Fluid evolution and ore deposition in the Harz Mountains revisited: isotope and crush-leach analyses of fluid inclusions

Stefan de Graaf, Volker Lüders, David A. Banks, Marta Sośnicka, John J. G. Reijmer, Heike Kaden, Hubert B. Vonhof

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Hydrothermal fluid flow along fault zones in the Harz Mountains led to widespread formation of economic vein-type Pb–Zn ore and Ba–F deposits during the Mesozoic. We reconstruct the fluid flow system responsible for the formation of these deposits using isotope ratios (δ2H and δ18O) and anion and cation contents of fluid inclusions in ore and gangue minerals. Building forward on extensive studies in the 1980s and 1990s, our new geochemical data reveal that seawater evaporation brines, which most likely originated from Zechstein evaporites, descended deeply into Paleozoic rocks to leach metals at depth. In Jurassic times, these metal-rich brines episodically recharged along fault zones and mixed with shallow crustal H2S-bearing brines. Primarily in the Upper Harz Mountains, this mixing system led to the formation of economic Pb–Zn–Cu mineralization, which locally shows banded textures with alternations of sulfide minerals and quartz or carbonate (mostly calcite). In the Middle and Lower Harz Mountains, Zechstein-derived brines interacted with K- and F-bearing basement rocks and/or magmatic rocks to deposit fluorite mineralization upon ascent in the Upper Cretaceous. The proposed model of mineralizing fluids originating as (evaporated) seawater has been shown to hold for numerous basin-hosted base-metal sulfide and fluoride deposits elsewhere in Europe.
Original languageEnglish
Pages (from-to)47-62
Number of pages16
JournalMineralium Deposita
Volume55
Issue number1
DOIs
Publication statusPublished - 2020

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fluid inclusion
Zechstein
isotope
mountain
fluid flow
fluid
fault zone
sulfide
mineralization
seawater
metal
gangue
fluorite
mineral
base metal
basement rock
hydrothermal fluid
evaporite
economics
fluoride

Cite this

de Graaf, Stefan ; Lüders, Volker ; Banks, David A. ; Sośnicka, Marta ; Reijmer, John J. G. ; Kaden, Heike ; Vonhof, Hubert B. / Fluid evolution and ore deposition in the Harz Mountains revisited: isotope and crush-leach analyses of fluid inclusions. In: Mineralium Deposita. 2020 ; Vol. 55, No. 1. pp. 47-62.
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abstract = "Hydrothermal fluid flow along fault zones in the Harz Mountains led to widespread formation of economic vein-type Pb–Zn ore and Ba–F deposits during the Mesozoic. We reconstruct the fluid flow system responsible for the formation of these deposits using isotope ratios (δ2H and δ18O) and anion and cation contents of fluid inclusions in ore and gangue minerals. Building forward on extensive studies in the 1980s and 1990s, our new geochemical data reveal that seawater evaporation brines, which most likely originated from Zechstein evaporites, descended deeply into Paleozoic rocks to leach metals at depth. In Jurassic times, these metal-rich brines episodically recharged along fault zones and mixed with shallow crustal H2S-bearing brines. Primarily in the Upper Harz Mountains, this mixing system led to the formation of economic Pb–Zn–Cu mineralization, which locally shows banded textures with alternations of sulfide minerals and quartz or carbonate (mostly calcite). In the Middle and Lower Harz Mountains, Zechstein-derived brines interacted with K- and F-bearing basement rocks and/or magmatic rocks to deposit fluorite mineralization upon ascent in the Upper Cretaceous. The proposed model of mineralizing fluids originating as (evaporated) seawater has been shown to hold for numerous basin-hosted base-metal sulfide and fluoride deposits elsewhere in Europe.",
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Fluid evolution and ore deposition in the Harz Mountains revisited: isotope and crush-leach analyses of fluid inclusions. / de Graaf, Stefan; Lüders, Volker; Banks, David A.; Sośnicka, Marta; Reijmer, John J. G.; Kaden, Heike; Vonhof, Hubert B.

In: Mineralium Deposita, Vol. 55, No. 1, 2020, p. 47-62.

Research output: Contribution to JournalArticleAcademicpeer-review

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AU - de Graaf, Stefan

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AU - Reijmer, John J. G.

AU - Kaden, Heike

AU - Vonhof, Hubert B.

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N2 - Hydrothermal fluid flow along fault zones in the Harz Mountains led to widespread formation of economic vein-type Pb–Zn ore and Ba–F deposits during the Mesozoic. We reconstruct the fluid flow system responsible for the formation of these deposits using isotope ratios (δ2H and δ18O) and anion and cation contents of fluid inclusions in ore and gangue minerals. Building forward on extensive studies in the 1980s and 1990s, our new geochemical data reveal that seawater evaporation brines, which most likely originated from Zechstein evaporites, descended deeply into Paleozoic rocks to leach metals at depth. In Jurassic times, these metal-rich brines episodically recharged along fault zones and mixed with shallow crustal H2S-bearing brines. Primarily in the Upper Harz Mountains, this mixing system led to the formation of economic Pb–Zn–Cu mineralization, which locally shows banded textures with alternations of sulfide minerals and quartz or carbonate (mostly calcite). In the Middle and Lower Harz Mountains, Zechstein-derived brines interacted with K- and F-bearing basement rocks and/or magmatic rocks to deposit fluorite mineralization upon ascent in the Upper Cretaceous. The proposed model of mineralizing fluids originating as (evaporated) seawater has been shown to hold for numerous basin-hosted base-metal sulfide and fluoride deposits elsewhere in Europe.

AB - Hydrothermal fluid flow along fault zones in the Harz Mountains led to widespread formation of economic vein-type Pb–Zn ore and Ba–F deposits during the Mesozoic. We reconstruct the fluid flow system responsible for the formation of these deposits using isotope ratios (δ2H and δ18O) and anion and cation contents of fluid inclusions in ore and gangue minerals. Building forward on extensive studies in the 1980s and 1990s, our new geochemical data reveal that seawater evaporation brines, which most likely originated from Zechstein evaporites, descended deeply into Paleozoic rocks to leach metals at depth. In Jurassic times, these metal-rich brines episodically recharged along fault zones and mixed with shallow crustal H2S-bearing brines. Primarily in the Upper Harz Mountains, this mixing system led to the formation of economic Pb–Zn–Cu mineralization, which locally shows banded textures with alternations of sulfide minerals and quartz or carbonate (mostly calcite). In the Middle and Lower Harz Mountains, Zechstein-derived brines interacted with K- and F-bearing basement rocks and/or magmatic rocks to deposit fluorite mineralization upon ascent in the Upper Cretaceous. The proposed model of mineralizing fluids originating as (evaporated) seawater has been shown to hold for numerous basin-hosted base-metal sulfide and fluoride deposits elsewhere in Europe.

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