Iron and titanium anomalies in till from the Transantarctic Mountains
the equilibrium solubility behavior of the hydrates of sodium borate (Bassett 1976; Nies and Hulbert 1967), we consider the most probable origin for this material to have been crystallization from a sub-glacial, alkaline brine generated by the mix ing of glacial meltwater with a warm, carbon dioxide-charged, boron-rich thermal fluid. Additional work is planned on samples retrieved during the 1988-1989 field season. This work will include carbon-14 dating of rim nahcolites, boron-11/boron-10 determinations on the borax to determine the source of the boron, isotopic oxygen18 and 8D determinations on sealed samples of borax (for H 2 0 - ) and nahcolite, and uranium-series age determinations on the core zones of pseudomorphs. Additional work is also planned on other deposits of nahcolite and trona in the area. This research was supported by National Science Foundation grant DPP 83-14496 with the cooperation of the U.S. Geological Survey, the Branch of Sedimentary Processes and the Branch of Isotope Geology. We wish to express our appreciation to William A. Cassidy for allowing us to participate in the 1987-1988 antarctic search for meteorites field activities and to all other members of the team without whose cooperation these samples could not have been retrieved.
References Bassett, R.L. 1976. Geochennstry of boron in the thermal waters. (Doctoral Thesis, Stanford University.). Bockheim, J.G. 1979. Relative age and origin of soils in eastern Wright Valley, Antarctica. Soils Science, 128, 142-152. Bowser, C.J., T.A. Rafter, and R.F. Black. 1970. Geochemical evidence for the origin of mirabilite deposits near Hobbs Glacier, Victoria Land, Antarctica. Mineralogical Society of America Special Paper 3, 261272. Eugster, H.P. 1966. Sodium carbonate-bicarbonate minerals as indi cators of P 0 Journal of Geophysical Research, 71, No. 14, 3,369-3,377. Ford, D.C., P.G. Fuller, and J . J . Drake. 1970. Calcite precipitation at the soles of temperate glaciers. Nature, 226, 441-442. Hallet, B. 1975. Subglacial silica deposits. Nature, 254(5,502), 682-683.
Iron and titanium anomalies in till from the Transantarctic Mountains ERIK H. HAGEN, KENNETH S. JOHNSON, MICHAEL
L. STROBEL, and GUNTER FAURE
Department of Geology and Mineralogy Ohio State University Columbus, Ohio 43210
Till in the Transantarctic Mountains is composed in part of minerals derived from the subglacial bedrock of East Antarctica. Rubidium/strontium dates of feldspar concentrated from 1989 REVIEW
Hallet, B. 1976. Deposits formed by subglacial precipitation of CaCO3. Geological Society of America Bulletin, 87, 1,003-1,015. Hanshaw, B.B., and B. Hallet. 1978. Oxygen isotope composition of subglacially precipitated calcite: Possible paleoclimate implications. Science, 200, 1,267-1,270. Hendy, C.H., A.T. Wilson, K.B. Popplewell, and D.A. House. 1977. Dating of geochemical events in Lake Bonney, Antarctica, and their relation to glacial and climate changes. New Zealand Journal of Geology and Geophysics, 20(6), 1,103-1,122. Jones, L.M., G. Faure, K.S. Taylor, and C.E. Corbato. 1983. The origin of salts on Mount Erebus and along the coast of Ross Island, Antarctica. Isotope Geoscience, 1, 57-64. Keys, JR., and K. Williams. 1981. Origin of crystalline, cold desert salts in the McMurdo region, Antarctica. Geochimica et Cosmochimica Acta, 45, 2,299-2,309. Magaritz, M. 1973. Precipitation of secondary calcite in glacier areas; carbon and oxygen isotopic composition of calcites from Mt. Hermon, Israel, and the European Alps. Earth and Planetary Science Letters, 17, 385-390. Nies, N. P., and R. W. Hulbert. 1967. Solubility isotherms in the system sodium oxide-boric oxide-water. Journal of Chemical Engineering Data,
12, 303-313. Pastor, J . , and J.G. Bockheim. 1980. Soil development on moraines of Taylor Glacier, lower Taylor Valley, Antarctica. Soil Science Society of America Journal, 44, 341-348. Peterson, J.A., and J.F. Moresby. 1979. Subglacial travertine and associated deposits in the Carstensz area, Irian Jaya, Republic of Indonesia. Zeitschrift für Gletscherkunde und Glazialgeologie Bd., 15, 1-1.1, 23-29. Tasch, P., and E.E. Angino. 1968. Sulfate and carbonate salt efflorescences from the antarctic interior. Antarctic Journal of the U.S., 3, 239241.
Vennum, W.R. 1979. Evaporite encrustations and yellow and green surficial salts from Orville Coast and eastern Ellsworth Land. Antarctic Journal of the U.S., 24(5), 22-24, Vennum, W.R. 1980. Evaporite encrustations and sulfide oxidation products from the southern Antarctic Penninsula. New Zealand Journal of Geology and Geophysics, 23, 499-505. Whilans, I.M., and W.A. Cassidy. 1983. Catch a falling star: Meteorites and old ice. Science, 222, 55-57. Wilson, AT., C.H. Hendy, T.R. Healy, J.W. Gumbley, A.B. Field, and C.P. Reynolds. 1974. Dry Valley lake sediments: A record of Cenezoic climatic events. Antarctic Journal of the U.S., 9, 134-135.
till by Faure and Taylor (1981), Faure, Taylor, and Mercer (1983), Faure and Taylor (1983), Taylor and Faure (1983), and Faure (1986) indicate that a Precambrian component, presumably derived from East Antarctica, is present in till deposited by the Byrd and Reedy glaciers. We now report preliminary results from a study of the heavy-mineral fraction of till collected at localities ranging from the Morozumi Range of northern Victoria Land to the Wisconsin Range of the Horlick Mountains adjacent to the Reedy Glacier. Thirty till samples were sieved into size fractions and the heavy minerals were separated from the sand fractions (35 to 120 mesh) by settling them in bromoform (specific gravity of 2.83). The heavy-mineral separates were ground and compressed into pellets for analysis by X-ray fluorescence using molybdenum/potassium alpha X-radiation and a lithium fluoride (220) diffracting crystal (Hagen 1988). Calibrations for iron and titanium were based on the standard rock samples of the 65
U.S. Geological Survey (Flanagan 1973). All samples were analyzed in triplicate, and the average analytical errors are ± 0.4 percent of the reported concentrations for iron and ± 1.3 percent for titanium. The concentrations of iron and titanium in 28 of the 30 samples vary within narrow limits and lie within the small rectangular area marked "TAM" in the figure; however, a sample of till from the plateau of the Wisconsin Range (85°48'S 125°24'W) has significantly higher concentrations of iron and titanium than most of the till samples from the Transantarctic Mountains. In addition, fill from Shapeless Mountain (77°26'S 160°26E) is enriched in titanium but depleted in iron relative to the other samples. The till sample from the Wisconsin Range was collected by the late John H. Mercer during the 1964-1965 austral summer (Mercer 1968) and contains marine diatoms as reported by Webb et al. (1984). The diagram contains the common iron- and titanium-bearing minerals that occur in the heavy-mineral fractions of till. Most of the samples cluster around the point representing pyroxene and other ferromagnesian minerals including hornblende. These samples evidently contain large amounts of pyroxene, presumably derived from the sills of the Ferrar Dolerite and are therefore of little geochemical interest.
The samples from Shapeless Mountain and from the Wisconsin Range are mixtures of magnetite, ilmenite, rutile, sphene, pyrite, and pyroxene. In addition, minor amounts of quartz and feldspar are also present as intergrowths with the other minerals. The diagram has been divided by drawing mixing lines between ilmenite and pyroxene and between ilmenite and quartz/feldspar which places the two anomalous samples in different sections of the diagram. The heavy-mineral fraction of till from the Wisconsin Range can be treated as a mixture of magnetite, ilmenite, and pyroxene which are characteristic of plutonic mafic igneous rocks like gabbro and peridotite. The sample from Shapeless Mountain lies in the mixing triangle containing ilmenite, rutile, sphene, and quartz/feldspar which occur in igneous and metamorphic rocks of granitic composition. Therefore, the heavy mineral fractions of till in the Wisconsin Range and at Shapeless Mountain appear to have originated from different kinds of rocks under the east antarctic ice sheet. We thank the pilots and crew of VXE-Six who helped us to collect the samples on which this study is based. This research was supported by National Science Foundation grant DPP 8714324.
References
Concentrations of iron (Fe) and titanium (Ti) of heavy-mineral fractions of till from the Transantarctic Mountains (TAM). The samples from the Wisconsin Range and from Shapeless Mountain are anomalous compared to the majority of the till samples.
66
Faure, C., and K.S. Taylor. 1981. Provenance of some glacial deposits in the Transantarctic Mountains based on Rb-Sr dating of feldspars. Chemical Geology, 32, 271-290. Faure, G., K. Taylor, and J. H. Mercer. 1983. Rb-Sr provenance dates of feldspar in glacial deposits of the Wisconsin Range, Transantarctic Mountains. Geological Society of America Bulletin, 94, 1,275-1,280. Faure, C., and K.S. Taylor. 1983. Sedimentation in the Ross Embayment: Evidence from RISP core 8 (1977/78). In R.L. Oliver, P.R. James, and J.B. Jago (Eds.), Antarctic earth science. Canberra: Australian Academy of Science. Faure, C. 1986. Provenance of feldspar in till from the Morozumi Range, northern Victoria Land. In E. Stump (Ed.), Geological Investigations in northern Victoria Land. (Antarctic Research Series, Vol. 46.) Washington, D.C.: American Geophysical Union. Flanagan, F.J. 1973. 1972 Values for international geochemical reference standards. Geochimica et Cosmochimica Acta, 37, 1,189-1,200. Hagen, E.H. 1988. Geochemical studies of Neogene till in the Transantarctic Mountains; evidence for an extraterrestrial component. (Unpublished Master of Science thesis, Department of Geology and Mineralogy, Ohio State University, Columbus, Ohio.) Mercer, J.H. 1968. Glacial geology of the Reedy Glacier area. Geological Society of America Bulletin, 79, 471-486. Taylor, KS., and G. Faure. 1983. Provenance dates of feldspar in glacial deposits, southern Victoria Land, Antarctica. In R.L. Oliver, P.R. James, and J.B. Jago (Eds.), Antarctic earth science. Canberra: Australian Academy of Science. Webb, P.N., D.M. Harwood, B.C. McKelvey, and J.H. Mercer. 1984. Cenozoic marine sedimentation and ice-volume variations on the East Antarctic craton. Geology, 12(5), 287-291.
ANTARCTIC JOURNAL
References Bassett, R.L. 1976. Geochennstry of boron in the thermal waters. (Doctoral Thesis, Stanford University.). Bockheim, J.G. 1979. Relative age and origin of soils in eastern Wright Valley, Antarctica. Soils Science, 128, 142-152. Bowser, C.J., T.A. Rafter, and R.F. Black. 1970. Geochemical evidence for the origin of mirabilite deposits near Hobbs Glacier, Victoria Land, Antarctica. Mineralogical Society of America Special Paper 3, 261272. Eugster, H.P. 1966. Sodium carbonate-bicarbonate minerals as indi cators of P 0 Journal of Geophysical Research, 71, No. 14, 3,369-3,377. Ford, D.C., P.G. Fuller, and J . J . Drake. 1970. Calcite precipitation at the soles of temperate glaciers. Nature, 226, 441-442. Hallet, B. 1975. Subglacial silica deposits. Nature, 254(5,502), 682-683.
Iron and titanium anomalies in till from the Transantarctic Mountains ERIK H. HAGEN, KENNETH S. JOHNSON, MICHAEL
L. STROBEL, and GUNTER FAURE
Department of Geology and Mineralogy Ohio State University Columbus, Ohio 43210
Till in the Transantarctic Mountains is composed in part of minerals derived from the subglacial bedrock of East Antarctica. Rubidium/strontium dates of feldspar concentrated from 1989 REVIEW
Hallet, B. 1976. Deposits formed by subglacial precipitation of CaCO3. Geological Society of America Bulletin, 87, 1,003-1,015. Hanshaw, B.B., and B. Hallet. 1978. Oxygen isotope composition of subglacially precipitated calcite: Possible paleoclimate implications. Science, 200, 1,267-1,270. Hendy, C.H., A.T. Wilson, K.B. Popplewell, and D.A. House. 1977. Dating of geochemical events in Lake Bonney, Antarctica, and their relation to glacial and climate changes. New Zealand Journal of Geology and Geophysics, 20(6), 1,103-1,122. Jones, L.M., G. Faure, K.S. Taylor, and C.E. Corbato. 1983. The origin of salts on Mount Erebus and along the coast of Ross Island, Antarctica. Isotope Geoscience, 1, 57-64. Keys, JR., and K. Williams. 1981. Origin of crystalline, cold desert salts in the McMurdo region, Antarctica. Geochimica et Cosmochimica Acta, 45, 2,299-2,309. Magaritz, M. 1973. Precipitation of secondary calcite in glacier areas; carbon and oxygen isotopic composition of calcites from Mt. Hermon, Israel, and the European Alps. Earth and Planetary Science Letters, 17, 385-390. Nies, N. P., and R. W. Hulbert. 1967. Solubility isotherms in the system sodium oxide-boric oxide-water. Journal of Chemical Engineering Data,
12, 303-313. Pastor, J . , and J.G. Bockheim. 1980. Soil development on moraines of Taylor Glacier, lower Taylor Valley, Antarctica. Soil Science Society of America Journal, 44, 341-348. Peterson, J.A., and J.F. Moresby. 1979. Subglacial travertine and associated deposits in the Carstensz area, Irian Jaya, Republic of Indonesia. Zeitschrift für Gletscherkunde und Glazialgeologie Bd., 15, 1-1.1, 23-29. Tasch, P., and E.E. Angino. 1968. Sulfate and carbonate salt efflorescences from the antarctic interior. Antarctic Journal of the U.S., 3, 239241.
Vennum, W.R. 1979. Evaporite encrustations and yellow and green surficial salts from Orville Coast and eastern Ellsworth Land. Antarctic Journal of the U.S., 24(5), 22-24, Vennum, W.R. 1980. Evaporite encrustations and sulfide oxidation products from the southern Antarctic Penninsula. New Zealand Journal of Geology and Geophysics, 23, 499-505. Whilans, I.M., and W.A. Cassidy. 1983. Catch a falling star: Meteorites and old ice. Science, 222, 55-57. Wilson, AT., C.H. Hendy, T.R. Healy, J.W. Gumbley, A.B. Field, and C.P. Reynolds. 1974. Dry Valley lake sediments: A record of Cenezoic climatic events. Antarctic Journal of the U.S., 9, 134-135.
till by Faure and Taylor (1981), Faure, Taylor, and Mercer (1983), Faure and Taylor (1983), Taylor and Faure (1983), and Faure (1986) indicate that a Precambrian component, presumably derived from East Antarctica, is present in till deposited by the Byrd and Reedy glaciers. We now report preliminary results from a study of the heavy-mineral fraction of till collected at localities ranging from the Morozumi Range of northern Victoria Land to the Wisconsin Range of the Horlick Mountains adjacent to the Reedy Glacier. Thirty till samples were sieved into size fractions and the heavy minerals were separated from the sand fractions (35 to 120 mesh) by settling them in bromoform (specific gravity of 2.83). The heavy-mineral separates were ground and compressed into pellets for analysis by X-ray fluorescence using molybdenum/potassium alpha X-radiation and a lithium fluoride (220) diffracting crystal (Hagen 1988). Calibrations for iron and titanium were based on the standard rock samples of the 65
U.S. Geological Survey (Flanagan 1973). All samples were analyzed in triplicate, and the average analytical errors are ± 0.4 percent of the reported concentrations for iron and ± 1.3 percent for titanium. The concentrations of iron and titanium in 28 of the 30 samples vary within narrow limits and lie within the small rectangular area marked "TAM" in the figure; however, a sample of till from the plateau of the Wisconsin Range (85°48'S 125°24'W) has significantly higher concentrations of iron and titanium than most of the till samples from the Transantarctic Mountains. In addition, fill from Shapeless Mountain (77°26'S 160°26E) is enriched in titanium but depleted in iron relative to the other samples. The till sample from the Wisconsin Range was collected by the late John H. Mercer during the 1964-1965 austral summer (Mercer 1968) and contains marine diatoms as reported by Webb et al. (1984). The diagram contains the common iron- and titanium-bearing minerals that occur in the heavy-mineral fractions of till. Most of the samples cluster around the point representing pyroxene and other ferromagnesian minerals including hornblende. These samples evidently contain large amounts of pyroxene, presumably derived from the sills of the Ferrar Dolerite and are therefore of little geochemical interest.
The samples from Shapeless Mountain and from the Wisconsin Range are mixtures of magnetite, ilmenite, rutile, sphene, pyrite, and pyroxene. In addition, minor amounts of quartz and feldspar are also present as intergrowths with the other minerals. The diagram has been divided by drawing mixing lines between ilmenite and pyroxene and between ilmenite and quartz/feldspar which places the two anomalous samples in different sections of the diagram. The heavy-mineral fraction of till from the Wisconsin Range can be treated as a mixture of magnetite, ilmenite, and pyroxene which are characteristic of plutonic mafic igneous rocks like gabbro and peridotite. The sample from Shapeless Mountain lies in the mixing triangle containing ilmenite, rutile, sphene, and quartz/feldspar which occur in igneous and metamorphic rocks of granitic composition. Therefore, the heavy mineral fractions of till in the Wisconsin Range and at Shapeless Mountain appear to have originated from different kinds of rocks under the east antarctic ice sheet. We thank the pilots and crew of VXE-Six who helped us to collect the samples on which this study is based. This research was supported by National Science Foundation grant DPP 8714324.
References
Concentrations of iron (Fe) and titanium (Ti) of heavy-mineral fractions of till from the Transantarctic Mountains (TAM). The samples from the Wisconsin Range and from Shapeless Mountain are anomalous compared to the majority of the till samples.
66
Faure, C., and K.S. Taylor. 1981. Provenance of some glacial deposits in the Transantarctic Mountains based on Rb-Sr dating of feldspars. Chemical Geology, 32, 271-290. Faure, G., K. Taylor, and J. H. Mercer. 1983. Rb-Sr provenance dates of feldspar in glacial deposits of the Wisconsin Range, Transantarctic Mountains. Geological Society of America Bulletin, 94, 1,275-1,280. Faure, C., and K.S. Taylor. 1983. Sedimentation in the Ross Embayment: Evidence from RISP core 8 (1977/78). In R.L. Oliver, P.R. James, and J.B. Jago (Eds.), Antarctic earth science. Canberra: Australian Academy of Science. Faure, C. 1986. Provenance of feldspar in till from the Morozumi Range, northern Victoria Land. In E. Stump (Ed.), Geological Investigations in northern Victoria Land. (Antarctic Research Series, Vol. 46.) Washington, D.C.: American Geophysical Union. Flanagan, F.J. 1973. 1972 Values for international geochemical reference standards. Geochimica et Cosmochimica Acta, 37, 1,189-1,200. Hagen, E.H. 1988. Geochemical studies of Neogene till in the Transantarctic Mountains; evidence for an extraterrestrial component. (Unpublished Master of Science thesis, Department of Geology and Mineralogy, Ohio State University, Columbus, Ohio.) Mercer, J.H. 1968. Glacial geology of the Reedy Glacier area. Geological Society of America Bulletin, 79, 471-486. Taylor, KS., and G. Faure. 1983. Provenance dates of feldspar in glacial deposits, southern Victoria Land, Antarctica. In R.L. Oliver, P.R. James, and J.B. Jago (Eds.), Antarctic earth science. Canberra: Australian Academy of Science. Webb, P.N., D.M. Harwood, B.C. McKelvey, and J.H. Mercer. 1984. Cenozoic marine sedimentation and ice-volume variations on the East Antarctic craton. Geology, 12(5), 287-291.
ANTARCTIC JOURNAL
