Characterisation and isotopic evolution of saline waters of the Outokumpu Deep Drill Hole, Finland: Implications for water origin and deep terrestrial biosphere

Riikka Kietäväinen (Corresponding Author), Lasse Ahonen, Ilmo T. Kukkonen, Nina Hendriksson, Mari Nyyssönen, Merja Itävaara

Research output: Contribution to journalArticleScientificpeer-review

23 Citations (Scopus)

Abstract

The isotopic composition of water and dissolved Sr as well as other geochemical parameters at the 2516m deep Outokumpu Deep Drill Hole, Finland were determined. The drill hole is hosted by Palaeoproterozoic turbiditic metasediments, ophiolite-derived altered ultramafic rocks and pegmatitic granitoids. Sodium-Ca-Cl and Ca-Na-Cl-rich waters (total dissolved solids up to ca. 70gL-1) containing significant amounts of gas, mainly CH4 (up to 32mmolL-1), N2 (up to 10mmolL-1), H2 (up to 3.1mmolL-1) and He (up to 1.1mmolL-1) discharge from fracture zones into the drill hole. This water is distinct from the shallow fresh groundwater of the area, and has an isotopic composition typical of shield brines that have been modified during long-term water-rock interaction. Based on water stable isotopes and geochemistry, the drill hole water profile can be divided into five water types, each discharging from separate fracture systems and affected by the surrounding rocks. The d2H varies from -90% to -56% (VSMOW) and d18O from -13.5% to -10.4% (VSMOW), plotting clearly above the Global and Local Meteoric Water Lines on a d2H vs. d18O diagram. The 87Sr/86Sr ratios range between 0.72423 and 0.73668. Simple two-component mixing between 2H and 18O rich end-member brine and meteoric water cannot explain the water stable isotopic composition and trends observed. Instead, hydration of silicates by ancient groundwaters recharged under different climatic conditions, warmer than at present, is the most likely mechanism to have caused the variation of the d2H and d18O values. Water types correlate with changes in microbial communities implying that different ecosystems occur at different depths. The different water types and microbial populations have remained isolated from each other and from the surface for long periods of time, probably tens of millions of years.
Original languageEnglish
Pages (from-to)37-51
JournalApplied Geochemistry
Volume32
DOIs
Publication statusPublished - 2013
MoE publication typeA1 Journal article-refereed

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Saline water
biosphere
Water
water
isotopic composition
meteoric water
Rocks
Groundwater
Saline Waters
Chemical analysis
groundwater
water-rock interaction
Water piping systems
metasediment
Silicates
ultramafic rock
Brines
fracture zone
hydration
ophiolite

Cite this

Kietäväinen, Riikka ; Ahonen, Lasse ; Kukkonen, Ilmo T. ; Hendriksson, Nina ; Nyyssönen, Mari ; Itävaara, Merja. / Characterisation and isotopic evolution of saline waters of the Outokumpu Deep Drill Hole, Finland : Implications for water origin and deep terrestrial biosphere. In: Applied Geochemistry. 2013 ; Vol. 32. pp. 37-51.
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abstract = "The isotopic composition of water and dissolved Sr as well as other geochemical parameters at the 2516m deep Outokumpu Deep Drill Hole, Finland were determined. The drill hole is hosted by Palaeoproterozoic turbiditic metasediments, ophiolite-derived altered ultramafic rocks and pegmatitic granitoids. Sodium-Ca-Cl and Ca-Na-Cl-rich waters (total dissolved solids up to ca. 70gL-1) containing significant amounts of gas, mainly CH4 (up to 32mmolL-1), N2 (up to 10mmolL-1), H2 (up to 3.1mmolL-1) and He (up to 1.1mmolL-1) discharge from fracture zones into the drill hole. This water is distinct from the shallow fresh groundwater of the area, and has an isotopic composition typical of shield brines that have been modified during long-term water-rock interaction. Based on water stable isotopes and geochemistry, the drill hole water profile can be divided into five water types, each discharging from separate fracture systems and affected by the surrounding rocks. The d2H varies from -90{\%} to -56{\%} (VSMOW) and d18O from -13.5{\%} to -10.4{\%} (VSMOW), plotting clearly above the Global and Local Meteoric Water Lines on a d2H vs. d18O diagram. The 87Sr/86Sr ratios range between 0.72423 and 0.73668. Simple two-component mixing between 2H and 18O rich end-member brine and meteoric water cannot explain the water stable isotopic composition and trends observed. Instead, hydration of silicates by ancient groundwaters recharged under different climatic conditions, warmer than at present, is the most likely mechanism to have caused the variation of the d2H and d18O values. Water types correlate with changes in microbial communities implying that different ecosystems occur at different depths. The different water types and microbial populations have remained isolated from each other and from the surface for long periods of time, probably tens of millions of years.",
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Characterisation and isotopic evolution of saline waters of the Outokumpu Deep Drill Hole, Finland : Implications for water origin and deep terrestrial biosphere. / Kietäväinen, Riikka (Corresponding Author); Ahonen, Lasse; Kukkonen, Ilmo T.; Hendriksson, Nina; Nyyssönen, Mari; Itävaara, Merja.

In: Applied Geochemistry, Vol. 32, 2013, p. 37-51.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Characterisation and isotopic evolution of saline waters of the Outokumpu Deep Drill Hole, Finland

T2 - Implications for water origin and deep terrestrial biosphere

AU - Kietäväinen, Riikka

AU - Ahonen, Lasse

AU - Kukkonen, Ilmo T.

AU - Hendriksson, Nina

AU - Nyyssönen, Mari

AU - Itävaara, Merja

N1 - Publ.year changed 30.4.2013 CA2: TK404 SDA: BIC

PY - 2013

Y1 - 2013

N2 - The isotopic composition of water and dissolved Sr as well as other geochemical parameters at the 2516m deep Outokumpu Deep Drill Hole, Finland were determined. The drill hole is hosted by Palaeoproterozoic turbiditic metasediments, ophiolite-derived altered ultramafic rocks and pegmatitic granitoids. Sodium-Ca-Cl and Ca-Na-Cl-rich waters (total dissolved solids up to ca. 70gL-1) containing significant amounts of gas, mainly CH4 (up to 32mmolL-1), N2 (up to 10mmolL-1), H2 (up to 3.1mmolL-1) and He (up to 1.1mmolL-1) discharge from fracture zones into the drill hole. This water is distinct from the shallow fresh groundwater of the area, and has an isotopic composition typical of shield brines that have been modified during long-term water-rock interaction. Based on water stable isotopes and geochemistry, the drill hole water profile can be divided into five water types, each discharging from separate fracture systems and affected by the surrounding rocks. The d2H varies from -90% to -56% (VSMOW) and d18O from -13.5% to -10.4% (VSMOW), plotting clearly above the Global and Local Meteoric Water Lines on a d2H vs. d18O diagram. The 87Sr/86Sr ratios range between 0.72423 and 0.73668. Simple two-component mixing between 2H and 18O rich end-member brine and meteoric water cannot explain the water stable isotopic composition and trends observed. Instead, hydration of silicates by ancient groundwaters recharged under different climatic conditions, warmer than at present, is the most likely mechanism to have caused the variation of the d2H and d18O values. Water types correlate with changes in microbial communities implying that different ecosystems occur at different depths. The different water types and microbial populations have remained isolated from each other and from the surface for long periods of time, probably tens of millions of years.

AB - The isotopic composition of water and dissolved Sr as well as other geochemical parameters at the 2516m deep Outokumpu Deep Drill Hole, Finland were determined. The drill hole is hosted by Palaeoproterozoic turbiditic metasediments, ophiolite-derived altered ultramafic rocks and pegmatitic granitoids. Sodium-Ca-Cl and Ca-Na-Cl-rich waters (total dissolved solids up to ca. 70gL-1) containing significant amounts of gas, mainly CH4 (up to 32mmolL-1), N2 (up to 10mmolL-1), H2 (up to 3.1mmolL-1) and He (up to 1.1mmolL-1) discharge from fracture zones into the drill hole. This water is distinct from the shallow fresh groundwater of the area, and has an isotopic composition typical of shield brines that have been modified during long-term water-rock interaction. Based on water stable isotopes and geochemistry, the drill hole water profile can be divided into five water types, each discharging from separate fracture systems and affected by the surrounding rocks. The d2H varies from -90% to -56% (VSMOW) and d18O from -13.5% to -10.4% (VSMOW), plotting clearly above the Global and Local Meteoric Water Lines on a d2H vs. d18O diagram. The 87Sr/86Sr ratios range between 0.72423 and 0.73668. Simple two-component mixing between 2H and 18O rich end-member brine and meteoric water cannot explain the water stable isotopic composition and trends observed. Instead, hydration of silicates by ancient groundwaters recharged under different climatic conditions, warmer than at present, is the most likely mechanism to have caused the variation of the d2H and d18O values. Water types correlate with changes in microbial communities implying that different ecosystems occur at different depths. The different water types and microbial populations have remained isolated from each other and from the surface for long periods of time, probably tens of millions of years.

U2 - 10.1016/j.apgeochem.2012.10.013

DO - 10.1016/j.apgeochem.2012.10.013

M3 - Article

VL - 32

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JO - Applied Geochemistry

JF - Applied Geochemistry

SN - 0883-2927

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