DOCSLIB.ORG

Glacial Flow Reorientation in the Southwestern Fosdick Mountains

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Glacial Flow Reorientation in the Southwestern Fosdick Mountains Bindschadler, R.A., S.N. Stephenson, D.R. MacAyeal, and S. Shabtaie. Shabtaie, S., I.M. Whillans, and C.R. Bentley. 1987 The morphology 1987 Ice dynamics at the mouth of ice stream B, Antarctica. Journal of ice streams A. B, and C, West Antarctica, and their environs. of Geophysical Research, 92(139), 8885-8894. Journal of Geophysical Research, 92(139), 8865-8883. Blankenship, D.D., R.B. Alley, and C.R. Bentley. 1989. Fabric devel- Shabtaie, S., C.R. Bentley, R.A. Bindschadler, and D.R. MacAyeal. opment in ice sheets: Seismic anisotropy. (Abstract.) EOS, 70(15), 1988. Mass-balance studies of ice streams A, B, and C, West Antarc- 462. tica, and possible surging behavior of ice stream B. Annals of Glaciol- Budd, W.F. and T.H. Jacka. 1989. A review of ice rheology for ice sheet ogy, 11, 137-149. modelling. Cold Regions Science and Technology, 16, 107-144. Whillans, I.M., J. Bolzan, and S. Shabtaie. 1987 Velocity of ice streams Engelhardt, H., N. Humphrey, B. Kamb, and M. Fahnestock. 1990. B and C, Antarctica. Journal of Geophysical Research, 92(139), 8895-8902. Physical conditions at the base of a fast moving Antarctic ice stream. Whillans, I.M., and S.J. Johnsen. 1983. Longitudinal variations in gla- Science, 248, 57-59. cial flow: Theory and test using data from the Byrd Station Strain Cow, A.J., R.B. Alley, and D. Meese. 1991. Ice-deformation processes Network, Antarctica. Journal of Glaciology, 29(101), 78-97. from mapping of c-axis fabrics. (Abstract.) EOS, 72(44), 150. Clasts of the Swanson Formation are medium gray, slightly Glacial flow reorientation cleaved, fine-grained sandstone or argillite. These sedimentary in the southwestern rocks are thin to very-thin bedded, and the sandstones appear Fosdick Mountains, to be quartzose. The Swanson Formation crops out widely south of the Fosdick Mountains but nowhere to the north Ford Ranges, Marie Byrd Land (Wade, Cathey and Oldham 1977a, 1977b, 1977c, 1978; Wade and Couch 1982; Adams 1986; Bradshaw et al. 1983, 1991). Other locally derived clasts are present in all of these deposits. STEPHEN M. RICHARD and BRUCE P. LUYENDYK In two places along the northern side of the Fosdick Moun- tains till deposits with exotic clasts were found (figure). A cin- Institute for Crustal Studies der cone northeast of Mount Avers is mantled with colluvium University of California interpreted to include minor reworked till; this surficial deposit Santa Barbara, CA 93106-1100 consists mostly of cobbles and boulders of the underlying basalt but includes about 10 percent rounded clasts of Fosdick gneiss The orientation of glacial striations on nunataks and clast and Byrd Coast granite. In addition, the fine-grained matrix of composition in tills in the southwestern Fosdick Mountains this deposit includes 10-20 percent of feldspathic grus, similar region (76°30S 145°W) indicate that during the most recent ice to that observed on weathered surfaces of Byrd Coast granite. high-stand when these nunataks were ice covered, the princi- The talus and till deposit in the wind scoop at the north end of pal glacial flow direction was from southeast to northwest, Mount Lockhart contains boulders of basalt with acicular, nearly perpendicular to the present drainage direction inferred glomerophyric plagioclase and sparse olivene. Although this from the topography and flow features on the ice surface. The basalt resembles that found at the cinder cone northeast of Fosdick Mountains and the Phillips Mountains 15 kilometers to Mount Avers, numerous other basalt outcrops are found in the the north, trend east to west and are separated by the Balchen eastern Fosdick Mountains (Wade, Cathey, and Oldham 1977b; Glacier which now flows from east to west. The Crevasse Valley Kimbrough et al. 1990), and these boulders could have been Glacier, south of the Fosdick and Chester Mountains, now derived from up-glacier. The exotic clasts found in till deposits flows from east-northeast to west-southwest. In the course of on the north side of the Fosdick Mountains could have been studying bedrock geology in the Fosdick and Chester Moun- derived from rocks exposed along the Balchen glacier up slope tains region of Marie Byrd Land during the 1989-1990 and 1990- from their present location. 1991 austral field seasons (Kimbrough et al. 1990), we measured Colluvium consisting of weathered Byrd Coast granite that glacial striations on the relatively flat summit ridges of nuna- mantles Mount Corey contains small angular fragments of bas- taks between the Chester Mountains and Fosdick Mountains alt, uniformly distributed over the north side of the nunatak. and in the eastern Fosdick Mountains. These striae trend 115- These are interpreted as air-fall tephra derived from an erup- 1200 on the nunataks between the Chester and Fosdick Moun- tion at one of the volcanic centers in the Fosdick Mountains. tains and 150-160° on outcrops in the eastern Fosdick Moun- This interpretation requires that the most recent eruptions in tains. On the southern part of Bird Bluff, we observed roche the Fosdick Mountains post-date ice-high stands during which moutonée with long axes parallel to striae on the rock surfaces Mount Corey and nearby nunataks were ice-covered. Available and steep sides facing northwest, indicating that ice flow across potassium-argon dates from volcanic rocks in the Fosdick these outcrops was from southeast to northwest (figure). Mountains are as young as 3.4±0.3 million years at Mount Unconsolidated till and talus deposits were observed along Perkins (LeMasurier and Rex 1982), providing a minimum ex- the base of steep cliffs all along the northern side of the Fosdick posure age for Mount Corey if these are indeed the youngest Mountains. Typically these consist of cobbles to boulders of volcanic rocks. rocks found in the adjacent outcrops. Till deposits that contain Because Swanson Formation has not been observed to crop clasts not locally derived mantle parts of Neptune Nunatak, out north of the Fosdick Mountains, the simplest explanation Mount Corey, and nunataks east and southeast of Bird Bluff of these observations is that when the outcrops where the stria- (figure). All of these deposits are characterized by subrounded tions are found were most recently under the ice, glacial flow and tooled clasts of Swanson Formation and Bird Coast granite. was to the northwest and carried clasts of Byrd Coast granite 67 1991 REVIEW colluvium on cinder cone contains Bird Coast / granite and Fosdick gneiss; matrix of deposit Block Bay ) contains arkosic grit Balchen Glacier talus/moraine at N end of ridge contains / basalt blocks that resemble cinder cone / I to SIN here Mt. Lockhart • O Mt Avers Mt. Perkins 1 Bird Bluff Li I i .. S-dicKv Mountains.rX. H 110 Neptune N.1 km Nunataks Explanation a I till containing clasts of Bird Coast ^^- angular basaft granite and very low-grade meta- Chester Mtns. cinders present sedimentary rocks (Swanson Fm?) in colluvium glacial striations; arrow head shows transport direction indicated by roche moutonee mt. C rey 4--. \ present ice flow direction Map showing location and orientation of glacial striations observed in the Fosdick Mounains area, and the location and nature of glacial deposits. and Swanson Formation from regions to the south or southeast Bradshaw, J.D., PB. Andrews, and B.D. Field. 1983. Swanson Forma- where these rocks are presently abundant in outcrop. The pres- tion and related rocks of Marie Byrd Land and a comparison with ent ice surface in this area slopes to the west and west-south- the Robertson Bay Group of Northern Victoria Land. In R.L. Oliver, west, south of the Chester Mountains. Flow of the Balchen P.R. James, and J.B. Jago (Eds.), Antarctic earth science. Cambridge: Glacier north of the Fosdick Mountains and the Crevasse Valley Cambridge University Press. Glacier south of the Chester Mountains is to the west and Bradshaw, ID.!, W.D. Dalziel, V. DiVernere, S.B. Mukasa, R.B. Pank- southwest. Mountain glaciers on the south flank of the Fosdick hurst, B.C. Storey, and S.D. Weaver. 1991. The southern rim of the range now flow south to southwest and have deposited lateral Pacific: New work on the pre-Cenozoic rocks of Marie Byrd Land. In moraines at the base of the range. This change in ice-flow the proceedings from the Sixth Symposium on Antarctic Earth Sci- direction may have accompanied a decrease in ice thickness ences, Ranzan-Machi, Japan, September 1991. Kimbrough, D.L., BR Luyendyk, S.M. Richard, and C.H. Smith. 1990. which has exposed the striated nunataks. Alternatively, ice Geology of metamorphic rocks: Ford Ranges of western Marie Byrd flow direction was reoriented by uplift of the ranges above the Land. Antarctic Journal of the U.S., 25(5), 3-5. ice surface in Neogene time. LeMasurier, WE., and D.C. Rex. 1982. Volcanic record of Cenozoic This work was supported in part by National Science Foun- glacial history in Marie Byrd Land and western Ellsworth Land: Re- dation grant DPP 88-17615. Contribution of the Institute for vised chronology and evolution of tectonic factors. In C. Craddock Crustal Studies 073-02UA. (Ed.), Antarctica geoscience. Madison, Wisconsin: University of Wis- consin Press. Wade, EA., C.A. Cathey, and J.B. Oldham. 1977a. Reconnaissance geo- logic map of the Boyd Glacier quadrangle, Marie Byrd Land, Antarctica, References 1:250,000. (U.S. Antarctic Research Program Map, A-6.) Reston, Vir- ginia: U.S. Geological Survey. Adams, C.J. 1986. Geochronological studies of the Swanson Formation Wade, EA., C.A. Cathey, and J.B. Oldham. 1977b. Reconnaissance geo- of Marie Byrd Land, West Antarctica, and correlation with Northern logic map of the Guest Peninsula quadrangle, Marie Byrd Land, Antarctica, Victoria Land, East Antarctica, and South Island, New Zealand.
Load more

Recommended publications
  • The Eastern Margin of the Ross Sea Rift in Western Marie Byrd Land
    Characterization Geochemistry 3 Volume 4, Number 10 Geophysics 29 October 2003 1090, doi:10.1029/2002GC000462 GeosystemsG G ISSN: 1525-2027 AN ELECTRONIC JOURNAL OF THE EARTH SCIENCES Published by AGU and the Geochemical Society Eastern margin of the Ross Sea Rift in western Marie Byrd Land, Antarctica: Crustal structure and tectonic development Bruce P. Luyendyk Department of Geological Sciences and Institute for Crustal Studies, University of California, Santa Barbara, California 93106, USA ([email protected]) Douglas S. Wilson Department of Geological Sciences, Marine Science Institute, Institute for Crustal Studies, University of California, Santa Barbara, California 93106, USA Also at Marine Science Institute, University of California, Santa Barbara, California 93106, USA Christine S. Siddoway Department of Geology, Colorado College, Colorado Springs, Colorado 80903, USA [1] The basement rock and structures of the Ross Sea rift are exposed in coastal western Marie Byrd Land (wMBL), West Antarctica. Thinned, extended continental crust forms wMBL and the eastern Ross Sea continental shelf, where faults control the regional basin-and range-type topography at 20 km spacing. Onshore in the Ford Ranges and Rockefeller Mountains of wMBL, basement rocks consist of Early Paleozoic metagreywacke and migmatized equivalents, intruded by Devonian-Carboniferous and Cretaceous granitoids. Marine geophysical profiles suggest that these geological formations continue offshore to the west beneath the eastern Ross Sea, and are covered by glacial and glacial marine sediments. Airborne gravity and radar soundings over wMBL indicate a thicker crust and smoother basement inland to the north and east of the northern Ford Ranges. A migmatite complex near this transition, exhumed from mid crustal depths between 100–94 Ma, suggests a profound crustal discontinuity near the inboard limit of extended crust, 300 km northeast of the eastern Ross Sea margin.
    [Show full text]
  • Selective Glacial Erosion and Weathering Zones in the Coastal Mountains of Marie Byrd Land, Antarctica
    Geomorphology 67 (2005) 317–334 www.elsevier.com/locate/geomorph Selective glacial erosion and weathering zones in the coastal mountains of Marie Byrd Land, Antarctica David E. Sugdena,*, Greg Balcob, Seth G. Cowderyb, John O. Stoneb, Louis C. Sass IIIc aInstitute of Geography, School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh, Scotland, EH8 9XP, UK bQuaternary Research Center and Department of Earth and Space Sciences, Box 351360, Seattle, WA 98195-1360, USA cGeology Department, Colorado College, Colorado Springs, CO 80903, USA Received 12 January 2004; received in revised form 13 October 2004; accepted 14 October 2004 Available online 16 December 2004 Abstract In the coastal mountains of Marie Byrd Land, Antarctica, there is a juxtaposition of ice moulded landforms at lower altitudes and upstanding summits with weathered surfaces bearing tors. This paper uses geomorphological mapping and exposure dating to test two hypotheses commonly used to explain such a landscape contrast: either the pattern reflects contrasts in glacial erosion related to the basal thermal regime beneath a former ice sheet or it represents a periglacial trimline marking the upper limit of ice cover during the Last Glacial Maximum (LGM). Cosmogenic nuclide measurements on erratics show that the mountains were covered by ice on several occasions, most recently during the LGM. Similar measurements on bedrock show that fragile landforms on weathered surfaces survived many glaciations. Nuclide concentrations in bedrock indicate both that subglacial erosion is insignificant and that ice-free periods of periglacial weathering are longer at higher elevations. We conclude that the pattern of landscape modification reflects both topographically controlled contrasts in the basal thermal regime of overriding ice and the longer exposure to periglacial conditions at higher elevations.
    [Show full text]
  • Multianalytical Provenance Analysis of Eastern Ross Sea LGM Till Sediments
    PUBLICATIONS Geochemistry, Geophysics, Geosystems RESEARCH ARTICLE Multianalytical provenance analysis of Eastern Ross Sea LGM 10.1002/2016GC006728 till sediments (Antarctica): Petrography, geochronology, and Key Points: thermochronology detrital data Provenance analysis of Late Quaternary glaciomarine sediments Matteo Perotti1 , Benedetta Andreucci2, Franco Talarico1, Massimiliano Zattin2 , and from Eastern Ross Sea was performed Antonio Langone3 using three distinct analytical techniques 1Department of Physical Sciences, Earth and Environment, University of Siena, Siena, Italy, 2Department of Geosciences, McAyeal and Bindschadler Ice 3 Streams catchment area is proposed University of Padova, Padova, Italy, Consiglio Nazionale della Ricerche-Istituto di Geoscienze e Georisorse, Unita di Pavia, as source region, with unexposed Pavia, Italy rock units suggested by detrital data AFT data in association with clasts occurrence point out to a localized Abstract In order to reveal provenance of detrital sediments supplied by West Antarctic Ice Sheet tectonic-related exhumation of portions of Marie Byrd Land (WAIS), 19 glaciomarine cores of Last Glacial Maximum age were analyzed from Eastern Ross Sea and Sulzberger Bay. Analytical techniques included petrographic analysis of gravel-sized clasts, geochronology Supporting Information: (zircon U-Pb: Zrn-UPb) and thermochronology (apatite fission track: AFT) of sand-sized fractions. Supporting Information S1 Petrographic analysis revealed a similarity with the lithologies presently exposed in western Marie Byrd Land (MBL), with major roles played by low-grade metamorphic rocks and granitoids. Furthermore Zrn-UPb Correspondence to: and AFT data allowed to identify the ages of formation and cooling of sedimentary source area, consisting M. Perotti, of Cambrian-Precambrian basement (i.e., Swanson Formation in western MBL) which underwent at least [email protected]; [email protected] two episodes of magma intrusion, migmatization and cooling during Devonian-Carboniferous and Cretaceous-Paleocene times.
    [Show full text]
  • Geological Surveys of Marie Byrd Land and the Central Queen Maud Range
    This research was supported by National Science Geological surveys of Marie Byrd Land Foundation grant ov-41037X. and the central Queen Maud Range F. ALTON WADE Initial strontium 87/86 ratios and zirconium concentrations, Kirkpatrick basalt, Storm Peak, Queen Alexandra Range. The Museum Texas Tech University 87Sr Zr Lubbock, Texas 79409 Sample Flow Set - (ppm) (81Sr), Marie Byrd Land. Geologic maps of three quad- rangles in Marie Byrd Land have been completed and 27.00 1 I 0.7094 81.0 submitted to the U.S. Geological Survey (usGs) for 27.1 2 II 0.7122 193.2 publication under an arrangement with the National 27.2 2 II 0.7123 196.9 Science Foundation. Base maps used were from the 27.3 2 II 0.7120 197.4 27.4 2 II 0.7112 190.5 1:250,000 Reconnaissance Series, Antarctica, pub- Average flow #2 II 0.7119 194.5 lished by the USGS. The quadrangles are Alexandra 27.51 3 II 0.7112 179.5 Mountains, Guest Peninsula, and Boyd Glacier; a 27.13 4 II 0.7115 177.5 fourth quadrangle, Gutenko Nunataks, is in prepara- 27.56 5 II 0.7113 177.5 27.17 6 III 0.7144 188.1 tion. 27.18 6 III 0.7122 190.9 Detailed studies of the plutons intruded in western Average flow #6 III 0.7133 189.5 Marie Byrd Land in Middle Paleozoic and Cretaceous 27.24 7 III 0.7129 195.8 are in progress. Granodiorites generally characterize 27.25 7 III 0.7120 192.0 the older plutons and granites, and leucogranites the Average flow #7 III 0.7125 193.9 27.64 8 III 0.7105 170.1 younger.
    [Show full text]
  • Geological Expedition to King Edward VII Peninsula and the Ford Ranges, Marie Byrd Land BRUCE P
    Geological expedition to King Edward VII Peninsula and the Ford Ranges, Marie Byrd Land BRUCE P. LUYENDYK and CHRISTINE H. SMITH, Institute for Crustal Studies, University of California, Santa Barbara, California 93106 ng Edward VII Peninsula, western Marie Byrd Land, is a ern Ford Ranges were also made. Field research was support- Kargely ice-covered, domal feature containing the sparsely ed by the seventh German National Antarctic Expedition exposed and widely separated rock outcrops of the Rocke- (GANOVEX VII), operating off the Norwegian-registered, ice- feller and Alexandra Mountains and outlying nunataks (figure strengthened ship, Polar Queen. 1). The primary objectives for the 1992-1993 season on King Geophysical program: Echo sounding from Polar Edward VII Peninsula were to extend gravity coverage over Queen apparent gravity features detected in an earlier survey (Beitzel 1972); to obtain samples for paleomagnetic study to augment he Polar Queen traversed to Marie Byrd Land from Gond- existing data from the northern Ford Ranges in Marie Byrd Twana Station on the west side of the Ross Sea, avoiding ice Land (Cisowski and Luyendyk 1991); and to explore the rela- pack seen on real-time satellite imagery. The ship rounded tionship between the Fosdick Metamorphic Complex (Smith Cape Colbeck and entered southwest Sulzberger Bay in mid- 1992) of northern Marie Byrd Land and the Alexandra Com- December 1992. Patchy pack ice in the bay at that time was plex of King Edward VII Peninsula (Adams et al. 1989). Ancil- negotiable by the ice-strengthened ship. By the first week of lary observations of glacial and volcanic features in the north- January, the bay was virtually ice-free.
    [Show full text]
  • KOMISJA STANDARYZACJI NAZW GEOGRAFICZNYCH POZA GRANICAMI POLSKI Przy Głównym Geodecie Kraju
    KOMISJA STANDARYZACJI NAZW GEOGRAFICZNYCH POZA GRANICAMI POLSKI przy Głównym Geodecie Kraju NAZEWNICTWO GEOGRAFICZNE ŚWIATA Zeszyt 8 Antarktyka GŁÓWNY URZĄD GEODEZJI I KARTOGRAFII Warszawa 2006 KOMISJA STANDARYZACJI NAZW GEOGRAFICZNYCH POZA GRANICAMI POLSKI przy Głównym Geodecie Kraju Maksymilian Skotnicki (przewodniczący), Ewa Wolnicz-Pawłowska (zastępca przewodniczącego), Izabella Krauze-Tomczyk (sekretarz); członkowie: Stanisław Alexandrowicz, Andrzej Czerny, Janusz Danecki, Janusz Gołaski, Romuald Huszcza, Sabina Kacieszczenko, Dariusz Kalisiewicz, Artur Karp, Andrzej Markowski, Zbigniew Obidowski, Jerzy Ostrowski, Jerzy Pietruszka, Andrzej Pisowicz, Bogusław R. Zagórski, Maciej Zych Opracowanie Maciej Zych Recenzenci Ryszard Czajkowski, Andrzej Czerny Komitet Redakcyjny Andrzej Czerny, Sabina Kacieszczenko, Dariusz Kalisiewicz, Izabella Krauze-Tomczyk, Jerzy Ostrowski, Maksymilian Skotnicki, Maciej Zych Redaktor prowadzący Maciej Zych Projekt okładki Agnieszka Kijowska © Copyright by Główny Geodeta Kraju ISBN 83-239-9709-8 Skład komputerowy i druk Instytut Geodezji i Kartografii, Warszawa Spis treści Od Wydawcy ....................................................................................................................... 5 Przedmowa .......................................................................................................................... 7 Wprowadzenie ..................................................................................................................... 11 Wielkie regiony, oceany .....................................................................................................
    [Show full text]