Saline ground waters and brines in the Canadian Shield: Geochemical and isotopic evidence for a residual evaporite brine component

Abstract Saline Ca-Na/Cl type groundwaters and brines sampled in deep mines over an extensive area of the Canadian Precambrian Shield have elevated Br Cl ratios which may indicate that the chlorinity of these waters was derived from the infiltration of residual evaporitic brines, remnants of the great marine incursions of the Paleozoic era. Boron concentrations in these waters are generally low (i.e., 11 B 10 B ratios of these waters are significantly greater than the average value for continental crustal rocks with the highest values (~4.19) approaching that of present-day seawater (4.20). Moreover, the boron isotopic ratios generally trend to higher values with increasing chlorinity which supports the conclusion from the Br-Cl relationship that most of the chloride in shield brines is of marine origin, rather than a product of water/rock interactions. If this is correct, crystalline rocks must then be sufficiently permeable on a regional scale to have allowed the brine to infiltrate to depths of several kilometers where it now resides.

[1]  J. Edmond,et al.  Boron isotope exchange between seawater and the oceanic crust , 1987 .

[2]  J. W. Ball,et al.  Groundwater chemistry and water-rock interactions at Stripa☆ , 1989 .

[3]  F. Albarède,et al.  Secular boron isotope variations in the continental crust: an ion microprobe study , 1992 .

[4]  D. C. Kamineni,et al.  A comparison of fracture styles in two granite bodies of the Superior Province , 1989 .

[5]  David T. Long,et al.  Geochemistry and isotope chemistry of Michigan Basin brines: Devonian formations , 1993 .

[6]  J. Gat,et al.  Activities and concentrations of oxygen-18 in concentrated aqueous salt solutions: Analytical and geophysical implications , 1972 .

[7]  L. M. Walter,et al.  Formation waters from Mississippian-Pennsylvanian reservoirs, Illinois basin, USA: Chemical and isotopic constraints on evolution and migration , 1993 .

[8]  H. Craig.  Isotopic Variations in Meteoric Waters , 1961, Science.

[9]  L. M. Walter,et al.  Strontium, boron, oxygen, and hydrogen isotope geochemistry of brines from basal strata of the Gulf Coast sedimentary basin, USA , 1993 .

[10]  J. Veizer,et al.  The nature of groundwater flow in fractured rock: Evidence from the isotopic and chemical evolution of recrystallized fracture calcites from the Canadian Precambrian Shield , 1992 .

[11]  J. Edmond,et al.  Temperature and pH controls over isotopic fractionation during adsorption of boron on marine clay , 1987 .

[12]  M. Nomura,et al.  Fundamental studies on the ion-exchange separation of boron isotopes. , 1977 .

[13]  D. C. Kamineni,et al.  Early Proterozoic deformation in the western Superior province, Canadian Shield , 1990 .

[14]  R. Bassett.  A critical evaluation of the available measurements for the stable isotopes of boron , 1990 .

[15]  D. Grégoire,et al.  Determination of boron isotope ratios in geological materials by inductively coupled plasma mass spectrometry , 1987 .

[16]  F. Haynes.  Fluid-inclusion evidence of basinal brines in Archean basement, Thunder Bay Pb-Zn-Ba district, Ontario, Canada , 1988 .

[17]  I. Kukkonen,et al.  Geochemistry and origin of saline groundwaters in the Fennoscandian Shield , 1988 .

[18]  R. Spencer.  Origin of CaCl brines in Devonian formations, western Canada sedimentary basin , 1987 .

[19]  G. Friedman,et al.  Sedimentology and Depositional Environments of Basin-Center Evaporites, Lower Salina Group (Upper Silurian), Michigan Basin , 1977 .

[20]  Darrell Kirk Nordstrom,et al.  Introduction to the hydrogeochemical investigations within the International Stripa Project , 1989 .

[21]  M. Gascoyne,et al.  The geochemistry, age, and origin of groundwater in a mafic pluton, East Bull Lake, Ontario, Canada , 1990 .

[22]  Michael G. Jones,et al.  The 87Sr86Sr values of Canadian Shield brines and fracture minerals with applications to groundwater mixing, fracture history, and geochronology , 1990 .

[23]  A. Chivas,et al.  Boron isotope geochemistry as a tracer for the evolution of brines and associated hot springs from the Dead Sea, Israel , 1991 .

[24]  L. Ovchinnikov,et al.  The precambrian continental crust: Its structure, composition and evolution as revealed by deep drilling in the U.S.S.R. , 1986 .

[25]  F. Millero,et al.  The ionization of boric acid in NaCl, NaCaCl and NaMgCl solutions at 25°C , 1986 .

[26]  A. Duba,et al.  Super‐deep, continental drilling in Germany , 1991 .

[27]  G. K. Billings,et al.  Geochemistry and origin of formation waters in the western Canada sedimentary basin—III. Factors controlling chemical composition☆ , 1971 .

[28]  P. Fritz,et al.  Strontium isotopic composition of some brines from the Precambrian Shield of Canada , 1984 .

[29]  P. Fritz,et al.  Water-rock interaction and chemistry of groundwaters from the Canadian Shield , 1984 .

[30]  D. Bottomley,et al.  Helium and neon isotope geochemistry of some ground waters from the Canadian Precambrian Shield , 1984 .

[31]  H. Pauwels,et al.  Water-rock interactions during experiments within the geothermal Hot Dry Rock borehole GPK1, Soultz-sous-Foreˆts, Alsace, France , 1992 .

[32]  D. Grégoire.  Determination of boron in fresh and saline waters by inductively coupled plasma mass spectrometry , 1990 .

[33]  L. P. Knauth,et al.  Isotope geochemistry of fluid inclusions in Permian halite with implications for the isotopic history of ocean water and the origin of saline formation waters , 1986 .

[34]  A. Chivas,et al.  Boron isotope variations during fractional evaporation of sea water: New constraints on the marine vs. nonmarine debate , 1992 .

[35]  R. Rye,et al.  Saline Minewaters of the Keweenaw Peninsula, Northern Michigan; Their Nature, Origin, and Relation to Similar Deep Waters in Precambrian Crystalline Rocks of the Canadian Shield , 1986, American Journal of Science.

[36]  P. Fritz,et al.  The chemistry and isotopic composition of saline groundwaters from the Sudbury Basin, Ontario , 1982 .

[37]  H. Schwarcz,et al.  Boron isotopic fractionation during clay adsorption from sea-water , 1969 .

[38]  C. C. McMullen,et al.  A study of the isotopic abundance of boron from various sources , 1968 .

[39]  K. Crowley.  Thermal history of Michigan Basin and Southern Canadian Shield from apatite fission track analysis , 1991 .

[40]  L. M. Walter,et al.  Origin and evolution of formation waters, Alberta Basin, Western Canada sedimentary Basin. I. Chemistry , 1990 .

[41]  S. Frape,et al.  The isotopic composition of precipitation and groundwater in Canada , 1987 .

[42]  Darrell Kirk Nordstrom,et al.  Fluid inclusions in the Stripa granite and their possible influence on the groundwater chemistry , 1989 .