSPARAT OTJOSONDU,SOUTH.WESTAFRICA 853 Cn2a,Crye and Ctur. These...dominant cation changes. BARIUM.FELDSPARAT OTJOSONDU, SOUTE-II/ESTAFRICA 855 Direct comparison of |  | | Journal (article/letter/editorial) | | equilibrating with associated phases such as bixbyite, hollandite and jacobsite during prograde reactions. Petrogenetic...Initially braunit%~ along with pyrolusite or hollandite were formed from appropriate precursors accompanying...converted to braunite(m. In assemblages where hollandite was absent, jacobsite appeared after bixbyite...metamorphism irrespective of the presence of hollandite in the assemblage. The fractured nature of bixbyite...ores into hollanditebearing and hollandite-free assemblages. In hollandite-bearing ores, the assemblage |  | | Journal (article/letter/editorial) | | bothcolloidaland metamorphic derivationjacobsite,hollandite, manganite, pyrolusite andcryptomelane werefound...generation (Braunite I) i• associated with bixbyite,hollandite,jacobsite,vredenburgite, and h•iusmannite. Bixbyiteveins...deformedgrainsof braunite. Hollanditeof first generation(Hollandite I) also replacesbraunite I irregularly. Seco...formedlater in elevatedtemperatureconditions (Fig. 7). Hollandite, like braunite, is of two generations. The hollanditesof...eI) are also deformedand intenselyshattered. Hollandite,with brauniteI, are dimensionallyorientedand |  | | Journal (article/letter/editorial) | | (Stilp)* Parsettensite (Pars)* Hyalophane (Hyal)* Hollandite(?) Graphite (?) Rutile 2) Mn oxide rock ~ Quartz...categories of feldspars from the Otjosondu manganese deposit, Namibia (Viswanathan and Kielhorn, 1983)...manganese oxides are lithiophorite, vernadite, hollandite, and nsutite. The manganese rocks of the Nangodi...Kajilidongri/India (Bhattacharya et al., 1984). Hollandite is stable only in high-temperature assemblages...spessartine + amphibole. During metamorphism, hollandite + clay may react to form hyalophane + spessartine |  | | Journal (article/letter/editorial) | | and sand, and these cryptomelane,psilomelane,hollandite,braunite,and youngdepositshavegreatlyhamperedthe...the Postdepositedby hypogenesolutions. masburg region and is a major constituentof the Kalahari ores...present Namibia (25.59%Fe•Os) found that at 100øC manganiteand cryptomelane in braunitefrom Otjosondu, form...Ka- be pyrolusite,cryptomelane,psilomelane, hollandite, todorokite,lithiophorite,and nsutite.Grains...indicated,and this suchlocalities asOtjosondu, Namibia(J.E. de Villiers, zoningwould be superimposed on |  | | Book | | Mountainland The Central Northern to Northwest Region including Damaraland The Central Namib Desertand...Copper Deposits The South The Pegmatitesin Central Namibia Luderitz and the Diamonds 44 49 241 254 272 275... Encyclopedia of the Mineralsof Namibia 443 Meteorites in Namibia Bibliography Index Photo credits...__ Republic of Namibia The President State House W°Ntdhoek FOREWORD Namibia is endowed with an...from near and far. Fine mineral specimen from Namibia are displayed in all the famous natural science |  | Dasgupta, Somnath, Sengupta, Pulak, Bhattacharya, P. K., Mukherjee, M., Fukuoka, M., Banerjee, H., Roy, Supriya (1989) Mineral reactions in manganese oxide rocks; P-T-X phase relations. Economic Geology, 84 (2) 434-443 doi:10.2113/gsecongeo.84.2.434 | Journal (article/letter/editorial) | | zone,660øC,6 kbars + Hs + Qz Urandi, Brazil Otjosondu, (iv) Br01q-Py q-Qz Chloritezone (v) Br0y q-Jbq-Hm...de Villiers (1983) Bhattacharyaet al. (1988) Namibia India California, (ix) Br + Rdh q-Hs ___ Qz ...amphibolitefaciesmineralassemblages of India (Table1). In hollandite-free assemblages, the braunite-hematite-jaeobsite |  | | Book (edition) | | strong red Stilleite Mottramite Acanthite Hollandite mosaic and polysynthetic Crednerite yes Cinnabar...Madenköy Mine, Çayeli, Rize Province, Black Sea Region, Turkey (sample: Halbach); XPL If marked in description... Taymyrskiy Autonomous Okrug, Eastern-Siberian Region, Russia (sample: Melcher/Oberthür); PPL D Fine-grained... Karabash, Chelyabinsk Oblast’, Southern Urals Region, Russia Au-Cu alloys, native Copper, native Gold...Potaro River, Kangaruma District, Potaro-Siparuni Region, Guyana Chalcopyrite, native Gold, Hematite, Millerite |  | | Journal (article/letter/editorial) | | deposited in deep water at a continental margin in a region of oceanic upwelling. Hein and Koski (1987) stressed...and Stribrny, 1986) and the Damara Supergroup, Namibia (Roper, 1956), interstratified Mn-oxide-chert occurrences...the isostructural Mn4+-rich series cryptomelane-hollandite-coronadite-manjirSite (cf. deposits of Nikopol...1149-1168. Roper, H., 1956. The manganese deposits at Otjosondu, Southwest Africa. 20th Int. Geol. Congr., Symp |  | | Book | | REPUBLIC OF NAMIBIA - MINISTRY OF MINES AND ENERGY GEOLOGICAL SURVEY THE MINERAL RESOURCES OF NAMIBIA FIRST...ENERGY Of the several hundred minerals present in Namibia, around sixty have been exploited. some, such as...base metals and industrial minerals have helped Namibia rank amongst the top five mining countries in Africa...terms of production and reserves. In this context, Namibia is a major producer of copper, lead, zinc, cadmium...unpublished. It is evident that mineral exploration in Namibia, as elsewhere. has changed from serendipitous discoveries |  | | Journal (article/letter/editorial) | | depositsare concentratedin two areas: in Ouarzazate,a region about 60 miles in diameterin southwesternMorocco...thesedeposits lie in the easterntwo-thirdsof the region,and they are veinslargely of manganeseoxides. Beds...Cretaceousage are found in the westernthird of the region. Most of the French geologistsagree that the older...somewhatsimilar situationis found in the Oujda region. Here, within a beltabout50 mileslongand 15 mileswide...district but are not recorded from the Ouarzazate region. Amongthe gangtieminerals,barite and quartz are |  | | Report (volume) | | mineralization in the PlioceneQuaternary Calatrava Region (central Spain) 29 43 81 91 105 117 123 139...consist of pyrolusite, cryptomelane, psilomelane, hollandite and todorokite, whereas others, formed from relatively...Interbanded Mn oxide orebodies (braunite, bixbyite, hollandite, jacobsite, hausmannite) and Mn silicate-oxide...run off. The Late Proterozoic Damara Sequence, Namibia (Table 7) consists mainly of shelf facies sedimentary...in Breitkopf 1988) of the Damara Sequence at Otjosondu consists of (bottom to top) lower quartzite, lower |  | | Book | | Accumulations in Paleokarst: Deposits of the Postmasburg Region, Griqualand West, Cape Province, South Africa 3...Bishop, Lohatlha, Glosam, and Kapstewel, Postmasburg Region, Griqualand West 3.3.2.3. Processes of the Manganese...the Tertiary Sediments 0/ the Ekaterinoslavskaya Region and the Vicinities o/the Krivoi Rog, published...concretions in the Jurassie sediments ofBavaria, Alpine region and neighboring areas. Later, on the basis of investigations...works greatly stimulated the investigations in this region. Heading the investigations of Mn ores in the Institute |  | | Book (volume) | | iron formations including those of the Great Lakes region (Canada and the USA), Venezuela, Brazil, Hamersley...metal 1,800-m.y.-old pegmatites of the White-Sea region and coeval mica pegmatites of the Mama Belt (Siberia)...parts of platforms, for example, in Timan-Pechora region. They are composed of thick sedimentary-volcanogenic...as, for example, Altay-Sayany region of the Soviet Union or Coastal region of Norway and Great Britain)...deposits of Australia , Tuva , and the Southern Baikal region (Ozyornoye deposit) . Caledonian granites accommodate |  | | Journal (volume) | | deposits at Långban in Sweden, the Kombat Mine in Namibia, and the Mammoth St. Anthony Mine in Tiger, Arizona...manganese-hosted Pb deposits found throughout the region. This has proved to be an unexpectedly complex...particular theme is one that repeats throughout the region. Complicating the matter still further is the fragmentary...to those found elsewhere throughout the Mendip region. These deposits are of the Mississippi Valley type...marked disconformity visible throughout much of the region, the disconformity representing a gap in the strata |  | | Book | | of the granite-gneissic Precambrian rocks of the region and of manganese mobilized by leaching of basalts...controlled by the structurally superimposed unwrapping region. This engendered the decisive conditions in the...granitized material itself. The wide country rock-region may in many cases be a significant contributor...the new mineral (metasome) or may diffuse into a region of increasing mobility, culminating in a solution...mineral parageneses of the Abu Dabbab area (Red Sea region, Egypt) showed that a lithophilic (crust) mineral |  | | Book | | Related Minerals Minerals Based on 4.8.8 Net Hollandite Structure Type . . The Hexagonal Structures ...'l" " ./ .. ,t " 1000 ·r :/ ~\\yimiting region for e-plog. ~ .\~\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\~...(J-M) has been proposed to explain the peristerite region. The Huttenlocher intergrowth is represented by...e-plagioclase probably develops inside the hatched region for cooling more rapid than that responsible for...mainly from annealing in the central part of the region outlined by hatched lines in Fig. l.4b. It must |  | | Book (edition) | | abbreviated, e.g. canton (Switzerland), vilayet (Turkey), region (Chile), kray and oblast (Russia). The country...by Mobutu, and is now the Katanga administrative region again. The former Kivu province is now divided...United States or of the Upper Silesian historical region in Poland, where the importance of ore-bearing... ah,c = 8. 4+, 11.12. 7.28, o.,~,y = 90°53', hollandite. and shattuckite, etc., in brownish red, metamorphic...Kunlun Mts., near Hotan, Xinjiang Uygur Autom. region, China, also at Fengtien, Taiwan. Green at Ospinskoye |  | | Report (issue) | | no. 2, 8990 (1979). Analysis from Lake Baikal region, x-ray, infra-red data. ALUMINITE. Farkas and Werner...(not in abs.; from metamorphic rocks, Altai-Sayan region. AMPHlBULh. Lesnov et al., (Tr. Inst. Geol. Geofiz...395, 133-147 (1978). Analyses from Altai-Sayan region. BIUTITL. Kupriidnova et al., Uokl. AKad. Nauk...8, 76021 (1980). Analyses (not in abs.), Gissar region. BIOTITE. Mendoza Sanchez, Bol. Geol., Publ. Espec...(1979). Re-analysis of calderite from Utjosondu, Namibia, gives composition as calderite (Mn3 Fe+3 (2) Si |
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