Trace Elements in Apatite as Genetic Indicators of the Evate Apatite-Magnetite Deposit, NE Mozambique

The Evate deposit is a Neoproterozoic (~590 Ma) magnetite-apatite-carbonate body emplaced parallel to foliation of the Monapo granulite complex in NE Mozambique. A complicated history of the deposit is recorded in apatite textures visualized in cathodoluminescence (CL) images. In spite of different solid and fluid inclusions, mineral assemblages, and the CL textures, electron probe microanalyses indicate relatively consistent apatite compositions corresponding to fluorapatite (XF = 0.51–0.73, XOH = 0.21–0.47, XCl = 0.02–0.06) with limited belovite- and cesanite-type substitutions. Laser ablation inductively coupled plasma mass spectrometric analyses show that apatites from unaltered magnetite-forsterite-spinel ores are depleted in Y, REE, Ba, and Sr compared to apatites from carbonate-anhydrite ores. Hydrothermally overprinted apatites with complex patchy domain CL textures are enriched in Y-REE in greenish-grey zones, Fe-U-Th in blue zones, and Mn-Sr-Ba in brown domains. Observed CL-emissions in the Evate apatites result from very subtle variations in REE, Mn, and U contents controlled by the variability of redox conditions. The decreased Th:U ratio in the hydrothermally overprinted apatites reflects the oxidation and partial removal of U4+ from the apatite structure during the interaction with oxidizing aqueous fluids capable of transporting U6+. Flat, LREE (La-Sm)-enriched chondrite-normalized patterns with Eu/Eu* = 0.7–1.4 and Ce/Ce* = 0.9–1.5, together with concentrations of diagnostic trace elements (Sr, Mn, Y, REE) are consistent with apatites from magmatic carbonatites and phoscorites. This study corroborates that the Evate deposit is a post-collisional orogenic carbonatite genetically linked with mafic plutonic rocks intruding the Monapo granulite complex after granulite-facies metamorphism, and later overprinted by intensive hydrothermalism. The Evate apatite is peculiar in retaining its pristine magmatic signature despite the extensive hydrothermal-metasomatic alteration accompanied by dissolution-reprecipitation.

[1]  M. Slobodník,et al.  Thermobarometric and geochronologic constraints on the emplacement of the Neoproterozoic Evate carbonatite during exhumation of the Monapo granulite complex, Mozambique , 2020 .

[2]  J. Baele,et al.  Unravelling the processes controlling apatite formation in the Phalaborwa Complex (South Africa) based on combined cathodoluminescence, LA-ICPMS and in-situ O and Sr isotope analyses , 2020, Contributions to Mineralogy and Petrology.

[3]  J. Gross,et al.  Apatite trace element geochemistry and cathodoluminescent textures—A comparison between regional magmatism and the Pea Ridge IOAREE and Boss IOCG deposits, southeastern Missouri iron metallogenic province, USA , 2020 .

[4]  L. Kogarko.  Chemical Composition and Petrogenetic Implications of Apatite in the Khibiny Apatite-Nepheline Deposits (Kola Peninsula) , 2018, Minerals.

[5]  A. Doroshkevich,et al.  The origin of magnetite-apatite rocks of Mushgai-Khudag Complex, South Mongolia: mineral chemistry and studies of melt and fluid inclusions , 2018, Lithos.

[6]  N. Cook,et al.  Numerical Modeling of REE Fractionation Patterns in Fluorapatite from the Olympic Dam Deposit (South Australia) , 2018, Minerals.

[7]  M. Reich,et al.  Kiruna-Type Iron Oxide-Apatite (IOA) and Iron Oxide Copper-Gold (IOCG) Deposits Form by a Combination of Igneous and Magmatic-Hydrothermal Processes: Evidence from the Chilean Iron Belt , 2018 .

[8]  M. Slobodník,et al.  Compositional variations of zirconolite from the Evate apatite deposit (Mozambique) as an indicator of magmatic-hydrothermal conditions during post-orogenic collapse of Gondwana , 2018, Mineralogy and Petrology.

[9]  J. Kynický,et al.  Apatite in carbonatitic rocks: Compositional variation, zoning, element partitioning and petrogenetic significance , 2017 .

[10]  J. Paquette,et al.  New insights into the origin of the Evate apatite-iron oxide-carbonate deposit, Northeastern Mozambique, constrained by mineralogy, textures, thermochronometry, and fluid inclusions , 2017 .

[11]  L. A. Coogan,et al.  Apatite Trace Element Compositions: A Robust New Tool for Mineral Exploration , 2016 .

[12]  B. Bingen,et al.  Granulite-facies metamorphism of the Palaeoproterozoic – early Palaeozoic gneiss domains of NE Mozambique, East African Orogen , 2016, Geological Magazine.

[13]  Gus Gunn,et al.  Evidence for dissolution-reprecipitation of apatite and preferential LREE mobility in carbonatite-derived late-stage hydrothermal processes , 2016 .

[14]  J. Baele,et al.  Fluorapatite in carbonatite-related phosphate deposits: the case of the Matongo carbonatite (Burundi) , 2016, Mineralium Deposita.

[15]  J. Webster,et al.  Magmatic Apatite: A Powerful, Yet Deceptive, Mineral , 2015 .

[16]  D. Harlov.  Apatite: A Fingerprint for Metasomatic Processes , 2015 .

[17]  M. Marks,et al.  Compositional variation in apatite from various host rocks: clues with regards to source composition and crystallization conditions , 2015 .

[18]  A. Chakhmouradian,et al.  Carbonatite-hosted niobium deposit at Aley, northern British Columbia (Canada): Mineralogy, geochemistry and petrogenesis , 2015 .

[19]  T. Kusky,et al.  Orogen styles in the East African Orogen: A review of the Neoproterozoic to Cambrian tectonic evolution , 2013, Journal of African earth sciences.

[20]  N. Tsuchiya,et al.  Comparison of the metamorphic history of the Monapo Complex, northern Mozambique and Balchenfjella and Austhameren areas, Sør Rondane, Antarctica: Implications for the Kuunga Orogeny and the amalgamation of N and S. Gondwana , 2013 .

[21]  Jodie Miller,et al.  Geology of the Monapo Klippe, NE Mozambique and its significance for assembly of central Gondwana , 2013 .

[22]  T. Zhao,et al.  Differentiation of nelsonitic magmas in the formation of the ~1.74 Ga Damiao Fe–Ti–P ore deposit, North China , 2013, Contributions to Mineralogy and Petrology.

[23]  C. Davidson,et al.  Hyperspectral Cathodoluminescence Imaging and Analysis Extending from Ultraviolet to Near Infrared , 2012, Microscopy and Microanalysis.

[24]  R. Thomas,et al.  Delamination-induced late-tectonic deformation and high-grade metamorphism of the Proterozoic Nampula Complex, northern Mozambique , 2012 .

[25]  K. Qin,et al.  Major and Trace Element Characteristics of Apatites in Granitoids from Central Kazakhstan: Implications for Petrogenesis and Mineralization , 2012 .

[26]  B. Mehrabi,et al.  Significance of apatite REE depletion and monazite inclusions in the brecciated Se–Chahun iron oxide–apatite deposit, Bafq district, Iran: Insights from paragenesis and geochemistry , 2011 .

[27]  R. Thomas,et al.  Mesoproterozoic geology of the Nampula Block, northern Mozambique: Tracing fragments of Mesoproterozoic crust in the heart of Gondwana , 2010 .

[28]  T. White,et al.  Nomenclature of the apatite supergroup minerals , 2010 .

[29]  W. Griffin,et al.  Apatite Composition: Tracing Petrogenetic Processes in Transhimalayan Granitoids , 2009 .

[30]  R. Thomas,et al.  Geochronology of the Precambrian crust in the Mozambique belt in NE Mozambique, and implications for Gondwana assembly , 2009 .

[31]  P. Montero,et al.  Trace elements in minerals as indicators of the evolution of alkaline ultrabasic dike series: LA-ICP-MS data for the magmatic provinces of northeastern Fennoscandia and Germany , 2009 .

[32]  I. Henderson,et al.  Growth and collapse of a deeply eroded orogen: Insights from structural, geophysical, and geochronological constraints on the Pan‐African evolution of NE Mozambique , 2008 .

[33]  B. Kjarsgaard,et al.  Carbonatite occurrences of the world: map and database , 2008 .

[34]  L. Panina.  Origin and evolution of carbonatite magmas , 2008 .

[35]  Y. Motoyoshi,et al.  Geodynamic Evolution of East Antarctica: A Key to the East–West Gondwana Connection , 2008 .

[36]  R. Armstrong,et al.  Terrane correlation between Antarctica, Mozambique and Sri Lanka; comparisons of geochronology, lithology, structure and metamorphism and possible implications for the geology of southern Africa and Antarctica , 2007 .

[37]  Pnrnn L. Rononn,et al.  Cathodoluminescence and microprobe study of rare-earth elements in apatite , 2007 .

[38]  J. P. Karlsson.  An investigation of the Felsic Ramiane Pluton in the Monapo Structure, northern Moçambique , 2006 .

[39]  D. Harlov,et al.  Origin of fluorapatite-monazite assemblages in a metamorphosed, sillimanite- bearing pegmatoid, Reinbolt Hills, East Antarctica , 2005 .

[40]  Hong‐fu Zhang,et al.  Geochemical and isotopic investigation of the Laiwu–Zibo carbonatites from western Shandong Province, China, and implications for their petrogenesis and enriched mantle source , 2004 .

[41]  R. A. Gault.  ALKALINE ROCKS AND CARBONATITES OF THE WORLD, PART 3: AFRICA.A.R. Woolley, 2001. The Geological Society Publishing House, Bath, U.K. U.S.A. Distributor AAPG Bookstore: bookstore@aapg.org. Hardback, 372 p. $142 ($85 AAPG members, $65 Geological Society of London members) , 2003 .

[42]  W. Griffin,et al.  Apatite as an indicator mineral for mineral exploration: trace-element compositions and their relationship to host rock type , 2002 .

[43]  U. Kempe,et al.  Cathodoluminescence (CL) behaviour and crystal chemistry of apatite from rare-metal deposits , 2002, Mineralogical Magazine.

[44]  A. Zaitsev,et al.  CALCITE – AMPHIBOLE – CLINOPYROXENE ROCK FROM THE AFRIKANDA COMPLEX, KOLA PENINSULA, RUSSIA: MINERALOGY AND A POSSIBLE LINK TO CARBONATITES. II. OXYSALT MINERALS , 2002 .

[45]  P. Candela,et al.  Apatite in Igneous Systems , 2002 .

[46]  M. Fleet,et al.  Compositions of the Apatite-Group Minerals: Substitution Mechanisms and Controlling Factors , 2002 .

[47]  Andre-Mathieu,et al.  Rare-earth element systematics of carbonatitic fluorapatites, and their significance for carbonatite magma evolution , 2001 .

[48]  M. Pagel,et al.  Cathodoluminescence study of apatite crystals , 2001 .

[49]  W. Seifert.  Compositional variation in apatite, phlogopite and other accessory minerals of the ultramafic Delitzsch complex, Germany: implication for cooling history of carbonatites , 2000 .

[50]  F. Stoppa,et al.  A multi-method analysis of Si-, S- and REE-rich apatite from a new find of kalsilite-bearing leucitite (Abruzzi, Italy) , 1999, Mineralogical Magazine.

[51]  R. Reeder,et al.  Intracrystalline rare earth element distributions in apatite: Surface structural influences on incorporation during growth , 1996 .

[52]  R. Frietsch,et al.  Rare earth elements in apatite and magnetite in Kiruna-type iron ores and some other iron ore types , 1995 .

[53]  F. Stoppa,et al.  Chemical composition and petrogenetic implications of apatites from some ultra-alkaline Italian rocks , 1995 .

[54]  L. Kogarko,et al.  Alkaline rocks and carbonatites of the world , 1995 .

[55]  J. Marques,et al.  The Mozambique Belt in northern Mozambique: Neoproterozoic (1100–850 Ma) crustal growth and tectogenesis, and superimposed Pan-African (800–550 Ma) tectonism , 1993 .

[56]  C. Merlet.  Accurate description of surface ionization in electron probe microanalysis: An improved formulation , 1992 .

[57]  John M. Hughes,et al.  Crystal structures of natural ternary apatites; solid solution in the Ca 5 (PO 4 ) 3 X(X = F, OH, Cl) system , 1990 .

[58]  D. K. Bailey.  Carbonate melt from the mantle in the volcanoes of south-east Zambia , 1989, Nature.

[59]  V. Cílek.  Industrial minerals of Mozambique , 1989 .

[60]  N. Grevesse,et al.  Abundances of the elements: Meteoritic and solar , 1989 .

[61]  P. Roeder,et al.  Cathodoluminescence and microprobe study of rare-earth elements in apatite , 1987 .

[62]  M. J. Bas.  Nephelinites and carbonatites , 1987 .

[63]  J. P. Deneufville,et al.  Selective detection of uranium by laser-induced fluorescence: a potential remote-sensing technique. 1: Optical characteristics of uranyl geologic targets. , 1981, Applied optics.

[64]  R. Bell.  Geological Survey of Canada , 1885, Nature.