Nb‐Ta‐Sn‐W Distribution in Granite‐related Ore Systems

Hulsbosch, Niels

doi:10.1002/9781119290544.ch4

Cited by 16 publications

(5 citation statements)

References 133 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…9), show some affinity to subduction-related rocks, but they are far more enriched in elements like Th, U, LREE, and Zr even when compared with continental arcs. Also, their high concentrations of elements like Be, Sn, and W are more suggestive of late-to post-orogenic and intracratonic settings (Ryan, 2002;Dailey et al, 2018;Hulsbosch, 2019;Lehmann, 2021).…”

Section: The Th-rich Unitsmentioning

confidence: 99%

Concurrent MORB-type and ultrapotassic volcanism in an extensional basin along the Laurentian Iapetus margin: Tectonomagmatic response to Ordovician arc-continent collision and subduction polarity flip

et al. 2021

View full text Add to dashboard Cite

Arc-continent collision, followed by subduction polarity flip, occurs during closure of oceanic basins and contributes to the growth of continental crust. Such a setting may lead to a highly unusual association of ultrapotassic and mid-ocean ridge basalt (MORB)-type volcanic rocks as documented here from an Ordovician succession of the Scandinavian Caledonides. Interbedded with deep-marine turbidites, pillow basalts evolve from depleted-MORB (εNdt 9.4) to enriched-MORB (εNdt 4.8) stratigraphically upward, reflecting increasingly deeper melting of asthenospheric mantle. Intercalated intermediate to felsic lava and pyroclastic units, dated at ca. 474−469 Ma, are extremely enriched in incompatible trace elements (e.g., Th) and have low εNdt (−8.0 to −6.6) and high Sri (0.7089−0.7175). These are interpreted as ultrapotassic magmas derived from lithospheric mantle domains metasomatized by late Paleoproterozoic to Neoproterozoic crust-derived material (isotopic model ages 1.7−1.3 Ga). Detrital zircon spectra reveal a composite source for the interbedded turbidites, including Archean, Paleo-, to Neoproterozoic, and Cambro-Ordovician elements; clasts of Hølonda Porphyrite provide a link to the Hølonda terrane of Laurentian affinity. The entire volcano-sedimentary succession is interpreted to have formed in a rift basin that opened along the Laurentian margin as a result of slab rollback subsequent to arc-continent collision, ophiolite obduction and subduction polarity flip. The association of MORBs and ultrapotassic rocks is apparently a unique feature along the Caledonian-Appalachian orogen. Near-analogous modern settings include northern Taiwan and the Tyrrhenian region of the Mediterranean, but other examples of strictly concurrent MORB and ultrapotassic volcanism remain to be documented.

show abstract

Section: The Th-rich Unitsmentioning

confidence: 99%

Concurrent MORB-type and ultrapotassic volcanism in an extensional basin along the Laurentian Iapetus margin: Tectonomagmatic response to Ordovician arc-continent collision and subduction polarity flip

et al. 2021

View full text Add to dashboard Cite

show abstract

“…These pegmatites are linked to the Neoproterozoic, ca. 1000-900 Ma, "Kibara tin granites" (Pohl et al 2013;Melcher et al 2015;Hulsbosch 2019) and they include the Gitarama-Gatumba field (Fig. 1) as one of the best representatives of the magmatic evolution and the related rare-metal mineralization (Dewaele et al 2011;Hulsbosch et al 2014Hulsbosch et al , 2016.…”

Section: Regional Contextmentioning

confidence: 99%

Paragenesis and precipitation stages of Nb-Ta-oxide minerals in phosphorus-rich rare-element pegmatites (Buranga dike, Rwanda)

Araujo

Hulsbosch

Muchez

2023

American Mineralogist

View full text Add to dashboard Cite

Nb-Ta-oxide minerals (NTO) are commonly associated with rare-element pegmatites where they are interpreted to precipitate at magmatic up to magmatic-hydrothermal conditions. Although high-temperature experiments show that phosphorus and other fluxing elements (e.g., Li, B, F) can affect the saturation of NTO in pegmatitic systems, it is still uncertain how NTO saturation occurs in natural, flux-rich pegmatitic melts and whether crystallization occurs at multiple stages during magmatic or subsolidus conditions. The LCT family P-rich Buranga granitic pegmatite (western Rwanda) is used as a type locality to address this question. NTO mineralization in the Buranga dike occurs in two mineralogical units: in mineralogically complex phosphatic nodules, and in albitized parts. In the phosphatic nodules, Fe-Nb-Ta-rich rutile and columbite-group minerals (CGM) are observed, while in the albitized parts, only CGM is found. Fe-Nb-Tarich rutile precipitates at the magmatic stage along with early primary phosphates (i.e., F-rich montebrasite, wyllieite, and fluorapatite). Conversely, CGM mineralization occurs at the magmatic-hydrothermal stage in association with replacement phosphates like bertossaite, after primary minerals (i.e., rutile, wyllieite, rosemaryite, and trolleite) are destabilized due to crystal-melt-fluid interactions. NTO textures and chemical zoning show uneven evolution from core to rim and are related to localized alteration phenomena of the surrounding minerals. This indicates that local processes and element transfers are more important than dikescale fractionation processes for NTO mineralization in P-rich granitic pegmatites. The restricted availability of Fe and Mn in the system, which is related to the competition between phosphate and oxide minerals, is identified as the main control on the CGM mineralization in the Buranga dike. CGM precipitation is only This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

show abstract

“…Il s'agit d'un "granite à étain" et est la source parentale des pegmatites à Nb, Ta, Sn, Li, Be et des veines de quartz hydrothermales riches en Sn et W observées à plusieurs endroits au Rwanda, au Burundi, en Ouganda et en R.D. Congo (Varlamoff, 1972;Pohl & Günther, 1991;Pohl, 1994;Romer & Lehmann, 1995;Dewaele et al, 2010;De Clercq, 2012;Goldmann et al, 2013;Pohl et al, 2013;Hulsbosch et al, 2014Melcher et al, 2015;Hulsbosch, 2019). Les pegmatites du Burundi ont été datées à 969 ± 17 Ma (roche totale Rb-Sr; Lehmann et al, 1994) et 969 ± 8 Ma (muscovite Rb-Sr; Brinckmann & Lehmann, 1983).…”

Section: Contexte Géologique Et Métallogénique Régionalunclassified

“…En d'autres termes, l'augmentation de Cs dans les micas pourrait théoriquement être modélisée dans un système cristal-magmafluide (e.g. Hulsbosch et al, 2016;Hulsbosch, 2019). Cependant, cela nécessite une évaluation réaliste du pourcentage massique de fluide présent dans le système K-Mp pour lequel nous n'avons pas de bonnes estimations pour le moment.…”

Section: Relation Co-génétique Entre Le Leucogranite Gr5 Et Les Pegmaunclassified

Géochimie des muscovites comme indicateur du fractionnement des pegmatites de la région de Kabarore-Mparamirundi (nord-ouest du Burundi, Afrique centrale) [Geochemical signature of muscovites as pathfinder for fractionation of pegmatites in the Kabarore-Mparamirundi area (northwestern Burundi, Central Africa)]

et al. 2020

Self Cite

View full text Add to dashboard Cite

The Kabarore-Mparamirundi area hosts numerous pegmatites spatiotemporally related to leucogranites dated at 986 ± 10 Ma in Karagwe-Ankole belt. The deposits are intensively exploited for columbite-tantalite and cassiterite. Alkali metals in muscovite (Rb 370–7590 ppm, Cs 8–1470 ppm) are modeled by Rayleigh fractional crystallization from a parental leucogranitic composition (K 4.1 wt%, Rb 321 ppm and Cs 9 ppm). The power law declining behavior of the ratio K/Rb versus Cs indicates the Rayleigh fractional crystallization as the main process of differentiation of the various pegmatite facies. Moreover, the continuous trend from granite to the most evolved, exploited pegmatites demonstrates a co-genetic link among them. The fractionation model shows that unmined and abandoned pegmatites are less fractionated (less than 94% of fractionation) while mined pegmatites are highly fractionated and constitute fractionated products of more than 94% of the initial leucogranite composition. The Rb, Cs, Ta, Sn and Li elements in muscovite can be used as a valuable tool in the exploration of fertile and sterile pegmatites in this area.

show abstract

Nb‐Ta‐Sn‐W Distribution in Granite‐related Ore Systems

Cited by 16 publications

References 133 publications

Concurrent MORB-type and ultrapotassic volcanism in an extensional basin along the Laurentian Iapetus margin: Tectonomagmatic response to Ordovician arc-continent collision and subduction polarity flip

Concurrent MORB-type and ultrapotassic volcanism in an extensional basin along the Laurentian Iapetus margin: Tectonomagmatic response to Ordovician arc-continent collision and subduction polarity flip

Paragenesis and precipitation stages of Nb-Ta-oxide minerals in phosphorus-rich rare-element pegmatites (Buranga dike, Rwanda)

Contact Info

Product

Resources

About