Interaction Of Rare-Metal Minerals With Hydrothermal Fluids: Evidence From Quartz–Epidote Metasomatites Of The Haldzan Buragtag Massif, Mongolian Altai

2015 ◽  
Vol 53 (6) ◽  
pp. 1015-1034 ◽  
Author(s):  
Ray MacDonald ◽  
Bogusław Bagiński ◽  
Pavel M. Kartashov ◽  
Dmitry Zozulya ◽  
Piotr Dzierżanowski
Keyword(s):  
Rare Metal ◽  
Hydrothermal Fluids ◽  
Mongolian Altai

Hydrothermal metasomatism of a peralkaline granite pegmatite, Khaldzan Buragtag massif, Mongolian Altai; complex evolution of REE-Nb minerals

2016 ◽  
Vol 66 (3) ◽  
pp. 477-495
Author(s):  
Bogusław Bagiński ◽  
Petras Jokubauskas ◽  
Justyna Domańska-Siuda ◽  
Pavel Kartashov ◽  
Ray Macdonald
Keyword(s):  
Low Temperature ◽  
Hydrothermal Alteration ◽  
Late Stage ◽  
Rare Metal ◽  
Hydrothermal Fluids ◽  
Granitic Pegmatite ◽  
Granite Pegmatite ◽  
Peralkaline Granite ◽  
Mongolian Altai

Abstract The low-temperature hydrothermal alteration of certain rare-metal minerals is recorded in a quartz-epidote metasomatite from the Tsakhirin Khuduk occurrence in the Khaldzan-Buragtag Nb-REE-Zr deposit, Mongolian Altai. A peralkaline granitic pegmatite was metasomatized by hydrothermal fluids released from associated intrusions, with the formation of, inter alia, chevkinite-(Ce), fergusonite-(Nd) and minerals of the epidote group. The textural pattern indicates recrystallization and coarsening of these phases. Later, low-temperature alteration by fluids resulted in the chevkinite-(Ce) being replaced by complex titanite-TiO2 -cerite-(Ce)-hingganite-hydroxylbastnasite-( Ce) assemblages. Calcite formed late-stage veins and patches. The hydrous fluids were poor in F and CO2 but had high Ca contents.

scholarly journals Geochemical Signature of Magmatic-Hydrothermal Fluids Exsolved from the Beauvoir Rare-Metal Granite (Massif Central, France): Insights from LA-ICPMS Analysis of Primary Fluid Inclusions

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-25 ◽  
Author(s):  
Matthieu Harlaux ◽  
Julien Mercadier ◽  
Wilédio Marc-Emile Bonzi ◽  
Valentin Kremer ◽  
Christian Marignac ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
Rare Metal ◽  
Hydrothermal Fluids ◽  
Raman Spectrometry ◽  
Peraluminous Granite ◽  
Geochemical Composition ◽  
Massif Central ◽  
Granite Massif ◽  
Rare Metal Granite ◽  
Primary Fluid

The Beauvoir granite (Massif Central, France) represents an exceptional case in the European Variscan belt of a peraluminous rare-metal granite crosscutting an early W stockwork. The latter was strongly overprinted by rare-metal magmatic-hydrothermal fluids derived from the Beauvoir granite, resulting in a massive topazification of the quartz-ferberite vein system. This work presents a complete study of primary fluid inclusions hosted in quartz and topaz from the Beauvoir granite and the metasomatized stockwork, in order to characterize the geochemical composition of the magmatic fluids exsolved during the crystallization of this evolved rare-metal peraluminous granite. Microthermometric and Raman spectrometry data show that the earliest fluid (L1) is of high temperature (500 to >600°C), high salinity (17–28 wt.% NaCl eq), and Li-rich (Te<−70°C) with Na/Li ratios ~5. LA-ICPMS analyses of L1-type fluid inclusions reveal that the chemical composition of this magmatic-hydrothermal fluid is dominated by Na, K, Cs, and Rb, with significant concentrations (101–104 ppm) in rare-metals (W, Nb, Ta, Sn, and Li). This study demonstrates that primary fluid inclusions preserved the pristine signature of the magmatic-hydrothermal fluids in the Beauvoir granite but also in the metasomatized W stockwork, despite the distance from the granitic cupola (>100 m) and interaction with external fluids.

Craniospermum volkovae (Boraginaceae), a new species from Mongolia

2019 ◽  
pp. 148-153
Author(s):  
S. V. Ovczinnikova
Keyword(s):  
New Species ◽  
Separate Section ◽  
Mongolian Altai ◽  
Relationship Of ◽  
A New Species

A new species Craniospermum volkovae Ovczinnikova (Boraginaceae) from relationship of C. pseudotuvinicum Ovczinnikova et A. Korolyuk, is described from the Central Mongolian-Altai province of Mongolia. Morphological and ecologo-cenotic peculiarities of the new species are discussed, and the necessity of its treatment within a separate section Pseudotuvinica Ovczinnikova is substantiated.

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