Rare-earth-element enrichment in post-Variscan polymetallic vein systems of the Harz Mountains, Germany

Published on Feb 1, 2019in Mineralium Deposita 3.37
· DOI :10.1007/s00126-018-0847-8
Jonas Alles1
Estimated H-index: 1
,
Alexander-Maria Ploch1
Estimated H-index: 1
+ 3 AuthorsBernd Lehmann32
Estimated H-index: 32
Abstract
Carbonate gangue in historically important post-Variscan polymetallic Pb-Zn-Cu-Ag vein systems in the Upper Harz Mountains has elevated rare earth element contents (ΣREE+Y, 1500 ± 340 ppm; n = 16) in bulk samples. This enrichment is due to the occurrence of abundant micrometer-sized synchysite inclusions in calcite, identified via Raman spectroscopy. Calcite bulk analyses have roof-shaped PAAS-normalized REE patterns with a Eu peak but without Ce or Y anomalies and with a steeply dipping HREE pattern. Microbeam analysis (electron microprobe and LA-ICPMS) identifies these patterns as dominated by synchysite-(Ce–Nd) with strong Eu enrichment in the weight percent range and LREE/HREE fractionation (La/Lu ~ 100, PAAS-normalized). The synchysite component in calcite gangue is detected in polymetallic veins all over the Harz Mountains, which seems to be a diagnostic feature of the region and suggests a large-scale Mesozoic fluid system. However, the Upper (western) Harz systems with no fluorite have more elevated REE content, compared with the Lower (eastern) Harz fluorite-rich systems with less REE content. Carbonate gangue in the Upper Harz systems has homogeneous 87Sr/86Sri around 0.714 and eNdi of ~ − 9, while carbonate gangue in the Lower Harz systems has 87Sr/86Sri around 0.716 and eNdi of − 2 to − 5. Fluorite in the Lower Harz Mountains has strong positive Y anomalies and variable Eu anomalies at generally low REE abundances and no REE-mineral inclusions. Both Sr and Nd isotope compositions in the fluorite are very variable and indicate an open system (87Sr/86Sri, 0.710–0.718; eNdi, − 3 to − 17). The synchysite MREE enrichment in calcite gangue in the Upper Harz Mountains compares favorably with carbonatite-related LREE-dominated bastnasite from China and elsewhere and allows an interesting perspective as a by-product of Pb–Zn mining.
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References49
Published on Jan 1, 2010in Scientific Investigations Report
Keith R. Long4
Estimated H-index: 4
(United States Geological Survey),
Bradley S. Van Gosen5
Estimated H-index: 5
(United States Geological Survey)
+ 1 AuthorsDaniel Cordier1
Estimated H-index: 1
(United States Geological Survey)
Demand for the rare earth elements (REE, lanthanide elements) is estimated to be increasing at a rate of about 8% per year due to increasing applications in consumer products, computers, automobiles, aircraft, and other advanced technology products. Much of this demand growth is driven by new technologies that increase energy efficiency and substitute away from fossil fuels. Production of these elements is highly concentrated in China, which is reducing its exports of REE raw materials as part o...
126 Citations Source Cite
Published on Oct 15, 1990in Chemical Geology 3.57
Scott A. Wood38
Estimated H-index: 38
(McGill University)
Abstract Stability constants for trivalent REE complexes containing fluoride, chloride, sulfate, carbonate or hydroxide ions have been predicted up to 350°C at saturated water vapor pressure using Helgeson's electrostatic approach, combined with the isocoulombic approach and available experimental thermodynamic data at low temperatures. In addition, the equilibrium boundary between divalent and trivalent REE ions was calculated at elevated temperatures and 1 kbar for Sm, Yb and Eu as a function ...
323 Citations Source Cite
Published on Mar 1, 2005in Mineralium Deposita 3.37
Marguerite Munoz12
Estimated H-index: 12
(Paul Sabatier University),
Wayne R. Premo17
Estimated H-index: 17
(United States Geological Survey)
A three-point Sm–Nd isotope isochron on fluorite from the very large Montroc fluorite vein deposit (southern Massif Central, France) defines an age of 111±13 Ma. Initial eNd of −8.6 and initial 87Sr/86Sr of ~0.71245 suggest an upper crustal source of the hydrothermal system, in agreement with earlier work on fluid inclusions which indicated a basinal brine origin. The mid-Cretaceous age of ~111 Ma suggests the Albian/Aptian transition as the most likely period for large-scale fluid circulation d...
32 Citations Source Cite
Published on Dec 1, 2003in Mineralium Deposita 3.37
Jens Schneider19
Estimated H-index: 19
(University of Giessen),
Udo Haack9
Estimated H-index: 9
(University of Giessen),
Klaus Stedingk2
Estimated H-index: 2
Rb–Sr isotope data for siderite and fluorite from sediment-hosted epithermal mineral veins in the eastern Harz Mountains (Germany) are presented. Several fluorite and siderite-bearing paragenetic stages have been proposed for these veins, with the most important mineralization being related to a quartz–sulfide and a subsequent calcite–fluorite–quartz stage, which occurred at 226±1 and 209±2 Ma, respectively. Our Rb–Sr data do not permit the identification of distinct generations of siderite and ...
15 Citations Source Cite
Published on Sep 1, 2000in Geochimica et Cosmochimica Acta 4.69
Martin Smith20
Estimated H-index: 20
(Natural History Museum),
Paul Henderson8
Estimated H-index: 8
(Natural History Museum),
L. S. Campbell8
Estimated H-index: 8
(Natural History Museum)
Abstract The composition of REE minerals from the Bayan Obo Fe-REE-Nb deposit, China, varies widely with paragenesis. The properties of fluid inclusions also vary with paragenesis, indicating changing fluid conditions during the deposits formation. In early disseminated monazite and in the main stage banded ores, the chondrite normalised La/Nd ratio varies from ∼3 to 7, whilst vein-hosted bastnasite and monazite show ratios in the range ∼4.8 to 5.8. The La-rich portion of this trend (La/Nd > 4) ...
131 Citations Source Cite
Published on Sep 1, 1979in Chemical Geology 3.57
P. Möller3
Estimated H-index: 3
,
G. Morteani3
Estimated H-index: 3
(Technical University of Berlin)
+ 1 AuthorsP.P. Parekh2
Estimated H-index: 2
Abstract Rare-earth element (REE) and stable-isotope distribution patterns in calcites from the mining areas of St. Andreasberg, Clausthal and Bad Grund, western Harz, Germany, have been determined. Three types of REE distribution patterns were found: type I is characterized by high amounts of light REE without any Ce and Eu anomalies and relatively homogeneous C- and O-isotopic composition. Type II displays conspicuous Ce and Eu anomalies at lower levels of concentration of the light REE. Type ...
36 Citations Source Cite
Published on Sep 1, 2010in Chemical Geology 3.57
Volker Lüders16
Estimated H-index: 16
,
Birgit Plessen23
Estimated H-index: 23
+ 5 AuthorsGeorg Schettler17
Estimated H-index: 17
Abstract Element concentrations and isotopic composition ( δ D, δ 18 O, δ 15 N of ammonium, 87 Sr/ 86 Sr) have been determined in highly-saline formation waters from the Rotliegend Altmark gasfield and the Upper Carboniferous Husum–Schneeren gasfield in the North German Basin. Both reservoirs have been covered by huge Zechstein evaporite caps since the Late Permian. Formation waters from the Altmark gasfield are characterized by high total dissolved solids and are enriched in δ 18 O relative to ...
48 Citations Source Cite
Published on Apr 1, 2010in Mineralium Deposita 3.37
Alain Cheilletz22
Estimated H-index: 22
(Nancy-Université),
Dominique Gasquet20
Estimated H-index: 20
(University of Savoy)
+ 2 AuthorsMassimo Nespolo19
Estimated H-index: 19
(Nancy-Université)
El Hammam is the only fluorite mine in Morocco (production 100,000 t/year). The fluorite mineralization is in an array of fluorite-calcite veins and is characterized by unusually high REE content in carbonate minerals (1,400 ppm in calcite; up to 2,000 ppm in siderite) and in fluorite (about 600 ppm). Since the 1960s, the genesis of the deposit has been attributed to a mesothermal hydrothermal event connected with late-Variscan granitic intrusions. Precise 40Ar/39Ar dating of hydrothermal K-feld...
19 Citations Source Cite
Published on Jan 1, 1994in Geochimica et Cosmochimica Acta 4.69
Bernd Lehmann32
Estimated H-index: 32
,
Shun'ichi Nakai18
Estimated H-index: 18
(University of Tokyo)
+ 4 AuthorsAkimasa Masuda32
Estimated H-index: 32
(University of Tokyo)
Abstract The 587 Ma-old hydrothermal bastnaesite mineralization of Gakara in the western branch of the East African Rift in Burundi has geological and chemical features typical of carbonatite-related REE ore deposits, but Nd, Ce, and Sr isotope data on the bastnaesite indicate a time-integrated LREE-enriched source with ϵ Nd ( T )−11.9, ϵ Ce ( T ) 1.6, and 87 Sr 86 Sr ≤0.7075 . The mid-Proterozoic Nd model age of this source coincides with the formation of the intracratonic Kibaran basin of cent...
23 Citations Source Cite
Published on Jul 1, 2001in Mineralogy and Petrology 1.66
H.-J. Forster1
Estimated H-index: 1
The Ca,REE-fluorocarbonate synchysite, which forms anhedral grains hosted in albite, was identified in the Markersbach pluton (Erzgebirge, Germany) composed of F-rich, highly fractionated and autometasomatically altered granites. These granites were emplaced in a post-collisional setting and are of aluminous A-type affinity. The grains were identified by electron microprobe analysis as intermediate members of the probably complete solid-solution series between synchysite-(Y) and synchysite-(Ce)....
33 Citations Source Cite
  • References (49)
  • Citations (1)
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