U.S. Geological Survey Polar Research Symposium­ Abstracts with Program

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In celebration of the 1OOth anniversary of the First International Polar Year, the 50th anniversary of the Second International Polar Year, and the 25th anniversary of the International Geophysical Year The U.S. Geological Survey Polar Research Symposium celebrates the lOOth and 50th anniversaries of the First and Second International Polar Years, respectively, and the 25th anniversary of the International Geophysical Year. The symposium is part of a series of worldwide activities that include lectures, symposia, and exhibits organized at the request of the International Council of Scientific Unions. The International Polar Years and especially the Interna­ tional Geophysical Year profoundly influenced the evolution of geophysics and served as models for international multidisciplinary cooperation in science. U.S. Geological Survey Polar Research Symposium­ Abstracts with Program

GEOLOGICAL SURVEY CIRCULAR 9 l l

In celebration of the 1OOth anniversary of the First International Polar Year, the 50th anniversary of the Second International Polar Year, and the 25th anniversary of the International Geophysical Year

October 12-14, 1983 United States Department of the Interior JAMES G. WATT, Secretary

Geological Survey Dallas L. Peck, Director

Free on application to Distribution Branch, Text Products Section, U. S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 CONTENTS

Page Progrmn------IV Introduction ------1 Antarctic progrmn ------1 .Arctic progrmn -----~------22 Abstracts not presented at the symposium ------52

III PROGRAM

Oct.ober 12, 1983 October 13, 1983 Introduction 8:30 ---- Medical Problems of Polar Regions in the Early 8:30 ---- Welcoming Comments - F. Press 20th Century - S. Boyer 8:35 ---- Introduction to Symposium - D.L. Peck 8:50 ---- Mars-Analog Studies in Wright and Victoria 8:40 ---- Arctic Research Policy Legislation - Honorable Valleys, Antarctica - E.C. Morris, H.E. Holt F.W. Murkowski 9:10 ----An Isotopic and Chemical Study of Lake Vanda and 9:00 ---- The Geological Survey in Polar Perspective - J.C. Don Juan Pond, Antarctica - I. Friedman, A. Reed.Sr. Rafter, G.I. Smith 9:30 ---- Climatic Significance of Lacustrine Deposits Antarctic progrom Around Lake Vanda and Don Juan Pond, Antarc­ Convener: J.C Behrendt tica - G.I. Smith, I. Friedman 9:20 ---- United States Research in Antarctica - E.P. Todd 9:50 ---- Program for Mapping Antarctica - P.F. Bermel, 9:30 ---- New USGS Research Initiatives in Antarctica - C.E. Morrison R.M. Hamilton 10:10 --- The use of Satellite Technology in the Search for 9:40 ---- Antarctic Mapping and International Coordination - Meteorites in Antarctica - T.K. Meunier R.B. Southard, W.J. Kosco 10:30 --- Glaciological and Geological Studies of Antarctica 10:00 --- Configuration of Eastern Gondwanaland - W. with Satellite Remote Sensing Technology - J.G. Hamilton Ferrigno, R.S. Williams, Jr., C.S. Southworth, 10:20 --- Mineral Resources of Antarctica - P.D. Rowley, T.K. Meunier P.L. Williams, D.E. Pride 10:50 --- USGS Program at the South Pole - T.G. Edmond­ 10:40 --- Speculations on the Petroleum Resources of Antarc­ son, K.S. Covert tica- J.C. Behrendt, C.D. Masters 11:10 --- Modeling the Movement of the Polar Ice Cap at the 11:00 --- Planned Marine Geophysical/Geological Surveys of South Pole - T. Henderson the Wilkes Land and Ross Sea Margins - S.L. 11:30 --- Lunch Eittreim 11:20 --- Satellite Image Atlas of Glaciers: The Polar Areas - R.S. Williams, Jr., J.G. Ferrigno Arctic progrom 11:40 --- Lunch Convener: G. Gryc 1:10 ----Wind, Waves, and Swell in the Antarctic Marginal 1:00 ---- History of U.S. Geological Survey Geologic Explo­ Ice 1.one by Seasat Radar Altimeter - W.J. ration and Mineral-Resource Evaluation, Arctic Campbell, N.H. Mognard Alaska - G. Gryc, R.M. Chapman 1:30 ---- Surveying in Antarctica During the International 1:20 ---- Tectonics of Arctic Alaska - l.L. Tailleur, 1.F. Geophysical Year - W.H. Chapman Ellersieck, C.F. Mayfield 1:50 ----The Dufek Intrusion of Antarctica and a Survey of 1:40 ---- Tectonic Evolution of the Arctic Continental its Minor Metals to Possible Resources - A.B. Margin in the Beaufort and Chukchi Seas­ Ford Evidence from Seismic Reflections - A. Grantz, 2:10 ---- Crystallization of the Dufek Intrusion, Antarc­ S.D.May tica - G.R. Himmelberg, A.B. Ford 2:00 ---- The Arctic Platform in the National Petroleum 2:30 ---- Geophysical Investigations of the Dufek Intrusion Reserve in Alaska-Deposition, Deformation, and the Surrounding Region - J.C. Behrendt and Petroleum Potential - C.E. Kirschner 2:50 ---- Geology of the Neptune Range, Antarctica - W.H. 2:20 ---- Oil and Gas Resources of the North Slope, Alaska - Nelson, P.L. Williams K.J. Bird 3:10 ---- Proterozoic to Mesozoic Mobile-belt Geology, Pen­ 2:40 ---- Petroleum Source Rock Richness, Type, and Matu­ sacola Mountains, Antarctica - D.L. Schmidt rity for Four Rock Units on the Alaskan North 3:30 ---- Sedimentology of the Horlick Formation (Lower Slope-Are They Sources for the Two Oil Types? - Devonian), Ohio Range, Transantarctic Moun­ L.B. Magoon, G.E. Claypool tains - L. McCartan, M.A. Bradshaw, G. Ayers 3:00 ---- Emerging Recognition of the Nonfuel Mineral 3:50 ---- Small-Scale Magnetic Features of the Polar Re­ Resources of Arctic Alaska - D. Grybeck gions - J.C. Cain, D.R. Schmitz 3:20 ----Coal Occurrence, Quality, and Resource Assess­ 4:10 ---- Paleomagnetic Studies in Antarctica - R.L. ment, National Petroleum Reserve in Alaska - Reynolds, K.S. Kellogg G.D. Stricker

IV October 14, 1983 11:30 --- Land Cover and Terrain Mapping for the Develop­ 8:30 ----Permafrost and the Geothermal Regime - A.H. ment of Digital Data Bases for Wildlife Habitat Lachenbruch, B.V. Marshall Assessment in the Yukon Flats National Wildlife 8:50 ---- Glaciation in Arctic Alaska - T.D. Hamilton Refuge, Alaska - M.B. Shasby, C. Markon, M.D. 9:10 ----A Pleistocene Sand Desert in Arctic Alaska - L.D. Fleming,D.L.Murphy,J.E. York Carter 11:50 --- Lunch 9:30 ---- Sedimentary Facies on an Ice-Dominated SheH, 1:30 ---- Geochemical Detection of Prospective Petroleum Beaufort Sea, Alaska - P.W. Barnes, E. Reimnitz Areas in Arctic Regions - A.A. Roberts, T.J. 9:50 ---- Quaternary Sedimentation on the Alaskan Beaufort Donovan, J.D. Hendricks, Kl. Cunningham SheH: Sediment Sources, Glacioeustatism, and Re­ 1:50 ---- Hydrology of the North Slope, Alaska - C.E. Sloan gional Tectonics - D.A. Dint.er 2:10 ---- Paleogeographic Affinities and Endemism of 10:10 --- Permafrost and Related Engineering Problems on Cretaceous and Paleogene Marine Faunas in the the North Slope and Beaufort SheH, Alaska - Arctic - L. Marincovich, E.M. Brouwers, D.M. O.J. Ferrians, Jr. Hopkins 10:30 --- Quaternary Microfossils on the Arctic SheH: Bio­ 2:30 ---- Remote Sensing Studies of Dynamic Environmental stratigraphy and Paleoecology - KA. McDougall Phenomena in Iceland - R.S. Williams, Jr. 10:50 --- A Comparison of Numerical Results of Arctic Sea 2:50 ---- Correlation of Late Cenozoic Marine Transgressions Ice Modeling With Satellite Images - Chi-Hai of the Arctic Coastal Plain With Those in Western Ling, C. Parkinson Alaska and Northeastern Russia- J.K. Brigham 11:10 --- Arctic Sea Ice by Passive Microwave Observations From the Nimbus-5 Satellite - W.J. Campbell, P. Gloersen, H.J. Zwally

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U.S. GEOLOGICAL SURVEY POLAR RESEARCH SYMPOSIUM-ABSTRACTS WITH PROGRAM

INTRODUCTION NEW USGS RESEARCH INITIATIVES IN ANTARCTICA THE GEOLOGICAL SURVEY IN BY ROBERT M. HAMILTON POLAR PERSPECTIVE BY JOHN C. REED, SR. 1 [No abstract]

In 1958, legislation was passed that authorized ANTARCTIC MAPPING AND the Survey to make studies in Antarctica Before INTERNATIONAL COORDINATION that time, so far as I know, only three men, two BY RUPERT B. SOUTHARD AND geologists and one topographic engineer, did Survey work in the Antarctic with authorization WILLIAM J. KOSCO and funding from other agencies. Even now International cooperation in Antarctica began Survey work in the Antarctic is supported largely long ago as expeditions from various countries fre­ by the National Science Foundation. quently supported each others efforts. This was so, Most of the Survey's Arctic work has been in even though strong nationalistic mo~ements Alaska Administratively such studies were not established territorial claims to Antarctica very separated from projects in non-Arctic parts of early. Alaska Because of time restrictions this discus­ It was during the third International Polar Year sion is limited largely to the geologic work of the of 1957-58 that the spirit of cooperation in Survey' s old Alaskan Branch. Survey field investi­ Antarctica most highly developed. During gations began in Alaska in 1889. The first appro­ ~as 1957-58 55 observatory stations were established priation item for Alaska was in 1895, for $5,000. From then on came a long line of outstanding to coo~rate in IGY programs in Antarctica Survey Alaskan geologists. Starting in the 1930's, Argentina, Chile, and ~he U~ted ~gd~m had already established stations pnor to this time. with more money, more men, better field methods, Following the International Geophysical Year, better communications, better transportation, and the Scientific Committee on Antarctic Research the like, the Survey' s investigations increased (SCAR) was formed within the Interna~onal Coun­ greatly in number, size, and scope. The Survey's cil of Scientific Unions. It was deternuned that a deep involvement is sketched in the Survey' s pro­ scientific organization such as SCAR was required grams of oil exploration in Naval Petroleum in order to provide the means for communication Reserve No. 4, known as Pet 7, from 1944to1953. amongst the various countries active in Antarc­

1U.S. Geological Survey, retired. tica It is through SCAR that the true spirit of international cooperation prevails by providing ANTARCTIC PROGRAM the coordinating mechanism which allows the in­ CONVENER: J. S. BEH REN OT volved countries to survey and map the continent and to exchange the products of these mapping UNITED STATES RESEARCH IN ANTARCTICA efforts. · BYE. P. TODD1 Mapping Antarctica poses both technical. and political problems that are beyond companson. [No abstract] The most difficult technical problems are the logistics required for transporting personnel and 1Natimal Scienre Foundation, Division of Polar Programs. equipment in that hostile environment. Geodetic

1 traverses are conducted by ground and air in order leave the marine Paleozoic and Mesozoic Tethyan to establish ground control for mapping. People north margin of India dead-ended against Antarc­ and equipment are moved in a leap-frog manner tica or southwest Australia The conventional fits over a wide area, disregarding real or implied produce untenable juxtapositions and separations political boundaries. To carry out the spirit of of Paleozoic and lower Mesozoic paleoclimatic and cooperation, logistic efforts are shared. Several paleobiogeographic indicators. USGS geodetic traverses have been conducted A reconstruction modified from those proposed jointly with the United Kingdom, New Zealand, by Carey, Krishnan, Shields, and a few others, and Australia placing the east side of India against the west side The basic data input for map compilation comes of Australia (see figure 1), satisfies constraints of from ground control and aerial photographs. In ocean-floor ages and magnetic anomalies, accounts the early days of mapping in Antarctica the U.S. for known paleomagnetic pole positions, and Navy VXE-6 squadron acquired trimetrogon mat.ches continental geology and rifting histories. aerial photographs over major map features. This fit, unlike the conventional one, leaves space Ground control was established by surveyors from for certain (Seychelles Plateau; Precambrian ex­ the U.S. Geological Survey. Trimetrogon photo­ posed), probable (N aturaliste Plateau and Broken grammetry was used to compile maps first in the Ridge), and possible (Kerguelen Plateau) continen­ Sentinel Mountains, Thurston Peninsula, Horlich tal fragments now in the Indian Ocean. Broken Mountains, Executive Committee Range, and Ridge and the Kerguelen and Naturaliste Plateaus McMurdo Sound. In recent years, standard over­ appear continental in foundering histories and lap aerial photography and image mapping have some geophysical features. Naturaliste Plateau played an important role in the mapping process. has yielded Cretaceous elastic sediments of con­ Ninety 1:250,000-scale topographic maps have tinental provenance and continental basaltic and been compiled by USGS over the Transantarctic rhyolitic rocks; Kerguelen volcanic rocks are of Mountains and Western Antarctica types that could be either continental or oceanic, Working through the SCAR nations involved in but they contain radiogenic strontium. Fossils in mapping, the Antarctic standard symbols and specifications have been developed for preparing these maps. The Working Group on Geodesy and Cartography, a standing Committee within SCAR, published these symbols in 1961 and again in 1980. An international agreement was reached in the early 60's on the basic horizontal and vertical datums to be used for mapping. Recently, agree­ ment was reached (1981) to include the contri­ bution to geodesy in this age of satellites, by changing the basic geodetic reference datum in Antarctica from the International Spheroid to the World Geodetic System.

CONFIGURATION OF EASTERN GONDWANALAND BY WARREN HAMILTON

Reconstructions of Gondwanaland by du Toit, FIGURE 1.-Reconstruction of Gondwanaland in Late Triassic by Smith and Hallam, and by many other recent and Early Jurassic time. The longitude lines, 15° apart, authors vary in some details but agree on placing illustrate the projection. Continental fragments: B, Broken the east side of India against Antarctica, and the Ridge; F, Falkland Plateau; K, Kerguelen Plateau; N, N aturaliste Plateau; S, Seychelles Plateau. Late Triassic­ west side of Australia against some other con­ Jurassic paleomagnetic poles: 1, Africa and South tinental mass now in, or under, Asia These fits, America; 2, Madagascar; 3, Australia (used for pole of map despite their wide acceptance, juxtapose unlike projection); 4, India; 5, East Antarctica Continents fitted Indian and Antarctic Precambrian terrains, and t;o 1,000-m isobaths.

2 Kerguelen Tertiary lignit.es include wet-t.emperat.e Phlogopit.e and rock crystal occur in Queen Maud austral araucarian and podocarpaceous conifers, Land and Enderby Land, and graphit.e and beryl and beech (Nothofagus), all of which are incapable are locally abundant in other parts of East Antarc­ of crossing lerge wat.er gaps and hence require tica Sizeable coal deposits are present in the Lat.e Cretaceous or Tertiary dry-land continuity Transantarctic and Prince Charles Mountains, and with Antarctica or Australia, and continuous sub­ smaller occurrences are in many other parts of sequent stand above sea level. Nepal (the north­ East Antarctica east part of Indian plat.e) and Timor (the imbri­ Gondwana reconstructions suggest that many cated northwest edge of the Australian plat.e) have more mineral deposits occur in Antarctica How­ strikingly similar t.emperat.e to subtropical Per­ ever, ice covers nearly 98 percent of the continent, mian marine faunas; the two t.errains are juxta­ and few of the bedrock areas have even been pros­ posed by the reconstruction supported here, pected or geologically, geophysically, or geochemi­ whereas they are far apart, and Nepal is at a cally mapped in detail. No known mineral deposits continental-int.erior position and an impossibly now can be developed economically. Probably high Permian paleolatitude, in the conventional some presently known deposits in Antarctica assembly. would be drilled or perhaps even mined if they were located in a continent more favorable for development. However, Antarctica's severe MINERAL RESOURCES OF ANTARCTICA climatic and logistic constraints and the fact that BY PETER D. ROWLEY, P. L. WILLIAMS, AND there are no int.emational agreements concerning D. E. PRIDP mineral rights or mining make it unlikely that ex­ Metallic and nonmetallic mineral occurrences ploitation will occur for many years. are abundant in Antarctica The most significant 1Department of Geology and Mineralogy, The Ohio State University, Columbus, known deposits are of iron, copper, and coal. In the OH 43210. Precambrian shield of East Antarctica, for exam­ ple, iron is present as banded iron-formation and SPECULATIONS ON THE as magnetit.e in veins, pods, and schist. The largest PETROLEUM RESOURCES OF ANTARCTICA deposits of iron are in the Prince Charles Moun­ BY JOHN C. BEHRENDT AND tains, where bodies of banded iron-formation at CHARLES D. MASTERS least as thick as 400 m ext.end, mostly under the ice, for at least 120 km. Widely scatt.ered morainal There are no known petroleum resources in boulders and outcrops of iron-rich rock suggest Antarctica, and the petroleum industry is not par­ that undiscovered iron deposits are also distrib­ ticularly int.erested at present. Economic and uted over many other parts of East Antarctica political considerations may change this in the Magmatic iron is present in Pleistocene lava flows next few years, and exploration and exploitation on Brabant Island, Antarctic Peninsula The are possible within one or two decades. A number Jurassic stratiform gabbroic Dufek intrusion in of countries are actively carrying out multichannel the Transantarctic Mountains contains locally seismic reflection surveys of the Antarctic con­ abundant magnetit.e and minor copper sulfides, tinental margin, which are obviously focused on and it may contain significant volumes of chro­ petroleum resource studies. Technology develop­ mium, nickle, vanadium, iron, and platinum-group ment will probably occur at a more rapid rat.e than minerals. However, the base of the intrusion­ research, exploration, and legal developments. By where economically important metals are most contrast, hard mineral exploitation in Antarctica likely to be concentrated-is not exposed. Low­ is probably much further in the future. The only grade copper and related metals are abundant in types of pot.entially exploitable petroleum re­ the Andean belt (mostly of Early Jurassic through sources in Antarctica from economic considera­ Cenozoic age) of the Antarctic Peninsula Here tions would be giant or supergiant fields of which possible porphyry copper-molybdenum deposits probably only four to t.en supergiants remain to be and associated hydrothermal vein deposits occur discovered in the world. The points made based on on King George Island, Livingston Island, Anvers my study of the available information on pot.ential Island, the Melchior Islands, Brabant Island, petroleum resources in Antarctica can be summa­ Lassit.er Coast, and east.em Ellsworth Land. rized as follows:

3 1. West Antarctica is probably the most prospec­ 6. If future geophysical and geological (deep drill­ tive area of Antarctica because it likely con­ ing) research were to indicate certain areas as tains large areas of unmetamorphosed sedi­ worth exploration, programs of environmen­ mentary rock of post-rift age. It is comprised tal research would be necessary to study pos­ of a number of microplates that have moved sible meteorological, glaciological, oceano­ significantly since the break-up of Gondwana­ graphic, and geologic hazards that might be land. East Antarctica probably contains a encountered that would adversely affect number of subglacial sedimentary basins par­ future exploration or exploitation. Concomi­ ticularly adjacent to high mountain ranges tant biological research programs into the and within the probable failed rift in the fragile ecosystems that might be affected by Amery Ice Shelf area. possible blowouts or oil spills would also be 2. Because of the moving grounded ice sheet required. several kilometers thick which covers most of Antarctica, the only practical areas for pos­ PLANNED MARINE GEOPHYSICAL GEOLOGICAL sible exploitation, were petroleum to exist, are SURVEYS OF THE WILKES LAND AND the continental margins (possibly including ROSS SEA MARGINS the parts covered by ice shelves) with the BY STEPHEN L. EITTREIM most likely areas those bordering the Ross, Amundsen, Bellingshausen, and Weddell In January and February of 1984, the ice­ seas, in West Antarctica, and the Amery Ice strengthened S.P. LEE will carry out 24-channel Shelf in East Antarctica. seismic surveys to better define the basins and 3. The sparse geophysical data suggest that there seismic stratigraphy of parts of the Antarctic is a > 8 kilometer thick section of sedimen­ margin south of Australia and New Zealand Grav­ tary rock beneath the Ross and 14-15 km ity and gradiometer-magnetic data also will be col­ section beneath the Weddell Sea continental lected underway, as well as sonobuoy refraction shelves. The Bellingshausen Basin probably and 3.5 and 12 kHz echo sounding. Seatloor sam­ contains > 3 km of sedimentary rock. There pling will be done for age determination, for phys­ is no available information on sedimentary ical and geochemical properties of sediments, and rock thickness beneath the continental for contained gases. A deep-towable side-scan shelves bordering the Amundsen Sea and system will be available for investigation of Amery Ice Shelf area but recent geophysical morphologic features. cruises can be expected to provide more in­ Australia and New Zealand rifted away from formation soon. Antarctica in the middle of the Cretaceous pro­ 4. DSDP holes on the Ross Sea continental shelf ducing rift basins, some of which are hydrocarbon­ indicate the presence of rocks from Oligocene rich, such as the Gippsland basin north of Tas­ to Pleistocene in age. Sedimentary rocks of mania. DSDP drilling in the region shows that the Cretaceous or possibly Jurassic age might be early phases of opening were a time of deposition present in the deepest parts of the section in­ of euxinic clays and silts, reflecting restricted dicated by seismic reflection data and depths basin circulation and probable local anoxic estimated from aeromagnetic data. Jurassic bottom-water conditions. Prior to the Eocene, a and Cretaceous and Tertiary sedimentary subtropical climate prevailed. On the Ross Sea rocks are probably present beneath the conti­ Shelf, German and French seismic data and DSDP nental shelf and adjacent glacierized areas of cores show sediment many kilometers thick in East Antarctica based on a number of sam­ three north-trending basins, with interstitial gases ples by several investigators. suggesting a thermogenic source. The Wilkes 5. There is presently no direct information on the Land to Victoria Land margin has been less ex­ petroleum geology beneath Antarctic conti­ plored, due partly to more difficult ice conditions, nental shelves relative to source and reservoir but thick sediments exist in places, and one major rocks, with the exception of the shows of gas basin, the Wilkes basin, may be a structural reported in core holes beneath the Ross Sea counterpart of the Otway basin of southern Aus­ continental shelf. tralia. In sum, the meager data existing at present

4 give reason to consider this part of the Antarctic areal extent of the Antarctic and Greenland ice margin as a possible petroleum resource area sheets and ice caps in Iceland, Svalbard, the Rus­ Besides the resource questions, several signifi­ sian Arctic islands, and northern Canada; (2) the cant marine-geologic questions can be addressed termini of most large valley glaciers; and (3) the on this ice-fringed passive continental margin. termini of tidal outlet glaciers. Because of its relative youth and the probability The polar areas, especially the Antarctic, repre­ that it has been sediment starved in the latter part sent some of the most poorly mapped regions of of the Tertiary, the Antarctic margin here is a our planet. Antarctica is estimated to contain 90 good place to study post-rift subsidence and struc­ percent of the glacier ice on Earth, yet only 20 per­ tures related to the Gondwana breakup. The frac­ cent of the continent has been mapped at a scale of ture zones tracing the motion of Australia-New 1:250,000 or larger. Kvitoya, a small, ice-capped ~aland from Antarctica intersect the Antarctic island east of Nordaustlandet in Svalbard, was, margin obliquely; the short ridge segments are off­ until the availability of Landsat, mapped as being set by large distances, and the mid-ocean ridge thin and cigar-shaped (see the Central Intelligence axis is abnormally close to the margin, similar to Agency's Polar Regions Atlas, May 1978). Land­ the equatorial Atlantic configuration. How these sat images showed the island to be oval, and new fracture zones and the ridge proximity have influ­ Norwegian maps of the area now show this radical enced basin development are interesting questions change in shape. A comparison of Landsat images for study. Two major climatic events, the drastic with published maps of the Arctic and Antarctic cooling of the Terminal Eocene Event and the ice reveals many discrepancies, including incorrect sheet growth in the Miocene probably left promi­ positions of glacier margins, inaccuracies in geo­ nent signatures in the seismic stratigraphy of this graphic locations of glaciers, coastlines, and off­ margin. shore islands. The hypotheses which exist to explain the anom­ In addition to serving as the basis for the prepa­ alously great depth of the shelf break of Ant­ ration of the "Satellite Image Atlas of Glaciers" to arctica (500 m) need to be tested. The deep shore­ support future and retrospective studies of fluc­ parallel troughs that exist on the inner shelf tuation in glacier termini and global climatological present an interesting topic of study as well as the studies, Landsat images are being increasingly general questions of ice influence on sedimentation used as base maps (controlled or uncontrolled) to and morphology and how this influence might con­ plot regional glaciological, geological, and geo­ trast to Arctic processes. In two months of time on physical data up to scales of 1:250,000 for Landsat the LEE (minus two weeks of transit time) we can multispectral scanner (MSS) images and up to only hope to establish a beginning toward address­ 1:100,000 for Landsat 3 return beam vidicon ing these and perhaps other more interesting ques­ (RBV) and Landsat 4 thematic mapper (TM) im­ tions for future years' work. ages. Landsat images have been used, in a time­ lapse fashion, to monitor advance or recession of SATELLITE IMAGE ATLAS OF GLACIERS: glaciers, to measure the velocity of outlet glaciers, THE POLAR AREAS and to monitor fluctuations in proglacial lakes. BY RICHARD S. WILLIAMS, JR., AND Because of the brief field season and logistical JANE G. FERRIGNO costs and mobility difficulties in polar areas, satellite data will be increasingly used to monitor In June 1977, the U.S. Geological Survey dynamic phenomena in these areas. The ''Satellite (USGS) began a long-term project to prepare a Image Atlas of Glaciers," which, in the polar USGS Professional Paper, "Satellite Image Atlas areas, involves a mutually beneficial exchange of of Glaciers." Now nearing completion, with publi­ scientific information among United States, Cana­ cation expected in 1985, the Atlas involves 55 gla­ dian, British, Norwegian, Swedish, Soviet, Danish, ciologists representing 30 United States, foreign, Icelandic, and New ~aland scientists, is repre­ and international organizations in an effort to pro­ sentative of the type of multinational cooperative duce a benchmark study of the glacierized areas of research endeavors that are possible with such Earth. Landsat images provide the common data data and which will jointly lead to better scientific base for locating, describing, and mapping: (1) the knowledge about the polar areas.

5 WIND, WAVES, AND SWELL IN THE ANTARCTIC the continent, they discovered that the existing MARGINAL ICE ZONE BY SEASAT RADAR maps contained many errors, particularly where ALTIMETER the original exploration was by aircraft. The BY WILLIAM J. CAMPBELL AND plotted flight paths of Byrd, Ronne, and the other NELLY M. MOGNARD1 earlier explorers contained position errors as large as 60 miles, and the aircraft crews had a tendency During the Austral winter of 1978, the Seasat to exaggerate their discoveries. As a result, it was satellite acquired repetitive radar altimeter obser­ very difficult to correlate the actual topography vations of the oceans surrounding Antarctica By with that shown on the map; nonexistent moun­ averaging these observations for three-day peri­ tains were shown, and existing mountains were ods, quasi-synoptic fields of ocean surface wind plotted with large positional errors. There was one speed, significant wave height, and significant case where a 20,000-foot mountain that was shown swell height have been computed for the entire on a map could not be found. It was obvious that three months the satellite operated. The genera­ the scientists needed maps for navigation, topo­ tion, migration, and attenuation of swell in the graphic data, and traverse planning that were southern oceans have been measured for the first more accurate than those available. time. In an attempt to utilize new technology for pro­ Extensive areas of pronounced significant wave ducing the needed maps, Major Lassiter led an height and swell height were found to occur some­ Air Force expedition of two DC-3 aircraft to the where near the Antarctic marginal ice zone every Ellsworth Station on the Weddell Sea During few days during the winter 1978. During the November and December of 1957, a test network period 7-9 October 1978, storms between Antarc­ of 10 control points was established 200 miles tica and Australia and in the eastern South Pacific south of the Ellsworth Station on the Filchner Ice with surface wind speeds as high as 20 mis gener­ Shell in the vicinity of the Pensacola Mountains. ated large areas with significant wave heights as The positions of these points were determined large as 16 m and significant swell heights as large by solar altitude measurements made every hour as 12 m. Extensive wave trains with significant for 24 hours. The test site elevations were wave height as large as 10-12 m and swell as large measured with barometric altimeters. The equip­ as 8-10 m were observed to impact large areas of ment that was to shorten the mapping cycle, a the Antarctic marginal ice zone. Return signals radio ranging system, was tested in January and from the ocean surface and the sea ice cover were proved to be unsatisfactory. Because of a strong analyzed, and it is shown that phenomena within ionospheric reflection, the range was limited to 75, the ice can be observed with the radar altimeter instead of the expected 300, miles. such as the opening of the Weddell Sea polynya in The following season, U.S. Geological Survey September 1978. See figures 2, 3, and 4. topographic engineers were assigned to IGY ship expeditions and geophysical traverses. In addition 1Groupe de Recherche de Geodesie Spatiale-CNES Toulouse, France. to navigating the traverses, the engineers were to survey any mountain ranges encountered. This SURVEYING IN ANTARCTICA DURING THE was done by establishing positions by solar INTERNATIONAL GEOPHYSICAL YEAR altitude measurement and elevations by baro­ BY WILLIAM H. CHAPMAN metric altimetry. The surveyor was generally at traverse camps, which were located on the flat The Antarctic International Geophysical Year snow surface within view of the mountains. The (IGY) program starting in 1956 initially empha­ coordinates were then projected to the mountain sized the gathering of geophysical measurements peaks by intersection from a taped baseline. Eleva­ throughout the western part of the continent. At tions were transferred by vertical angle observa­ the bases, the major scientific programs involved tions. This technique for obtaining control for meteorology, seismology, geomagnetism, and mapping continued for several years and was then measurements of the ionosphere. The traverse replaced by helicopter-supported survey traverses parties' efforts were directed toward glaciology, using electronic distance measuring instruments. geology, and geophysics. As IGY scientists made The Navy's VXE-6 squadron was taking aerial flights and ground traverses into the interior of photographs over major mountain ranges using

6 2 270°t-t----1~~:-a..~-..~+--7'-T"TI

180° FIGURE 2.-Southem ocean field of significant wave height (m) derived from the Seasat radar altimeter measurements for Oct& her 7 to 9, 1978.

P-2V aircraft equipped with trimetrogon cameras. THE DUFEK INTRUSION OF ANTARCTICA AND The aerial photography was combined with the A SURVEY OF ITS MINOR METALS RELATED TO control established by the surveyors at the U.S. POSSIBLE RESOURCES Geological Survey, Branch of Special Maps, to BY ARTHUR B. FORD produce 1:250,000-scale topographic maps. The first maps produced covered the Thurston Penin­ The Dufek intrusion is an unusually large differ­ sula, Sentinel Mountains, Horlick Mountains, Ex­ entiated layered mafic igneous complex of Jurassic ecutive Committee Range, and McMurdo Sound. age in the northern Pensacola Mountains (lat 82 °

7 270°1--__,~~~~~~~~=-t-rf 8

FIGURE 3.-Southern ocean field of surface altimeter measurements (m) for October 7 to 9, 1978.

30' S., long 50 ° W.). Although it is mostly covered 1.8- to 3.5-km-thick basal section beneath the by ice, geophysical surveys indicate that it has an Dufek Massif rocks and a 2- to 3-km-thick inter­ 2 area (50,000+ km ) compar~ble to that of South mediate interval, underlying Sallee Snowfield, be­ Africa's Bushveld Complex: Geologic studies by tween the two exposed sections. Except for late U.S. Geological Survey parties in 1965-66, silicic differentiates of the Lexington Granophyre 1976-77, and 1978-79 determined that, of its total at the top, the rocks are generally well-layered 8-9 km estimated thickness, nearly 2 km of a cumulates of predominantly gabbroic composi­ lower (not lowest) part of the body is exposed in tion. These gabbroic cumulates chiefly contain the Dufek Massif and about 1. 7 km of the Fe­ cumulus plagioclase and two pyroxenes (augite­ enriched highest part is exposed in the Forrestal ferroaugite and inverted pigeonite); additionally, Range. Major concealed stratigraphic parts are a cumulus magnetite and ilmenite are abundant in

8 FIGURE 4.-Southem ocean field of minimum swell height (m) deduced from the significant wave height and surface wind speed measurements by Seasat altimet.er and using Pierson and Moskowitz wave model for October 7 to 9, 1978. the Forrestal Range section. In many areas, the variation in thickness: one, the Frost Pyroxenite, gabbroic cumulates are interlayered with conspic­ is traceable for 35 km before disappearing under uous but volumetrically minor layers, a few centi­ ice cover. The general association of such layers meters to tens of meters thick, of plagioclase with cut-and-fill channel structures (troughs) cumulate (anorthosite and leucogabbro), pyroxene suggests a depositional origin related to magma­ cumulate (pyroxenite), and Fe-Ti oxide cumulate current activity. Layer-parallel alinements of xeno­ (magnetitite) that typically show modal gradation lith trains in many places also indicate current upward from sharp basal to gradational top con­ activity. tacts with the gabbroic cumulates. Most layers of The intrusion was emplaced in a multiply de­ this kind have great lateral continuity with little formed mobile belt at the margin of the Antarctic

9 craton, in which strong compressive deformations above the ·chief platinum-group-metal horizons of are of late Precambrian and Cambrian(?), Late Cam­ the pyroxenitic Merensky Reef of the Bushveld brian to Silurian, and probable Triassic age. K-Ar­ Complex. The Merensky-equivalent level in the age determinations of 172+4 m.y. indicate con­ Dufek intrusion is probably in the middle to upper temporaneity of the intrusion with sills, dikes, and part of the concealed basal section. Considering flood lavas of the Middle Jurassic tholeiitic Ferrar Antarctic operating costs, platinum-group metals igneous province throughout the Transantarctic would be of chief resource interest, but the absence Mountains. Representatives of the Ferrar in the of placers and soils will make exploration difficult. Pensacola Mountains have high Si02 contents Correlation studies suggest that V may be a useful (53-55 weight percent), anomalously high 87Sr/86Sr pathfinder element in a geochemical exploration initial ratios (0.7104-0.7126), and other chemical for the metals within exposed units; however, drill­ and petrographic features that characterize the ing would be needed to explore basal layers, where province elsewhere. If the original magma of the metals are most likely to occur. Dufek intrusion had similar characteristics, this body provides a record of strong fractionation of a mafic magma different from those inferred for other CRYSTALLIZATION OF THE major layered intrusions, which contain less Si02 DUFEK INTRUSION, ANTARCTICA and more MgO. The Ferrar province, including the BY GLEN R. HIMMELBERG AND A. B. FORD Dufek intrusion, may have formed in a failed~rift arm of a radial-rift system centered near the Sollth America-Africa-Antarctica join and associated with The Dufek intrusion is an unusually large dif­ the breakup of this part of Gondwanaland. ferentiated layered gabbro of Jurassic age in the Other major intrusions of this type contain eco­ northern Pensacola Mountains (lat 82°30' S., long nomically significant magmatic deposits of one or 50° W.). The intrusion is mostly covered by ice, more metals, generally concentrated in lower parts but geophysical surveys indicate it has an area of of the bodies and associated with early mafic and 50,000+ km2, comparable to that of the Bushveld ultramafic cumulates. In view of the small percent­ Complex. The gabbros are exposed in two partial, age of rock exposure and the present reconnais­ nonoverlapping sections. The lowermost 1.8 km of sance scale of investigation, nearly all such de­ exposed rocks make up the Dufek Massif section, ,posits are considered to be "speculative resources" and the uppermost 1. 7 km of rock make up the of the Dufek intrusion. Disseminated sulfides have Forrestal Range section. The concealed inter­ been found locally in trace amounts to several per­ mediate section between the two ranges is esti­ cent, the greatest amounts in Fe-Ti oxide-rich mated to be 2-3 km thick, and geophysical evi­ layers in the Forrestal Range. A reconnaissance dence suggests that the concealed basal section is geochemical survey of average-appearing rocks 1.8-3.5 km thick. Thus the total thickness of lay­ shows marked enrichment in Cu, V, Ti, Pt, Pd, and ered rocks may be as much as 8-9 km. Sin the upper (Forrestal Range) section in com­ The layered rocks are dominantly gabbro with parison with the lower (Dufek Massif) section, and lesser amounts of anorthosite and minor pyrox­ corresponding depletion in Cr and Ni. The varia­ enite. A 300-m-thick granophyre layer caps the in­ tions relate to differentiation by fractional crystal­ trusion. The anorthosites are plagioclase and lization. Pt, Pd, and Rh have been found only in plagioclase-augite cumulates; the gabbros are concentrations near or below their limits of deter­ dominantly plagioclase-augite-inverted pigeonite mination (Pt, 10 ppb; Pd, 4 ppb; Rh, 5 ppb) in the cumulates except near the base of the Dufek lower section, but in greater concentrations (max Massif section where the Ca-poor pyroxene is or­ 35 ppb Pt, 44 ppb Pd, and 12 ppb Rh) in the upper thopyroxene, and in the upper Forrestal Range section. Platinum-group minerals have not been section where the magma differentiated beyond found. the two-pyroxene stability field and ferroaugite is Petrologic comparisons with other complexes, the only cumulus pyroxene. Titaniferous magne­ including use of cumulus a-rival of pigeonite as a tite and ferrian ilmenite are cumulus phases in correlation marker, suggest that the major pyrox­ most of the layered rocks from the uppermost enitic members of the Dufek Massif section lie at a Dufek Massif section through the Forrestal Range position analogous to a level about 2 km or more section.

10 In the upper part of the Dufek Massif section of magma or influx of more primative magma to and in the Forrestal Range section the anortho­ the crystallization site. The major reversal in sites have sharp basal contacts and grade upward mineral fractionation trends near the top of the in­ into gabbros, a sequence that is repeated in a trusion, which coincides with an angular discord­ cyclic manner. The succession of appearance of ance in layering dip, strongly indicates an influx of cumulus phases in these sequences indicate the new magma at the site of crystallization. Reversal crystallization sequence plagioclase, plagioclase magnitudes suggest incursion of either less frac­ + augite, and plagioclase + augite + pigeonite. In tionated magma from some other part of the cham­ the lower part of the Dufek Massif section the ber or mixing of primative magma with Fe-rich anorthosites have sharp basal and upper contacts residual magma. with gabbro and there are no sequences of 1-phase cumulates progressing through 2- and 3-phase GEOPHYSICAL INVESTIGATIONS OF THE DUFEK cumulates to indicate a crystallization sequence. INTRUSION AND THE SURROUNDING REGION Very slight changes in bulk composition or phase BY JOHN C. BEHRENDT boundaries can affect crystallization sequence, and marked changes in crystallization sequence have been documented for other large layered intru­ Aeromagnetic, gravity, and seismic reflection sions. Thus there is no reason to infer that the measurements made in 1957, 1963-64, 1965-66, crystallization sequence of the concealed basal sec­ and 1978 over the Dufek layered mafic intrusion of tion and of most of the Dufek Massif section was 172±4 m.y. age in the Pensacola Mountains area the same as the sequence for the upper part of the of Antarctica have allowed extension of the known intrusion. geology beneath areas covered by thick ice. Cumulus pyroxenes show a general iron enrich­ A combined aeromagnetic and radio echo ice­ ment with stratigraphic height. Superimposed on sounding survey (4,200 km of traverse) made in the trend are (1) a 1-km-thick section in the lower 1978 over the Dufek intrusion suggests a mini­ 2 part of the exposed intrusion that shows slight to mum area of about 50,000 km , making it compar­ no iron-enrichment and (2) a marked reversal in the able in size with the Bushveld Complex of Africa. Fe/(Fe+ Mg) ratio at about 1 km below the top of Comparisons of the magnetic and subglacial the body. Cumulus plagioclase in the gabbros topographic profiles illustrate the usefulness of shows a general decrease in anorthite content with this combination of methods in studying bedrock stratigraphic height and also shows a marked geology beneath ice-covered areas. Rocks are ex­ reversal in composition near the top of the body. posed in only 3% of the inferred area of the intru­ The section with little pyroxene fractionation is sion. It is about 400 km long along a NNE trend not reflected in the plagioclase trend, and there are from about 80°45' s. across the front of the Trans­ other reversals in the plagioclase composition antarctic Mountains. Interpretation of the mag­ trend that are not paralleled by reversals in the netic data indicates that the northern part of the pyroxene trend. These differences in detail may intrusion is downdropped about 4 km across the reflect, in part, different degrees of interaction of mountain front and underlies the l, 700-m-deep cumulus minerals with upward migrating inter­ Crary trough. cumulus liquid. The chemistry of cumulus iron­ West Antarctica has been interpreted to com­ titanium oxides are dominated by subsolidus re­ prise several crustal blocks (microplates) that equilibration, although the contents of V2.0 3 and moved and rotated into their present configura­ AlJla in ilmeno-magnetite parallels the pyroxene tion. In a recent paper Dalziel and Elliott (1982) compositional trend. suggested that the Ellsworth Mountain block was The layering, textures, and mineral chemistry formerly placed against the present Transantarc­ variation with stratigraphic height make it clear tic Mountains. Thus, if the Ellsworth Mountain that the dominant process in the formation of the block earlier occupied the area presently underlain intrusion was fractional crystallization with ac­ by the northern part of the Dufek intrusion, the cumulation, or crystallization, from the base up­ block must have been displaced either prior to or ward. The cyclic sequence of plagioclase cumulates synchronous with rifting in Early Jurassic time grading upward to plagioclase-pyroxene cumu­ that led to emplacement of that intrusion and the lates suggests either periodic convective overturn coeval Ferrar intrusive group.

11 Magnetic anomalies measured a few hundred Patuxent Formation. These rocks were all tightly meters above outcrops of the intrusion range in folded during the Beardmore orogeny. peak-tc>-trough amplitude from about rv 50 nT over The Nelson Limestone, and shale, siltstone, and the lowermost exposed portion of the section in the fine-grained sandstone of the late Cambrian Wiens Dufek Massif to about rv3,600 nT over the upper­ Formation, unconformably overlie the Patuxent most part of the section in the Forrestal Range. Formation. Silicic volcanic rocks, mostly volcani­ Theoretical magnetic anomalies, computed from clastic, derived from centers within the Neptune models based on the subice topography fitted to Range compose the Gambacorta Formation, in­ the highest-amplitide observed magnetic anoma­ cluding the Hawkes Rhyodacite Member. Locally, lies, required normal and reversed magnetizations the upper part of the Gambacorta interfingers ranging from 10-4 to 10-2 emu/cm3 having direc­ with the lower part of the Wiens Formation. tions and magnetizations consistent with measure­ The Cambrian and older rocks were moderately ments previously made on oriented samples. This to strongly deformed during the early Paleozoic result is interpreted as indicating that the Dufek Ross orogeny, later beveled by. erosion, and are intrusion cooled through the Curie isotherm dur­ now overlain unconformably by weakly to locally ing one or more reversals of the Earth's magnetic strongly folded elastic rocks of Ordovician(?) to field. Devonian ages. Still later, massive diamictite-the A broad regional Bouguer anomaly has gradi­ Gale Mudstone, probably tillite, of Permian(?) ents parallel to the northwest edge of the Pensa­ age-was deposited. cola Mountains block. Bouguer anomaly values The general trends of structures in the Neptune decrease from 82 to -90 mgal across this transi­ Range and in the Transantarctic Mountains, of tion from West Antarctica to East Antarctica which the Neptunes are a part, all generally Theoretical profiles fitted to the gravity data in­ parallel the Pacific-Atlantic edge of the Antarctic dicate either an abnormally thin crust on the West craton, which lies mostly in eastern longitudes. Antarctica side or a normal crust on the West Ant­ Although published descriptions of rocks of the arctica side and a steep steplike transition from Ellsworth Mountains about 500 km from the Nep­ West Antarctica to East Antarctica that suggests tune Range suggest possible correlations with a fault extending from the crust-mantle boundary rocks of the Neptune Range, structural trends in to near the surface. Gravity, magnetic, and seismic the Ellsworth Mountains at nearly right angles to data suggest a thick section of low-velocity, low­ the trend of the Transantarctic Mountains, sug­ density, nonmagnetic, presumably sedimentary gest different tectonic histories for these two rock beneath the ice northwest of the Pensacola areas. Mountains. A least-squares regression of the Bouguer anomalies compared with elevation in the PROTEROZOIC TO MESOZOIC MOBILE-BELT Pensacola Mountains area suggests that the am­ GEOLOGY, PENSACOLA MOUNTAINS, plitude of the gravity anomaly associated with the ANTARCTICA Dufek intrusion is about 85 mgal, corresponding BY DWIGHT L. SCHMIDT to about 8.8- to 6.2-km thickness for the intrusion, assuming reasonable density contrasts. The Pensacola Mountains consist of four uncon­ formable sequences of (1) graywacke (oldest), (2) GEOLOGY OF THE NEPTUNE RANGE, platform, (3) molasse, and (4) continental (young­ ANTARCTICA est) deposits that were deformed during three suc­ BY WILLIS H. NELSON AND PAUL L. WILLIAMS cessive pre-Jurassic compressional tectonic events and a superposed Jurassic extensional rift event. Two superposed unconformities separate the The first sequence of Middle .Proterozoic gray­ rocks of the Neptune Range into three sequences. wacke deposits (Patuxent Formation), at least sev­ The oldest sequence, the Patuxent Formation of eral kilometers thick, consists of turbidite quartz­ late Precambrian age, consists of several thousand bearing sandstone and slate and volcanic rocks. meters of argillaceous metasandstone (metasub­ The distribution of intercalated basalt flows, some graywacke), slate, and minor amounts of conglom­ pillow-structured, and sparse dacitic to rhyolitic erate. Igneous rocks, mostly mafic extrusive flows, ignimbrites, and tuffs suggests a nearby rocks, locally compose important members of the island-arc source on the West Antarctic side of the

12 Pensacola Mountains. These subduction-related Transantarctic Mountains; the huge stratiform rocks were isoclinally folded and thrust most likely gabbroic pluton of the Dufek intrusion was in­ toward the East Antarctic shield during the Late truded into the Pensacola Mountains. The con­ Proterozoic Beardmore orogeny. tinental rifting was shortly followed, during Late A major angular unconformity underlies the sec­ Jurassic time, by more vigorous extension result­ ond sequence consisting of extensive platform ing from major transform faulting, and perhaps by deposits of Lower Cambrian archaeocyathid­ minor oblique formation of oceanic crust as East bearing limestone and Middle Cambrian trilobite­ Antarctica was right laterally displaced 500 to bearing limestone (Nelson Limestone) that are 1,000 km relative to West Antarctica and as overlain by shale (Wiens Formation), and silicic Africa separated from East Antarctica during the volcanic rocks (Gambacorta Formation) including initial opening of the Indian Ocean. During this rhyolitic ignimbrite (510±35 Ma) of caldera origin. time, West Antarctica remained attached to South The second sequence was intruded by calc-alkalic America. According to this reconstruction, ·the granite plutons of Late Cambrian age and deformed northern Marie Byrd Land part of West Antarc­ during the Cambrian-Ordovician Ross orogeny, tica, prior to transform faulting, was positioned in which is interpreted as a cratonization event that the present-day Ross Sea opposite north Victoria was distally associated with subduction-related col­ Land. lisional tectonics in West Antarctica. The third sequence is the pre-Devonian Neptune SEDIMENTOLOGY OF THE Group that is above an angular unconformity and HORLICK FORMATION (LOWER DEVONIAN), consists of basal orogenic conglomerate and more OHIO RANGE, TRANSANTARCTIC MOUNTAINS than 1,500 m of quartz-sandstone molasse that BY LUCY McCARTAN, 1 resulted from the erosion of the early Paleozoic MARGARET A. BRADSHAW , AND mountains of the Ross orogeny. The fourth se­ GRAEME AYERS2 quence of continental deposits of the Beacon Supergroup disconformably overlies the Neptune Investigation of the sedimentology and paleo­ Group. The Beacon Supergroup consists of Devo­ ecology of the Horlick Formation was the main nian quartz sandstone (Dover Sandstone), Per­ goal of a 1979-1980 New Zealand expedition to the mian glacial tillite (Gale Mudstone), and Permian Ohio Range. The study followed the reconnais­ siltstone and shale (Pecora Formation) containing sance work of previous expeditions, mainly from glossopterid-bearing coal beds. Ohio State University, and was supported by The rocks of the Pensacola Mountains again grants from the National Science Foundation, the were deformed into tight to open folds during the New Zealand Antarctic Division, the Canterbury Weddell orogeny of Triassic age. This latest com­ Museum. pressional event was caused by intracratonic The Horlick Formation of Early Devonian age orogeny distally associated with latest Paleozoic consists of 10-50 m of subhorizontal interbedded to early Mesozoic subduction of the Pacific Ocean subarkosic sandstone and chloritic shale and mud­ beneath the northern margin of West Antarctica stone. It is exposed only in the Ohio Range of the (including the ancestral Antarctic Peninsula). The Transantarctic Mountains between the Ross Ice transverse structure of the Ellsworth Mountains Shelf and Ronne Ice Shelf, at about lat. 85 ° S. and probably was a direct, in-situ product of Weddell long. 110°-117° W. orogeny and does not require rotation as inter­ The Horlick Formation nonconformably overlies preted in a 1969 study by J.M. Schopf. The Wed­ granitic basement rocks and is overlain by glacial dell orogeny resulted in the final consolidation of and periglacial rocks of Permian age. It contains this part of Gondwanaland. marine fossils, bone fragments and phosphatic During Early and Middle Jurassic time, a Trans­ clasts in several thin beds especially near the base, antarctic continental rift extensionally split the and calcareous concretions and beds of limestone. East Antarctic craton from West Antarctica as Quartz and lesser amounts of muscovite and Gondwanaland began to break up. Continental feldspar are the dominant minerals in the sand­ tholeiitic flood basalt (Kirkpatrick Basalt) was stones; biotite is subordinate. Magnetite, epidote, deposited on, and tholeiitic diabasic sills (Ferrar sphene, and tourmaline are trace minerals. Second­ Dolerite) were intruded into, the rift margin in the ary calcite is locally abundant in sandstones, and

13 authigenic chlorite is ubiquitous in shales and representation is potential, it is thus possible to mudstones. produce maps in any of the commonly used geo­ Some beds are laterally persistent for tens of magnetic components. At this degree and order, meters whereas others contain different facies features down to about 1,400 km in size may be within a few meters. Channels filled with shale or displayed. The intensity at the center of the cells sandstone with festoon crossbedding are common. depicted for these regions is stronger than those at Some sandstones are planar bedded or contain in­ lower latitudes by about the factor of two that one terference ripples. Bioturbation has destroyed would expect from crustal material magnetized in primary structures in many beds. Trace fossils on the Earth's predominantly dipole field. bedding surfaces and burrows suggestive of The strongest anomaly noted in this representa­ shallow-water deposition are found in several beds. tion is that near the Alpha and Mendeleyev Current directions are indicated by crossbed­ Ridges. The vertical (and total) intensity peak is ding, channel axes, current lineations, ripple near 95 nT at about 150 ° W. and 85 ° N. Except for marks, direction of sediment accumulation, and this positive cell, the remainder of the Arctic low-angle crossbeds probably deposited in the Ocean area extending into the northern Canadian swash zone of a beach. These indicate that the off­ Islands shows weaker negative cells. Greenland is shore direction was dominantly southward and covered by two positive cells, each about half the longshore drift was westward. Northward-dipping intensity of the north polar high, with one in the crossbeds were probably formed on the landward north and the other in the south. side of submerged bars. The strongest anomaly over Antarctica has a All evidence indicates that the Horlick Forma­ +65 nT maximum in total intensity (but negative tion is an eastward-trending, long, linear body that in the vertical contours since the vector is reck­ accumulated primarily in a shallow, marginal­ oned positive downward), and centered over marine environment. The source, as indicated by Wilkes Land. This feature is surrounded on the the mineralogy, was southward-sloping granitic ocean side by a general negative pattern which terrane, similar to the underlying basement rocks. also intrudes into the Ross Ice Shelf. There are No marine correlative of the Horlick Formation strong negative cells over both East and West is known from Antarctica, but nonmarine beds Antarctica separated by a weak positive near the that may be Lower Devonian are present in Vic­ geographic pole. A positive feature of comparable toria Land. Bradshaw correlates the Horlick For­ intensity is seen over Enderby Land. mation with a fossiliferous formation in south­ There is surprisingly good agreement with the western New Zealand. The lack of tilting in most patterns published by Behrendt and Bentley of the Ohio Range reflects a non-orogenic tectonic (1968) from an analysis of surface data, though environment. their intensity variations are an order of magni­ tude greater. 'cant.erbury Museum. Christchurch, New Zealand. If 2Mount Cook National Park, New Zealand. the high order and degree components of this expansion arise from the crust, the positive areas SMALL-SCALE MAGNETIC FEATURES would represent regions where the total magneti­ OF THE POLAR REGIONS zation was highest. Possible geologic correlations BY JOSEPH C. CAIN AND DAVE RAY SCHMITZ have been investigated by Taylor (1982) for the north pole high, by Coles and others (1982) for A 29th degree and order spherical harmonic northern Canadian area, and by Ritzwoller and model was created from the vector and scalar Bentley (1982) for the Antarctic. These other Magsat data taken over the period November workers have constructed residual maps derived 1979-June 1980 (Cain and others, 1983). The field from selections of Magsat data averaged after from the first 13 orders was subtracted from that reduction by a 13th degree and order field model. computed by the total set of coefficients to They obtain very good agreement with most of the simulate the trend removal commonly used by features in our representations for the vertical or geophysicists in studying magnetic anomalies. total field, and larger differences in the horizontal The resulting differences were then contoured at components. the Earth's surface to produce maps of magnetic There are some questions as to whether these "anomalies" in the polar regions. Since the field features are completely representative of the

14 crustal field. It is not likely that the truncation of a PALEOMAGNETIC STUDIES IN ANTARCTICA spherical harmonic expansion gives a clean separa­ BY RICHARD L. REYNOLDS AND tion of crustal from core components. Judging KARL S. KELLOGG from the results of Meyer and others (1983) the field model to n=13 must also contain a crustal contribution. If the source of the high order The use of paleomagnetism to determine rota­ features were in the core, it would imply that they tions and translations of crustal blocks has con­ were not simple extensions of the lower order tributed to our understanding of the tectonic terms, but of greatly enhanced power. evolution of Antarctica. The units most thorough­ There is also the possibility that some of the ly studied paleomagnetically in East Antarctica features arise from average external field effects. are the Lower Jurassic Ferrar sills and Dufek Most of the external currents are field aligned and intrusion of the Transantarctic Mountains. Virtual being nonpotential, appear to have little effect on geomagnetic poles calculated from these intru­ the potential expansion. Those other workers who sives cluster closely and yield a paleomagnetic have made residual maps from 13th degree poten­ pole at latitude 54° S., longitude 153° W. The tial expansions have carefully selected the data for corresponding paleolatitude requires about 35 ° of passes containing little obvious current signa­ southward drift for cratonic East Antarctica since tures. Their results generally agree with our own, its separation from Africa in Middle to Late Juras­ especially for the vertical component of field. sic time. Either the horizontal component of the mostly ver­ Geologic relationships point to a more complex tical field-alined currents, or the E-layer iono­ late Mesozoic and Cenozoic tectonic history of spheric currents below the spacecraft orbit, could West Antarctica than of East Antarctica, and contribute to the residual maps. Due to the careful they lead to speculation that West Antarctica con­ selection of the data that entered our model and sists of at least three distinct crustal segments or the residual maps of the other workers, these cur­ provinces having separate patterns of consolida­ rents are thought to produce only second order tion with the present continent. Paleomagnetic affects. However, until the currents can be numeri­ data have been obtained from each of the three cally modeled and their magnetic components provinces-the Antarctic Peninsula, the Ellsworth evaluated, their possible contamination cannot be Mountains, and Marie Byrd Land. evaluated. Paleomagnetic studies of the Antarctic Penin­ sula have focused on the nature-oroclinal or REFERENCES primary?-and age of the pronounced structural curvature along the peninsula. Mean paleomag­ Behrendt, J.C., and Bentley, C.R., Gravity and magnetic maps netic declinations and associated uncertainty of the Antarctic, American Geographical Society Antarc­ limits, determined for widespread Andean-type tic Map Series, Folio 9, 1968. Cain, Joseph C., Muth, Lorant, and Schmitz, Dave, Small scale Late Cretaceous to Middle Tertiary plutons and anomalies observed by Magsat, submitted to J. Geophys. dikes north of latitude 68 ° S., do not require large­ Res., 1983. scale structural rotations, suggesting that any Coles, R. L., Haines, G. V., van Beek, G. Jansen, Nandi, A., and oroclinal bending occurred prior to Late Cretace­ Walker, J. K, Magnetic anomaly maps from 40° N to 83° N derived from Magsat satellite data, Geophys. Res. Lett., ous time. In contrast, paleomagnetic data from 9, 281-284, 1982. rocks of similar type and age from the Orville Meyer, J., Hufen, J. H., Siebert, M., and Hahn, A., Investiga­ Coast (latitudes 74°-76° S.) are interpreted to indi­ tions of the internal field by means of a global model of the cate a clockwise rotation of the terrane by about earth's crust (to be published), Zeit. fur Geophysik, 1983. 50°, thus accounting for the curvature of the Ritzwoller, M. H., and Bentley, C.R., Magsat magnetic anom­ alies over Antarctica and the surrounding oceans, Geo­ southern Antarctic Peninsula by oroclinal folding. phys. Res. Lett., 9, 285-288, 1982a For the intervening area of the Lassiter Coast (lati­ Ritzwoller, M.H., and Bentley, C.R., Magnetic anomalies over tudes 72 ° -74 ° S.), steep paleomagnetic incli­ Antarctica measured from Magsat, in Oliver, R. L., Jago, nations combined with large uncertainty limits J.B., and James, P.R., Antarctica Earth Science, Austra­ preclude assessment of oroclinal bending. Paleo­ lian Academy of Science, Canberra, 1983. magnetic inclinations from these Andean-type Taylor, P., Nature of the Canada Basin: Implications from satellite-derived magnetic anomaly data, J. Alaskan Geol intrusives are consistently steep and indicate a Soc., 2, 1-8, 1983. lack of significant displacement of the Antarctic

15 Peninsula relative to the south pole in the past 100 (1911-1914), Douglas Mawson, Xavier Mertz, m.y. and Belgrave Ninnis made a sled journey of sev­ A number of investigators have postulated that eral hundred miles with dogs into King George V a small continental fragment containing the Ells­ Land. The setting for dietary restriction was worth Mountains occupied an original position created when Ninnis fell into a crevasse with the along the Transantarctic Mountains-Cape Fold food sled. Mawson and Mertz then began their Belt margin of the Gondwana craton. Only prelim­ return to the coast, working the remaining dogs inary paleomagnetic results from Cambrian argil­ to exhaustion and starvation before eating their lit.es in the Ellsworth Mountains are available to remains, including the livers. Descriptions in t.est this postulat.e, but the data are consist.ent their journals of loss of epithelial tissues (hair, with such a reconstruction. skin, bowel lining) and our current understanding Data from Marie Byrd Land are also sparse. A of the concentration of vitamin A in predators' paleomagnetic pole (latitude 36 ° S., longitude 116 ° livers and its metabolism in humans have led to a E.) derived from Early Cretaceous intrusive rocks relatively certain diagnosis of hypervitaminosis are highly divergent from the Jurassic pole of East A as the cause of death of Mertz and the near Antarctica and from the Cretaceous-Tertiary poles demise of Mawson. of the Antarctic Peninsula On the second British South Pole Expedition The available paleomagnetic data thus support a (1910-1913), R. F. Scott and his four companions picture of different t.ectonic histories for differ­ reached the pole January 17, 1912. The dietary ent parts of West Antarctica, but are still too few restriction inherent in a man-hauling polar sled to t.est complex models. Continued paleomagnetic journey was exacerbated by Scott's last-minut.e research offers pot.ential for clarifying the t.ec­ decision to include Bower in the polar party, re­ tonic evolution of this enigmatic sector of quiring that five men live on rations int.ended for Gondwanaland. four. In addition to the caloric deficiency, the diet was devoid of vitamin C. On the return, Evans died at the base of the Beardmore several days MEDICAL PROBLEMS OF POLAR REGIONS after a fall into a crevasse. Again, detailed journal IN THE EARLY 20TH CENTURY descriptions of his medical course enable us to BY STEVE BOYER, M.D. creat.e a differential diagnosis, among the likeliest causes of death being a subdural hematoma from Many diseases occur in specific t.emporal and minor trauma, a complication of scurvy (vitamin regional settings. Some occur only until their C deficiency). pathophysiology is understood; with the advance­ While these Antarctic expeditions were taking ment of medical knowledge they are easily pre­ place, Bernhard Hantzsch, a German zoologist, vented and become historical curiosities. These was leading a party of explorers into the Foxe diseases may require infectious agents or dietary Basin coast of Baffin Island in the Canadian Arc­ or other habits specific to certain regions. Polar tic. Dietary restriction this time was created by explorers of the early 20th century occasionally the sinking of their ship in Cumberland Sound, experienced severe prolonged dietary restriction despit.e which they set off in the spring of 1910 to which, with the stat.e of medical understanding of explore the coast to the north. Returning a year vitamin metabolism at the time or with their own lat.er they were forced to live on polar bear meat ignorance of disease processes, created the setting which Hantzsch preferred to eat frozen, raw. He for some interesting medical problems. did not realize the symptoms he accurat.ely de­ During the period 1910-1914 at least three polar scribed in his own journals were those of trichi­ expeditions occurred in which one member of the nosis from which, there is little doubt, he died. party died from an unknown cause. Detailed de­ With a clear understanding of the pathophysi­ scriptions of the slow deaths in the journals of the ology of each of these illnesses, they have been dying or of their companions have enabled physi­ eliminated as problems of modem expeditions, cians to diagnose retrospectively the problems but so too has the remot.eness of the polar regions with varying degrees of certainty. been eliminated. These case histories are of great During the Australian Antarctic Expedition medical and historical int.erest.

16 MARS-ANALOG STUDIES IN WRIGHT AND troughs, typically 1 m wide and 10 to 15 cm deep, VICTORIA VALLEYS, ANTARCTICA are visible at the Lander 2 site. These troughs BYE. C. MORRIS AND H. E. HOLT form a polygonal network that probably devel­ oped from contraction either by cooling of lava or During the 1971-72 field season, 1,300 photo­ from thermal expansion and contraction of frozen graphs were taken of various geologic features in ground. Victoria and Wright Valleys for comparative The features seen in the Viking pictures that analysis with the pictures expected to be returned are analogous to those photographed in Antarc­ from the Viking Mars Mission in 1976. The cold tica include: armored pavements, wind tails (ero­ dry weathering environments of the ice-free sional and depositional features that record wind valleys of Antarctica provide one of the best ter­ direction), ventifacts, frost shattering, and pat­ restrial analogs of surface conditions on the terned ground. planet Mars. The features photographed in Wright and Victoria Valleys, such as frozen AN ISOTOPIC AND CHEMICAL STUDY OF dunes, patterned ground, various rock weather­ LAKE VANDA AND DON JUAN POND, ing phenomena, ventifacts, felsenmeers, tors, and ANTARCTICA desert pavements, have proved to be valuable in BY IRVING FRIEDMAN, 1 understanding features seen in the Viking ATHOL RAFTER , AND GEORGE SMITH photographs. The scene at the Viking landing sites is reminis­ Temperature measurements made in Lake cent of the rock-littered landscape of Wright and Vanda and in the lake subbottom sediments show Victoria Valleys. The Viking Lander 1 pictures that the high temperatures in the lake are not due show a surface strewn with rocks in the centi­ to geothermal heat flow, but are probably trapped meter to meter size range. Between the rocks, the solar energy as suggested by Wilson. 7 86 surface is blanketed by very fine grained ( < 100 On the basis of Sr8 / ratios the salts in Lake mm) material that has been sculptured by mar­ Vanda can be derived by a mixture of 58% weath­ tian winds into "tails" behind the rocks. Light ered rock plus 42% from sea water or precipita­ and dark drifts of this material are distributed tion. Loss of efflorescences high in sodium, across the surface; these drifts probably are rem­ potassium and magnesium by high winds can yield nants of a thick blanket of very fine grained the salt compositions present in both Lake Vanda material that once covered the area and was sub­ and Don Juan Pond. 18 13 7 86 sequently eroded by wind. From isotopic data on deuterium, 0 , C , Sr8 / , The Viking 2 landing site is a flat boulder­ 8 34 as well as from chemical data on Lake Vanda strewn landscape that is part of the vast plains waters, interstitial brines contained in the subsur­ which occupy much of the northern hemisphere of face sediment and C14 dates we propose the follow­ Mars. Large blocks are more numerous here than ing lake history: at the Viking 1 site and are almost monotonous in (1) Fiord. their similarity to one another. Most of these (2) Uplift caused isolation of Wright Valley from blocks are subangular, equidimensional, and have the Ross Sea numerous pits or holes a few millimeters to a few (3) Some of the sea water flushed out by glacial centimeters across that impart a sponge-like ap­ meltwater. pearance to their surfaces. The interblock areas (4) Glacial melt water flowed into the basin. Solu­ are composed of fine-grained material and ble salts, formed by weathering of local bed­ patches of pebbly fragments; in places, this fine­ rock and salt contributed by original sea grained material is banked into small drifts be­ water and by precipitation slowly accumu­ tween blocks. The surface has a windswept or lated in the Lake. The climate cooled and in­ scoured appearance, and some boulders appear to flow was less than evaporation. The lake stand on pedestals of fine-grained material. In desiccated. The final desiccation yielded a many of the interblock areas the fine-grained CaCl2-NaCl brine. Sodium, potassium, and material forms a discontinuous crust that breaks maoonesium chloride sulfate and carbonate into platy fragments. A series of interconnecting minerals formed an efflorescence that was

17 blown away, leaving a brine enriched in from their drainage or ground-water supply rather

calcium chloride. than by the total amount of H 20. Thus, it is the in­ 18 (5) Crystals of CaCl2 • 6H20 formed, enriched in 0 tensity and length of the warm period during the but depleted in deuterium relative to the summer months, acting on the ice areas at lower precursor brine. elevations, that control the amount of melting and (6) A brief climatic warming occurred 2,600±100 the sizes of lakes in the Dry Valley area years ago resulting in the filling of the basin Expansion of Lake Vanda as a result of warmer to the high stand now preserved as high temperatures was suggested by Nichols (1962), beach levels. but he related the lake rise to the warming that (7) This episode was short lived, and a climate caused the retreat of Trilogy-age glaciers which cooler than the present caused the lake to had been dated as more than 7,000 yr B.P. The shrink to a low level, or to desiccate C14 dates on algae from around the edges of completely. Lake Vanda suggest that its expansion occurred (8) Another climatic warming occurred about 2,000 to 3,000 yr B.P. It seems more likely that the 1,200 years ago filling the basin to its present expansions of Lake Vanda and Don Juan Pond level. The initial warming was warmer than were the result of a more recent episode of warm­ the present, since the inflow shows evidence ing, but it may not be documented by the exposed of possible polar plateau glacier inflow or in­ evidence of glacial retreats. The sizes of the pres­ creased melt water from valley glaciers. ent glaciers are presumably in equilibrium with the present climate, and we suspect the enlarged 1Inst.itute for Nuclear Studies (DSIR), Lower Hutt, New l.ealand lakes are correlative with major glacial retreats that deposited moraines in areas now re-covered CLIMATIC SIGNIFICANCE OF by ice. LACUSTRINE DEPOSITS AROUND LAKE VANDA The expanded lakes, therefore, seem to indicate AND DON JUAN POND, ANTARCTICA a period, possibly only a few centuries long, 2,000 BY GEORGE I. SMITH AND IRVING FRIEDMAN to 3,000 years ago, characterized by slightly­ warmer-than-present summers; they raised the Geologic reconnaissance in the valleys sur­ snowline, increased the volumes of ice that melted rounding Lake Vanda and Don Juan Pond in annually from the lower parts of the glaciers and Wright Valley, Antarctica, was carried out over a ice-cored debris flows, and caused the glaciers to . period of several days during November 1973. It retreat and the lakes to expand. When the sum­ was a byproduct of the drilling program at Lake mers cooled and the snowline again lowered, little Vanda (DVDP 4) carried out during the Dry Valley or no ice remained at the levels where summer Drilling Project, sponsored in part by the U.S. Na­ melting could occur, and at first the lakes received tional Science Foundation. The reconnaissance in­ almost no runoff and nearly desiccated, as inferred cluded observations and sampling of lacustrine from other evidence by Wilson (1964). Eventually, sediments exposed around both lakes. Erosional however, the surplus ice accumulating above the shorelines around Lake Vanda have been reported new snowline would have been transported by gla­ by several workers; lake sediments, also described ciers far enough down into the valleys for summer previously, lie well above the present lake level and melting to again produce sufficient runoff to consist of thick layers of sand and fine gravel that nourish lakes of the sizes and levels we now find. rest on older coarse gravels. The lacustrine deposits around Don Juan Pond are silts that had PROGRAM FOR MAPPING ANTARCTICA not been described prior to our earlier note (Smith BY PETER F. BERMEL AND and Friedman, 197 4). CHARLES E. MORRISON Large volumes of solid H 20-ice-exist on the flanks and ends of most closed basins in the Dry Valley area, and a small amount of this ice melts Mapping has been such an integral part of most annually to supply the lakes. The sizes of most nations' programs in Antarctica over the past closed-basin lakes in these areas are limit.ed, quarter century that it may come as a surprise to

therefore, by the amount of liquid H 20 available learn that a program for Antarctic mapping was

18 not among the activities recommended for the In­ overland traverse. During the 1969-70 field ternational Geophysical Year (IGY) in 1957-58. season, however, Japanese scientists discovered When the decision was made to pursue a post-IGY nine stony meteorites in a blue-ice area of the long-range Antarctic research program, the Queen Fabiola (Yamato) Mountains and suggested lessons of the IGY left no doubt that mapping that Antarctica might prove to be an excellent must be included. source of meteorites. In 1973, Prof. William A. In the case of the United States, the Antarctic Cassidy, a meteoriticist at the University of Pitts­ cartographic effort has been located at the U.S. burgh, reached the same conclusion and proposed Geological Survey (USGS), funded by the National a U.S. program to search for meteorites in blue-ice· Science Foundation as part of the U.S. Antarctic areas accessible by helicopter from McMurdo Sta­ Research Program (USARP). The USGS has fo­ tion. Approximately 5,400 meteorite fragments cused its mapping on West Antarctica and the have now been recovered from Antarctica, mostly Transantarctic Mountains to support the require­ from blue-ice areas, especially where the normal ments of USARP. It has sent field parties to Ant­ flow of glacier ice is impeded or stopped; hence arctica every year since 1957 to establish geodetic blue ice is of special significance in the search for control and has worked closely with U.S. Navy more meteorites. Squadron VXE-6 to acquire mapping-quality Delineation of surficial blue-ice patches in Ant­ aerial photographs. arctica north of about 81° S. latitude became The program has been very productive, result­ possible after the launch of the first Landsat ing in over 90 1:250,000-scale topographic recon­ spacecraft in July 1972 by providing higher resolu­ naissance maps of West Antarctica and the Trans­ tion satellite images of various parts of Antarc­ antarctic Mountains. Other products include tica. Beyond 81° S. latitude advanced very high 1:50,000-scale topographic maps, 1:500,000-scale resolution radiometer (A VHRR) images from the sketch maps, 1:1,000,000-scale topographic maps NOAA series of weather satellites can be used to and shaded-relief reconnaissance maps, as well as identify areas of blue ice, although the 1-km pixel satellite image maps at several mapping scales. size of the image provides 10 times less detail than Future needs can be met by: that available from Landsat MSS. This resolution 1. A primary series at 1:250,000 scale covering all proved to be adequate in detecting the relatively mapworthy features in the area of West Ant­ large blue-ice areas, however. Landsat l, 2, and 3 arctica and between longitudes 150° E and MSS have a pixel (picture element) size of about 80 180° E. m. The images are usually acquired in four spectral 2. IMW sheets at 1:1,000,000 scale prepared from bands: MSS band 4, 0.5 to 0.6 cm; MSS band 5, 0.6 published 1:250,000-scale maps. to 0.7 cm; MSS band 6, 0.7 to 0.8 cm; and MSS 3. Satellite image maps at scales of 1:250,000 and band 7, 0.8 to 1.1 cm. In the identification of blue­ smaller. ice areas, MSS bands 6 and 7 are similar, with 4. Larger scale (1:100,000 and larger) maps of band 7 somewhat better than MSS band 6. MSS areas of special interest where greater detail is band 5, however, is best in areas of bedrock expo­ warranted. sure, because blue ice and rock outcrops usually The USGS effort in support of NSF's USARP is have a similar spectral response. a remarkable story unequaled in An~tica. Over Various types of satellite data were used during 100 National Mapping Division personnel have the 1982-83 austral summer field season on Prof. worked there in the field, and the challenge of "the Cassidy' s United States Meteorite-Search Project ice" continues to be a lure to the candidates apply­ in Antarctica, in the isolated, unmapped polar ing to work on the mapping projects. plateau region called the "Far Western Ice Fields.'' In the past, a dead-reckoning type of THE USE OF SATELLITE TECHNOLOGY IN traverse would normally have to be employed for THE SEARCH FOR METEORITES IN ANTARCTICA daily trips to meteorite-collecting areas. The field BY TONY K. MEUNIER party used a 1:250,000-scale Landsat 1 image (1200-20293; 8 February 1973) of the meteorite­ Until 1969 only four meteorites had been search area for the planning and execution of recovered from Antarctica, each during an oversnow traverses. Although the polar plateau on

19 a continental scale is a relatively flat, featureless GLACIOLOGICAL AND GEOLOGICAL STUDIES ·area, from a regional perspective, as in the 60 km2 OF ANTARCTICA WITH "Far Western Ice Field," there is significant SATELLITE REMOTE SENSING TECHNOLOGY topographic relief that resembles an undulating BY JANE G. FERRIGNO, ridge- and valley-type terrain. This made local RICHARDS. WILLIAMS, JR., traverses very difficult to negotiate by line-of­ c. scon SOUTHWORTH, AND sight techniques. Landsat images permitted the TONY K. MEUNIER field party to intermittently check their positions by locating and following features visible on the The Satellite Glaciology Project of the U.S. images, such as fim patches. Hence, the use of Geological Survey has been using remotely sensed Landsat images was instrumental in successfully data to support a variety of glaciological and completing a number of difficult traverses in both geological investigations in Antarctica. A signifi­ the "Far Western" and "Far Northwestern Ice cant attribute of the Landsat image is that it con­ Fields.'' tains the precise time of acquisition, providing a Satellite tracking data were also used, for the method for making "time-lapse" measurements of first time, to accurately map meteorite finds by us­ the dynamics of the coast of Antarctica. Two ing a portable Magnavox 1502 Satellite Tracking Landsat images, 1185-13530 and 2022-13582, ac­ Positioning System. This state-of-the-art geo­ quired on 24 January 1973 and 13 February 1975, ceiver, on loan from the Bureau of Land Manage­ respectively, were used to determine the velocity ment, proved to be very effective in these remote of the terminus of the Pine Island Glacier, a tidal expanses of snow and ice. With the Magnavox outlet glacier on the Walgreen Coast, West Ant­ 1502, a base line consisting of five geodetic posi­ arctica. During the 750-day interval, the terminus tions over a 30 km X 2 km collecting area was of Pine Island Glacier moved about 4.5 km at an established. At the site of each meteorite find, the assumed average velocity of 6 m per day. meteorite identification number was written on a Landsat images of the Amery Ice Shelf and ter­ flag implanted in the ice. After an area was sys­ minus of the Lambert Glacier were combined as a tematically searched, and all the meteorites had 1:500,000-scale uncontrolled image mosaic to been collected, the angles and odometer distances serve as a base for compilation of 1- and 5-m con­ between the base station and the numbered flags tours of the shelf derived from 45 Seasat radar were recorded. Final mineralogical identification of altimeter traverses. The successful experiment each specimen by NASA's Johnson Space Cent.er reemphasized the fact that satellite image mosaics along with the acquired control will result in a and maps can be effectively used as the compila­ thematic map of the "Far Western Blue Ice Field" tion base for various types of geological, glaciolog­ collecting area. These are the first controlled ical, and geophysical data. survey points ever established in this remote area. Preliminary research with Charles W. M. Swith­ In addition, these positions can be reoccupied in inbank has established that Landsat images of the future to measure the change in the x, y, and z Antarctica can be used to prepare 1:1,000,000- parameters. Determining the rate of ice movement scale planimetric maps of coastal areas, bedrock in this area will be an important contribution to exposures, and blue-ice areas of Antarctica. A the understanding of the mechanisms which lead more accurate delineation of: (1) the coast of Ant­ to the concentration of meteorites at blue-ice arctica, including the type of coast (bedrock, locations. floating ice, grounded ice, outlet glacier terminus); Aerial photographs were also used to help select (2) areas of bedrock; (3) areas of blue ice; and (4) areas for potential collecting sites. All the five plotting of other glaciological features (medial blue-ice areas, selected from satellite images and moraines, crevasse areas) will result from comple­ aerial photographs for field investigation, were tion of this effort. The accurate location of blue-ice found to contain concentrations of meteorit.es. areas is important to the international program to This was totally unexpected and highly signifi­ recover meteorites from Antarctica. cant. The use of satellite technology proved to be Preliminary research was carried out to deter­ effective, and its continued use will be an impor­ mine whether digital processing of Landsat multi­ tant tool in the systematic search for and recovel°Y" spectral scanner (MSS) images of rock outcrops in of meteorites in Antarctica. Antarctica could lead to a method of mapping rock

20 units from nunatak to nunatak on the basis of made by various Pole parties between 1956 and their spectral reflectance characteristics. The 1970 to establish the position of the old base with BorgmassivetJAhlmannryggen region of western respect to the Pole. These were also used to esti­ Queen Maud Land, East Antarctica, located with­ mate the rate and direction of movement of the in the Iron Metallogenic Province, was targeted polar ice cap. In 1970, Bill Chapman and Bill Jones for analysis because of the availability of of the U.S. Geological Survey, National Mapping 1:250,000-scale reconnaissance geological maps Division, published mathematical models describ­ (printed on a Landsat image mosaic base) pub­ ing the movement. The latitude-longitude posi­ lished by the South African Scientific Committee tions calculated from the astronomic observations for Antarctic Research. were first converted to an X-Y rectangular coor­ dinate system, the Y-axis of which was coincident with the average longitude of the observation posi­ USGS PROGRAM AT THE SOUTH POLE tions (24 ° 40' W.). The equations of straight lines BY THOMAS EDMONDSON AND KATHY COVERT were then fit by least squares to the plots of X ver­ sus time and Y versus time. The models indicated The United States Geological Survey, National a movement of 19 m per year parallel to the 37° W. Mapping Division, has sent 11 consecutive winter­ meridian. over teams to the South Pole. This continuing ef­ The U.S. Geological Survey began sending fort has been in support of two ongoing projects. winter-over teams to South.Pole in 1972, primarily The first project, USGS Doppler Satellite Track­ to man geodetic satellite tracking receivers. This ing, was initiated in 1972. Data are collected from continual tracking results in precise position overflights of Navy navigation satellites, trans­ measurements for the tracking antenna site. mitted to the United States for further data reduc­ A substantial amount of position information tion, and then shared with other investigators for has been collected for the current site since it was detailed analysis. The second project is the USGS established in 1975. The coordinates computed Antarctic Seismic Project. In 1974 new seismom­ from satellite data represent a significant improve­ eters were installed at the South Pole. The seismic ment in both accuracy and precision over astro­ station is now part of the Worldwide Standardized nomic positions. By analyzing the Doppler fre­ Seismograph Network because of its unique loca­ quency shift curves received from passing tion in the Southern Hemisphere and an important satellites, ground points are resolved to within 1 m source of seismic data. The USGS is responsible of their true coordinates. This information, then, for relocating and remonumenting the true geo­ provides a more accurate data base for modeling graphic South Pole. the ice movement. This presentation will be a summary of the ob­ During the winter of 1982, the author set about jectives and accomplishments of the ongoing to generate new models based on the satellite-. USGS projects at Amundsen-Scott South Pole derived positions from 1975-81. Coordinates are Station, Antarctica. provided in a geocentric X-Y-Z reference system, so the data are immediately usable in rectangular MODELING THE MOVEMENT AT THE plots. Compensation is made for the slight wobble POLAR ICE CAP AT THE SOUTH POLE in the Earth's polar axis when reducing to the BY THOMAS HENDERSON geocentric system to eliminate this source of com­ parison difference. Again, linear least squares fits The United States has continuously occupied were made to the plots of X versus time and Y ver­ the South Pole since the International Geophys­ sus time. The resulting three models fit the data ical Year in 1957-58. The original base was with a standard deviation of 0.9 min both X and approximately 1 km from the Geographic South Y. They indicate a movement of 10 m per year Pole and was used until the 197 4-75 season. Snow parallel to the 41°11' W. meridian. drift accumulation over the old facility forced the The models enable the prediction of the Pole po­ construction of a new station about 400 m from sition for a future date. Since the new antenna site the Pole. Manned since 1975, it features a large is tied into a local survey network, the physical geodesic dome that shelters the main buildings. marking of the Pole for that date is reduced to a A number of astronomic observations were simple surveying operation.

21 ARCTIC PROGRAM the essential geologic conditions for petroleum ac­ CONVENER: G. GRYC cumulation were present, but cautioned would-be prospectors against the adverse geographic fac­ HISTORY OF U.S. GEOLOGICAL SURVEY tors and the consequent high development costs. They recommended that the next step should be GEOLOGIC EXPLORATION AND drilling in the Cape Simpson area, followed by MINERAL-RESOURCE EVALUATION, ARCTIC geologic studies and more drilling in other areas ALASKA BY GEORGE GRYC AND ROBERT M. CHAPMAN that appeared favorable. However, very little additional exploration was conducted on the North Slope until 1944, when a The history of geologic exploration, mineral wartime effort (1944-53) was initiated by the U.S. resource evaluation, and topographic mapping in Navy to further evaluate the petroleum resources Alaska's Arctic region is well chronicled and of what was then popularly referred to as Pet-4. documented in U.S. Geological Survey (USGS) Again the USGS was asked to undertake the geo­ publications and activities. Although several logic aspects of the work. The Pet-4 program recorded expeditions traversed parts of the region established the surface and subsurface framework before 1900, the USGS party in 1901, headed by geology of the North Slope and proved the feasibil­ W. J. Peters and F. C. Schrader, was the first to ity of operating a modem-oil exploration program map in some detail the geologic structure and in the Arctic. All the technical results were pub­ stratigraphy and topography along a transect lished in USGS Professional Papers 301 through from the Brooks Range to the Arctic coast. Their 306. report, published in 1904 as USGS Professional Stimulated by a major oil discovery in Cook In­ Paper 20, named and described the Lisburne For­ let in 1957 and building on the knowledge base and mation, of Mississippian and Pennsylvanian age know-how provided by the Pet-4 program, the oil and described the sequence and structure of the industry took up the search for oil in the Arctic Cretaceous rocks, both destined to become major and 10 years later discovered the largest field in petroleum exploration targets in Arctic Alaska. In North America at Prudhoe Bay, east of Pet-4. USGS Professional Paper 109, published in 1919, The USGS, partly in cooperation with the U.S. E. de K. Leffingwell reported on the oil seepages at Navy, continued its work in northern Alaska dur­ Cape Simpson, described and named the Sadler­ ing this period, particularly in the Arctic foothills ochit Group and Shublik Formation of Prudhoe and Brooks Range provinces. While examining Bay fame, and described and mapped the geology and sampling oil shales in northern Alaska in of the Canning River region, now included in the 1968, I. L. Tailleur collected stream sediment Arctic National Wildlife Refuge. Leffingwell's samples in the Red Dog area of the DeLong Moun­ description of the ice wedges and other frozen­ tains. Chemical analyses indicated 10 weight per­ ground phenomena along the Arctic coast and his cent Pb and thus provided the first hint of sulfide proposed explanation for their formation remains mineralization in the western Brooks Range. Fol­ a classic reference for students of permafrost. A low-up by other agencies and industry has now knowledge of permafrost and its applications to defined a ''world class'' belt of stratabound sulfide engineering and exploration projects is essential to deposits that could provide the Nation with a successful operations in the Arctic. 10-year supply of zinc and a 5-year supply of lead On the basis of these early reports, President at present consumption rates. On the basis of Harding set aside the Naval Petroleum Reserve limited Pet-4 data, F. F. Barnes in 1967 estimated No. 4 (NPR-4) in 1923, and the U.S. Navy re­ the coal resources of northern Alaska at about 130 quested that the USGS map and report on the billion tons. More recent work by J. E. Callahan geology and potential resources of the region. and others suggests a hypothetical resource of as From 1923 through 1926, eight USGS parties much as 3 trillion tons of low-sulfur subbitumi­ crossed the Brooks Range and the NPR-4 along nous coal. New concepts and syntheses of the geol­ many of the major rivers. Their findings were ogy of Arctic Alaska and the adjacent continental published in 1930 in USGS Bulletin 815, in which shelves continue to be formulated and published P. S. Smith and J. B. Mertie, Jr., concluded that by USGS geologists.

22 USGS studies in the Brooks Range and on the TECTONIC EVOLUTION OF THE North Slope have been stimulated and funded in ARCTIC CONTINENTAL MARGIN IN THE response to a steady stream of national programs BEAUFORT AND CHUKCHI SEAS-EVIDENCE and needs, such as the trans-Alaska oil and gas FROM SEISMIC REFLECTIONS pipelines, the Alaska Mineral Resource Assess­ BY ARTHUR GRANTZ ANDS. D. MAY ment Program (AMRAP), the offshore leasing pro­ gram, and the recently concluded program man­ dated by the Naval Petroleum Production Act of Multichannel seismic-reflection profiles in the 1976. This act transferred the responsibility for northern Chukchi and Beaufort Seas suggest that Pet-4 to the Secretary of the Interior and renamed three pulses of rifting created the first-order it the "National Petroleum Reserve in Alaska" geologic structures and localized the sedimentary (NPRA). The USGS was directed to (1) continue basins of the continental margin north of Alaska. the exploration program begun by the U.S. Navy A Late Triassic-Early Jurassic pulse isolated shelf in 197 4; (2) continue to operate and maintain the deposits of the Mississippian to Triassic Arctic Barrow gas fields, which are virtually the sole Alaska Basin from their sourceland in the present energy source for the growing community of Bar­ area of the Arctic Ocean and created the east­ row; (3) complete a cleanup and rehabilitation pro­ westerly trending Dinkum graben. This graben, gram begun by the U.S. Navy; and (4) participate which underlies the eastern half of the Alaskan in various resource surveys (the so-called 105(c) Beaufort shelf, contains 2 to 4 km of inferred studies) and the petroleum resource assessment, Jurassic to Paleogene elastic rocks. (the 105(b) studies). All of the resulting technical Late Neocomian to Albian rifting completed the data are being released by the Survey, utilizing the process of continental breakup and formed the National Oceanic and Atmospheric Administra­ Canada Basin of the Arctic Ocean by sea-floor tion Data Center in Boulder, Colo., and through spreading. From 4 to 10 km of submarine-fan and regular USGS map and book publications. abyssal-plain deposits partially fill this ocean The USGS's experience in Arctic Alaska in basin. Clastic sediment from southern sourcelands gathering geologic and geophysical data, provid­ overstepped the newly rifted margin by Albian ing new concepts and syntheses of these data, and time and prograded the present continental­ assessing resources is an excellent example of the terrace sedimentary prism. This prism, more than scientific accomplishments that are possible and 13 km thick, is dominated structurally by growth enhanced by working closely with other agencies faults and rotational megaslumps; off northeast­ and industry. It also illustrates the long leadtime ern Alaska it contains large syndepositional needed to build a knowledge base leading to dis­ diapiric-shale ridges and Quaternary detachment covery and development. This knowledge base folds. must be communicated on a timely basis and be in Both late Neocomian(?) and latest Cretaceous or the public domain so that all concerned have ac­ early Paleogene pulses of rifting between Wrangell cess on an equal basis. Old data must be inte­ Island and the Chukchi Continental Borderland grated with new findings and periodically appear to have thinned the continental crust into reviewed to see what new concepts and interpreta­ which the North Chukchi Basin subsided. The tions may result. Although some programs may earlier pulse is recorded by marked basinward have narrowly defined objectives, spinoffs in other thickening of Cretaceous strata, and the later one areas and scientific disciplines and serendipitous by numerous antithetic faults and foundered fault discoveries are virtually certain, especially in such blocks in the Cretaceous strata. Sediment in the a frontier region as the Arctic. basin is more than 12 km thick. Because the basin underlies the shelf only adjacent to the borderland, these contiguous features may be tectonically TECTONICS OF ARCTIC ALASKA related. BY I. L. TAILLEUR, I. F. ELLERSIECK, AND C. F. MAYFIELD

[No abstract]

23 . THE ARCTIC PLATFORM IN THE NATIONAL imal northerly-provenance t.errane. There are no PETROLEUM RESERVE IN ALASKA-DEPOSITION, similar shell deposits on the Arctic platform in DEFORMATION, AND PETROLEUM POTENTIAL post-Triassic time. These sandstone and bioclastic BY C. E. KIRSCHNER limestone beds are the reservoirs for the giant Prudhoe Bay oilfield east of the NPRA, where these reservoirs are sealed by the overlapping The National Petroleum Reserve in Alaska pebble-shale unit of Neocomian age. Only the Bar­ (NPRA) covers an area of 93,240 km2 or about half row gasfields in the NPRA have a similar t.ectono­ of the Arctic slope in the west-central part of stratigraphic setting. The early and middle Elles­ northern Alaska. This paper outlines the major ele­ merian reservoir beds in the NPRA are int.erpreted ments of the geology and a few aspects of the not to form traps because the rocks are time trans­ stratigraphic history and structural development gressive on the platform, and so petroleum prob­ of the Arctic platform that have a significant bear­ ably migrated updip with the strandline facies. ing on the oil and gas pot.ential of the region. The The upper Ellesmerian subsequence, of Jurassic Arctic platform was originally defined as a pre­ and Early Cretaceous (Neocomian) age, includes Albian t.ectonic feature that occupied the northern marine shale, minor sandstone, and mudstone that part of the present coastal plain and the adjacent form a blanketlike package across the platform. The area of the Arctic Ocean. I view the area of the distribution of sandstone facies and southerly pro­ platform as ext.ending southward in the subsur­ grading foreset beds in the Kingak Shale is int.er­ face across the NPRA at least to the north front of pret.ed to define a distal northerly provenance that the Brooks Range. ceased to supply detritus to the platform by lat.e The stratigraphy is subdivided into three major Neocomian time. Other workers have stated that Phanerozoic sequences: the Franklinian, the the upper Ellesmerian rocks were deposit.ed in a Ellesmerian, and the Brookian. The Franklinian shallow-marine shell environment. However, pale­ sequence, of pre-Mississippian age, consists ontologic bathymetric indicators, core lithologies, primarily of metamorphosed sedimentary rocks electric-log characteristics, and seismic­ that are complexly deformed and thus constitut.e stratigraphic int.erpretation all suggest a deep­ economic basement for petroleum exploration. wat.er basinal environment in which suspended-load The Ellesmerian sequence, of Mississippian to or turbidit.e processes were involved. The upper Early Cretaceous age, consists of elastic, bio­ part of the Ellesmerian sequence is int.erpret.ed to clastic, and associated sediment in part derived have been deposit.ed in a southerly, southwest.erly, from a northern provenance (Barrovia) that was and southeasterly prograding turbidit.e fan com­ partly rifted away by the end of Neocomian time. plex. The sandstone beds that make up the pot.en­ In the following discussion, this sequence is sub­ tial reservoir rocks are composed of turbidit.e chan­ divided into three distinct subsequences: lower, nel sandstone that commonly fines upward and of middle, and upper. The lower Ellesmerian subse­ suprafan sandstone sequences that are cyclic and quence, of Mississippian to Early Permian age, thicken upward. Following this line of reasoning, consists of nonmarine elastic rocks overlain by the Kuparuk River oilfield reservoirs are int.er­ marine-shell bioclastic strata that fill grabens and pret.ed to be turbidit.e sandstone in a combined overlap adjacent horst blocks and uplifts on the structural-stratigraphic trap in which the pebble­ Franklinian basement. This subsequence is very shale unit forms the overlying stratigraphic seal. In thick in the riftlike graben lows and thins rapidly the northwest.em part of the NPRA, significant gas by time-transgressive onlap in a northerly shows were penetrat.ed in the Tunalik well within a direction. setting that may be similar to the Kuparuk field. The middle Ellesmerian subsequence, of Lat.e The concept of turbidit.e reservoirs enhances the Permian and Triassic age, includes fluvial to pot.ential for primarily stratigraphic entrapment, marine-shell elastic and bioclastic strata that form although these reservoirs may also consist of low­ a sheetlike package across the Arctic platform. porosity and low-permeability fine-grained silty This subsequence is relatively thin and, like the sandstone with low producing capabilities. Further­ underlying lower Ellesmerian subsequence, is also more, oil shows are more common east of the Meade time transgressive northerly on the platform. The arch, whereas gas shows are more common west of distribution of sandstone facies dictat.es a prox- the arch. The lat.est Neocomian beds are distal

24 pyritiferous shale, rich in organic mat.erial, and are separated by long narrow faulted diapiric an­ mudstone deposits. Seismic stratigraphy suggests ticlines. Seismic data do not appear to define that these beds were derived from the south in the evidence of the style of frontal thrust folds in Brooks Range provenance and indicat.es that "flip" Ellesmerian rocks that are productive, for exam­ in provenance to the Arctic platform was completed ple, at Turner Valley in Alberta or the Paint.er by the end of Neocomian time. Creek reservoir in Wyoming. The Brookian sequence, of Early Cretaceous to The Brooks Range province in the NPRA is Holocene age, includes the lat.est Neocomian charact.erized by imbricat.ely stacked and folded strata and all post-Neocomian formations. The se­ thrust sheets in mainly Ellesmerian rocks. Current quence consists mainly of thick flysch and molasse int.erpretation suggests that these thrust se­ deposits flushed from the rising Brooks Range oro­ quences have been involved in very large scale tec­ gen and dumped into the Colville foredeep to pro­ tonic transport and crustal short.ening in the range grade northward and eastward across the Arctic of 250-600 km. The data suggest that vertical up­ platform and the present Barrow arch. Lowermost lift and subhorizontal tectonic transport of Elles­ Brookian sequence rocks of the Torok Formation merian rocks in the west.em Brooks Range may be are deep-wat.er prodelta turbidit.es deposited on at least twice as great as in the Canadian Rockies the platform and over the Barrow arch before west of Turner Valley and thus that diagenesis of uplift during post-Albian time. The turbidit.e sand­ the source and reservoir beds may be significantly stone may offer reservoir targets in a variety of great.er. structural and stratigraphic settings. Upper Because of the structural complexity and the Brookian sequence rocks of the Nanushuk and Col­ disappointing history of the few wells drilled in the ville Groups are delta-plain sandstone and shale foothills and thrust-belt provinces, it is difficult to that are marine in the east and nonmarine and coal develop enthusiasm for their petroleum potential. bearing in the west. They offer reservoir sandstone However, the region is only lightly explored, and targets that are generally at shallow depths and on new concepts and new data could require a reeval­ small structures, so that the economics of these uation in the future. The pot.ential for deep to very plays may not be attractive unless a local need is deep reservoirs on basement-controlled structures developed. of rather large areal dimensions is unt.ested. These The Arctic platform province is defined by seis­ include such features as the Oumalik, Umiat, and mic and well data beneath the Arctic Coastal Utukok platforms, where reservoir objectives Plain. The platform dips regionally south beneath might be present in the depth range of 2,400- the northern foothills province and is int.erpreted 7 ,600 m. Although present concepts of the gener­ to continue to dip south beneath the southern foot­ ation and preservation of hydrocarbons suggest hills province at least as far as the north front of that reservoirs may be gas prone only below the Brooks Range thrust belt. The platform also depths of about 3,600 m and there may also be dips regionally west and east from the north­ serious question as to the presence of adequat.e south-trending Meade arch in the central part of reservoir facies, these are apparently large struc­ theNPRA. tures that would seem to warrant serious con­ The northern foothills province is a broadax­ sideration as candidates for future drilling. shaped wedge incorporating a wrinkled-carpet pat­ Three unique catastrophic-type structures on t.em of detachment folds in Brookian rocks that and adjacent to the Barrow arch are the Avak overlie the regionally south-dipping homoclinal structure on the Barrow high, Simpson paleocan­ Ellesmerian sequence. yon beneath Dease Inlet, and the Fish Creek paleo­ The southern foothills province encompasses landslide east of the Fish Creek platform. The two contrasting styles of complex structure. Sub­ Avak structure is situated on the crest of the Bar­ parallel to the north front of the Brooks Range row high. It is a semicircular feature, 13 km in thrust belt, the structure, in mainly Lower Creta­ diamet.er, that contains severely disrupted beds in ceous shale and graywacke, involves very complex the core zone and distinct listric slump faults bed crenulation, isoclinal folding, and thrust around the periphery. Gravity and seismic data de­ faulting. Northwest of this band, broad ridge­ fine a circular low within the boundary of the forming bathtub-shaped synclines, which appear structure and a central high. The Avak well, which to float on a shale substrat.e (Torok Formation), was drilled near the crest of the high, has a large

25 number of core dips ranging from 40 ° to 90°. Seis­ about 1,200 km2 on the east-southeast flank of the mic data, lithology, and paleontology define severe Fish Creek platform in the northeasternmost part bed disruption and uplift of about 100 to 500 m in of the NPRA. The boundary of the area is irregular the core. Oil shows were common, and there is no but broadly simple; its internal structure as de­ lithologic or petrographic evidence for high­ fined by seismic and well data is very complex and temperature/high-pressure metamorphism. Previ­ has not yet been mapped in detail. The disrupted ous reports have suggested that this structure was beds involved in the slide are the Neocomian formed by meteorite impact, as a cryptovolcanic pebble-shale unit and the prodelta and turbidite structure, or simply by submarine canyon erosion beds in the lower part of the Torok Formation. An and landsliding. There are major difficulties, how­ interpretation by Tetra-Tech, Inc., concluded that ever, with all these interpretations. The enigma is, the seismic-diffraction pattern was universally what geologic force could uplift about 11 km3 of symmetrical and probably due to gas-charged tur­ semiconsolidated sediment as much as 500 m with bidite sand bodies. This interpretation is suspect no disruption of the flanking sediment that now because there are not only symmetrical diffrac­ contains the South and East, postdisruption, Bar­ tions but also one-sided bed-termination diffrac­ row gasfields? tions, and well data define 20°-40°-W.-dipping The Simpson paleocanyon trends northeasterly beds in the Torok Formation that are antiregional across the Simpson Peninsula between Dease Inlet in comparison with the regional eastward dip. and Smith Bay. There is very good seismic, well, These west-dipping beds are confined to the and corehole control onshore to define the canyon disrupted part of the Torok Formation and occur configuration on the southeast. A total of 32 shal­ in wells where the pebble-shale unit is missing. The low core tests were drilled in the vicinity of the pebble-shale unit is interpreted to be cut out by East Simpson Nos. 1and2 wells and the Simpson normal listric faulting, which also causes the an­ No. 1 well. On the west beneath Dease Inlet, mud­ tiregional panels of westward dip. Although some gun seismic data are poor in quality, but these gas or oil accumulations may be present within the data in combination with well control establish slide complex as interpreted by Tetra-Tech, Inc., reasonable constraints on the northwesterly can­ the larger potential could be related to turbidite yon margin. The canyon was cut in Early Cretace­ reservoirs of the lowermost part of the Torok ous time in the Nanushuk delta-plain and Torok trapped at the periphery of the slide. Similar but prodelta sequences. Some data indicate that the younger normal listric faulting traps the small canyon axis may reach as deep as the top of the Fish Creek oil accumulation. The disruption pebble-shale unit near the present coastline. The caused by the Simpson paleolandslide is clearly canyon was backfilled by shale of the Upper Creta­ established as having occurred early in Torok ceous Colville Group. The core tests partly define time. The ages of the Simpson paleocanyon and the Simpson oilfield, and a few tests penetrated the Avak structure are not so well defined but the basal canyon beds, which have a chaotic struc­ could be about the same as that of the Fish Creek ture typical of a submarine-canyon wall. The shal­ paleolandslide. low Simpson oilfield reservoirs are in Nanushuk All three of these catastrophic-type structures sandstone, trapped by a leaky seal at the canyon are, broadly speaking, situated on the Barrow margin. The potential for deeper, possibly eco­ arch. There may be a common casual mechanism, nomic reserves in turbidite sandstone of the lower possibly the disruption of gas-hydrate deposits part of the Torok trapped at the canyon wall has during the beginning of uplift on the Barrow arch. not yet been explored. It has also been suggested In the case of the Fish Creek paleolandslide, a that reservoir sandstone beds may be present in broadly simple but internally complex landslide the canyon axis; no data are available to confirm or resulted. In the case of the Simpson paleocanyon, deny this possibility. Offshore data show a com­ landslum.ping triggered the rapid headward ero­ plex of listric gravity faults that may have a head­ sion of a large submarine canyon. Lastly, in the wall scarp near the present coastline. I conclude case of the Avak structure, the disruptive force that this faulting may indicate the presence of a must have been phenomenal, to uplift the beds of submarine landslide which localized the headward the Neocomian pebble-shale unit at least 500 m. erosion of the canyon. The Jurassic sandstone reservoirs of the Barrow The Fish Creek paleolandslide covers an area of gasfields are overlapped by the pebble-shale unit

26 on the northwest. This zero line probably produced Survey (USGS) onshore and offshore studies, the an areally large petroleum reservoir in the early lit.erature, and industry drilling results. history of the development of the Barrow high. North Slope oil and gas resources occur in a re­ When the Avak structure breached this high, the gion of similar geology, informally referred to here­ accumulation was flushed into the Arctic Ocean. in as the North Slope petroleum province, great.er than 260,000 km2 in area, that includes all lands north of the Brooks Range, an undet.ermined part OIL AND GAS RESOURCES OF THE of the Brooks Range, and the continental shelf and NORTH SLOPE, ALASKA slope adjacent to the North Slope (fig. 5). This BY KENNETH J. BIRD province displays a complex geologic history that includes marine and nonmarine sedimentation After 40 years of oil and gas exploration by from the Precambrian to the Holocene int.errupted Government and industry, the North Slope is now by uwiconformities, some of which represent known to contain resources of both conventional periods of orogeny. Although oil indications are and unconventional oil and gas. Conventional oil is known from pre-Mississippian metamorphic rocks, currently the only economic resource, but an im­ these rocks are generally considered nonprospec­ portant one that contribut.es one-fifth of daily U.S. tive for petroleum and, therefore, economic base­ production. Unconventional oil resources include ment. The petroleum-prospective sedimentary heavy oil, tar, and oil shale; unconventional gas rocks in this province consist of two depositional resources include tight-gas sand, gas hydrat.es, sequences: an older (Mississippian to Early Creta­ coalbed methane, and geopressured methane. Our ceous) relatively thin northern-derived sequence current understanding of these resources is based and a younger (Early Cretaceous to Quat.ernary) on two Government exploration programs, com­ relatively thick southern-derived sequence. A long­ bined with information from U.S. Geological lasting t.ectonic event, which began in the Lat.e

FIGURE 5.-North Slope of Alaska petroleum province, showing oilfields and gasfields, major structural features, Trans-Alaska Pipeline (TAP), and locations of cross sections (A-A', B-B') in figure 6.

27 Jurassic or Early Cretaceous, initially transposed terized by low-angle northward-directed thrust the sediment-source areas and later formed most faulting (the ancestral Brooks Range) shed debris of the structural features observed in the region to­ into an adjacent foredeep (the Colville trough). A day. The time of generation and the locations of prograding wedge of sediment, characterized by a most, if not all, North Slope petroleum accumula­ distinctive shelfuslope-basin geometry, filled the tions are thought to have been controlled by Creta­ foredeep with at least 6 km of deep-marine to non­ ceous and Tertiary tectonics and sedimentation. marine elastic sediment (Brookian sequence) and The northern-source assemblage of sedimentary eventually overlapped the now-submerged Barrow rocks (Ellesmerian sequence), which averages arch. Reservoir rocks in this sequence consist of about 2 km in thickness but locally may be three sandstone rich in lithic fragments, deposited in times as thick, was deposited on and partly de­ nonmarine to deep-marine environments. The rived from an erosionally subdued Late Devonian reservoir quality of these rocks is generally poorer orogenic landmass (economic basement). This than that of Ellesmerian reservoir rocks. The assemblage is characterized in the north by good petroleum source rocks consist of marine prodelta, to excellent reservoir rocks (including those in tile slope, and basinal shale units. Basin filling, max­ Prudhoe Bay field) composed of compositionally imum sediment loading, and the deformation of mature sandstone and dolomite deposited during these rocks into a series of long linear fault-cored several transgressions and regressions in non­ detachment folds proceeded from the southwest­ marine to shallow-marine environments along an ern part of the North Slope during Albian(?) time east-west-trending shoreline. These rocks grade to the northeastern part of the North Slope during southward into finer grained relatively deep late Tertiary time. Deposition of the Brookian se­ marine rocks that are potential source rocks. The quence is believed to have provided the deep burial most important petroleum-source rocks in this and subsequent heating of source rocks necessary assemblage are marine shale units deposited dur­ for the generation of oil and gas in this province. ing transgressions of the sea: the Shublik Forma­ Folding and faulting of reservoir rocks accom­ tion, the Kingak Shale, and the pebble. shale unit panying deposition of the Brookian sequence pro­ (fig. 6). ' vided traps for migrating oil and gas. Oil and gas Rifting during Jurassic and Early Cretaceous indications are known in nearly every reservoir time formed the proto-Canada basin and an up­ rock in the province. lifted basement ridge, part of which is the To date, 21 oilfields and gasfields have been dis­ southeast-trending Barrow arch. This feature later covered on the North Slope and nearby offshore became the focus of migrating hydrocarbons and areas, but only two oilfields, the Prudhoe Bay and is now the site of most North Slope oil and gas ac­ the Kuparuk River, are economic. These two oil­ cumulations in both Ellesmerian and Brookian fields are among the largest in the United States reservoir rocks. To the south, continental subduc­ and currently produce 1.6 million barrels of oil per tion and mountain building, possibly linked to the day via the Trans-Alaska Pipeline. All North Slope rifting event, formed the ancestral Brooks Range. gasfields are subeconomic-including the 29 tril­ During middle Neocomian time, renewed uplift of lion ft3 of gas in the Prudhoe Bay field, represent­ the rifted margin to the north created a regional ing about 14 percent of 1981 U.S. gas reserves. erosional unconformity in northernmost Alaska However, gas is produced from the South and and the offshore areas. Sandstone reservoirs East Barrow fields for local consumption by the beneath this unconformity locally show· improved village of Barrow. The South Barrow field, discov­ porosity by leaching. During late Neocomian time, ered in 1949, is distinguished as the earliest Arctic a northward transgression of the sea in response to gas to be discovered and produced. subsidence of the rift margin resulted in the depo­ The latest USGS estimates of petroleum re­ sition of a thin marine shale, rich in organic mate­ source remaining to be discovered in the entire rial, that capped the regional unconformity and onshore and offshore North Slope petroleum prov­ thus sealed several important reservoir rocks and ince (mean value of recoverable resources) are 14.4 terminated deposition of the northern-source billion barrels of oil and 73.2 trillion ft3 of gas. The Ellesmerian-sequence sediment. area of most exploratory interest is currently the In the south, a rising orogenic landmass charac- Barrow arch, particularly its offshore extension.

28 A A' SOUTH & EAST FISH POINT THOMSON & SIMPSON PRUOHOE SL WALAKPA BARROW CREEK FLAXMAN ISLAND SL

5

0 2 0 OIL AND GAS 0 RESOURCES x Oilfield ...w e w IL 10 -3'.;:t Gasfield 3 * Oil- and Gasfield @ Oil shale @ Heavy oil I tar 4 © Coalbed methane o· 15 © Tight gas sand & geopressured methane Slope angles~ ...l...l..ll. Base of methane hydrate stability zone 1· 5 Vertical exaggeration x45-·~\" • 2 B B'

10

0 0 4 ~ x a: w... "'w w ... IL w ~ 20 BASIN 6 0 ..I Vertical exaggeration x20 ;;;: Slope angles

~1:· 8 ' ~f.~'t 2· y,~sf. 30 o'lJi.\C 0 60 Ml. f.CO~ 100 KM 10

FIGURE 6.-Cross sections of North Slope petroleum province, showing occurrence of oil and gas resources. Thin vertical lines are selected· wells. Horizontal scale and resource symbols are the same for both sections. See figure 5 for locations.

As reserves of conventional oil and gas resources to occur in the North Slope petroleum province. decline and their replacement becomes more dif­ Figure 6 shows the locations of these resources or ficult, more interest is generated in unconven­ the places where the requisite physical conditions tional oil and gas resources to meet the need for exist. General evaluation of these resources, how.­ replacement. These resources or the requisite ever, is in only the very earliest stages. Heavy oil physical conditions for their existence are known and (or) tar, which reportedly amounts to 18-40

29 billion barrels in place, occurs in shallow Upper east in the Prudhoe Bay area and from rocks ex­ Cretaceous sandstone reservoirs overlying the posed in the Arctic National Wildlife Refuge and Kuparuk River field; an additional 2 billion barrels in the Brooks Range from Cape Lisburne to the in place is reported at the base of the oil column in Unit.eel States/Canadian border. More than 17 dif­ the Prudhoe Bay field. Small amounts of heavy oil ferent kinds of rock analyses, eight different oil have been recovered from several wells in other analyses, and three gas analyses are being used to areas of the Barrow arch. Oil-shale occurrences are evaluate rock (outcrop samples, core, drill cut­ limit.eel to small isolat.ed surface exposures in the tings), oil (seeps, drill stem test, oil-stained core, foothills of the Brooks Range. These oil-shale oc­ producing well), and gas (drill stem test, producing currences, which apparently represent basinal con­ well) samples on the North Slope. To date, the densed deposition during Mississippian, Triassic, more than 60,000 analyses complet.ed on these and Jurassic time, are tectonically displaced and of samples have been placed into a computer-based limit.eel areal extent. Tight-gas sand and geopres­ file for storage and retrieval in tabular, graphical, sured methane are known in several areas of the or map form; numerous graphical software pro­ Colville trough in Brookian and uppermost Elles­ grams have been written to facilitate interpreta­ merian rocks. Gas hydrates were report.edly cored tion and publication. So far, these petroleum in an industry well near Prudhoe Bay, and the geochemical data have been used to map and pressure and temperature conditions necessary for evaluate the organic matter content, type, and the existence of hydrates occur over a wide on­ thermal maturity of the major rock units and to shore area generally within 50 km of the shoreline. characterize the known oil and gas occurrences. Coalbed methane potential is limit.eel to the rela­ This evaluation of petroleum source rock tively shallow occurrences in the nonmarine part richness, type, and thermal maturity on the of the Brookian sequence and the relatively deep Alaskan North Slope is based on five petroleum

occurrences in the lowermost part of the Elles­ geochemical analyses (organic carbon content, C15+ merian sequence. Brookian coal volumes are very hydrocarbon content, elemental analysis, visual large, whereas Ellesmerian coal volumes are large­ kerogen, and vitrinite reflectance) that were ly unknown. routinely performed on rock samples from 63 The role of the USGS in the exploration and Government-drilled wells within or adjacent to the development of North Slope oil and gas resources NPRA. Samples were select.eel from rocks ranging continues to be important. From the earliest gen­ widely in depth and age: from surface to 20,000 ft eral North Slope studies at the tum of the 20th and from Tertiary to Ordovician. Sample material century to the current focused studies of oil and includes drill cuttings, sidewall cores, and conven­ gas resources, the USGS has provided the public tional cores. Contour maps to evaluate the petro­ with an impressive body of useful scientific data leum source rock richness, type, and thermal and interpretations pertinent to hazard identifica­ maturity were drawn for 12 of the stratigraphic tion, land classification, and resource evaluation. units penetrated.

Organic carbon content (wt%), C15+ hydrocarbon PETROLEUM SOURCE ROCK RICHNESS, content (ppm), elemental analysis, and visual kero­ TYPE AND MATURITY FOR FOUR ROCK UNITS gen type indicate that the Shublik Formation (Tri­ ON THE ALASKAN NORTH SLOPE-ARE THEY assic), the Kingak Shale (Jurassic), the pebble shale SOURCES FOR THE TWO OIL TYPES? unit, and the Torok Formation (both Cretaceous) BY LESLIE B. MAGOON AND are petroleum source rocks. Even though rock units GEORGE E. CLAYPOOL younger than the Nanushuk Group (Cretaceous) have organic carbon contents higher than 1 wt%, Since 1976, the U.S. Geological Survey (USGS) they are so immature that they can be considered has been engaged in a comprehensive petroleum only potential source rocks. The Nanushuk Group geochemical study to assess the petroleum and the Sag River Formation (Triassic) include resources on the Alaskan North Slope. This study shale that, in most places, resembles the source involves the collection and interpretation of shale within the Torok Formation and the Shublik geochemical data not only from exploratory wells Formation/Kingak Shale, respectively. The En­ drilled in the National Petroleum Reserve in dicott (Devonian and Mississippian), Lisburne Alaska (NPRA) but also from wells drilled to the (Mississippian and Pennsylvanian), and Sadlerochit

30 (Permian and Triassic) Groups, though not source Association of Petroleum Geologists (AAPG), in­ rocks, contain migrated hydrocarbons. cluded a 4-day research conference in 1983, a 1-day Thermal maturity, measured by vitrinite reflec­ short course at the AAPG 1983 Annual Meeting tance (% Re,), increases from north (the Barrow in Dallas, and a symposium volume that will be high) to south (the Colville trough). Within the Col­ published in 1984. There were three objectives: (1) ville trough, for a given stratigraphic depth, the to provide similar data on the same samples from western part of the NPRA region has a higher re­ various research groups for interlaboratory com­ flectance value than the eastern part. Within the parison; (2) to compare various analytical tech­ NPRA, well control is sufficient to indicate that niques used by different research groups in eval­ the Upper Cretaceous and Tertiary rocks are in the uating petroleum source rocks and oils; and (3) to diagenetic stage (~0.6% Ro) of petroleum genera­ determine which shale units penetrated in the tion. Substantial volumes of the Jurassic and NPRA could have been sources for North Slope Lower Cretaceous rocks have reached the liquid oils. Research methods, results, and interpreta­

window or catagenic stage (0.6-2.0% R0), whereas tions varied widely. One method that was com­ most of the pre-Jurassic rocks are in the metagen­ monly used was a conventional one-gas chroma­

etic stage (¥22.0% R0) of petroleum generation. tography. In addition, other groups applied the A total of 40 oil samples from across the North more advanced technology of computerized gas Slope have been analyzed by the U.S. Bureau of chromatography/mass spectrometry (GC-MS), Mines and the U.S. Geological Survey. Results of which enabled the researchers to examine both these analyses suggest two distinct genetic oil saturated and aromatic hydrocarbons in greater types. The first, the Simpson-Umiat oil type, oc­ detail; carbon isotope, fluorescence, and pyrolysis curs in reservoir rocks of Cretaceous and Quater­ were other methods employed. Results from a few nary age and includes oil from seeps in the Skull groups indicated no correlation between any of the Cliff, Cape Simpson, Manning Point, and Ungoon shale units and oils. However, the consensus was Point areas, and oils from WoH Creek test well no. that the Shublik Formation and the Kingak Shale 3 and the Cape Simpson and Umiat oil fields. correlate with the Barrow-Prudhoe oil type and the These are higher gravity, low-sulfur oils with no, pebble shale unit and, possibly, the Torok Forma­ or only slight, odd-numbered n-alkane predomi­ tion are the source for the Simpson-Umiat oil type. nance and pristane-to-phytane ratios greater than Future work for our group will include (1) further 1.5. Also, these oils have 13C values ranging from investigation into oil-rock correlation to refine our -29.1 to -27.8 permil and 34Svalues ranging from understanding of the origin of North Slope oil and -10.3 to -4.9 permil. (2) interpretation of the large number of petroleum The second type, the Barrow-Prudhoe oil type, geochemical data on samples acquired in the occurs in reservoir rocks of Carboniferous to Brooks Range thrust belt. Results of investiga­ Cretaceous age and includes oils from South Bar­ tions should provide clues to the oil and gas poten­ row gas field, Prudhoe Bay oil field, and Fish tial of the thrust belt and reveal how this belt Creek test well no. 1. Physical properties of the relates to the oil accumulations in the north. Barrow-Prudhoe oil vary, but generally the oil is a medium-gravity high-sulfur oil with slight even­ EMERGING RECOGNITION OF THE NONFUEL numbered n-alkane predominance and pristane-to­ MINERAL RESOURCES OF ARCTIC ALASKA phytane ratios less than 1.5. This oil has 13C values BY DONALD GRYBECK of -30.3 to -29.8 permil and 34S values of from -3.0 to +2.1 permil. Some of the most exciting new mineral discover­ The next phase of this work is to determine ies in Alaska during the past two decades have which rock unit may have generated a particular been in the Brooks Range, yet conventional oil type. Toward this goal, a unique 2-year study wisdom 25 years ago was that northern Alaska has been carried out by 30 research groups from was rather unpromising, if not geologically unfav­ Government, industry, and academia, represent­ orable for mineral deposits. Nonetheless, what has ing the United States and seven other countries, to emerged in the Brooks Range is a mineral frontier, analyze the same 15 rocks and nine oils from the largely as a result of detailed geologic mapping, North Slope. This study, conceived and organized systematic mineral exploration, better accessibil­ by the USGS and sponsored by the American ity, and new ore-deposit models.

31 In 1898, a wave of prospectors began moving their locations. However, even if some of the larger through northern Alaska in their quest for gold, deposits have already been found, large areas have and by 1909 they had discovered all the gold placer yet to be examined in any but cursory fashion and districts that are known today-Chandalar, Koy­ the expanding geologic data base and catalog of ukukk, and Kiana-as well as several lode pros­ identified types of deposits strongly suggest that pects. Also in 1898, the U.S. Geological Survey many other large deposits do exist in the Brooks (USGS) began its geologic exploration of northern Range. Alaska and by the early 1940's had mounted sev­ eral expeditions that defined the basic geographic COAL OCCURRENCE, QUALITY, and geologic framework of northern Alaska. In AND RESOURCE ASSESSMENT, 1944, the USGS began extensive geologic studies NATIONAL PETROLEUM RESERVE IN ALASKA of Naval Petroleum Reserve Number 4, and by BY GARY D. STRICKER 1953 had a good understanding of the geology of the Arctic Coastal Plain and the Arctic foothills. But by 1950, in spite of more than a half-century of Field studies by U.S. Geological Survey person­ work, the geologic map of the Brooks Range still nel in 1977 and 1978 of the Cretaceous Torok, had large blank areas, most of the range remained Kukpowruk, and Corwin Formations in the west­ essentially inaccessible, and relatively little ern portion of the NPRA (National Petroleum Re­ mineral exploration had been done. In the early serve in Alaska) and Cretaceous Torok, Tuktu, 1950's, helicopters were first used for geologic Grandstand, and Chandler Formations in the east­ mapping in the Brooks Range. Although their in­ ern portion of NPRA indicate that two major delta troduction produced no immediate breakthroughs, systems are responsible for most of the coal in retrospect it was pivotal. Systematic geologic accumulation in this area. The Corwin delta in the mapping and mineral exploration became practical western portion of NPRA was an early Albian to for the first time and has continued unabated Cenomanian, north and east prograding system, since. whereas the slightly younger mid-Albian to Ceno­ In 1957, Bear Creek Mining Co. began explora­ manian Umiat delta system prograded north and tion of the bornite copper deposit in the Ambler northeast in the eastern portion of NPRA. Investi­ district and soon after began mineral exploration gations of the lithologies, fossils, and primary throughout the Brooks Range. Their first world­ depositional structures of these formations indi­ class discovery was the Arctic copper-zinc massive cate that the Corwin system was deposited as a sulfide deposit in 1965. Further work by several large, high-constructional, ''birdfoot'' shaped delta companies has now detailed a belt of copper-zinc on which thick (as much as 10 m) and numerous massive sulfide deposits more than 160 km long coals developed on splay and interdistributary bay along the south flank of the Brooks Range. Sim­ platforms away from the influence of the Cretace­ ilarly, the initial discovery of zinc-lead mineral­ ous epicontinental sea. The Umiat delta started ization in the De Long Mountains by LL. Tailleur out as a high-constructional system but in time of the USGS in 1969 has led to delineation of the became wave dominated, and its shape changed to Red Dog deposit, a large volocanogenic massive lobate. Boreholes indicate that north of the out­ sulfide deposit now being developed by Cominco crop belt, the rocks of the Umiat delta quickly lose Ltd., as well as several smaller similar deposits, their non-marine characteristics. Because of the and to recognition of widespread potential for small size of the Umiat delta and marine influences other volcanogenic deposits along the northwest on it, coals were laid down in sparse, thin, and flank of the Brooks Range. Though not so note­ discontinuous beds. worthy, numerous other deposits of various types Eighty-six coal samples have been collected have been found in the past 20 years, including from NPRA as part of a comprehensive program several porphyry copper deposits, one porphyry by the U.S. Geological Survey to describe the molybdenum deposit, several barite deposits, and chemistry of United States coal. These samples many others. consist of face channel, grab, auger, and drill core In view of the naivete of past projections, it may samples. Proximate and ultimate analyses, heat­ be premature to suggest how many mineral de­ of-combustion, air-dried loss, and forms-of-sulfur posits yet lie undiscovered in northern Alaska, or determinations were run on 36 samples; major and

32 minor oxides and trace element analyses were per­ inversely with regional heat flow and directly with formed on all 86 samples to determine coal quality. thermal conductivity, and the subzero value of An additional 20 proximate and ultimate analyses mean surface temperature. Thus the heat flow and were determined by the U.S. Bureau of Mines. In a surface temperature are similar at Barrow and total of 106 samples, 10 samples are from the Prudhoe Bay, but permafrost is twice as thick at eastern portion, 9 samples from the central por­ Prudhoe Bay (620 m) because the thermal conduc­ tion, and the remaining 87 are from the western tivity of the ice-rich siliceous sediments there is portion of NPRA. twice as great. The primary cause of variable per­ Apparent coal rank ranges from lignite A to mafrost thickness at NPRA (200-400 m) is prob­ high volatile A bituminous coal, with the highest ably local variation in thermal conductivity. ranked coals located in the southern half of NPRA. However, work in progress by our colleagues, John Sulfur content ranges from 0.10 percent to 2.0 per­ Sass and Robert Munroe, suggests that there cent, which appears comparable to that of other might also be important lateral variations in heat Western United States coals of similar rank. The flow, possibly associated with migration of fluids concentrations of trace elements of environmental deep in the sedimentary basin. concern such as As, Be, Hg, Mo, Sb, and Se also The periodic variation in surface temperature appear similar to major Western United States from summer to winter determines the position of coals. the top of permafrost, as it generates the active Published estimates of unidentified coal re­ (seasonally thawed) layer upon which man's ac­ sources in NPRA range from just over 100 billion tivities take place. The thickness of the active to 3.3 trillion short tons. Based on published data, layer is very sensitive to its thermal properties and there are approximately 50 billion short tons of to the mean and annual range of surface temper­ identified coal resources in NPRA. For an area as ature. Modification of the surface, whether by large as NPRA, available data are insufficient to natural processes or by man, generally changes all indicate any realistic potential coal resources. three parameters and the thickness of the active layer as well. Seasonal temperature variations also PERMAFROST AND THE GEOTHERMAL REGIME cause visco-elastic thermal stress in permafrost BY ARTHUR H. LACHENBRUCH AND which results in networks of recurring tension B. V. MARSHALL cracks, meters deep and tens of meters apart. Seasonal freezing of meltwater in the cracks Permafrost is the region in the solid earth where results in the growth of networks of massive ice the temperature is below 0°C summer and winter. wedges; differential settlement of the tundra sur­ Within this region, water usually occurs as ice, face above these wedges under changing active often in massive segregated forms, although capil­ layer conditions, controls surface drainage pat­ lary water, brines, and gas hydrates also occur. terns and is a principal cause of damage to engi­ The frozen condition renders permafrost imperme­ neering structures. able to water flow, subject to brittle fracture under Recent systematic changes in the mean annual seasonally induced thermal stress, and subject to surface temperature leave tell-tale curvature in the mechanical failure and flow when thawed by geothermal profile from which the surface change natural processes or disturbed by man. Hence an can be investigated by conduction theory. Obser­ understanding of the factors controlling the geo­ vations in wells along the Alaskan Arctic Coast in­ thermal regime is necessary for an understanding dicate a surface warming of 1 Y2 to 3 ° C in the last of geomorphic processes and for successful design 100 years or so with a net accumulation of heat by of engineering structures such as roadways, the solid earth surface of 5-10 Kcal/cm2 during the heated buildings, pipelines, and oil wells in perma­ event. frost terrains. Studies of these factors are greatly Surface bodies of water such as lakes, rivers, and simplified by the general absence of heat transfer shallow seas that do not freeze to the bottom by flowing ground water; temperatures can be represent hot spots on the surface in permafrost estimated with confidence from heat-conduction terrain. In northern Alaska, such bodies deeper theory if the ground surface temperature, regional than 2 m have mean bottom temperatures close to heat flow, and thermal properties are known. 0°C, about 10°C warmer than the emergent sur­ The equilibrium thickness of permafrost varies face beyond their shores. The configuration of

33 these bodies continually changes as lakes are Pre-P/,eistocene(?) Glaciation. The oldest glacial drained or shorelines migrate as a result of thermal interval in the Brooks Range is represented by the erosion. Two- and three-dimensional transient informally named "Gunsight Mountain" erratics­ conduction models permit a calculation of the isolated boulders of highly resistant rock types configuration of the underlying thawed region for beyond the limits of recognizable drift of Pleisto­ application to water-supply problems, or a recon­ cene age. These erratics typically occur on uplifted struction of the shoreline history from the linger­ plateaus along the north flank of the Brooks ing thermal effects at depth. According to a recent Range; they cannot be traced to existing mountain synthesis by David Hopkins, rising sea level and valleys. The extent of erratics north of the range thawing ice-rich sea cliffs probably caused the suggests that much of the precipitation that nour­ shoreline of the Beaufort Sea to retreat tens of ished the glaciers may have been derived from the kilometers in the last 20,000 years inundating a north, probably prior to formation of the present part of the Alaskan continental sheH that is sea-ice cover over the Arctic Basin. presently the target of intensive oil exploration. A Early(?) Pleistocene Glaciation. The oldest simple transient conduction model applied to the recognizable drift sheet in the Brooks Range is Prudhoe Bay area suggests that this recently in­ assigned to the Anaktuvuk River Glaciation. undated region is underlain by near-melting, ice­ Glaciers of Anaktuvuk River age flowed through rich permafrost to depths of 300-500 m; its pres­ mountain valleys at levels generally 100 m or more ence is important to seismic interpretations in oil above their modem floors. Extenstve moraines exploration and to engineering considerations in beyond the mountains are fairly continuous but oil production. When permafrost configurations subdued, with low slope angles, mature drainage are confirmed by offshore drilling, heat-conduction networks, complex thaw-lake basins, and sparse models should yield reliable new information on erratics. The drift sheets have been dissected by the chronology of arctic shorelines. streams that flowed 40-65 m above modem levels and eroded valleys as wide as 10 km within the GLACIATION IN ARCTIC ALASKA glacial deposits. BY THOMAS D. HAMILTON Middle Pleistocene Glaciation. The complex of drift sheets assigned to the Sagavanirktok River The glacial record of arctic Alaska includes ad­ Glaciation was deposited after a long interval of vances of late Tertiary age, a complex sequence of valley enlargement and pedimentation that fol­ Pleistocene fluctuations, and minor expansions of lowed Anaktuvuk River time. Drift extends into cirque glaciers during the Holocene. Glaciers valley centers, where it generally stands within originated mainly within the Brooks Range, a 40 m of modem stream levels. Moraines retain 150-km-wide mountain chain that extends across much of their original morphology, but deposits northern Alaska The range evidently supported are deeply oxidized, subdued by mass wastage, extensive ice caps during late Tertiary and early and dissected by streams. Two separate drift Pleistocene glaciations, because erratics of Brooks sheets assigned to the Sagavanirktok River Gla­ Range provenance indicate that large ice streams ciation are present locally. and piedmont glaciers fed from alpine sources ex­ Late Pleistocene Glaciation. Glacial deposits of tended far to the north across the Arctic Slope. late Pleistocene age occupy modem valley floors Glaciers of middle and late Pleistocene age were and generally are little eroded; their stony surfaces successively less extensive; they were mainly con­ lack deep weathering. The drift sheets are divisible fined to mountain valleys and flowed only short into older and younger complexes, assigned re­ distances beyond the north flank of the range.. A spectively to the Itkillik and Walker Lake Glacia­ second ice source, probably in the Canadian Arc­ tions of early and late Wisconsin age. Itkillik tic, was responsible for ice-rafted erratics in late deposits are slightly oxidized, and are somewhat Cenozoic marine deposits along the Arctic coast subdued by postglacial solifluction and pattemed­ east of Barrow. A third ice source may be indi­ ground formation. Walker Lake deposits, dated by cated by erratics of unknown provenance in Ter­ radiocarbon at between 24,000 and 11,500 yr B.P., tiary(?) gravel near the Colville River delta Only are morphologically fresh, have little solifluction the record produced by Brooks Range glaciers will cover, and still are partly ice cored. be considered here (fig. 7). Ho/,ocene Glaciation. An interval of milder

34 HOLOCENE ~ Drift of Fan Mountain Glaciation

LATE WISCONSIN Drift of Walker Lake Glaciation

EARLY WISCONSIN Drift of ltkillik Glaciation

"Bettles Gravel"

Drift (upper) of Sagavanirktok River Glaciation

MIDDLE PLEISTOCENE

Drift (lower) of Sagavanirktok River Glaciation

Deep incision of mountain valleys

EARLY(?) PLEISTOCENE Drift of Anaktuvuk River Glaciation

Deep incision of mountain valleys

PRE-PLEISTOCENE "Gunsight Mountain" erratics

Figure 7.-Tim&distance diagram, showing lat;e Cenozoic events and glacial deposits of the north-central Brooks Range, Alaska. Horizontal axis (not to scale) shows distance north of modem valley heads along Continental Divide.

35 climate in northern Alaska was followed by ice ad­ wedges in Antarctica indicate that these wedges vances and alluviation of mountain streams begin­ develop beneath vegetation-free surfaces in the ning around 4,500 to 3,000 yr B.P. Drift formed by most arid regions by the repeated formation of expanded cirque glaciers in the Brooks Range is thermal-contraction cracks and subsequent filling assigned to the Fan Mountain Glaciation, which with loose sand. The Alaskan fossil sand wedges occurred in two phases separated by a milder inter­ are composed of sand that is texturally· distinct val between about 2,000 and 1,000 years ago. from the host materials but similar to the sand composing the dunes. The loose sand that filled the thermal-contraction cracks evidently was derived from wind-driven sand moving across the A PLEISTOCENE SAND DESERT IN ARCTIC coastal plain toward the dunes. ALASKA The linear dunes and sand wedges thus define a BY L. DAVID CARTER zone of mobile sand that was dry, barren, and windswept during middle and late Wisconsinan time and, possibly, throughout the Wisconsinan. A sand desert composed of large dunes and bar­ During this same period, however, large lakes ren sand plains extended across a significant part formed south of this zone where drainage from the of Arctic Alaska north of the Brooks Range during Arctic Foothills was blocked by the dunes; and in late Pleistocene time. The dunes occupied about the loess terrane south and west of the lakes, sur­ 11,600 km2 of the Arctic Coastal Plain west of the face moisture was sufficient to create syngenetic Colville River, and the sand plains extended at ice wedges. Extensive tracts of barren ground may least 100 km northeast of the dunes. This sand have been limited to the zone of mobile sand dur­ desert was part of an eolian system that extended ing much of this period because radiocarbon about 400 km from sediment sources on outwash dating of fossil bones indicates that before 28,000 plains and fans in the east to where waning winds years B.P. vegetation in the loess terrane was suf­ deposited loess along the margin of the Arctic ficient to support such large herbivores as mam­ Foothills southwest of the dunes. moth, horse, and bison (Carter, 1982). However, Linear dunes, as much as 20 km long and 1 km none of the dates on these mammals is less than wide (Carter, 1981), make up the eastern 7,000 km2 28,000 years B.P., and few organic remains have of the dwie field, but dune types in the rest of the been found in coastal-plain deposits between area have not yet been classified. All the Pleisto­ 14,500 and 28,000 years old relative to both older cene dunes are obscured by a thin cover of younger and younger deposits. Desert conditions may have eolian sand that includes small stabilized longitudi­ expanded beyond the zone of mobile sand during nal and parabolic dunes, identified during earlier the late Wisconsinan cold phase to include most of U.S. Geological Survey fieldwork (Black, 1951). In the Arctic Coastal Plain and the Arctic Foothills. addition, the Pleistocene dunes have been exten­ Steppe-tundra vegetation and large mammals may sively modified by thermokarst processes. not have persisted into late Wisconsinan time Radiocarbon ages of herbaceous plants from throughout this vast region. eolian and lacustrine sand within the dune field in­ dicate that the dunes were active from before 36,000 to nearly 12,000 yr B.P. Bedding attitudes, REFERENCES CITED dune-ridge orientations, and measurements of pseudocrosslamination formed by climbing adlhe­ Black, R. F., 1951, Eolian deposits of Alaska: Arctic, v. 4, po 89-111. sion ripples demonstrate a wide regime similar to Carter, L. D., 1981, A Pleistocene sand sea on the Alaskan that of the present and indicate that the dominant Arctic Coastal Plain: Science, v. 211, p. 381-383. directions of sand-moving winds were easterly to Carter, L. D., 1982, Lare Wisconsin desertification in northern northeasterly. ' Alaska: Geological Society of America Abstracts with Pro­ Former barren-ground and dry-surface condi­ grmns, v. l 4, no. 7, p. 461. Carter, L. D., in press, Fossil sand wedges on the Alaska Arctic tions upwind of the dunes are indicated by fossil Coastal Plain and their paleoenvironmental significance, in sand wedges, as much as 7 m deep and 3 m wide Proceedings of the Fourth Inoomational Conference on (Carter, in press). Observations of modem sand Permafrost: Washington, National Academy Press.

36 SEDIMENTARY FACIES ON AN finer material with finer grained beds often ICE DOMINATED SHELF, BEAUFORT SEA, contorted, mottled and structureless. Lat­ ALASKA erally discontinuous beds are composed of ice BY PETER W. BARNES AND ERK REIMNITZ gouge infill which results in linear "shoe­ string" deposits characterizing this part of Sea ice is a major factor influencing the char­ the shelf. acter of high latitude shelf deposits today and has 3) Stamukhi zone facies-Ice gouging becomes the been throughout the Quaternary. Ice impacts sedi­ dominant agent in forming sedimentary mentation by physically disrupting the sea floor, structures plowing and replowing the seafloor by influencing wave and current regimes, by raft­ mixing the sediments into a heterogeneous ing sediments to depocenters and by affecting the mass. The resulting facies in this zone grades erodability of seabed materials. As a result of this seaward from the fast ice zone facies ·through interaction distinctive facies are developed in the a zone of contorted bedded sequences to com­ surficial sediments. pletely heterogeneous sequences of gravelly The ice environments affecting the shelf stratig­ muds in waters 30 to 40 m deep. raphy can be divided into three zones. Inshore of 4) Outer shelf facies-In waters deeper than 50 m, about 20 m is the semistationary fast-ice, which is few ice ridges grow large enough to interact inundated with flood waters near rivers in the with the seafloor and hydraulic processes spring. Between about 20 m and 40 m a zone of dominate sedimentary structures. The result­ grounded ice ridges composed of seasonal and mul­ ing outer shelf facies is characterized by tiyear ice (called stamukhi) is present during the bedded sequences of muds and sandy muds winter and often lasts into the summer months. which are laterally continuous. Seaward of the stamukhi zone, polar pack ice is in During the transgressions and regressions of the motion through much of the year, its depth of pen­ Quaternary these facies extended to deeper water etration onto the shelf is controlled by seasonal on the arctic shelves and would have been a part of weather pattern and ice draft. the facies on subarctic shelves where sea ice was The ice zonation has resulted in a characteristic present. These facies would also be present in sedimentary facies in the different ice environ­ glacial lakes where lake ice formed and interacted ments as follows: with the lake beds. 1) Delta facies-The normal interplay of sediment supply and marine reworking is seasonally in­ QUATERNARY SEDIMENTATION ON THE terrupted by ice flooding and vertical drain­ ALASKAN BEAUFORT SHELF: SEDIMENT age through the ice canopy (strudel) creating SOURCES, scour depressions whose fill becomes the GLACIOEUSTATISM, AND REGIONAL TECTONICS dominant delta facies. Bedding is laterally BY DAVID A. DI NTER discontinuous due to repeated strudel scour­ ing. The stratigraphy is characterized by Shallow sedimentary strata underlying the mid­ alternating layers of sand and finer materials dle and out.er continental shelf of the Alaskan and layers of fibrous organic matter. Gravel is Beaufort Sea compose, in general, a sequence of notably absent in the marine part of modem wedges, each of which thickens seaward to the delta facies. shelf break. At least seven such wedges, with max­ 2) Fast ice zone facies-Although ice gouging in imum seaward thicknesses on the order of 15 to 40 this zone occurs at a rate high enough to com­ meters, are recognized on high-resolution seismic pletely rework the surficial sediments in less reflection profiles. The wedges are bounded by than. 200 years, hydraulic processes are disconformities that presumably represent suc­ resp6nsible for the sedimentary structures ob­ cessive subaerial exposures of the shelf during served in this zone. These processes infill Quaternary glacioeustatic sealevel minima. Many gouges with finely laminated sands and mud of these surfaces are intermittently channelled while unbedded sandy mud is derived from beneath the middle shelf, and some are overlain by the gouging and mixing processes. The result­ thin, discontinuous, acoustically chaotic layers in­ ing facies is a bedded sequence of sand and ferred to be nonmarine or shallow marine in origin.

37 Seaward of several river mouths foreset sequences over great distances beneath the shelf cannot be less than 15 meters thick are intercalated between traced further downslope on reflection seismic some of the wedges. profiles. Several of the wedge-shaped strata die out in­ shore beneath the middle shelf. At least three, REFERENCES CITED however, persist in thicknesses of 2 to 10 meters at the shoreward ends of seismic profiles, which typ­ Dint.er, David A., 1982, Holocene marine sediments on the mid­ dle and outer continental shelf of the Beaufort Sea north of ically lie close to the 25-meter isobath some 20 to Alaska: U.S. Geological Survey Map 1-1182-B, with t.ext, 30 kilometers from shore. Tentative correlations 5 p., 1 fig., 2 map sheets. with shallow boreholes seaward of the barrier Grantz, Arthur, and Dint.er, David A., 1980, Constraints of islands (Peggy Smith and David Hopkins, per­ geologic processes on petroleum development in the West­ sonal commun., 1983) support the interpretation ern Beaufort Sea: Oil and Gas Journal, v. 78, no. 18, p. 304-319. that these strata are primarily marine, and ac­ Rodeick, C. A., 1979, The origin, distribution, and depositional cumulated in late Quaternary time during relative history of gravel deposits on the Beaufort Sea continental highstands of the sea. shelf, Alaska: U.S. Geological Survey Open-File Report Lithologies of surficial gravel samples from 79-234, 87 p., 31 figs. seabottom exposures of the top of the youngest wedge are exotic to Alaska, but similar to Paleo­ PERMAFROST AND RELATED ENGINEERING zoic suites exposed on the shores of Coronation PROBLEMS ON THE NORTH SLOPE AND Gulf in the Canadian Arctic Islands. Rodeick BEAUFORT SHELF, ALASKA (1979) has proposed this area as the probable BY OSCAR J. FERRIANS, JR. source of the gravels and suggested ice-rafting as the most feasible transport mechanism. A great The critical need for finding and developing new volume of sediment-laden icebergs must have been and dependable sources of hydrocarbon resources shed from the Canadian Arctic Islands into the has caused a tremendous increase in exploration Arctic Ocean during the decay of the Laurentide and development activities on the North Slope of Ice Sheet in late Wisconsin/early Holocene time. Alaska and on the shelf of the Beaufort Sea. These This period coincides with the early phases of the regions pose special engineering problems and are reinundation of the shelf subsequent to the latest environmentally ''sensitive.'' Consequently, they glacioeustatic sea level minimum approximately require careful study and consideration to ensure 18,000 years ago and so appears to be a likely time the integrity of engineering structures and to of deposition for the now-relict gravels on the minimize adverse environmental impacts. One of shelf. It is possible that earlier Canadian Arctic ice the most important factors to be considered in sheets were significant sediment sources for the these northern regions is permafrost. older Quaternary wedges underlying the Alaskan Permafrost, or perennially frozen ground, is a Beaufort shelf. widespread natural phenomenon. It underlies ap­ An exception to the idealized shallow strati­ proximately 20 percent of the land area of the graphic geometry discussed above occurs on the world, and 85 percent of Alaska is within the per­ eastern part of the Alaskan Beaufort shelf, where a mafrost region. In Alaska, the known permafrost persistent structural high some 30 km wide and thickness ranges from about 600 m near Prudhoe 60 km long trends northeast from Camden Bay. Bay to less than a meter at the southern border of The youngest sedimentary wedges on the shelf on­ the permafrost region. On the North Slope, perma­ lap the. flanks of this arch, and nearly every earth­ frost thickness generally is greater than 200 m. quake recorded from the shelf has an epicenter in Locally, however, it is absent under large lakes the area marked by a paucity of late Quaternary deep enough so that they do not freeze to their bot­ sediment (Grantz and Dinter, 1980; Dinter, 1982). toms in the winter. Near the axis of the arch strongly deformed strata The distribution and character of subsea perma­ of unknown age are exposed within 1 meter of the frost is still poorly understood; however, ice­ seafloor. bonded permafrost is known to be widespread Seaward of the shelf break, slides and slumps under the shelf of the Beaufort Sea. This subsea pervasively disrupt the shallow sedimentary permafrost generally differs from the adjacent on­ strata such that stratigraphic horizons prominent shore permafrost by being warmer and containing

38 less ice. Most of the subsea permafrost is relict, tive to depth, temperature, salinity or oxygen, can having formed under subaerial conditions at a be used to identify the transgressive-regressive time when sea level was much lower than it is cycles through faunal changes which correspond today. to the environmental changes. Thawing of ice-rich permafrost, the most serious Benthic foraminifers have been identified in a permafrost-related engineering problem, results in series of offshore boreholes along the Arctic a loss of strength and a change in volume of the Coastal Plain. Transgressions represented in these ice-rich soil. Under severe conditions, the ice-rich boreholes range from Berringian to Holocene in soil can liquefy and lose essentially all of its age. Foraminiferal faunas in the oldest transgres­ strength. A more common occurrence is differen­ sions (Berringian to Fishcreekian) are poorly tial settlement of the ground surface. represented as material of this age is rarely Proposals to chill the natural gas in buried pipe­ encountered. The younger transgressions (Kotze­ lines as a means of mitigating the problems caused buan through Holocene) are well represented, and by the thawing of permafrost pose different microfossils associated with these transgressions problems-the most difficult to solve is frost heav­ can be described and traced throughout the Arctic ing caused by the freezing of unfrozen soils sur­ Coastal Plain. rounding the pipe. Kotzebuan and Pelukian faunas are character­ The two basic methods of constructing on per­ ized by moderate foraminiferal numbers, moderate mafrost are (1) the active method and (2) the pas­ diversities, indigenous Pacific and Atlantic sive method. The active method is used in areas species, warmer temperatures and deeper waters. where permafrost is thin and generally discontinu­ Kotzebuan faunas generally indicate greater water ous, or where it contains relatively small amounts depths and a greater Pacific and Atlantic influence of ice. The object of this method is to thaw the than during the Pelukian. permafrost and, if the thawed material has a satis­ Kotzebuan assemblages are recognized only in factory bearing strength, then to proceed with con­ boreholes seaward of the barrier island chain from struction in a normal manner. Flaxman Island to Prudhoe Bay. Although the The object of the passive method is to keep the strata are of variable thickness, Pelukian assem­ permafrost frozen so that it will provide a firm foun­ blages are present in most boreholes on the Arctic dation for engineering structures. Obviously, the Coastal Plain between Flaxman Island and the passive method has wide application on the North Jones Islands. Both Kotzebuan and Pelukian Slope where permafrost is widespread, thick, and assemblages contain common occurrences of generally ice rich near the surface. When using this Cassidulina teretis, C. norcross~ C. islandica, method, every effort should be made to minimize Elphidium orbiculare, E. incertum, and BucceUa disturbing the ground surface, and when the frigUJ,a. Outer neritic and deeper water species ground surface is disturbed, to take carefully such as Stainforthia concava are sparse, whereas planned mitigative measures immediately. Various elphidiums and other inner neritic species are more techniques used to help keep the permafrost frozen common in the Pelukian than in the Kotzebuan, include using different kinds of insulation (both reflecting the higher stand of sea level in the natural and man-made), elevating heated structures Kotzebuan. Elphidiella groenlandica, Elphidium abOve ground, and using refrigeration. asklu~ Eggerella advena, and Gordiospira arc­ tica are present as a result of the warmer temperatures and the influx of Atlantic and QUATERNARY MICROFOSSILS ON THE Pacific waters. ARCTIC SHELF Faunas of the early Wisconsin, Flaxman trans­ BY KRISTIN McDOUGALL gression, have moderate foraminiferal numbers, lower diversities, and indicate that water depths Late Pliocene and Quaternary marine transgres­ and temperatures were shallower and cooler than sions on the Arctic Coastal Plain are each defined during the Pelukian or Kotzebuan transgressions, by a particular sea level stand and by temperature but deeper and warmer than at present. Cassidu­ changes relative to the present conditions. Micro­ linids decrease significantly in abundance and con­ fossils are common and generally well preserved in stitute only a minor component of the Flaxman the marine strata. Foraminifers which are sensi- faunas. Elphidiella groenlandica, Elphidium

39 asklundi, and Elphidium excavatum alba also stress and strain, and an equation of state that become increasingly rare as the temperatures cool. relates the sea ice pressure to the ice concentra­ The Flandarian transgression is marked by low tion, thickness, and velocity. It lacks a complete foraminiferal numbers, low diversities and cold energy equation, although thermodynamic effects shallow waters which were less saline than at pres­ are treated parametrically. ent. Elphidium c/,avatum is the dominant species The numerical scheme of the combined model in most Flandarian faunas. keeps track of the amount of ice entering each grid Holocene faunas are best preserved and most square. In locations with a net inflow of ice, the variable. In general, the foraminiferal numbers are concentration increases according to the inflow high and species diversities are moderate to low. values as long as the concentrations do not exceed Elphidium orbiculare and Elphidium excavatum 99.5%. When calculated concentrations exceed alba are the most common species. Since the 99.5%, the Parkinson and Washington model re­ Holocene record is most complete, faunal changes duces all inflow velocities to the relevant grid are numerous and correspond to increasing water squares. The current model, however, with the depths associated with the transgression. Shallow­ Ling et al. formulation, retains the originally ing is observed in several of the boreholes and calculated ice velocities and appropriately thick­ related to the migration of the barrier islands or ens the ice to conserve ice volume. A fluid-type deltaic deposits. stress-strain relationship is used in the formula­ tion of internal ice stress, in which the normal A COMPARISON OF NUMERICAL RESULTS OF stress, or the sea ice pressure, is postulated to be ARCTIC SEA ICE MODELING proportional to the concentration and velocity WITH SA TE LUTE IMAGES convergence. The momentum equations, which are BY CHI-HAI LING AND CLAIRE PARKINSON 1 second order partial differential equations, are solved using successive over-relaxation and a nine­ The results of a dynamic/thermodynamic numer­ point finite difference method. ical model of Arctic sea ice are being comp~ Atmospheric inputs are mean monthly surface­ with satellite images from the Nimbus 5 electri­ air temperatures, surface dew points and sea level cally scanning microwave radiometer (ESMR). geostrophic winds from Jenne et al. (1969), while The model combines aspects of two previous sea the initial ice extent is from the ESMR data for ice models-those of Parkinson and Washington January 1, 1974. The ESMR sea ice extent data (1979) and Ling, Rasmussen, and Campbell (1980). for the remainder of 197 4 is then used for compar­ It is a solid/fluid model basically following the for­ ison against the model results. Model calculations mulation of the Parkinson and Washington model and ESMR data correspond well in the central with the addition of the constitutive equation and Arctic but reflect the lack of oceanographic inputs equation of state from the Ling et al. model. in the marginal ice zone regions. For instance, the The Parkinson and Washington model simulates model fails to produce the prominent indentation the seasonal cycle of sea ice thicknesses and con­ of open water often observed along the west coast centrations with a horizontal resolution of roughly of Greenland, which is presumably due to the 200 km and a timestep of 8 hours. The thermody­ warm West Greenland current. namics are calculated through energy balances at the interfaces between ice and air, water and ice, 1Goddard Space Flight CentA!r, NASA. Greenbelt. Maryland. and water and air. The ice dynamics are calculated through a momentum equation balancing air ARCTIC SEA ICE BY PASSIVE MICROWAVE stress, water stress, dynamic topography, and OBSERVATIONS FROM THE NIMBUS-5 SATELLITE Coriolis force, with an adjustment for internal ice BY WILLIAM J. CAMPBELL, PER GLOERSON1, resistance. This model has yielded results which AND H. JAY ZWALLY2 compare favorably with observed Arctic and Ant­ arctic sea ice variations. Observations made from 1972 to 1976 with the The Ling et al. model treats sea ice as a large­ Electrically Scanning Microwave Radiometer scale fluid. It uses a viscous fluid constitutive (ESMR) on board the Nimbus 5 Satellite provide equation that specifies the relationship between sequential synoptic information of the Arctic sea

40 ice cover. This 4-year data set was used to con­ LAND COVER AND TERRAIN MAPPING FOR THE struct a fairly continuous series of 3-day average DEVELOPMENT OF DIGIT AL DATA BASES FOR 19-GHz passive microwave images which has WILDLIFE HABITAT ASSESSMENT IN THE YUKON become a valuable source of polar information, FLA TS NATIONAL WILDLIFE REFUGE, ALASKA 1 2 yielding many anticipated and unanticipated dis­ BY MARK B. SHASBY , CARL MARKON , 1 1 coveries of the sea ice canopy observed in its en­ MICHAEL D. FLEMING , DENNIS L. MURPHY , tirety through the clouds and during the polar AND JAMES E. YORK1 night. Interpretation of the passive microwave satellite data set was performed by comparing The U.S. Geological Survey's EROS Field Office selected sequential images with corresponding and the U.S. Fish and Wildlife Services's Refuges microwave profiles and images acquired by the Division, both in Anchorage, Alaska, are currently NASA CV-990 airborne laboratory and with var­ working together on the use of Landsat multispec­ ious "in situ" microwave and physical observa­ tral scanner (MSS) data and digital elevation tions. These aircraft and surface microwave pro­ model (DEM) data to develop and test digital land grams were performed as part of the Arctic Ice cover and terrain data bases for assessing wildlife Dynamics Joint Experiments (AIDJEX) of 1972, habitat in Alaska's National Wildlife Refuges 75, and 76. Mesoscale microwave images of the (NWR). The inventory and assessment of re­ AIDJEX manned drifting station array (Triangle) sources for all NWR's in Alaska are being carried were obtained by aircraft during every season, and out under the mandates of the Alaska National extensive aircraft transects covering major por­ Interest Lands Conservation Act of 1980, which tions of the Arctic Basin in spring, summer, and requires the development of a comprehensive man­ fall. At the main camp within the AIDJEX tri­ agement plan for each refuge by 1987. The work angle detailed multifrequency passive microwave reported here was performed on the Yukon Flats observation, ice crystallographics, and dielectric NWR under an Interagency Support Agreement properties were measured in three test areas with that provided for the cooperative development of 2 areas of approximately 1.5X104 m • land cover and terrain digital data bases. Analysis of this three-level, three-resolution data The Yukon Flats NWP consists of approximately set has shown how satellite passive microwave 8.63 million acres of land and water in the upper observations can be used to map key sea ice param­ watershed of the Yukon River in northeastern eters on synoptic scales at time scales ranging from Alaska. Portions of seven summer and five winter several days to interannual: ice edge position, ice Landsat scenes were digitally registered to a concentration, multiyear ice, first-year ice, mixtures 127-meter Universal Transverse Mercator (UTM) of these two ice types, and snow melt on the ice. grid and processed to derive land cover information Significant variations of ice concentration are found for the refuge and an additional 4.5 million acres of to occur in various parts of the Arctic during all adjacent lands. DEM data acquired from the U.S. seasons. During every August-September period of Geological Survey's National Cartographic Infor­ the 4 years ESMR operated, large areas of low mation Center for the ten 1:250,000-scale USGS microwave radiances, attributed to low ice concen­ quadrangles comprising the study areas were tration, formed deep within the ice pack. In 1972, mosaicked and registered to the same 127-meter 73, and 76, these extensive zones of low ice concen­ UTM grid From the registered DEM data, slope tration occurred generally along the Transpolar and aspect information was derived to complete the Drift Steam. The anomalous distribution was in terrain information portion of the data base. 1975 when they appeared in a ring of 85° N. cutting Landsat and DEM digital data were processed across the Beaufort Sea Gyrc with another array by computer in the EROS Field Office Digital along the Transpolar Drift Steam between the Analysis Laboratory. Land cover was classified on North Pole and East Greenland Sea. See figure 8. summer Landsat MSS data utilizing a modified cluster-block approach followed by postclassifica­ tion stratification. The winter Landsat data were 1Goddard Laborat.ory for Atmospheric Sciences, Goddard Space Flight Cent.er, used to more accurately identify water and ripar­ Greenbelt, MD 20711. 2Goddard Laborat.ory for Atmospheric Sciences, Goddard Space Flight Cent.er, ian areas. Using terrain information (elevation, Tacoma, WA 98416. slope and aspect), certain spectral/information

41 1973 1974

w I.!> (Y)

1975 1976

fatd Near Minimum Sea Ice Extent - 6 September 1973, 26 September 1974, 11 September 1975, 11 September 1976 ~ Near Maximum Sea Ice Extent 23 February 1973, 20 March 1974, 18 March 1975, 27 March 1976 II Envelope of Low Microwave Ice Radiances during August and September.

FIGURE 8.-Arctic sea ice parameters for 1973-76.

classes were stratified into more meaningful map waterfowl populations are of primary importance classes. on the Yukon Flats Refuge. To address this infor­ The resultant digital data base containing land mation need, a computer-aided procedure for build­ cover information and the three terrain variables ing a lake inventory data base was developed for provides a flexible tool for subsequent wildlife assessing the current status of water bodies within habitat assessment and resource inventory. Mon­ the refuge and as a basis for future monitoring itoring and assessment of waterfowl habitat and activities.

42 The lake inventory data base is developed treme mobility, helium is one of the components of through a series of computer programs which ex­ oil and gas reservoirs most likely to escape and tract all water bodies from the land cover layer of subsequently migrate to the surface. Because data in raster format, to produce a new layer com­ helium is not of biogenic origin, its presence in prised only of water, and then convert the raster anomalous concentrations near the surface is an file to a vector data file from which a data base file indication of a subsurface source. Permafrost is produced. In the data base, each lake is iden­ samples are collected and hermetically sealed in tified with a unique number and is associated with aluminum cans, leaving 5-10 cc of air above the the following variables: latitude and longitude sample. The helium in the permafrost is then coordinates for the centroid of each lake, surface allowed to equilibrate with the air in the head area estimated in acres, and a water quality class space. Subsequently, the helium in the head space based on sediment loads or depth derived in the is analyzed and the concentration of helium in the Landsat-analysis phase of the project. Informa­ original sample is calculated through the use of tion from the data base can be queried and sum­ corrections for temperature, pressure, pore marized based on user specified criteria For par­ volume, and water content. Normal concentrations ticular lakes or regions, additional data variables of helium were observed in the permafrost overly­ can be added or derived. Options exist for output ing a variety of nonproductive areas in the Na­ in tabular form or in a plotted map format from tional Petroleum Reserve in Alaska and in an area the data base. Potential uses include investiga­ subsequently drilled as a dry hole. Abnormally tions relating waterfowl population to lake den­ high helium concentrations were observed on the sities, size, proximity to different cover types, and Simpson Peninsula over the Simpson oil field and other parameters. These investigations will help around the subsurface Simpson Canyon and are in­ managers gain a greater understanding of the re­ terpreted as being related to seepage of gases in source they are managing. areas where gently dipping Cretaceous strata have been truncated by the canyon. 1Tecbnicokr Government Services, Inc., work performed under U.S. Geological Survey Cantract Number 14-08-001-20129. The second technique involves the detection of 2u.s. Fish and Wildlife Service. anomalous shallow-subsurface occurrences of mag­ netic minerals through the use of low-altitude (90 m), special purpose, aeromagnetic surveys. GEOCHEMICAL DETECTION OF PROSPECTIVE PETROLEUM AREAS IN ARCTIC REGIONS These magnetic materials are interpreted to be the result of chemical reduction of normally fully oxi­ BY A. A. ROBERTS, T. J. DONOVAN, dized iron minerals to magnetite in the presence of J. D. HENDRICKS AND K. I. CUNNINGHAM seeping hydrocarbons. The magnetic contrast be­ tween typical sedimentary rocks and those en­ Geochemical prospecting for petroleum is based riched with this epigenetic magnetite results in on the premise that microseepage of compounds distinctive high wave-number and low-amplitude from oil and gas reservoirs does occur and that total field anomalies. Detection of these shallow these compounds subsequently migrate to the magnetic mineral occurrences is strongly en­ Earth's surface. These techniques involve the hanced through the use of a horizontal-gradient detection of epigenetic alteration of near-surface magnetic survey, which concurrently greatly rocks due to the presence of these seeping hydro­ reduces interpretation problems associated with carbons, or the detection of alterations of the diurnal variations and solar storms present at chemical composition of the near-surface soils and these high latitudes. Surveys over the Arctic soil gases themselves. Two geochemical explora­ Coastal Plain revealed magnetic anomalies over tion techniques that have been developed for use in the Barrow gas fields, over the Simpson Canyon the contiguous United States have been investi­ area of Cape Simpson, and slightly offshore in the gated for their applicability in the permafrost envi­ Dease Inlet off the National Petroleum Reserve. In ronment of the Arctic coastal plain. addition, surveys over the Arctic National Wildlife The first of these involves the detection of Refuge revealed a large area of anomalously high anomalously high concentrations of the noble gas magnetic gradients over the Marsh Creek anticline helium in near-surface permafrost. Owing to its suggesting that it may be a prime petroleum small molecular size, chemical inertness, and ex- prospect.

43 HYDROLOGY OF THE NORTH SLOPE, ALASKA shallow lakes that freeze nearly to the bottom the BY CHARLES E. SLOAN water can become so concentrated in dissolved solids by late winter that it would be unacceptable as a potable supply. The widespread occurrence of permafrost on the North Slope acts as an impervious barrier to the The hydrology of the North Slope is dominated movement of ground water, limiting its availabil­ by the cold, dry climate and permafrost. Stream­ ity, preventing the infiltration of surface water, flow virtually ceases during the long winter. and consequently accelerating runoff. Ground Precipitation occurs mainly as snow from Septem­ water is present beneath lakes and pools in rivers ber to May and is stored in the snowpack until that do not freeze to the bottom. However, water breakup, a dynamic flow period in late May and in the fine-grained sediments beneath lakes is early June. Most of the annual runoff occurs in the generally saline, and there is limited storage in the brief 2- to 3-week breakup period. The estimated unfrozen sediments beneath deep river pools. Most mean annual runoff on the North Slope averages water beneath the permafrost is also saline. Thaw­ about 0.5 cubic feet per second per square mile and ing of permafrost creates thaw lake depressions. ranges from about 0.3 on the Coastal Plain to Thermal erosion of ice-rich permafrost also leads about 2.0 in the mountains. Peak flows usually oc­ to rapid and spectacular erosion of coastal bluffs cur during spring breakup when the height of the and riverbanks, as well as rapid enlargement of flood flow is significantly increased by the lakes. presence of ice jams. Maximum evident floods A significant ground-water resource exists in range from about 7 to 80 and average about 40 carbonates of the Lisbume Group and in coarse cubic feet per second per square mile in large elastic rocks of the Sadlerochit Formation in the streams on the North Slope. eastern part of the Brooks Range near the moun­ The water quality of streams is generally excel­ tain front. Numerous springs, some quite large, oc­ lent. However, during periods of high flow the cur in this area. Sadlerochit Spring, which has a streams carry high concentrations of suspended discharge of about 35 cubic feet per second, the sediment and during periods of low or zero flow Shublik Spring, which flows at about 25 cubic feet dissolved solids may become concentrated and the per second, are individual springs that flow from water may become depleted in dissolved oxygen. bedrock. Discharge from the springs freezes in Lakes are the most conspicuous hydrologic fea­ winter to form large icings (aufeis). Icings are quite ture on the North Slope, in places composing as conspicuous and easily discernible on Landsat im­ much as 40 percent of the surface area of the agery. The source at springs can be found by going Coastal Plain. The lakes range in size from Teshek­ upstream from the icings. Tributaries of the puk Lake which covers about 315 square miles, to Ivishak River, including the Echooka River, Flood small pounds of less than an acre. There are Creek, Saviukviayak River, and the main stem of estimated to be more than 40,000 lakes greater the Ivishak, have a cumulative discharge of more than 1 acre in size in the. National Petroleum than 300 cubic feet per second from springs near Reserve in Alaska (NPRA) alone. Most of the lakes the mountain front. on the Coastal Plain are shallow and freeze to the Snow and ice are important as construction bottom during winter. Teshekpuk Lake is about 20 materials for roads, workpads, and airfields, and feet deep and stores about 4 million acre feet of as sources of water supply. Snow accumulation water, which is equivalent to about 2 years of can be managed through use of snow fences and average flow from the Colville River. A number of other wind barriers that influence snow deposition. deep lakes to the south of Teshekpuk Lake range Snowfall may occur during any month of the year, in depth from 20 to more than 70 feet. but usually sticks to the ground starting in Water quality in the lakes is generally very September and remains until late May or early good. Shallow lakes may become turbid when wind June. Drifts along river and lake banks frequently and wave action stirs up the bottom sediments. persist until late summer. Lake and river ice at­ Glacial lakes in the mountains and southern foot­ tains an average thickness of about 6 feet by late hills also have varying degrees of turbidity. In winter and occasionally is 8 to 9 feet thick.

44 PALEOGEOGRAPHIC AFFINITIES AND An unusual assemblage of Paleogene mollusks, ENDEMISM ostracodes, brachiopods, benthic foraminifers, OF CRETACEOUS AND PALEOCENE dinoflagellates and palynomorphs occurs at Ocean MARINE FAUNAS IN THE ARCTIC Point, northern Alaska (fig. 9). The endemic nature BY L. MARINCOVICH, JR., E. M. BROUWERS, of this assemblage suggests the possibility that D. M. HOPKINS the Arctic Ocean was not then in communication with the world ocean. Tentative correlation based The Arctic Ocean is the last of the world's on mollusks and ostracodes can be made with the oceans whose paleobiogeographic history is large­ early Paleocene Cannonball Formation of North ly unknown. The general configuration of the Arc­ and South Dakota, but not with some other ap­ tic Ocean and the presence or absence of major proximately coeval northern high-latitude faunas; connecting seaways to the North Pacific and this suggests a geographically restricted arctic North Atlantic influenced the composition of Late faunal realm. The molluscan and ostracode faunas Cretaceous and Cenozoic shallow-water arctic of the Ocean Point and Cannonball deposits have marine faunas. New finds of early Cenozoic marine relatively low species diversities, in strong con­ faunas in onshore stratigraphic sections along the trast to the highly diverse approximately coeval arctic margin of North America are providing faunas of tropical aspect in the Gulf of Mexico fresh insights into the early history of the Arctic embayment, West Greenland (Disko), and north­ Ocean. western Europe. Faunal composition and low

ARCTIC OCEAN + .·' ~ • SVALBARD l ~

•

PACIFIC OCEAN

/ CANNONBALL FM.OUTCROPS ATLANTIC OCEAN

FIGURE 9.-Location of areas with Upper Cretaceous or Paleogene marine faunas noted in text.

45 species diversity suggest a temperate rather than West, R. M., Dawson, M. R., Hickey, L. J., and Miall, A. D., tropical aspect for the Ocean Point and Cannon­ 1981, Upper Cretaceous and Paleogene sedimentary rocks, ball faunas and imply a major separation of Arctic eastern Canadian Arctic and related North Atlantic areas, in J. W. Kerr and A. J. Fergusson, eds., Geology of the and Atlantic faunal realms in the early Tertiary. North Atlantic Borderlands: Canadian Society of Paleogene molluscan faunas on Svalbard (fig. 9) Petroleum Geologists, Memoir 7, pp. 279-298. are of moderate diversity and of probable Atlantic affinities. The Ocean Point and Cannonball beds REMOTE SENSING STUDIES OF DYNAMIC are approximately coeval with the upper part of ENVIRONMENTAL PHENOMENA IN ICELAND the Eureka Sound Formation of the Canadian Arc­ BY RICHARDS. WILLIAMS, JR tic Archipelago, which contains Paleocene and Eocene vertebrates, megaflora and pollen (West In 1966, the U.S. Geological Survey (USGS) and others, 1981). Marine mollusks are known began a geological remote-sensing project in Ice­ from the dominantly nonmarine Eureka Sound land to study and t.o monitor various types of deposits on Ellesmere Island, but have not been dynamic environmental phenomena By mid-1983, extensively collected or studied, and are thought more than 50 abstracts, papers, and maps, mostly t.o be of relatively low diversity. Because the in collaboration with Icelandic scientists, have Eureka Sound Formation contains the thickest ac­ been or are about to be published on the following cumulation of arctic Paleogene deposits, study of topics: thermal-infrared surveys of volcanoes and its marine mega- and microfaunas is central t.o an geothermal areas; volcanology; glaciology; geo­ understanding of the early Tertiary hist.ory of the morphology; geologic hazards, marine geology, Arctic Ocean. Sparse information available on and bibliography of the geological literature of Eureka Sound marine fossils allies them with the Iceland. endemic low-diversity Ocean Point and Cannon­ During the course of three aerial thermographic ball faunas and suggests that this formation was (airborne thermal-infrared) surveys, two by the Air also deposited in an Arctic Ocean largely or entire­ Force Cambridge Research Laboratories in 1966 ly separated from the world ocean during part of and 1968 and one by the National Aeronautics and the Paleogene. Space Administration in 1973, surface patterns of The hist.ory of connecting seaways between the thermal emission were recorded of all of the known Arctic and Pacific Oceans is poorly known. Most high-temperature geothermal areas and of several current plate-tect.onic models suggest closure of volcanoes in Iceland. In 1973, color and color­ marine connections between these oceans during infrared aerial photographs were also acquired. A the Late Cretaceous (Churkin and Trexler, 1981), series of preliminary papers on the analysis of the although few paleont.ologic data are available to aerial thermographic data has been published, and test this idea preparation of a USGS Professional Paper, "Re­ Paleontologic research done t.o date on Late mote Sensing of High-Temperature Geothermal Cretaceous and Paleogene marine faunas from the Areas of Iceland," in cooperation with the onshore arctic margin of North America has been National Energy Authority of Iceland, is nearing limited by the small amount of collected fossils completion. available for study. Still, the endemic character of Volcanological studies have included analysis of the faunas is clear and supports the hypothesis of thermal data of an effusive eruption on Surtsey a geographically isolated Arctic Oce'an during recorded by the Nimbus 2 spacecraft and publica­ some portion of Paleogene time. tion of a USGS scientific leaflet on diversion of lava by water cooling during the course of the eruption of Eldfell on Heimaey, Vestmannaeyjar, REFERENCES CITED Iceland. Satellite imagery of Iceland's glaciers established that variations in the termini of ice Churki.n, M., Jr., and Trexler, J. H., Jr., 1981, Continental caps and outlet glaciers could be measured by plates and accreted oceanic terranes in the arctic, in A. E. M. Nairn, M. Churkin, Jr., and F. G. Stehli, eds., The Landsat imagery. This research provided the Ocean Basins and Margins, v. 5, The Arctic Ocean, Plenum catalyst for the initiation, in 1977, of a USGS­ Press, New York, pp. 1-20; sponsored international project to prepare a

46 "Satellite Image Atlas of Glaciers (of the World)." CORRELATION OF LATE CENOZOIC MARINE Analysis of satellite imagery resulted in the TRANSGRESSIONS OF THE ARCTIC COASTAL publication of two 1:500,000-scale Landsat image PLAIN maps of Vatnajokull ice cap, preparation of a WITH THOSE IN WESTERN ALASKA AND special computer-enhanced image, and new knowl­ NORTHEASTERN RUSSIA edge about poorly known or unknown glaciolog­ BY JULIE K. BRIGHAM ical, structural, and tectonic features under and adjacent to the Vatnajokull ice cap. Six distinct marine transgressions of Pliocene (?) Geomorphological research involved the use of and Pleistocene age have been differentiated aerial thermographs and color-infrared aerial within the Gubik Formation across the western photographs to map periglacial phenomena in Ice­ part of the Alaskan Arctic Coastal Plain (fig. 10; land, including frost-crack polygons and palsas Brigham, 1983). The recognition of these superim­ (frost mounds). Comparative planetology studies posed but lithologically similar marine units is established that concentric ridges on the Arsia based on the detailed stratigraphic study of un­ Mons volcano on Mars are best explained by the consolidated sediment in coastal and river-bluff analog of recessional moraines in Iceland. More­ exposures and the amino-acid geochemistry of over, comparative planetology research, in a joint mollusks from these deposits (table 1). The extent effort with the late Sigurdur Thorarinsson and of isoleucine epimerization (alle/Ile) in free Elliot C. Morris, resulted in a new classification for (naturally hydrolyzed)- and total (free plus peptide the 27 types of Iceland's volcanoes. The classifica­ bound)- amino-acid fractions in Hiatella arctica tion is based on the nature of the volcanic activity, (Linne), Mya truncata Linne, and M arenaria environment during formation, and configuration Linne from Gubik deposits cluster into groups of of feeder conduit, for the three primary composi­ ratios that differentiate temporally distinct high­ tional classes of Icelandic volcanoes. sea-level events (table 2). A new classification scheme has been developed Amino-acid data have also been acquired from for the four principal geologic hazards of Iceland: mollusks representing the transgressions docu­ geomorphic, geothermic, seismic, and volcanic. mented by Hopkins (1967, 1973) along the west Historically, seismic (earthquakes and rifting) and coast of Alaska and from similar sequences de­ volcanic (lava flows, tephra falls, volcanic gases, scribed on the Soviet coasts of the Bering and maars (explosion craters), jokulhlaups (glacier­ Chukchi Seas (Petrov, 1966, 1976, 1982; Khoreva, outburst floods), and other floods) hazards have 1974). Aile/Ile ratios (G. H. Miller, unpublished had the most impact on Iceland and its people. data, 1976) inHiatella andMya provided by D. M. In marine geology, analysis of a Landsat multi­ Hopkins from the Nome region approach racemic spectral scanner (MSS) band 4 image off the south­ equilibrium in the free-amino-acid fraction of the west coast of Iceland has revealed the complex oldest unit (table 2). Similarly, alle/Ile ratios in pattern of coastal currents in this area, including shells from the Soviet coast (provided by 0. M. eight large eddies (40 km in diameter), all appar­ Petrov, Geological Institute of Moscow) gradually ently made visible by variations in the concentra­ increase over time (table 2; Brigham, 1981). In tion of phytoplankton in near-surface waters. general, the higher alle/Ile ratios in mollusks from A "Bibliography of the Geological Literature of · the Kamchatka deposits reflect more rapid epimer­ Iceland: 1777-1983" is also nearing completion, ization resulting from the relatively warmer ther­ with approximately 5,000 citations already pre­ mal regime (current mean annual air temperature, pared and indexed. The multilanguage geoscience CMAT, -0.9 to l.5°C) affecting the peninsula literature of Iceland is particularly rich in the throughout the late Cenozoic. Latitudinal temper­ topics of volcanology, goethermal activity, geo­ ature gradients along the Soviet and Alaskan chemistry, geophysics, tectonics, tephrochronol­ coasts today are sharp (l.4°C per degree of lati­ ogy, glaciology, petrology, and geologic hazards, tude), although the Soviet shore averages 2 ° -6 °C and having the extant literature available in Eng­ cooler than the Alaskan coast at similar latitudes. lish will make it more widely known to English­ All the sites sampled, except those from Kamchat­ speaking scientists. ka, lost most of their maritime influence during

47 ARCTIC OCEAN

\ CHUKCHI SEA

BERING SEA ,.

ST. PAUL I. • PRIBILOF IS. • ti \ ST. GEORGE I. • COMMANDER ISLANDS 300 KM

FIGURE 10.-West.em Alaska and northeast.em Russia, showing locations of sample sit.es (shaded areas) on either side of the Bering and Chukchi Seas.

the glacial episodes of low sea level and presum­ A major middle Pleistocene interglacial trans9 ably had significantly lower mean annual tempera­ gression is recognized along numerous reaches of tures (e.g., Brigham and Miller, 1983). the Bering and Chukchi Seas, as indicated by the The correlation of marine units within Alaska Kotzebuan, Karmuk, Karaginsk, and Pinakul' ma­ and across the Bering Strait to the Kamchatka rine units (table 3). and Chukotka Peninsulas (table 3, fig. 11) is based The los alle/Ile ratios in shells from the Pinakul' on the relative differences in alle/Ile ratios and on suite off Siberia (0.035, total) preclude the correla­ assumptions concerning the integrated thermal tion by Khoreva (1974), who suggested that this history of the samples since deposition. The low suite correlated with the highly epimerized Alas­ alle/Ile ratios suggest that the Attarmen beds of kan Anvilian deposits (0.47, total). Moreover, simi­ Kamchatka may be only 35,000-40,000 yr old, lar alle/Ile ratios in shells from the V al'katlen, rather than 125,000 yr old as suggested by Kresta, and Pinakul' beds suggest that any age Hopkins (1973), Gladenkov (1981), and Petrov differences between these beds are small. (1966, 1982). If the Attarmen beds are assumed to The correlation of deposits older than middle be as old as 125,000 yr, then the alle/Ile ratios re­ Pleistocene, however, is less certain. Aile/Ile ratios quire an effective diagenetic temperature of -9°C, in the upper (0.22, total) and lower (1.04, total) some 8 °C cooler than today. This thermal term parts of the Olkhovaya suite on the Kamchatka seems much too cold, especially in light of Peninsula indicate that this unit spans a great deal CLIMAP (Climate/Long Range Investigation, of Pliocene and Pleistocene time. The lower part of Mapping and Predictions) reconstructions for the the Olkhovaya suite is probably much older than North Pacific (Moore et al., 1980) that indicate sea­ the Beringian transgression in western Alaska, surface temperatures only about 2°C cooler than especially in comparison with total-amino-acid those 18,000 yr B.P. ratios in Pliocene shells from Britain (CMAT,

48 TABLE 1. Pliocene and Pleistocene marine stratigraphy and sea level history of the Gubik Formation on the Alaskan Arctic Coastal Plain west of Barrow, Alaska Informal units Stratigraphic Estimated Evidence for Correl at ion with of Position Marine Age Age Western Alaska Gubik Fm. (Locations, Fig. 1) Environment (years) (Hopkins 1967, 1973 (youngest Distribution limited to Arctic waters aojooo- Correlation deposits) Beaufort Sea coast at similar to 105,ooo with oxygen- unit not <7 m above sea level today ; sotope record preserved beyond radio­ along Chukchi carbon dating Sea Coast Walakpa Extensive beach and Marine 120,000- Amino-acid age Pelukian beds barrier deposits at environment 125,000 estimate; asso- Barrow, Wal akpa Bay, slightly ciated with Wainwright, and coast warmer than relatively warm south of Wainwright up today. fauna; correla- to 12 m above sea level Numerous tion with extral imital oxygen-isotope species record; beyond radiocarbon dating Karmuk Blankets the upper half Arctic waters 250,000- Ami no-acid age Kot zeb uan beds of bluffs along parts like today; 500,000 estimate; of Skull Cliff, deposits no extra- tentative at Karmuk Pt., and beach 1 imita l or correlation deposits 30-33 m above extinct with Kotzebuan sea level south of Icy ·species that is K-Ar Cape. Reworked shells dated at •250,000 yr in al 1 uvium 25 km south of Atkasook. Unit locally folded

Tuapaktushak Extensive exposures Marine conditions ? ? beds along Skull Cliff, much warmer than between Barrow and today; includes Peard Bay; also near several extinct Mil imankav i, south of mollusk and Wainwright; reworked ostracode shell samples at 60 forms, as ~11 as m above sea level along extremely extra- Kukpowrik River. Unit 1 imital species locally folded

Ki 11 i Creek Discontinu~us basal do. 1,700,000- Simi 1 ar faun al Probably marine unit along 2,200,000 elements and Anvil i an Skull Cliff. Extent stage of evolu- above present sea tion of fossil level unknown sea otter found in deposits at Ocean Pt. with similar aile/Ile ratios (L.D. Carter, unpublished data, 1982)

Nul av ik Discontinuous basal conditions 2.5-3.5 m.y. Differentiated Beringian marine unit along not well only on the basis Skul 1 Cliff. Trans­ doc tJTiented of aile/Ile ratios. gressive extent Oldest unit recog- unknown nized therefore correlated with

49 Table 2. Jlrninostratigraphy of marine transgressions in northwestern and western Alaska and on the Kamchatka and Chukotka Peninsulas, U.S.S.R. = . 1 2 Unit Spec1es No. of valves all e/I 1e an al yzed FREE TOTAL northwestern Alaska (CMAT, -10° to -13°C)

Modern ------Ha 3 0. 011±0. 002 Walakpa beds ------Ha 16 ND 0.014±0.002 Ma 2 ND 0.018±0.001 Karmuk beds ------Ha 26 o. 40±0. 052 0.038±0.007 Mt-Ma 19 0. 37±0. 085 0.038±0.006 Tuapaktushak beds - Ha 4 o. 51±0. 025 0.086±0.009 Mt-Ma 15 0. 54±0. 057 0.086±0.013 Killi Creek beds -- Ha 4 0. 50±0. 072 0.15±0.007 Mt-Ma 3 0. 52± o. 057 0.15±0. 023 Nulavik beds ------Ha 3 o. 75±0. 067 0.23±0.016 Nome, western Alaska (CMAT, -4.7°C)

Pelukian ------Ha 2 0.16±0. 001 0.040±0.002 Mt 4 o. 28±0. 03 0.042±0.005 Kotzebuan ------Mt 2 o. 46±0. 04 0.093±0.001 Anvilian ------Ha 3 0. 90±0. 02 0.47±0.03 Beringian ------Ha 3 1. 04±0. 03 0.56±0.07 Mt 2 o. 94±0. 03 0. 56±0. 04 Chukotka Peninsula (CMAT, -7.5° to -l0°C)

Val'katlen beds --- Mt 3 0.17±0. 011 0. 018±0. 002 Kresta suite ------Ha 1 0.23 0.022 Mt 2 o. 22± 0. 02 o. 020±0. 002 Pinakul suite ----- Ha 1 0.26 0.031 Mt 1 0.21 0.035 Kamchatka Peninsula (CMAT, -0.9° to -1.5°C)

Attarmen beds ----- Ha 1 0.17 0.038 Mt 1 0.14 0.027 Karaginsk beds ---- Mt 3 o. 43± o. 05 0.115±0. 013

Upper 01 khov aya Mt 3 0. 44± 0. 01 o. 22 ±Q. 012 suite Tusa t uv i am bed s Mt 2 1.16±0. 03 o. 577±0. 004

Lower 01 khov aya Ha 2 1. 38±0. 03 1. 04 ±Q. 06 suite Mt 2 1. 28±0. 03 1. 04 ±Q. 05 Ha, Hiatella arctica; Mt, Mya truncata; Ma, Mya arenaria; Mt-Ma, Mya truncata and M. arenarTa results combined 2 Values represent the mean ±Io for peak-height measurements. 3 ND, not detect ab 1e . Table 3. Aminostratigraphic correlation of late Cenozoic marine­ transgress ive units across the Bering and Chukchi Seas

Estimated Absolute Kamchatka, Chukotka, Nome, Coastal Plain, Age (m.y.) U.S.S.R. U.S.S.R. W. Alaska NN. Alaska

0.035-0.040 Attarmen beds

0. 08-0.100 Youngest deposits

0.125 ? Val' katlen Pel uki an Walakpa beds

0.150 Kr est a

0. 25-0. 50 Karaginsk Pin akul ' Kotzebuan Karmuk beds

? Upper 01 khov aya (no older Tuapaktushak beds (?) suite

1. 7-2. 2 Tusatuv i am(?) samples Anv i 1 i an Ki 11 i Creek beds beds

2.5-3.5 analyzed) Beringian Nu 1 av i k beds

>3.0 Lower 01 khov aya suite

+ 10°C) of 1.20±0.002 (Miller et al., 1979). This in­ Alaska, in Hopkins, D. M. (ed.), The Bering Land Bridge: terpretation differs from the correlation proposed Stanford University Press, p. 4 7-86. Hopkins, D. M., 1973, Sea level history in Beringia during the by Gladenkov (1981, p. 20), who equated the entire past 250,000 years: Quaternary Research, v. 3, p. 520-540. Olkhovaya suite with marine deposits younger Khoreva, I. M., 1974, Stratigraphy and Foraminifera of the than the Anvilian transgression. Marine Quaternary Deposits of the west shore of the Ber­ ing Sea, Akademy Nauk USSR Geologic Institute, v. 225, 152p. REFERENCES Miller, G. H., Hollin, J. T., and Andrews, J. T., 1979, Amino­ stratigraphy of UK Pleistocene deposits: Nature, v. 1981, Brigham, J. K., 1981, Amino acid geochronology of late Plio­ p. 539-543. cene and Pleistocene marine transgressions on the Arctic Moore, T. C., Jr., Burckle, L. H., Geitzenauer, K., Luz, B., Coastal Plain, northwestern Alaska: Geological Society of Molina-Cruz, A., Robertson, J. H., Sachs, H., Sancetta, C., America Abstracts with Programs, v. 13, no. 7, p. 417. Thiede, J., Thompson, P., Wenham, C., 1980, The recon­ Brigham, J. K., 1983, Marine stratigraphy, amino acid geo­ struction of sea surface temperatures in the Pacific Ocean chronology, and sea level history of the Gubik Formation, of 18,000 B.P.: Marine Micropaleont.ology, v. 5, p. 215-247. Arctic Coastal Plain, northwestern Alaska, Ph.D. disserta­ Petrov, 0. M., 1966, Stratigraphy and fauna of marine mol­ tion, University of Colorado, available December, 1983. lusks in the Quaternary deposits of the Chukotsk Penin­ Brigham, J. K., and Miller, G. H., 1983, Paleotemperature esti­ sula: Akademy Nauk USSR, Geological Institute Trudy mates of the Alaskan Coastal Plain during the last 125,000 115, Iad-vo "Nauka", Moscow, 288 p. In Russian. years: Proceedings of the Foorth International Conference Petrov, 0. M., 1967, Paleogeography of Chukotka during Late on Permafrost, Fairbanks, National Academy of Science, Neogene and Quaternary time, in Hopkins, D. M. (ed.), The in press. Bering Land Bridge, Stanford University Press, Gladenkov, Y. B., 1981, Marine Plio-Pleistocene of Iceland and p.144-171. the problems of its oonelation: Quaternary Research, v. 15, Petrov, 0. M., 1982, Marine mollusks of the Anthropogene p.18-23. from the northern region of the Pacific, "Nauka", v. 357, Hopkins, D. M., 1967, Quaternary marine transgressions in 144 p. In Russian.

51 1.0

:; 0.9 ~ cC :::l en t- c ~ 0.8 ·2 ...._, Cl) a. 0 a:s t= 0.7 ~ cC 0 a: ~- Cl) 0.6 :::l .c ...... 0 ..! 0.5 a; 0.4 0.3 GUBIK FM. 0.2 e -1-- - NULAVIK BEDS -- e- KILLI CREEK BEDS 0.1 --- -0----e ------e- TUAPAKTUSHAK BEDS 0.05 ------e ===----~------~ ~WALAKPAKARMUK BEDS BEDS 2 0 -2 -4 -6 -8 -10 -12 -14 CURRENT MEAN ANNUAL AIR TEMPERATURE ( °C)

FIGURE 11.-Tentative COITelation of transgressive marine units between Alaska and northeastern Russia, based on total-amino acid alle/Ile ratio plotted against current mean annual temperature.

ABSTRACTS NOT PRESENTED much lower fineness. Typically, grains of gold in AT THE SYMPOSIUM the veins occur as small, discontinuous blebs, wires, stringers, or crystals that weigh only a few POSSIBLE ORIGINS OF PLACER GOLD IN milligrams at most and have a fineness of KOVUKUK AND CHANDALAR DISTRICTS, 800-825. Nuggets in nearby placers, however, BROOKS RANGE, ALASKA sometimes exceed an ounce in weight and have a BY JOHN C. ANTWEILER, JOHN R. WATIERSON, fineness of 900-970. JOHN B. CATHRALL, AND ELWIN L. MOSIER Finely disseminated gold that occurs in schists, veins, stringers, and blebs in many Alaskan gold In regions of permafrost, gold nuggets may form fields can be dissolved by several agents. These in­ when mineral or organic acids dissolve, transport, clude cyanogenic compounds in organic materials, and then deposit finely divided gold on spores of organic acids in the layer of humus-rich muskeg psychrophilic (cold-loving) bacteria. As an exam­ over permafrost and bedrock exposures, and sul­ ple, in the Kovukuk and Chandalar districts, furic acid with traces of arsenic and antimony in Brooks Range, Alaska, gold-quartz-antim(>ny­ pyrite-rich zones. In addition, various micro­ arsenic-sulfide veins have been suggested as, the biological processes may contribute to the solubili­ source of gold in a number of placer deposits. In zation of gold. addition to the gold-bearing veins, gold often oc­ The spores of bacteria can precipitate gold from curs as tiny particles disseminated in schists .and solution. In laboratory experiments, suspensions of in igneous rocks such as diorites. There, as else­ Bacillus cereus spores added to 1,000 micrograms/ where in Alaska, gold in those veins is of smaller milliliter solutions of gold chloride have been grain size than that in the placers and is also of shown to bind gold chemically. They have also

52 been shown to be nucleation cent.ers for the growth The need for quick assessment of permafrost of microscopic 8- and 12-sided gold polygons conditions during World War II demanded better similar to small crystalline gold nuggets found in understanding of the age and origin of the proc­ placers. X-ray diffraction and scanning electron esses involved in the growth of ice in the ground microscope confirmed the crystalline nature of and of the significance of surface features, par­ gold fixed to bact.erial spores. ticularly polygonal patterns, in evaluating the We therefore propose the following: finely di­ character of the permafrost. My work through the vided gold may be solubilized in several ways and change in seasons at Barrow substantiated fully is carried to solution through channels or fractures the observations and interpretations of Leffing­ in permanently frozen ground. The same channels well. Precise measurements of ground contraction may also transport psychrophilic bact.eria that showed that the ground responded to temperature thrive at temperatures near 0°C. The spores of changes as would be expected and that cracking these bacteria at favorable sites may be nucleation and partial filling did occur. The average rate of centers for the growth of crystalline gold nuggets. growth in width of the ice wedges was about 1 mm/ year. Modified techniques and equipment of glaciologists and petrologists also were used to PERMAFROST STUDIES IN ALASKA prepare and study numerous thin sections of the BY ROBERT F. BLACK1 ground ice. Interpretation of the detailed fabrics of ice wedges corroborated and reconstruction of During the period 1945-1952 detailed studies of their manner of growth and of the thermal stresses permafrost were carried on in central and northern and strains that took place seasonally. Alaska, and reconnaissance was made of many Buried, inactive ice wedges also were studied in areas throughout the region. The main focus of the the field and laboratory, but they were not ame­ initial work was to resolve the opposing view­ nable to dating in those earlier years. Samples for points of E. de K. Leffingwell and Stephen Taber. radiocarbon dating, collected recently in northern Leffingwell in 1919 published the contraction Alaska, show the wedges to be very old, probably hypothesis for origin of ice wedges in permafrost. spanning most if not all the Wisconsinan Stage. In this concept ice wedges at the top of the per­ The deeply truncated roots of buried wedges are mafrost table were initiated by ground-contraction rising very slowly, like diapirs, because of horizon­ cracking in early winter, the cracks filling with tal stresses from the growth of large surface snow, hoar frost, and freezing water during the wedges and from thermal changes. The permafrost spring thaw. Moisture came from the atmosphere is active in its upper part. and surface. Taber in 1943, however, denied this A knowledge of ice wedges in Alaska has aided was an active process and proposed that the ice immeasurably in identifying true ice-wedge casts wedges were fossil features that grew at the time in the temperature regions of the United States. of the formation of the permafrost by water being Permafrost climates associated with the margins drawn up from below. Thus, the age, significance, of former ice sheets have been postulated on the and engineering implications of the ice wedges basis of wedge structures that have been misiden­ were thrown into doubt. tified in many places, such as southern New It is interesting to note that Leffingwell's study England. was done over a period of many years while he 1Department of Geology and Geophysics, University of Connecticut, St.orrs, CT lived year-around in extreme northern Alaska-a 06268. region of continuous permafrost. In contrast, Taber's work had been concentrated on seasonal PLEISTOCENE OF NORTHERN GREENLAND frost in connection with highway construction and BY WILLIAM E. DAVIES maintenance and on simple laboratory experi­ ments with the freezing of small samples. His one North of 79 degrees, a zone of ice-free land, 100 to summer in Alaska was confined essentially to the 200 km wide, extends across the north part of discontinuous and sporadic zones of permafrost-a Greenland. In this area are coastal alpine moun­ time when the contraction cracks of the previous tains south of which are high, dissected plateaus. winter were obscured by thaw and luxuriant The land is segmented by long fjords extending - vegetation. from the sea to the inland ice sheet.

53 In the area of ice-free land there is evidence of ice sheet and smaller ice caps, movement from the three pre-late Wisconsinan glacial advances. The ice centers was concentrated in long valley glaciers features related to the oldest advance and retreat occupying the major valleys. Successive retreatal are numerous ice-marginal channels that are not in positions follow valleys and are more or less paral­ accord with the geometry of features developed by lel to present ice fronts. Uplift since retreat began later Wisconsin glacial events. A later stage of varies from 25 m on the northern Arctic coast to a glaciation is in Knud Rasmussen Land north of maximum of 129 m between Independence and Hyde Fjord where the mountains are cut by inter­ Hyde Fjords. connected cirques many of which have been trun­ During retreat of the ice, varved clay and silt cated at their heads or toes by younger glaciers deposits 20 m or more thick were laid down in moving across them. Some were buried by later ice most of the large, interconnecting valleys in lakes sheets and at present are partially exhumed or are formed behind ice-tongue dams. Extensive marine recognizable from the surface configuration of the deposits formed along the coast of the Greenland ice cover. Sea and were reworked into seven main levels of Two large terminal moraines extend along Inde­ raised beaches and delta terraces. End moraines pendence Fjord in the vicinity of Hagen and Den­ are well developed in valleys and on coastal plains mark Fjords. The northernmost is a ridge over but are generally not well developed on the upland. 50 km long and up to 200 m high formed of un­ weathered clayey and silty sand with cobbles and THERMODYNAMICS AND OCEANOGRAPHY boulders. Bordering this moraine to the south is OF THE SEA ICE EDGE one of similar but deeply weathered material which BY EDWARD G. JOSBERGER has been planed off by overriding of more recent glaciers. Sea ice melting at the ice edge is one of the During Wisconsinan glaciation there were six primary processes that determines the ice edge major ice centers. The inland ice sheet of Green­ position; the melting results from the upward heat land expanded north to Independence Fjord, J.P. flux from the underlying upper ocean. The melting Koch Fjord and westward towards Nares Strait. process occurs during both the winter and the The ice sheet in Nares Strait and to the north did summer because the adjacent open ocean in the not connect with the one on Ellesmere Island and Marginal Ice Zone (MIZ) is at a temperature above only snouts of valley glaciers extended into the the salinity determined freezing point. The ice is strait. The ice caps of Hans Tausen Land and then either blown out into this relatively warm Nordkronnen expanded southwards coalescing water or this water flows under the ice. This with and buffering the inland ice sheet in In­ melting produces the large horizontal gradients of dependence Fjord as well as moving northeast­ temperature and salinity that characterize the ward down Hyde Fjord. North of Hyde Fjord MIZ. Melt rate measurements from the winter there is no evidence of extensive overriding by an Bering Sea and the summer Greenland Sea show ice cap. At the time of maximum extent of glaciers that the melt rates reach 20 mm per hour for there were extensive mountain icefields with typical upper ocean temperature, salinity and valley glaciers coalescing to form piedmont velocity conditions. Figure 12 shows the melt rates glaciers along the north coast of Greenland. The and sea water temperature and speed 2 m below center of another local ice cap was on the north the ice from the winter Bering Sea experiment. side of Hyde Fjord near its mouth. Similar condi­ A properly formulated model of ice melting in tions existed in a greatly expanded Flade lsblink sea water must include the eutectic relationship east of the mouth of Danmark Fjord. The area be­ between temperature and salinity and both the tween Independence and Hyde Fjords appears to heat and salt transfer from the underlying upper have been free of ice cover, and there remain a ocean. The results of such a model show the follow­ number of high level, interlaced valleys that car­ ing: first, the ice-sea water interface temperature ried meltwater from the ice sheet to the Greenland is within 10% of the far-field salinity determined Sea. freezing point not at 0°C nor at the far-field freez­ Based on marine terraces, the retreat of the ice ing point; second, the melting rates are of the in Nares Strait and to the north began 7 ,000 to order of 1 m/day; finally, the effect of the melting 8,000 years B.P. During the retreat of the inland on the upper ocean dynamics, as characterized by

54 the Obukov length, are minimized by the upward salt flux reaching the ice. In this case the Obukov lengths are greater than the planetary boundary layer depth.

120 40

/'\ ~ ,. T-../" .,/ \r-J '-- ..... / +1 30 / I' I I I iii I e I u 0 :§: ~ 20 I- ::J

-1 10

-2 10 20 30 40 TIME (hrs) FIGURE 12.-Ice thickness, ocean t.emperature, and ocean speed taken during the Bering Sea MIZEX experiment, Febru­ ary 1983. The closing of switches set at increasing depths in the ice gave the ice thickness during the experiment. A current meter suspended 2.5 m below the ice gave the ocean t.emperature and speed. Initially the ice was in wat.er at -1 °C and was melting at 7 mm/hr. Then the ice moved into wat.er at + 1 °C, and the melting increased to 20mm/hr.

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