scholarly journals Magmatic-Hydrothermal Processes Associated with Rare Earth Element Enrichment in the Kangankunde Carbonatite Complex, Malawi

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 442 ◽  
Author(s):  
Frances Chikanda ◽  
Tsubasa Otake ◽  
Yoko Ohtomo ◽  
Akane Ito ◽  
Takaomi D. Yokoyama ◽  
...  
Keyword(s):  
Rare Earth ◽  
Geochemical Data ◽  
Carbonatite Complex ◽  
Compositional Zoning ◽  
Ree Mineralization ◽  
Hydrothermal Processes ◽  
Magmatic Stage ◽  
Isotope Study ◽  
Late Magmatic Stage ◽  
Element Enrichment

Carbonatites undergo various magmatic-hydrothermal processes during their evolution that are important for the enrichment of rare earth elements (REE). This geochemical, petrographic, and multi-isotope study on the Kangankunde carbonatite, the largest light REE resource in the Chilwa Alkaline Province in Malawi, clarifies the critical stages of REE mineralization in this deposit. The δ56Fe values of most of the carbonatite lies within the magmatic field despite variations in the proportions of monazite, ankerite, and ferroan dolomite. Exsolution of a hydrothermal fluid from the carbonatite melts is evident based on the higher δ56Fe of the fenites, as well as the textural and compositional zoning in monazite. Field and petrographic observations, combined with geochemical data (REE patterns, and Fe, C, and O isotopes), suggest that the key stage of REE mineralization in the Kangankunde carbonatite was the late magmatic stage with an influence of carbothermal fluids i.e. magmatic–hydrothermal stage, when large (~200 µm), well-developed monazite crystals grew. The C and O isotope compositions of the carbonatite suggest a post-magmatic alteration by hydrothermal fluids, probably after the main REE mineralization stage, as the alteration occurs throughout the carbonatite but particularly in the dark carbonatites.

scholarly journals The Saint-Honoré Carbonatite REE Zone, Québec, Canada: Combined Magmatic and Hydrothermal Processes

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 397 ◽  
Author(s):  
Alexandre Néron ◽  
Léo Bédard ◽  
Damien Gaboury
Keyword(s):  
Rare Earth ◽  
Late Stage ◽  
High Volume ◽  
Primary Crystallization ◽  
Hydrothermal Activity ◽  
Hydrothermal Crystallization ◽  
Carbonatite Complex ◽  
Hydrothermal Processes ◽  
Rare Earth Minerals ◽  
New Evidence

The Saint-Honoré carbonatite complex hosts a rare earth element (REE) deposit traditionally interpreted as being produced by late-stage hydrothermal fluids that leached REE from apatite or dolomite found in the early units and concentrated the REE in the late-stage units. New evidence from deeper units suggest that the Fe-carbonatite was mineralized by a combination of both magmatic and hydrothermal crystallization of rare earth minerals. The upper Fe-carbonatite has characteristics typical of hydrothermal mineralization—polycrystalline clusters hosting bastnäsite-(Ce), which crystallized radially from carbonate or barite crystals, as well as the presence of halite and silicification within strongly brecciated units. However, bastnäsite-(Ce) inclusions in primary magmatic barite crystals have also been identified deeper in the Fe-carbonatite (below 1000 m), suggesting that primary crystallization of rare earth minerals occurred prior to hydrothermal leaching. Based on the intensity of hydrothermal brecciation, Cl depletion at depth and greater abundance of secondary fluid inclusions in carbonates in the upper levels, it is interpreted that hydrothermal activity was weaker in this deepest portion, thereby preserving the original magmatic textures. This early magmatic crystallization of rare earth minerals could be a significant factor in generating high-volume REE deposits. Crystallization of primary barite could be an important guide for REE exploration.

scholarly journals REE Enrichment during Magmatic–Hydrothermal Processes in Carbonatite-Related REE Deposits: A Case Study of the Weishan REE Deposit, China

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 25 ◽  
Author(s):  
Yu-heng Jia ◽  
Yan Liu
Keyword(s):  
Rare Earth ◽  
Late Stage ◽  
Earth Element ◽  
Low Grade ◽  
Scattered Electron ◽  
Ree Mineralization ◽  
Hydrothermal Processes ◽  
Informative Case ◽  
Main Factors

The Weishan carbonatite-related rare earth element (REE) deposit in China contains both high- and low-grade REE mineralization and is an informative case study for the investigation of magmatic–hydrothermal REE enrichment processes in such deposits. The main REE-bearing mineral is bastnäsite, with lesser parisite and monazite. REE mineralization occurred at a late stage of hydrothermal evolution and was followed by a sulfide stage. Barite, calcite, and strontianite appear homogeneous in back-scattered electron images and have high REE contents of 103–217, 146–13,120, and 194–16,412 ppm in their mineral lattices, respectively. Two enrichment processes were necessary for the formation of the Weishan deposit: Production of mineralized carbonatite and subsequent enrichment by magmatic–hydrothermal processes. The geological setting and petrographic characteristics of the Weishan deposit indicate that two main factors facilitated REE enrichment: (1) fractures that facilitated circulation of ore-forming fluids and provided space for REE precipitation and (2) high ore fluorite and barite contents resulting in high F− and SO42− concentrations in the ore-forming fluids that promoted REE transport and deposition.

New petrological and geochemical data on mid-Paleozoic island-arc volcanics of northern Sierra Nevada, California: evidence for a continent-based island arc

1989 ◽  
Vol 26 (12) ◽  
pp. 2465-2478 ◽  
Author(s):  
O. Rouer ◽  
H. Lapierre ◽  
C. Coulon ◽  
A. Michard
Keyword(s):  
Rare Earth ◽  
Sierra Nevada ◽  
Rare Earth Element ◽  
Earth Element ◽  
Island Arc ◽  
Geochemical Data ◽  
Light Rare Earth ◽  
Calc Alkaline ◽  
Strong Light ◽  
Element Enrichment

The mid-Paleozoic volcanics of northern Sierra Nevada consist of the Sierra Buttes rhyolites, the Taylor basalts and andesites, and the Keddie Ridge basalt–latite–rhyolite suite. The Sierra Buttes calc-alkaline rhyolites display strong light rare-earth element enrichment and negative εNd values. The Taylor basalts and andesites in the northern Hough and Genesee blocks exhibit calc-alkaline affinities (REE rare-earth element patterns highly enriched in LREE), whereas in the southern Hough block they are tholeiitic (flat rare-earth element patterns). The abundance of silicic lavas, the low εNd values of both the Sierra Buttes and Taylor volcanics and the δ18O values of the Sierra Buttes rhyolite and Bowman Lake trondjhemite provide evidence that the northern Sierra Nevada island arc was continent based. The Keddie Ridge differentiated volcanics, characterized by high Zr, Y, Nb, K, and light rare-earth elements, are geochemically similar to a shoshonite suite. Their eruption at the end of the mid-Paleozoic volcanic episode suggests a reversal of subduction, uplift, and block faulting in the island arc.The mid-Paleozoic volcanics of the northern Sierra Nevada are thought to represent the remnant of a mature island arc because calc-alkaline rocks predominate over tholeiitic ones, the lavas display a K enrichment with time, and the volcanics are evolved in their isotopes, compared with rocks erupted in young or primitive island arcs.

scholarly journals Mineralogical and Geochemical Constraints on Magma Evolution and Late-Stage Crystallization History of the Breivikbotn Silicocarbonatite, Seiland Igneous Province in Northern Norway: Prerequisites for Zeolite Deposits in Carbonatite Complexes

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 537 ◽  
Author(s):  
Dmitry Zozulya ◽  
Kåre Kullerud ◽  
Erling Ravna ◽  
Yevgeny Savchenko ◽  
Ekaterina Selivanova ◽  
...  
Keyword(s):  
Trace Element ◽  
Tectonic Setting ◽  
Spatial Proximity ◽  
Geochemical Data ◽  
Chemical Compositions ◽  
Igneous Province ◽  
Magmatic Stage ◽  
Stage Crystallization ◽  
History Of ◽  
Late Magmatic Stage

The present work reports on new mineralogical and whole-rock geochemical data from the Breivikbotn silicocarbonatite (Seiland igneous province, North Norway), allowing conclusions to be drawn concerning its origin and the role of late fluid alteration. The rock shows a rare mineral association: calcite + pyroxene + amphibole + zeolite group minerals + garnet + titanite, with apatite, allanite, magnetite and zircon as minor and accessory minerals, and it is classified as silicocarbonatite. Calcite, titanite and pyroxene (Di36–46 Acm22–37 Hd14–21) are primarily magmatic minerals. Amphibole of mainly hastingsitic composition has formed after pyroxene at a late-magmatic stage. Zeolite group minerals (natrolite, gonnardite, Sr-rich thomsonite-(Ca)) were formed during hydrothermal alteration of primary nepheline by fluids/solutions with high Si-Al-Ca activities. Poikilitic garnet (Ti-bearing andradite) has inclusions of all primary minerals, amphibole and zeolites, and presumably crystallized metasomatically during a late metamorphic event (Caledonian orogeny). Whole-rock chemical compositions of the silicocarbonatite differs from the global average of calciocarbonatites by elevated silica, aluminium, sodium and iron, but show comparable contents of trace elements (REE, Sr, Ba). Trace element distributions and abundances indicate within-plate tectonic setting of the carbonatite. The spatial proximity of carbonatite and alkaline ultramafic rock (melteigite), the presence of “primary nepheline” in carbonatite together with the trace element distributions indicate that the carbonatite was derived by crystal fractionation of a parental carbonated foidite magma. The main prerequisites for the extensive formation of zeolite group minerals in silicocarbonatite are revealed.

scholarly journals Mineralogical and Geochemical Constraints on the Origin and Late-Stage Crystallization History of the Breivikbotn Silicocarbonatite, Seiland Igneous Province in Northern Norway: Prerequisites for Zeolite Deposits in Carbonatite Complexes

2018 ◽  
Author(s):  
Dmitry Zozulya ◽  
Kåre Kullerud ◽  
Erling Ravna ◽  
Yevgeny Savchenko ◽  
Ekaterina Selivanova ◽  
...  
Keyword(s):  
Trace Element ◽  
Tectonic Setting ◽  
Spatial Proximity ◽  
Geochemical Data ◽  
Chemical Compositions ◽  
Igneous Province ◽  
Magmatic Stage ◽  
Stage Crystallization ◽  
History Of ◽  
Late Magmatic Stage

The present work reports new mineralogical and whole rock geochemical data from the Breivikbotn silicocarbonatite (Seiland igneous province, North Norway), allowing conclusions to be drawn concerning its origin and the role of late fluid alteration. The rock shows a rare mineral association: calcite + pyroxene + amphibole + zeolite group minerals + garnet + titanite, with apatite, allanite, magnetite and zircon as minor and accessory minerals, and it is classified as silicocarbonatite. Calcite, titanite and pyroxene (Di36-46 Acm22-37 Hd14-21) are primarily magmatic minerals. Amphibole of hastingsitic composition has formed after pyroxene at a late-magmatic stage. Zeolite group minerals (natrolite, gonnardite, Sr-rich thomsonite-(Ca)) were formed during hydrothermal alteration of primary nepheline by fluids/solutions with high Si-Al-Ca activities. Poikilitic garnet (Ti-bearing andradite) has inclusions of all primary minerals, amphibole and zeolites, and presumably crystallized metasomatically during a late metamorphic event (Caledonian orogeny). Whole rock chemical compositions of the silicocarbonatite differs from the global average of calciocarbonatites by elevated silica, aluminium, sodium and iron, but show comparable contents of trace elements (REE, Sr, Ba). Trace element distributions indicate within-plate tectonic setting of the carbonatite. The spatial proximity of carbonatite and alkaline ultramafic rock (melteigite), the presence of “primary nepheline” in carbonatite together with the trace element distributions indicate that the carbonatite was derived from crystal fractionation of a parental carbonated foidite magma. The main prerequisites for the extensive formation of zeolite group minerals in silicocarbonatite are revealed.

scholarly journals Origin of the Middle Paleoproterozoic Tiksheozero Ultramafic-Alkaline-Carbonatite Complex, NE Fennoscandian Shield: Evidence from Geochemical and Isotope Sr-Nd-Hf-Pb-Os Data

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 570
Author(s):  
Maria Bogina ◽  
Boris Belyatsky ◽  
Evgenii Sharkov ◽  
Alexey Chistyakov ◽  
Robert Krymsky
Keyword(s):  
Mantle Source ◽  
Incompatible Element ◽  
Crustal Contamination ◽  
Geochemical Data ◽  
Carbonatite Complex ◽  
Karelian Craton ◽  
Nd Isotope ◽  
Isotope Studies ◽  
Element Enrichment ◽  
Silicate Rocks

This article reports new geochemical, Sr-Nd-Hf-Pb and Re-Os data on the rocks of the Middle Paleoproterozoic (1.99 Ga) Tiksheozero ultramafic-alkaline-carbonatite complex confined to the northeastern margin of the Karelian Craton. We focus on the poorly studied silicate rocks. Based on petrographic and geochemical research, the silicate rocks are subdivided into two groups: an ultramafic-mafic series depleted in REE, and other incompatible elements and an alkaline series enriched in these elements. Isotope studies showed that all rocks have juvenile isotope signatures and were likely derived from a primitive OIB-type mantle source with possible contributions of the subcontinental lithospheric mantle (SCLM). Insignificant crustal contamination is recorded by Pb and Os isotopic compositions. The incompatible element enrichment in the alkaline rocks and depletion in ultramafic-mafic rocks of the mildly alkaline series with allowance for insignificant crustal contamination confirm their derivation from different primary melts. However, a narrow range of Sr, Nd, Hf, and Pb isotope compositions and compact clusters in 207Pb/204Pb-206Pb/204Pb, Nd-87Sr/86Sr and Hf-Nd isotope diagrams indicate their origination from a common mantle source. A model of subsequent two-stage melting is being most consistent with the geochemical data for this complex.

scholarly journals Mineralogy of Dolomite Carbonatites of Sevathur Complex, Tamil Nadu, India

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 355
Author(s):  
Maria Rampilova ◽  
Anna Doroshkevich ◽  
Shrinivas Viladkar ◽  
Elizaveta Zubakova
Keyword(s):  
Tamil Nadu ◽  
Minor Amount ◽  
Carbonatite Complex ◽  
Accessory Minerals ◽  
Main Mass ◽  
Fault Systems ◽  
Hydrothermal Processes ◽  
Lree Enrichment ◽  
Primary Minerals

The main mass of the Sevathur carbonatite complex (Tamil Nadu, India) consists of dolomite carbonatite with a small number of ankerite carbonatite dikes. Calcite carbonatite occurs in a very minor amount as thin veins within the dolomite carbonatite. The age (207Pb/204Pb) of the Sevathur carbonatites is 801 ± 11 Ma, they are emplaced within the Precambrian granulite terrains along NE–SW trending fault systems. Minor minerals in dolomite carbonatite are fluorapatite, phlogopite (with a kinoshitalite component), amphibole and magnetite. Pyrochlore (rich in UO2), monazite-Ce, and barite are accessory minerals. Dolomite carbonatite at the Sevathur complex contains norsethite, calcioburbankite, and benstonite as inclusions in primary calcite and are interpreted as primary minerals. They are indicative of Na, Sr, Mg, Ba, and LREE enrichment in their parental carbonatitic magma. Norsethite, calcioburbankite, and benstonite have not been previously known at Sevathur. The hydrothermal processes at the Sevathur carbonatites lead to alteration of pyrochlore into hydropyrochlore, and Ba-enrichment. Also, it leads to formation of monazite-(Ce) and barite-II.

Lithospheric roots beneath western Laurentia: the geochemical signal in mantle garnets

2003 ◽  
Vol 40 (8) ◽  
pp. 1027-1051 ◽  
Author(s):  
D Canil ◽  
D J Schulze ◽  
D Hall ◽  
B C Hearn Jr. ◽  
S M Milliken
Keyword(s):  
Rare Earth ◽  
North America ◽  
Trace Element ◽  
Earth Element ◽  
Geochemical Data ◽  
Trace Element Data ◽  
Mantle Lithosphere ◽  
Western North America ◽  
Wyoming Province ◽  
Thick Mantle

This study presents major and trace element data for 243 mantle garnet xenocrysts from six kimberlites in parts of western North America. The geochemical data for the garnet xenocrysts are used to infer the composition, thickness, and tectonothermal affinity of the mantle lithosphere beneath western Laurentia at the time of kimberlite eruption. The garnets record temperatures between 800 and 1450°C using Ni-in-garnet thermometry and represent mainly lherzolitic mantle lithosphere sampled over an interval from about 110–260 km depth. Garnets with sinuous rare-earth element patterns, high Sr, and high Sc/V occur mainly at shallow depths and occur almost exclusively in kimberlites interpreted to have sampled Archean mantle lithosphere beneath the Wyoming Province in Laurentia, and are notably absent in garnets from kimberlites erupting through the Proterozoic Yavapai Mazatzal and Trans-Hudson provinces. The similarities in depths of equilibration, but differing geochemical patterns in garnets from the Cross kimberlite (southeastern British Columbia) compared to kimberlites in the Wyoming Province argue for post-Archean replacement and (or) modification of mantle beneath the Archean Hearne Province. Convective removal of mantle lithosphere beneath the Archean Hearne Province in a "tectonic vise" during the Proterozoic terminal collisions that formed Laurentia either did not occur, or was followed by replacement of thick mantle lithosphere that was sampled by kimberlite in the Triassic, and is still observed there seismically today.

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