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Rolf L Romer - One of the best experts on this subject based on the ideXlab platform.
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U-Pb isotopic dating of Columbite-tantalite minerals: Development of reference materials and in situ applications by ion microprobe
Chemical Geology, 2019Co-Authors: Hélène Legros, Rolf L Romer, Julien Mercadier, Johan Villeneuve, Etienne Deloule, Marieke Van Lichtervelde, Stijn Dewaele, Philippe Lach, Xudong Che, Rucheng WangAbstract:Columbite-tantalite group minerals are the most common Nb-Ta minerals. Columbite-tantalite is particularly suitable for U-Pb dating due to its high U and low common Pb contents. In situ isotopic dating of Columbite-tantalite by LA-ICP-MS or SIMS requires certified reference material to properly account for potential matrix effects linked to substitutions between Nb and Ta and between Mn and Fe. Our study has two objectives: i) establish a database of reference materials for in situ U-Pb isotopic dating of Columbite-tantalite minerals and ii) test the capability of SIMS to in situ U-Pb date Columbite-tantalite minerals of different chemical composition. Tests of in situ U-Pb dating demonstrate that SIMS can easily be used to date Columbite-tantalite minerals with errors and precisions overlapping the reference ID-TIMS age. There are, however, significant matrix effects for non-matching Nb-Ta-Fe-Mn compositions of sample and reference material. Matrix effects are highly correlated with the Ta/(Ta + Nb) ratio of Columbite-tantalite, due to the significant difference in the atomic mass of Nb and Ta. The Mn/(Mn + Fe) ratio does not significantly contribute to the observed matrix effect as the two elements have similar atomic masses. The linear correlation between Ta/(Nb + Ta) and ((206Pb/238U)SIMS/(206Pb/238U)ID-TIMS) obtained for Columbite-tantalite minerals of known ID-TIMS age demonstrates that the SIMS matrix-effect can be properly accounted for by using the chemical composition as determined by EMPA. The ability to measure 204Pb by SIMS also allows the use of reference materials with a small common lead contribution and to calculate accurate and precise ages for Columbite-tantalite minerals with contributions of common lead.
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Secondary Fe–Mn-oxides in minerals heavily damaged by α-recoil: possible implications for palaeomagnetism
International Journal of Earth Sciences, 2007Co-Authors: Rolf L Romer, Norbert Nowaczyk, Richard WirthAbstract:Sub-micron Fe,Mn-oxides in Columbite–tantalite minerals are bound to metamict domains in the host. These nano-oxides are secondary minerals as the metamict zones formed through accumulation of damages from α-recoil, each of which in a small volume destroys the crystal lattice of the U and Th bearing Columbite–tantalite host. Transmission electron microscope investigations demonstrate that the oxides fall in the compositional range of magnetite–jacobsite–iwakiite (Fe,Mn)_3O_4 and of hematite-type minerals along the Fe_2O_3–Mn_2O_3 join, i.e., minerals that are known to be major carriers of magnetic remanence. Measured magnetic properties of isolated Columbite–tantalite crystals demonstrate in some samples magnetic remanence, which is bound to sub-micron pseudosingle-domain crystals rather than to the host. Thus, the magnetic remanence is not related to the formation of Columbite–tantalite, but to the crystallization of the nano-oxides, which occur in metamict domains of the host and therefore are secondary. Depending on the content and distribution of U and Th, the nano-oxides may form diachronously within an individual and among several host crystals. Magnetic secondary nano-oxides are not restricted to Columbite–tantalite minerals, but may occur in other minerals where high contents of Fe and Mn are associated with high contents of U and Th. Rocks that show the same spatial distribution for U and Fe, as for instance some red sandstones, may display magnetic properties that are controlled by recoil-induced growth of secondary Fe-oxides.
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U-Pb Columbite age of Neoproterozoic Ta-Nb mineralization in Burundi
Economic Geology, 1995Co-Authors: Rolf L Romer, Bernd LehmannAbstract:Tin granites and associated Ta-Nb pegmatites in the Kibaran belt of central Africa have been dated earlier only by highly scattered Rb-Sr data that were interpreted to reflect events at 1000 to 900 and 650 to 550 Ma. New U-Pb dating of Columbite from the Kivuvu and Ruhembe pegmatites in Burundi precisely determines the age of the mineralization and indirectly also the age of the associated granite magmatism. Columbites from the Kivuvu and Ruhembe pegmatites have variably discordant U-Pb data that define emplacement ages at 962 + or - 2 Ma (2sigma ) and 968 (super +33) (sub -29) Ma, respectively. The lower intercept ages at 628 + or - 110 Ma and 622 + or - 56 Ma are interpreted to reflect the Pan-African brittle reworking of the pegmatite system when Au and Bi were redistributed on fractures and secondary sericite formed. The U-Pb age data from Columbite thus confirm earlier interpretations of Rb-Sr data.
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U-Pb Columbite-tantalite age constraints for Late Svecofennian crustal deformation in SW Finland
1995Co-Authors: Alf Lindroos, Rolf L Romer, Carl Ehlers, Reijo AlviolaAbstract:U-Pb Columbite-tantalite age constraints for Late Svecofennian crustal deformation in SW Finland
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Is the Bohus granite related with the post-kinematic rare-element pegmatites of southwestern Sweden? : a U-Pb Columbite investigation
1995Co-Authors: Rolf L Romer, Stenanders SmedsAbstract:Is the Bohus granite related with the post-kinematic rare-element pegmatites of southwestern Sweden? : a U-Pb Columbite investigation
Stenanders Smeds - One of the best experts on this subject based on the ideXlab platform.
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geochemistry of oxide minerals of nb ta sn and sb in the varutrask granitic pegmatite sweden the case of an anomalous Columbite tantalite trend
American Mineralogist, 2004Co-Authors: Petr Cerny, Ron Chapman, Karen Ferreira, Stenanders SmedsAbstract:The complex, petalite-subtype Varutrask pegmatite in the Proterozoic rocks of northern Sweden is, as a whole, rather poor in Nb and Ta. The pegmatite consolidated in eight units, but the (Nb,Ta)-oxide minerals attained saturation levels only in a late albite + lepidolite-bearing unit under conditions of high activity of alkali fluorides. Consequently, the compositional trends of Columbite-group minerals and cassiterite mimic those typically displayed in pegmatites of the lepidolite subtype: from ferroan manganoColumbite [with Mn/(Mn + Fe)(at.) of 0.35 and Ta/(Ta + Nb) of 0.08] through near-end-member manganoColumbite (0.95 and 0.20, respectively) to Fe-depleted manganotantalite (0.99 and 0.55, respectively), and from (Fe ≫ Mn, Nb > Ta)-bearing to (Mn > Fe, Ta > Nb)-enriched cassiterite. To date, rare occurrences of cassiterite with Mn > Fe are restricted solely to the lepidolite-enriched granitic pegmatites. The degree of cation order in the Varutrask Columbite-group minerals increases from early to late phases, and with decreasing amounts of heterovalent substitutions. Slower cooling of initially disordered structures in late phases, or their diminished compositional complexity may be responsible for the higher degree of order. Rare primary microinclusions of cassiterite in Columbite-group minerals show consistent and systematic preference for Ta and Fe, suggesting an approach to chemical equilibrium, but Columbite-group inclusions in cassiterite show in part a compositional scatter. In contrast, rare inclusions of ferrotapiolite and wodginite closely reflect the (Fe, Mn, Ta, Nb) compositional features of the host cassiterite. Stibiotantalite shows high values of Ta/(Ta + Nb) and mere traces of Bi, reflecting the relative abundance of native antimony and stibarsen in the pegmatite, and the absence of Bi-bearing minerals. Rare primary microlite is Ta- and F-rich, whereas the more widespread pyrochlore-microlite metasomatic after Columbite-group minerals reflects the Ta/(Ta + Nb) values of the precursors, as does the stibiomicrolite replacing stibiotantalite. Cesium is elevated in several grains of primary and metasomatic pyrochlore-group phases that also are enriched in Sb, but not in stibiomicrolite. The array of large cations in pyrochlore-microlite metasomatic after Columbite-group minerals is quite different from that typical of stibiomicrolite, suggestive of differences in the nature of the parent fluids. The lepidolite-subtype signature of the Columbite-group minerals and cassiterite in the petalite-subtype Varutrask pegmatite emphasizes the importance of specific conditions controlling stabilization of these minerals. The restriction of the Columbite-group minerals to a very late lepidoliterich unit imposes a lepidolite-subtype signature on the whole petalite-subtype pegmatite, a signature grossly different from the characteristics typical of petalite-subtype pegmatites elsewhere.
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Geochemistry of oxide minerals of Nb, Ta, Sn, and Sb in the Varuträsk granitic pegmatite, Sweden: The case of an “anomalous” Columbite-tantalite trend
American Mineralogist, 2004Co-Authors: Petr Černý, Ron Chapman, Karen Ferreira, Stenanders SmedsAbstract:The complex, petalite-subtype Varutrask pegmatite in the Proterozoic rocks of northern Sweden is, as a whole, rather poor in Nb and Ta. The pegmatite consolidated in eight units, but the (Nb,Ta)-oxide minerals attained saturation levels only in a late albite + lepidolite-bearing unit under conditions of high activity of alkali fluorides. Consequently, the compositional trends of Columbite-group minerals and cassiterite mimic those typically displayed in pegmatites of the lepidolite subtype: from ferroan manganoColumbite [with Mn/(Mn + Fe)(at.) of 0.35 and Ta/(Ta + Nb) of 0.08] through near-end-member manganoColumbite (0.95 and 0.20, respectively) to Fe-depleted manganotantalite (0.99 and 0.55, respectively), and from (Fe ≫ Mn, Nb > Ta)-bearing to (Mn > Fe, Ta > Nb)-enriched cassiterite. To date, rare occurrences of cassiterite with Mn > Fe are restricted solely to the lepidolite-enriched granitic pegmatites. The degree of cation order in the Varutrask Columbite-group minerals increases from early to late phases, and with decreasing amounts of heterovalent substitutions. Slower cooling of initially disordered structures in late phases, or their diminished compositional complexity may be responsible for the higher degree of order. Rare primary microinclusions of cassiterite in Columbite-group minerals show consistent and systematic preference for Ta and Fe, suggesting an approach to chemical equilibrium, but Columbite-group inclusions in cassiterite show in part a compositional scatter. In contrast, rare inclusions of ferrotapiolite and wodginite closely reflect the (Fe, Mn, Ta, Nb) compositional features of the host cassiterite. Stibiotantalite shows high values of Ta/(Ta + Nb) and mere traces of Bi, reflecting the relative abundance of native antimony and stibarsen in the pegmatite, and the absence of Bi-bearing minerals. Rare primary microlite is Ta- and F-rich, whereas the more widespread pyrochlore-microlite metasomatic after Columbite-group minerals reflects the Ta/(Ta + Nb) values of the precursors, as does the stibiomicrolite replacing stibiotantalite. Cesium is elevated in several grains of primary and metasomatic pyrochlore-group phases that also are enriched in Sb, but not in stibiomicrolite. The array of large cations in pyrochlore-microlite metasomatic after Columbite-group minerals is quite different from that typical of stibiomicrolite, suggestive of differences in the nature of the parent fluids. The lepidolite-subtype signature of the Columbite-group minerals and cassiterite in the petalite-subtype Varutrask pegmatite emphasizes the importance of specific conditions controlling stabilization of these minerals. The restriction of the Columbite-group minerals to a very late lepidoliterich unit imposes a lepidolite-subtype signature on the whole petalite-subtype pegmatite, a signature grossly different from the characteristics typical of petalite-subtype pegmatites elsewhere.
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Is the Bohus granite related with the post-kinematic rare-element pegmatites of southwestern Sweden? : a U-Pb Columbite investigation
1995Co-Authors: Rolf L Romer, Stenanders SmedsAbstract:Is the Bohus granite related with the post-kinematic rare-element pegmatites of southwestern Sweden? : a U-Pb Columbite investigation
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implications of upb ages of Columbite tantalites from granitic pegmatites for the palaeoproterozoic accretion of 1 90 1 85 ga magmatic arcs to the baltic shield
Precambrian Research, 1994Co-Authors: Rolf L Romer, Stenanders SmedsAbstract:Abstract The Palaeoproterozoic growth of the Baltic Shield involved the accretion of several ∼1.90–1.85 Ga old magmatic arcs to the southwest of the Archaean craton and the deformation and migmatization of sedimentary basins located between the arcs. During crustal thickening after the collision of the arcs, the sedimentary basin fill became intruded by peraluminous two-mica granites. Locally, Columbite-bearing pegmatites are genetically associated with these granites. Columbites from lithium-cesium-tantalum-type (LCT-type) pegmatites from the Stockholm area (Sormland gneisses) yield UPb ages at 1815–1820 Ma, while niobium-yttrium-fluorine-type (NYF-type) pegmatites from the same area are younger (1795±2 Ma, 2σ). Farther to the north, LCT-type pegmatites from the central Bothnian Basin, that correspond geochemically and mineralogically to those of the Stockholm area, yield UPb Columbite ages at 1795–1800 Ma, while LCT-type pegmatites in the sedimentary basin between Skelleftea and Lulea yield less well constrained UPb Columbite ages at 1765–1775 Ma. LCT-type pegmatites are mainly associated with crustal melts that form during postcollisional thickening of continental crust. They represent markers for the time when the Palaeoproterozoic Baltic Shield suffered sufficient thickening to yield voluminous anatectic melts. The UPb Columbite ages from the LCT-type pegmatites indicate that comparable phases of post-collisional crustal thickening of the Svecofennian area of the Baltic Shield occurred later to the north.
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Implications of UPb ages of Columbite-tantalites from granitic pegmatites for the Palaeoproterozoic accretion of 1.90–1.85 Ga magmatic arcs to the Baltic Shield
Precambrian Research, 1994Co-Authors: Rolf L Romer, Stenanders SmedsAbstract:Abstract The Palaeoproterozoic growth of the Baltic Shield involved the accretion of several ∼1.90–1.85 Ga old magmatic arcs to the southwest of the Archaean craton and the deformation and migmatization of sedimentary basins located between the arcs. During crustal thickening after the collision of the arcs, the sedimentary basin fill became intruded by peraluminous two-mica granites. Locally, Columbite-bearing pegmatites are genetically associated with these granites. Columbites from lithium-cesium-tantalum-type (LCT-type) pegmatites from the Stockholm area (Sormland gneisses) yield UPb ages at 1815–1820 Ma, while niobium-yttrium-fluorine-type (NYF-type) pegmatites from the same area are younger (1795±2 Ma, 2σ). Farther to the north, LCT-type pegmatites from the central Bothnian Basin, that correspond geochemically and mineralogically to those of the Stockholm area, yield UPb Columbite ages at 1795–1800 Ma, while LCT-type pegmatites in the sedimentary basin between Skelleftea and Lulea yield less well constrained UPb Columbite ages at 1765–1775 Ma. LCT-type pegmatites are mainly associated with crustal melts that form during postcollisional thickening of continental crust. They represent markers for the time when the Palaeoproterozoic Baltic Shield suffered sufficient thickening to yield voluminous anatectic melts. The UPb Columbite ages from the LCT-type pegmatites indicate that comparable phases of post-collisional crustal thickening of the Svecofennian area of the Baltic Shield occurred later to the north.
Petr Cerny - One of the best experts on this subject based on the ideXlab platform.
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compositional and structural variations in Columbite group minerals from granitic pegmatites of the brunswick and oxford fields maine differential trends in f poor and f rich environments
Canadian Mineralogist, 2012Co-Authors: Michael A Wise, Carl A Francis, Petr CernyAbstract:The Coastal Lithotectonic Block of the Brunswick pegmatite field and the Central Maine Synclinorium of the Oxford pegmatite field, in Maine, are intruded by numerous rare-element granitic pegmatites that carry Columbite-group minerals (CGM) as the principal (Nb,Ta)-bearing phases. Generally, the CGM from Maine are hosted by pegmatites characterized by a LCT (Li–Cs–Ta) geochemical signature and are infrequent in pegmatites with NYF (Nb–Y–F) characteristics ( e.g ., Topsham area of the Brunswick pegmatite field). Significant chemical-compositional and structural differences are observed between the CGM from the Brunswick and Oxford pegmatite fields. Columbite-group minerals from the Brunswick pegmatite field mainly consist of Columbite-(Fe), commonly with elevated Ti and Mg contents. By comparison, pegmatites from the Oxford field carry Columbite-(Fe), Columbite-(Mn) and tantalite-(Mn) with low Ti and Mg contents. The structural state of CGM from the Brunswick pegmatite field ranges from highly cation-disordered to cation-ordered, in contrast to predominantly highly ordered CGM in the Oxford pegmatite field. Limited concurrent fractionation of Mn from Fe and Ta from Nb observed in the Brunswick pegmatite field is characteristic of F-poor environments in general, and of F-enriched pegmatites with high μHF/μalkF (stability field of topaz). However, the extensive Fe–Mn fractionation preceding moderate to strong enrichment in Ta is typical of the Oxford pegmatite field, and apparently promoted by lepidolite-generating environments with prominent chemical potential of alkali fluorides and low μHF/μalkF. This observation finds support in data on CGM from numerous other pegmatite populations worldwide. In contrast, the structural state of CGM does not seem to be linked to the activity of different forms of fluorine. The overall abundance, diversity and temporal extent of the volatile components were undoubtedly different in the two pegmatite fields under study, and were apparently enhanced in the more fractionated pegmatites of the Oxford pegmatite field.
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geochemistry of oxide minerals of nb ta sn and sb in the varutrask granitic pegmatite sweden the case of an anomalous Columbite tantalite trend
American Mineralogist, 2004Co-Authors: Petr Cerny, Ron Chapman, Karen Ferreira, Stenanders SmedsAbstract:The complex, petalite-subtype Varutrask pegmatite in the Proterozoic rocks of northern Sweden is, as a whole, rather poor in Nb and Ta. The pegmatite consolidated in eight units, but the (Nb,Ta)-oxide minerals attained saturation levels only in a late albite + lepidolite-bearing unit under conditions of high activity of alkali fluorides. Consequently, the compositional trends of Columbite-group minerals and cassiterite mimic those typically displayed in pegmatites of the lepidolite subtype: from ferroan manganoColumbite [with Mn/(Mn + Fe)(at.) of 0.35 and Ta/(Ta + Nb) of 0.08] through near-end-member manganoColumbite (0.95 and 0.20, respectively) to Fe-depleted manganotantalite (0.99 and 0.55, respectively), and from (Fe ≫ Mn, Nb > Ta)-bearing to (Mn > Fe, Ta > Nb)-enriched cassiterite. To date, rare occurrences of cassiterite with Mn > Fe are restricted solely to the lepidolite-enriched granitic pegmatites. The degree of cation order in the Varutrask Columbite-group minerals increases from early to late phases, and with decreasing amounts of heterovalent substitutions. Slower cooling of initially disordered structures in late phases, or their diminished compositional complexity may be responsible for the higher degree of order. Rare primary microinclusions of cassiterite in Columbite-group minerals show consistent and systematic preference for Ta and Fe, suggesting an approach to chemical equilibrium, but Columbite-group inclusions in cassiterite show in part a compositional scatter. In contrast, rare inclusions of ferrotapiolite and wodginite closely reflect the (Fe, Mn, Ta, Nb) compositional features of the host cassiterite. Stibiotantalite shows high values of Ta/(Ta + Nb) and mere traces of Bi, reflecting the relative abundance of native antimony and stibarsen in the pegmatite, and the absence of Bi-bearing minerals. Rare primary microlite is Ta- and F-rich, whereas the more widespread pyrochlore-microlite metasomatic after Columbite-group minerals reflects the Ta/(Ta + Nb) values of the precursors, as does the stibiomicrolite replacing stibiotantalite. Cesium is elevated in several grains of primary and metasomatic pyrochlore-group phases that also are enriched in Sb, but not in stibiomicrolite. The array of large cations in pyrochlore-microlite metasomatic after Columbite-group minerals is quite different from that typical of stibiomicrolite, suggestive of differences in the nature of the parent fluids. The lepidolite-subtype signature of the Columbite-group minerals and cassiterite in the petalite-subtype Varutrask pegmatite emphasizes the importance of specific conditions controlling stabilization of these minerals. The restriction of the Columbite-group minerals to a very late lepidoliterich unit imposes a lepidolite-subtype signature on the whole petalite-subtype pegmatite, a signature grossly different from the characteristics typical of petalite-subtype pegmatites elsewhere.
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Scandium substitution in Columbite-group minerals and ixiolite
Canadian Mineralogist, 1998Co-Authors: Michael A Wise, Petr Cerny, Alexander U. FalsterAbstract:Columbite-group minerals and ixiolite with extremely variable concentrations of scandium are widespread in moderately to highly fractionated rare-element granitic pegmatites. Columbite-group minerals with 1-3 wt.% Sc 2 O 3 are referred to as scandian Columbite-tantalite and show degrees of structural order similar to Columbite-tantalite lacking Sc. Disordered structures remain orthorhombic and become ordered upon heating. Pseudo-orthorhombic stannian (Sn-rich), titanian (Ti) and wolframian (W) variants of ixiolite may contain as much as 3.7 wt.% Sc 2 O 3 and revert to monoclinic phases upon heating. Similarly, scandian ixiolite that contains Sc in excess of 3.0 and up to 18.8 wt.% Sc 2 O 3 converts from orthorhombic to monoclinic symmetry upon heating and has a stoichiometry that approaches Sc(Nb, Ta)O 4 . Scandium-bearing Columbite-tantalite and ixiolite show similar ranges in Mn/(Mn+Fe) and Ta/(Ta+Nb) values, but noticeably different Sn, Ti and Sc contents. Scandium is incorporated into the Columbite and ixiolite structures via the coupled substitution Sc (super 3+) +(Ti,Sn) (super 4+) = (Fe,Mn) (super 2+) +(Nb,Ta) (super 5+) ; it is strongly partitioned into the (Fe,Mn) site, whereas the Ti and Sn prefer the (Nb,Ta) site. Within the (Fe,Mn) site, the substitution of Sc for Fe is more prevalent. In most pegmatites, Sc fractionation in Columbite-tantalite, stannian ixiolite, titanian ixiolite and wolframian ixiolite is erratic, unlike scandian ixiolite, which shows strong enrichment in Sc with increasing Mn, Ta and Sn.
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Compositional, structural and phase relationships in titanian ixiolite and titanian Columbite-tantalite
Canadian Mineralogist, 1998Co-Authors: Petr Cerny, Michael A Wise, Ron Chapman, T. Scott Ercit, Harvey M. BuckAbstract:Titanium-enriched members of the Columbite family (orthorhombic) commonly contain exsolved niobian-tantalian rutile, or are aggregated with a coprecipitated rutile phase. This assemblage is the Fe, Mn, Nb, Ta-rich counterpart of the Ti-dominant niobian rutile+exsolved titanian Columbite pair. The rutile phase is enriched in Fe (super 2+) , Ta, Fe (super 3+) and Sn, whereas the orthorhombic phase favors Mn, Nb, Sc, W and Zr. Most samples of the orthorhombic phase are defined as titanian Columbite - tantalite; they have low to moderate Ti content, moderately to considerably disordered structure, and convert to highly ordered Columbite-tantalite on heating. A minor number of samples of the orthorhombic phase develops the highly ordered structure of wodginite on heating, which identifies them as titanian ixiolite, the disordered counterpart of titanowodginite. These samples are highly disordered in the natural state. They are Ti-rich, with Mn>Fe and Ta>Nb; these features correspond to the composition of natural titanowodginite and of the only titanowodginite synthesized to date. However, subordinate but significant Sn seems to be present in all samples of titanian ixiolite as well as natural titanowodginite, and it may affect the path of ordering. Excess of Ta over the (Fe, Mn)(Nb, Ta) 2 stoichiometry of Columbite, characteristic of most compositions of wodginite, may play a significant role. Ordered nuclei potentially present in the bulk of natural disordered phases also may be important.
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Compositional and structural systematics of the Columbite group
American Mineralogist, 1995Co-Authors: T. Scott Ercit, Michael A Wise, Petr CernyAbstract:ABSTRACf The systematics of the Columbite group have been studied to quantify variations in composition and structure. Multiple regression methods involving 89 heated samples and five synthetic equivalents of Columbite-group minerals give equations that permit prediction of the effects of composition on unit-cell parameters for fully ordered samples. The results are: aD= 14.258 + 0.166Mn/(Mn + Fe) + O.0072Ta/(Ta + Nb) - 0.06Ti 0.02Sn + 0.05Sc; ho = 5.7296 + 0.03 1Mn/(Mn + Fe) + 0.0024Ta/(Ta + Nb) - 0.024Ti - 0.009Sn + 0.02Sc; Co= 5.0495 + 0.033Mn/(Mn + Fe) + O.OllTa/(Ta + Nb) 0.004Ti, where aD,ho, and Coare the cell parameters (A) calculated from unit-cell concentrations of elements. With these equations, crystal-chemical trends, the effects of heating experiments, the degree of cation order, and the structural effects of heterovalent cation substitution can be predicted for samples of Columbite-group minerals.
Jianping Liu - One of the best experts on this subject based on the ideXlab platform.
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age of the dahongliutan rare metal pegmatite deposit west kunlun xinjiang nw china constraints from la icp ms u pb dating of Columbite fe and cassiterite
Ore Geology Reviews, 2016Co-Authors: Qinghe Yan, Zengwang Qiu, He Wang, Min Wang, Xiaopeng Wei, Rongqing Zhang, Jianping LiuAbstract:Abstract Dahongliutan is a medium-size Li–Be–Ta–Nb rare metal pegmatite deposit in the Tianshuihai terrane, West Kunlun orogenic belt (NW China). In this paper, LA–ICP–MS U–Pb ages of Columbite-(Fe) and cassiterite are reported to constrain the metallogenic age. Columbite-(Fe) (with high U and low Th) yielded a Late Triassic weighted mean 206 Pb/ 238 U age of 211.9 ± 2.4 Ma, whilst cassiterite yielded a 206 Pb/ 238 U– 207 Pb/ 235 U concordia lower intercept age of 218 ± 12 Ma and a Tera-Wasserburg lower intercept age of 218 ± 12 Ma, which is identical to the Columbite-(Fe) U-Pb age and thus represents the emplacement age of the pegmatite dikes. The ore-hosting pegmatite dikes are intimately time-space related to the Dahongliutan S-type granite (ca. 220–217 Ma), indicating that they may have been cogenetic. Integrating new and published geological data, we suggest that the Dahongliutan pegmatites may have evolved from the granitic magma represented by the Dahongliutan S-type pluton in a post-collisional tectonic setting. Regionally, the Tianshuihai terrane is the western extension of the Songpan-Ganzi block, and thus the Kunlun Li-mineralization belt may have been connected to the Songpan-Ganzi Li-mineralization belt which contains eleven lithium deposits with about 9.8% of Li 2 O reserves in China, implying that the Dahongliutan pegmatite deposit may also have favorable ore-forming conditions. The similar Columbite-(Fe) and cassiterite ages demonstrate that these minerals can be precisely dated and could provide useful alternatives to accurately constrain the timing and evolution of rare metal mineralization.
Qinghe Yan - One of the best experts on this subject based on the ideXlab platform.
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age of the dahongliutan rare metal pegmatite deposit west kunlun xinjiang nw china constraints from la icp ms u pb dating of Columbite fe and cassiterite
Ore Geology Reviews, 2016Co-Authors: Qinghe Yan, Zengwang Qiu, He Wang, Min Wang, Xiaopeng Wei, Rongqing Zhang, Jianping LiuAbstract:Abstract Dahongliutan is a medium-size Li–Be–Ta–Nb rare metal pegmatite deposit in the Tianshuihai terrane, West Kunlun orogenic belt (NW China). In this paper, LA–ICP–MS U–Pb ages of Columbite-(Fe) and cassiterite are reported to constrain the metallogenic age. Columbite-(Fe) (with high U and low Th) yielded a Late Triassic weighted mean 206 Pb/ 238 U age of 211.9 ± 2.4 Ma, whilst cassiterite yielded a 206 Pb/ 238 U– 207 Pb/ 235 U concordia lower intercept age of 218 ± 12 Ma and a Tera-Wasserburg lower intercept age of 218 ± 12 Ma, which is identical to the Columbite-(Fe) U-Pb age and thus represents the emplacement age of the pegmatite dikes. The ore-hosting pegmatite dikes are intimately time-space related to the Dahongliutan S-type granite (ca. 220–217 Ma), indicating that they may have been cogenetic. Integrating new and published geological data, we suggest that the Dahongliutan pegmatites may have evolved from the granitic magma represented by the Dahongliutan S-type pluton in a post-collisional tectonic setting. Regionally, the Tianshuihai terrane is the western extension of the Songpan-Ganzi block, and thus the Kunlun Li-mineralization belt may have been connected to the Songpan-Ganzi Li-mineralization belt which contains eleven lithium deposits with about 9.8% of Li 2 O reserves in China, implying that the Dahongliutan pegmatite deposit may also have favorable ore-forming conditions. The similar Columbite-(Fe) and cassiterite ages demonstrate that these minerals can be precisely dated and could provide useful alternatives to accurately constrain the timing and evolution of rare metal mineralization.