Major Domes Research Articles

Extended Silicic Volcanism in the Gruithuisen Region—Revisiting the Composition and Thermophysical Properties of Gruithuisen Domes on the Moon

The formation mechanisms, extent, and compositions of red spots on the lunar surface have intrigued the lunar community for decades. By identifying a new dome and another silicic crater in the highlands nearby, we find that the silicic volcanism in the Gruithuisen region extends beyond the three major domes. Our observations indicate that the Gruithuisen domes have low iron and titanium contents. They are enveloped by ejecta from surrounding regions and host silica-rich material excavated by the young craters consistent with previous work. Our boulder maps of the Gamma dome display a high boulder count and indicate that the Diviner rock abundance maps are only sensitive to boulders larger than ∼2 m. The H-parameter values are sensitive to presence of rocks and may be a better indicator of rocks at submeter scales. The Delta dome has gentle slopes, lower rock abundance, and one young crater, and it could serve as a safe and scientifically valuable site for landing and exploration of the domes and nearby region. The dome also displays anomalously high H-parameter in the same region as the crater, indicating the potential presence of pyroclastic materials. We observe up to 200 ppm of OH/H2O on the domes and nearby mare despite the presence of a weak magnetic field to the south of Delta dome, further supporting the potential presence of pyroclastics in the region. This study could potentially aid in logistical and scientific decisions of the future NASA missions in the region.

Deglaciation of the Laurentide Ice Sheet from the Last Glacial Maximum

The last deglaciation of the Laurentide Ice Sheet (LIS) was associated with major reorganisations in the ocean-climate system and its retreat also represents a valuable analogue for understanding the rates and mechanisms of ice sheet collapse. This paper reviews the characteristics of the LIS at its Last Glacial Maximum (LGM) and its subsequent deglaciation, with particular emphasis on the pattern and timing of ice margin recession and the driving mechanisms of retreat. The LIS initiated over the eastern Canadian Arctic ~116-110 ka (MIS 5d), but its growth towards the LGM was highly non-linear and punctuated by several episodes of expansion (~65 ka: MIS 4) and retreat (~50-40 ka: MIS 3). It attained its maximum position around 26-25 ka (MIS 2) and existed for several thousand years as an extensive ice sheet with major domes over Keewatin, Foxe Basin and northern Quebec/Labrador. It extended to the edge of the continental shelf at its marine margins and likely stored a sea-level equivalent of around 50 m and with a maximum ice surface ~3,000 m above present sea-level. Retreat from its maximum was triggered by an increase in boreal summer insolation, but areal shrinkage was initially slow and the net surface mass balance was positive, indicating that ice streams likely played an important role in reducing the ice sheet volume, if not its extent, via calving at marine margins. Between ~16 and ~13 ka, the ice sheet margin retreated more rapidly, particularly in the south and west, whereas the north and east underwent only minimal recession. The overall rate of retreat decreased during the Younger Dryas (YD), when several localised readvances occurred. Following the YD, the ice sheet retreated two to five times faster than previously, and this was primarily driven by enhanced surface melting while ice streams reduced in effectiveness. Final deglaciation of the Keewatin and Foxe Domes, left a remnant Labrador Dome that disappeared ~6.7 ka.

THE TIMING AND DISTRIBUTION OF CADDO SALT PRODUCTION IN NORTHWESTERN LOUISIANA

In the fall of 2012, the Alabama Museum of Natural History’s Gulf Coast Survey conducted an archaeological survey of four major salt domes in northwestern Louisiana. In total, 13 discrete “salt licks” were visited at these salt domes. The results of this survey indicate that along with Potter’s Pond, the Drake’s Salt Works Site Complex was one of northwestern Louisiana’s most intensively utilized salines during the protohistoric and early historic periods. It is argued here that salt production in this area developed largely in response to an increased demand for salt and salttreated commodities following European contact. Although numerous salt licks would have been known to the Caddo, only a fraction of these licks were involved in salt making. While there were likely many factors involved in determining which licks were favored over others, the availability and strength of liquid brine, resistance to flooding, fuel availability, and proximity to European traders would have been several important considerations.

Where to find 1.5 million yr old ice for the IPICS "Oldest-Ice" ice core

Abstract. The recovery of a 1.5 million yr long ice core from Antarctica represents a keystone of our understanding of Quaternary climate, the progression of glaciation over this time period and the role of greenhouse gas cycles in this progression. Here we tackle the question of where such ice may still be found in the Antarctic ice sheet. We can show that such old ice is most likely to exist in the plateau area of the East Antarctic ice sheet (EAIS) without stratigraphic disturbance and should be able to be recovered after careful pre-site selection studies. Based on a simple ice and heat flow model and glaciological observations, we conclude that positions in the vicinity of major domes and saddle position on the East Antarctic Plateau will most likely have such old ice in store and represent the best study areas for dedicated reconnaissance studies in the near future. In contrast to previous ice core drill site selections, however, we strongly suggest significantly reduced ice thickness to avoid bottom melting. For example for the geothermal heat flux and accumulation conditions at Dome C, an ice thickness lower than but close to about 2500 m would be required to find 1.5 Myr old ice (i.e., more than 700 m less than at the current EPICA Dome C drill site). Within this constraint, the resolution of an Oldest-Ice record and the distance of such old ice to the bedrock should be maximized to avoid ice flow disturbances, for example, by finding locations with minimum geothermal heat flux. As the geothermal heat flux is largely unknown for the EAIS, this parameter has to be carefully determined beforehand. In addition, detailed bedrock topography and ice flow history has to be reconstructed for candidates of an Oldest-Ice ice coring site. Finally, we argue strongly for rapid access drilling before any full, deep ice coring activity commences to bring datable samples to the surface and to allow an age check of the oldest ice.

Dome Fuji Station in East Antarctica and the Japanese Antarctic Research Expedition

AbstractJapanese Antarctic Research Expedition (JARE) commenced on the occasion of International Geophysical Year in 1957–1958. Syowa Station, the primary station for JARE operations, is located along the northeastern coastal region of Lützow-Holm Bay, East Antarctica (69° 00′S, 39° 35′E), and was opened on 29 January 1957. Since then, JARE have been carrying out research in various fields of earth and planetary sciences and life science. Astronomical science, however, has not been popular in Antarctica. In 1995, JARE established a new inland station, Dome Fuji Station (77° 19′S, 39° 42′E), which, at 3,810 m a.s.l., is located on one of major domes of the Antarctic ice sheet, some 1,000 km south of Syowa. The climatic conditions at Dome Fuji are harsh, with an annual average air temperature of −54°C, and a recorded minimum of −79°C. In 2007, JARE completed scientific drilling to obtain ice core samples of the Antarctic ice sheet reaching 3,050 m in depth. These ice cores record environmental conditions of the earth extending back some 720,000 B.P. In recent years, it is widely known that the high-altitude environment of inland Antarctica is suitable for astronomical observations and the Japanese astronomy community identified Dome Fuji Station as a potential candidate for a future astronomical observatory. In this article, the history of Japanese Antarctic activities are described in terms of access to the inland plateau of the Antarctic continent. The general scheme and future plans of science objectives and logistics of JARE will also be introduced.

Configuration and Dynamics of the Laurentide Ice Sheet During the Late Wisconsin Maximum

Prior to 1943 the Laurentide Ice Sheet was considered to have three major domes centered in Keewatin, Labrador, and Patricia (TYRRELL, 1898 a, b; 1913). FLINT (1943) argued that these centres were of only local and temporary importance and favoured a single-domed ice sheet. Despite the lack of supporting geological evidence, and despite the proposition of a Foxe Dome in the interim (IVES and ANDREWS, 1963), the single-dome concept was not seriously challenged until the late 1970's and, in fact, is still strenuously supported (HUGHES era/., 1977 ; DENTON and HUGHES, 1981). This paper extends and modifies recent conclusions that the Laurentide Ice Sheet had more than one dome at the Late Wisconsin maximum. We propose a model incorporating five domes (M'Clintock, Foxe, Labrador, Hudson, and (?) Caribou) based on the position of ice divides, ice flow patterns, drift composition, late-glacial features, postglacial isostatic recovery and free-air gravity anomalies. Our Labrador and Hudson domes closely correspond to Tyrrell's Labradorean and Patrician ice sheets; our Caribou and M'Clintock domes together with the Franklin Ice Complex over the Queen Elizabeth Islands north of the Laurentide Ice Sheet, correspond to Tyrrell's original Keewatin Ice Sheet. The style of glaciation of the Foxe Basin region was not known to Tyrrell, but our reconstruction of the Foxe Dome is in close agreement with the original proposal of Ives and Andrews. Like Tyrrell, our reconstruction is based on field evidence obtained through extensive mapping; the single dome model continues to be unsupported by geological data.

Geometry and evolution of the Mesoproterozoic Irumide Belt of Zambia

Abstract The Irumide Belt of eastern Zambia is one of a number of complex Proterozoic orogenic belts found in the African continent. The belt lies along the southeastern flank of the Tanzania-Bangweulu Craton and to the NW of the Mozambique Belt of East Africa. The dominant tectonic features of the belt are ductile shear zones, thrusts and folds related to a Mesoproterozoic, NW-SE crustal shortening event, and late-tectonic granite emplacement. Later tightening of Irumide structures and localized deformation of granites is also widespread. The timing of post-Irumide deformation is poorly constrained but is believed to be a mix of Pan-African and Late Palaeozoic reactivation and thermal reworking. This complex history is recently overprinted by significant Tertiary rifting. The Irumide deformation is evident in three tectonic zones stretching from the NW foreland of Mporokoso to the SE hinterland of Lundazi: (1) the NW-facing basement shear zones and associated cover deformation of the Luongo Fold Belt; (2) the Foreland Fold Belt of large upright folds defined by the kilometre-thick quartzite ridges of the Irumi, Shiwa Ngandu and Isoka hills; (3) an intensely deformed Internal Zone of basement and granite gneisses folded into major domes and associated tight synclines. Post-tectonic granites intrude the last of these zones and define an end to the Irumide deformation. The linking of these three zones is based on geometric, kinematic and geochronological evidence. The main Irumide deformation and metamorphism is believed to have occurred between 1100-950 Ma with a metamorphic peak between 1050 and 1000 Ma. Termination of Irumide deformation is dated by the emplacement of the post-tectonic granite and K/Ar biotite and hornblende closure dates of c. 950 Ma. Similar K/Ar dates from the Luongo shear zone indicate biotite closure and cooling during the period 1020-950 Ma. Together with parallel kinematic indicators, this supports a coeval development and tectonic link between the Irumide Belt and the Luongo Fold Belt. The intracontinental Irumide Belt deformation was driven by an accretionary collisional margin, to the SE of the present-day Irumide Belt, in southern Malawi and Mozambique. This accretionary margin is today represented by arc and island-arc magmatism and the complex terranes of the Mozambique Belt of East Central Africa.

Geomorphological reconstruction of the Labrador Sector of the Laurentide Ice Sheet

The Labrador sector formed one of three major domes of the Laurentide Ice Sheet during the last (Wisconsinan) glaciation. Reconstruction of its evolution is important because it modulated atmospheric and oceanic circulation over 1–100 ka time scales. This paper reports new geomorphological evidence of ice flow, which is used to reconstruct glimpses of the behaviour of the Labrador Sector during its evolution. Flow evidence indicates a southern position (51°N) of the Labrador ice divide, presumed to be the usual location when the ice sheet was close to its maximum extent. A previously inferred dramatic surge of Labrador ice across Hudson Strait and onto Baffin Island (at 9.9–9.4 ka) is verified. Seemingly contradictory evidence regarding deglaciation in northern Quebec has been analysed and a reconstruction developed that solves this problem. Deglacial retreat of the Labrador Ice Sheet was highly asymmetric with rapid retreat of the southern margin, northwards migration of the centre of mass by 500 km, and slow retreat along the northern margin. As it shrank its thermal regime changed from cold-centred to entirely cold-based and it finally fragmented into many residual ice caps and glaciers. This dynamic and asymmetric behaviour may be due to destabilisation of the Labrador Ice Sheet triggered by Heinrich-event ice streaming through Hudson Strait.

Mongolian plateau: Evidence for a late Cenozoic mantle plume under central Asia

Research Article| April 01, 1993 Mongolian plateau: Evidence for a late Cenozoic mantle plume under central Asia Brian F. Windley; Brian F. Windley 1Department of Geology, Leicester University, Leicester LE1 7RH, England Search for other works by this author on: GSW Google Scholar Mark B. Allen Mark B. Allen 1Department of Geology, Leicester University, Leicester LE1 7RH, England Search for other works by this author on: GSW Google Scholar Author and Article Information Brian F. Windley 1Department of Geology, Leicester University, Leicester LE1 7RH, England Mark B. Allen 1Department of Geology, Leicester University, Leicester LE1 7RH, England Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1993) 21 (4): 295–298. https://doi.org/10.1130/0091-7613(1993)021<0295:MPEFAL>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Brian F. Windley, Mark B. Allen; Mongolian plateau: Evidence for a late Cenozoic mantle plume under central Asia. Geology 1993;; 21 (4): 295–298. doi: https://doi.org/10.1130/0091-7613(1993)021<0295:MPEFAL>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The 2500 x 700 km Mongolian plateau (average elevation 2000 m) is situated between the Altai orogen and the Siberian craton and occupies much of Mongolia and Transbaikalia in Russia. The plateau is characterized by (1) basin and range topography and two major domes(Hentai, 600 x 300 km, and Hangai, 800 x 550 km), where altitudes reach 3905 m; (2) lithosphere that is thinner than adjacent areas (minimum ∼50 km); (3) elevated heat flow (up to 120 mW/m2); (4) dominantly alkaline basaltic volcanism in the form of cones, lava fields, and volcanic plateaus mostly of Miocene-Quaternary age, and (5) rifts, including Baikal (main evolution in the Pliocene-Quaternary), Tunka (Oligocene-early Miocene), and Hobsogol (Pliocene-Quaternary). Existing models explain these features in terms of diapiric upwelling of a mantle asthenolith below the main rifts and/or as a long-distance effect of the India-Asia collision. We propose that the late Cenozoic uplift of the whole Mongolian plateau and associated rifting, magmatism, high heat flow, and lithospherec thinning are not externally driven by the India-Asia collision, but are the expression of the interaction of a mantle plume with overlying lithosphere. Some rifts link and interact with major strike-slip faults, such as the Bolnai. Such faults may be the major expression of the India-Asia collision in this region. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The ice sheets of Northern Eurasia and their role in the history of the ocean

Abstract On the basis of a systems analysis of the end moraines and indicators of ice flow, the authors contend that the northern margins of Eurasia, including the arctic continental shelves, were entirely and repeatedly glaciated by vast marine ice sheets during the Pleistocene ice ages. All available information on late Pleistocene ice‐marginal features was included in a numerical reconstruction of a three‐dimensional model of the Eurasian Ice Sheet. This reconstruction suggested that the ice sheet was formed by the merging of three major ice domes (the Scandinavian, Kara, and East Siberian domes) and one lesser one (the Chukchi dome). These domes covered respectively 3.4, 6.1, 2.3, and 0.4 million km2, and the total areal extent of the ice sheet was 12.2 million km2. A further 2 million km2 was covered by mountain glacier complexes, and no less than 3 million km2 was inundated beneath proglacial lakes. According to different determinations, the volume of the last Eurasian Ice Sheet was about 15 to 18 m...

Use of foraminiferal data in analysis of Taranaki Basin, New Zealand

Geohistory analyses of Cenozoic marine basins rely heavily on the precision of foraminiferal dating and paleodepth determinations. A rapid method of paleodepth assessment has been devised for the New Zealand region, using a combination of planktonic percentage and the derived depth ranges of dominant benthic foraminifera and a number of diagnostic intrabathyal benthic taxa. This method together with biostratigraphic dating has been applied to approximately 2,000 foraminiferal faunas in 26 drillhole sequences and used to construct paleobathymetric, subsidence, and tectonic curves and maps for Taranaki Basin, New Zealand. Taranaki Basin sequences show a late Cretaceous-early Miocene transgressive phase initiated by Tasman Sea rifting which split New Zealand continental crust off from Gondwana. A pulse of basin-wide rapid subsidence in the late Oligocene to early Miocene resulted from the propagation through New Zealand of an obliquely extensional boundary between the Pacific and Indian Plates. The early middle Miocene heralded a switch to regression as mountains were uplifted along the plate boundary and abundant sediment began to fill the basin, advancing northwestward as a 1-km-high front of giant foreset beds that formed an extensive continental shelf. The abundant sediment masked the middle Miocene to Recent tectonic deformation that occurred in the eastern parts of the basin within the plate boundary zone. Several Neogene episodes of oblique extension and compression, with formation of deep grabens, major domes and thrusts, are identifiable using foraminiferal data.

Market and Merit Factors in the Determination of Academic Salaries

This paper examines the criteria and decisions of the Academic Salaries Tribunal and its predecessors with reference to the question of whether imposed uniformities have unduly limited the ability of universities to take account of market conditions for various disciplines and to provide adequate incentives and rewards for outstanding performance. Types and degrees of uniformity and their causes are reviewed and data are presented regarding the internal and external competitiveness of the university salary structure. This data and a chi square analysis of rank structure by discipline lead to the conclusion that university administrators have not been unduly constrained in matching the supply of and demand for academic personnel. Academic salaries were found to be competitive with those of major English-speaking countries and domes tically competitive with those in public and private sectors. Most important, the paper concludes that university administrators have been able to dis criminate in favour of "short-supply" disciplines and thus have been able to overcome many of the problems arising from a uniform rank and salary struc ture and from lack of authority to provide discretionary salary increases in significant amounts.

Regional Geology And Hydrocarbon Potential of the Canadian Arctic Islands

Abstract The geology of the Canadian Arctic Islands, with its major structures, favorable hydrocarbon source rock and extensive reservoirs, suggests that giant oil and gas fields similar to those of the Persian Gulf, North Africa and Prudhoe Bay will also be found in the High Arctic of Canada. This potential has attracted multimillion dollar expenditures and future commitments by the natural resources industry and the Canadian Government. The total hydrocarbon province of the Canadian Arctic Islands is centered around the elongate east-west Mesozoic Sverdrup Basin, with a complex of older Paleozoic arches and basins to the south and a younger Cenozoic shelf basin to the north. The Mesozoic and Cenozoic rocks are predominately terrigenous clastics consisting of sandstones and shales which attain cumulative thicknesses of over 30,000 feet. The Upper Paleozoic sediments include shelf carbonates, evaporites and thick terrigenous clastics which also have cumulative thicknesses- of over 30,000 feet. The Lower Paleozoic rocks are predominantly shelf carbonates evaporites and basinal pelagic sediments which may reach combined thicknesses of over 20,000 feet. Several major arches, anticlines, faults and evaporite domes are indicated from surface geology, and many more are being located by geophysical methods. The major Palesozoic reservoirs are:the Lower Triassic Bjorne sandstone formation which occurs along the southern margins of the Sverdrup Basin with thicknesses of over 2,000 feet; the Upper Triassic Heiberg Formation, a regressive sandstone extending over most of the Sverdrup Basin with measured thicknesses of over 4,000 feet; and the Lower Cretaceous Isachsen sandstone formation which is over 4,000 feet thick in the deeper portions of the Sverdrup Basin and is expected to be a major target within the Cenozoic coastal basin. The major Paleozoic reservoirs are coarse terrigenous sandstones and marine carbonate clastics. The Siluro- Devonian and Permo-Pennsylvanian carbonate reefs exhibit thicknesses of several thousands of feet and are widely distributed along Paleozoic interbasinal arches or platforms. Natural gas in major quantities has been found in wells drilled on Melville and King Christian Islands, and many other favorable indications of hydrocarbons are present on the surface throughout the Islands. It appears to be only a matter of time until the potential of the Canadian Arctic Islands will be realized. INTRODUCTION THE GEOLOGY of the Canadian Arctic Islands, with its major structures, favorable hydrocarbon source rock and extensive reservoirs, suggests that giant oil and gas fields similar to those of the Persian Gulf, North Africa and Prudhoe Bay will also be found in the High Arctic of Canada. This potential has attracted multi-million-dollar expenditures and future commitments by the natural resources industry and the Canadian Government. In this paper, the authors will present some highlights of the potential and speculate where this potential might be found. The interpretations are based mostly on published information from the Geological Survey of Canada. Detailed references to publications are not included in the text; however, a general list is appended. Of the three basic requirements for the accumulation of major economic hydrocarbon deposits trap, hydrocarbon source rock and reservoir rock.

The glacial anticyclone theory examined in the light of recent meteorological data from Greenland—Part 2

The frequent bad weather on the Greenland Ice Sheet is caused by cyclones which although they may be deflected along the coasts, can and do cross Greenland. Eismitte surface records are presented as evidence of an actual crossing. Cyclones along the east coast are as important as those on the west coast as a source of the ice sheet's alimentation. Further supporting evidence on the storminess of the Greenland interior is given by the records of three other expeditions. Despite the use of only a few summers of records, conclusions may be considered reliable since the records of several different expedition years are all in agreement with respect to the lack of fair weather.The existence of three distinct major domes on the ice sheet precludes, in itself, the single fixed anticyclone which Hobbs postulates. Radially outflowing winds do not in themselves signify the presence of an anticyclone. Hobbs' persistent confusion of the downslope, gravity‐caused flowing of cooled surface air with the general outward radiating winds of a high pressure center, the only anticyclone defined in meteorology, has been the basic misconception of his belabored theory. The “anticyclone” as defined by Hobbs was pointed out by Mills in 1926 as being entirely different from the meteorologists' concept of a high pressure area, and it seems time that the continued confusion of ideas be replaced by clear thinking.

Review of Developments in 1938, Gulf Coast of Southeast Texas and Louisiana

A progressive change in the outstanding structural type, from major piercement domes with very shallow salt cores, to deeper piercement domes, to deep-seated major closure domes, and finally to the important minor closure features of today, has characterized the history of field discovery on the Gulf Coast since Spindletop. Because of depositional influences that are fundamental to the local occurrence of oil, commercial deposits on the coast are related to geologic and geographic zones, the boundaries of which are arbitrarily recognized. This change in discovery type partly explains the fact that despite a very active year throughout the coastal districts of Texas and Louisiana during 1938, newly discovered reserves that have resulted from recent exploration do not compare favorably with the totals of previous years. Most of the twenty new producing areas of Louisiana are characterized by production from sands at great depths, where gas-oil ratios are sufficiently high to be a troublesome factor. Of the nine Texas discoveries, three indicate that they may justify a major rating, while the remainder are of unproved potentiality or are of very questionable merit. Additional discoveries in the Sparta-Wilcox sand zone along the Conroe trend, both in Texas and Louisiana, have assured this area an intensive period of activity for the immediate future. It is generally conceded that this is the most important new Coastal sand development since the discovery of production in the Frio. Extensions to proved fields and development in deeper sands have added greatly to the reserves in established areas of production during 1938.

Overhanging Cap Rock and Salt at Barbers Hill, Chambers County, Texas

Overhanging cap rock and salt were discovered on this dome in January, 1930, when a well on encountering salt was drilled deeper through more than 800 feet of salt into the sedimentary beds below. Up to the present, fifty-two wells have been drilled through the cap rock and salt. The greatest thickness of salt penetrated was 2,419 feet. The overhang is shallowest on the north, east, and south flanks, where drilling has shown that it projects outward distances ranging from 400 feet to 1,300 feet. The projection of the cap rock and salt on the west flank lies much deeper below the surface and has had very little exploration. The movement producing the overhang seems to have disturbed only slightly the prolific oil sands of the Miocene and Oligocene ages lying below it. Three general theories of the origin of salt-dome overhangs are given: upward and outward movement of the salt; downbuilding of salt domes; and solution of salt on the flanks. The writers believe that the first of these was the main cause of the overhang at Barbers Hill, and that the third was a lesser contributing factor. The discovery of the overhang has uncovered reserves of oil sufficiently large to establish Barbers Hill as one of the major producing domes of the Gulf Coast.