Premium
Compilation and Review of 87 Sr / 86 Sr and Stable Isotopes from Groundwater, Calcite Fracture Fillings, Mineral, and Whole‐Rock Sampling at Äspö, Sweden
Author(s) -
Wallin Bill,
Peterman Zell
Publication year - 2015
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/gwat.12173
Subject(s) - geology , calcite , groundwater , isotopes of strontium , geochemistry , plagioclase , strontium , biotite , aquifer , mineralogy , meteoric water , groundwater recharge , quartz , chemistry , geotechnical engineering , paleontology , organic chemistry
Integrated isotopic and hydrochemical studies of groundwater at Äspö, Sweden, support mixing models involving deep saline water, low‐solute infiltration, and Baltic Sea water. Carbon, oxygen, and strontium isotope analyses of calcite fracture fillings indicate that paleohydrologic conditions were different than those of today in terms of the isotopic composition of water flowing through fractures. Sr isotopes of whole‐rock and mineral (plagioclase, microcline, biotite, and epidote) samples are used to assess the effects of water‐rock interaction. Biotite is a major reactant in the early stages of water‐rock interaction. Strontium isotope systematics of groundwater from deep in the Hard Rock Laboratory, and underground research facility, and from low conductivity zones revealed a first order mixing line defined by a high‐chloride saline component with 66 mg/L Sr and an ancient sea water component with approximately 4.5 mg/L. Dilution with low salinity recharge has produced groundwater with variable Sr contents and 87 Sr / 86 Sr values between 0.7186 and 0.7160. Differences between Äspö and Laxemar groundwater are shown by trends in Sr concentrations plotted against 87 Sr / 86 Sr . The Äspö trend shows increasing 87 Sr / 86 Sr values with increasing concentrations of Sr, whereas the Laxemar groundwater trend shows little variability in 87 Sr / 86 Sr with increasing Sr concentrations. These trends are controlled by the differences in 87 Sr / 86 Sr composition of the saline end members in the two areas.