Eskers as mineral exploration tools

Cummings, Don I.; Kjarsgaard, Bruce A.; Russell, H A J; Sharpe, D R

doi:10.1016/j.earscirev.2011.08.001

Cited by 13 publications

(19 citation statements)

References 66 publications

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“…Cummings et al, 2011;Gorrell and Shaw, 1991). The sedimentation associated with the polar, Antarctic ice shelves is described by Domack et al (1999), Evans and Pudsey (2002) and Evans et al (2005).…”

Section: Terminal Zonesmentioning

confidence: 91%

Modes of Sedimentation and Glaciological Aspects of the Permo-Carboniferous Dwyka Group in the Elandsvlei - Elandsdrif Area, South Africa

Blignault

Theron

2012

South African Journal of Geology

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A field investigation resulted in a detailed stratigraphic profile of the full sequence of the Permo-Carboniferous, glaciomarine Dwyka Group in the Elandsvlei-Elandsdrif area. Six cycles of a basal tillite unit capped by a terminal zone of stratified sediments, are documented. Of note is the recurrence in the tillite units of the association diamictite-boulder beds-eskers. This facies association is interpreted as a subglacial deformation tillite, with the boulder beds as products of the deforming-bed process. The sediments of the terminal zones indicate a sub-ice shelf environment. Nine advance/ retreat fluctuations are interpreted from the facies associations. The immature eskers and lack of sorted sediments point to a low level of melt water supply, pointing to a polar ice sheet. Westward ice-flow is supported by macrofabric data, basal and boulder pavements. An analysis of the boulder lithologies shows that the source area stayed the same throughout the glacial period. It is proposed that part of the onset area due east is an extrusive-intrusive complex with a chert-carbonate-banded iron formation component. This investigation supports a series of glacial advance/ retreat cycles rather than the previous model of deglaciation. Figure 4. The diamictites and eskers of the basal tillite units. (A) An outsize erratic of banded iron formation in the basal tillite of Cycle 4 (locality 5; the walking stick is 1 m long). (B) The character of massive diamictite changes across the spaced boulder bed (Cycle 1, locality 2) represented by the large boulder embedded in the lower diamictite . (C) The erosional lower contact of the clast-poor, basal tillite of Cycle 2 (locality 1). (D) The arched roof structure of a white esker (locality 5; the walking stick is 1 m long). (E) The black weathering (carbonate impregnated), poorly sorted conglomerate of the red esker suite embedded in a massive diamictite of Cycle 2 (locality 7); note the flat bottom turning into a subvertical side wall (F) Profile of a red esker: a graded conglomerate overlain by a red sandstone (Cycle 3).

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Section: Terminal Zonesmentioning

confidence: 91%

Modes of Sedimentation and Glaciological Aspects of the Permo-Carboniferous Dwyka Group in the Elandsvlei - Elandsdrif Area, South Africa

Blignault

Theron

2012

South African Journal of Geology

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“…The primary factor controlling transport distance in esker systems downflow of the sediment source-which is typically a till dispersal train, not the bedrock itself (e.g., Bolduc, 1992)-would be the overall length of the meltwater conduit within which esker material was deposited. In the two end-member scenarios discussed in Chapter 1 (Figure 1.1), only the long conduit model has the potential for long distance transport downflow of the till dispersal train source (Cummings et al, 2011). In this study, a time-transgressive, short-conduit esker depositional model is of similar length in other eskers based mainly on morphological analysis (e.g., Shilts, 1973;St.…”

Section: Transport Distance Within Eskersmentioning

confidence: 97%

“…Sutherland, 1982). However, the publicly available data put this exploration model into question: esker dispersal trains published to date are generally short and typically extend no more than several kilometers past the till-dispersal trains from which they were derived (Cummings et al, 2011). Does this reflect how eskers form?…”

Section: Introduction and Research Goalsmentioning

confidence: 99%

“…The chapters in this thesis present the methodology and results of the study, and discuss the implications of the results with respect to esker genesis and mineral exploration. Figure 1.1: End-member scenarios for esker deposition (Cummings et al, 2011). (A) The "short conduit" model of esker deposition (e.g., DeGeer, 1912;Wilson, 1939;Banerjee and MacDonald, 1975;Shilts, 1984;Boulton, 2008) that invokes a relatively steep ice front, a narrow ablation zone, and time-transgressive esker deposition in short subglacial meltwater conduits as the ice front retreats.…”

Section: Introduction and Research Goalsmentioning

confidence: 99%

“…4.1 Introduction ................................................................................................................118 4.2 Deposition of Lac de Gras eskers ..............................................................................118 4.3 Table 2.1: Esker components: morphology and surficial sediment…………….……….19 Table 3.1: 500 MHz radar facies……………………………………….…………...…...55 Table 3.2: 100 MHz radar facies………………………………………………………...59 Table 3.3: Summary of GPR characteristics of the identified esker components…...…..84 vii LIST OF FIGURES Figure 1.1: End-member scenarios for esker deposition (Cummings et al, 2011) Chapter 1: Introduction…”

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confidence: 99%

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Morphology and Sedimentology of Eskers in the Lac de Gras Area, Northwest Territories, Canada

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An integrated dataset, including LiDAR, grain-size samples, GPR, and augered boreholes, was used to perform a morphological and sedimentological analysis of eskers in the Lac de Gras area, NWT. Esker segments were classified based on morphology and surficial grain size, and depositional environments were interpreted based on sedimentological data gathered from GPR and boreholes. Peaked ridges of cobbles and boulders (Type 1 components) are inferred to be deposited subglacially, and flat topped ridges of finer sediment (Type 2, 3, 4 components) are inferred to have been deposited deltaically. Deltaic deposits are either found overlying or at the down esker extents of Type 1 ridges. Evidence points to a time transgressive depositional model, with maximum length of depositionaly related esker segments not exceeding approximately 5 km in the study area. These results have potential implications for mineral exploration. Transport distance within eskers may not substantially exceed that of the subglacial till. iii ACKNOWLEDGEMENTS Working on this thesis was a fantastic opportunity to expand my knowledge of Quaternary geology and sedimentary processes. For this opportunity, and for all the support, assistance, and ideas along the way, I would like to give my deepest gratitude to Dr. Don Cummings. My field work was made possible by the organization and hard work of Barrett Elliott and the Northwest Territories Geological Survey, with funding provided by the Canadian Northern Economic Development Agency. I must also thank the research team, and all of my fellow students, at the field camp over the summer of 2015. Their expertise and enthusiasm created an atmosphere of academic collaboration and an excellent work environment. I extend a special thank you to Dr. Stephen Gruber, for an incredible LiDAR DEM and some quick programming wizardry that solved what could have been a major problem. Finally, I give my thanks to the faculty, staff and students of the Earth Sciences department at Carleton University, for all the support over my two degrees.

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