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You searched for subject:(glacial advance AND retreat). Showing records 1 – 2 of 2 total matches.

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University of Canterbury

1. Reznichenko, Natalya. Rock Avalanches on Glaciers: Processes and Implications.

Degree: PhD, Geology, 2012, University of Canterbury

This thesis examines the role of rock avalanches in tectonically active terrains including the effects of the deposits on glacier behaviour and their contribution to moraine formation. The chronologies of mountain glacier fluctuations, based on moraine ages, are widely used to infer regional climate change and are often correlated globally. In actively uplifting mountain ranges rock avalanches that travel onto the ablation zone of a glacier can reduce ice-surface melting by insulating the ice. This can cause buried ice to thicken due to slower ablation and can significantly alter the overall glacier mass balance. This glacier response to supraglacial rock avalanche deposits can confound apparent climatic signals extracted from moraine chronologies. This thesis investigates the processes through which rock avalanche deposits may affect glaciers and develops a new technique to identify the presence of rock avalanche debris in glacial moraines. From laboratory experiments on the effects of debris on ice ablation it is demonstrated that the rate of underlying ice ablation is controlled by diurnal cyclicity and is amplified at high altitude and in lower latitudes. The relatively low permeability of rock avalanche sediment in comparison with non-rock avalanche supraglacial debris cover contributes to the suppression of ablation, at least partly because it greatly reduces the advection of heat from rain water to the underlying ice. The laboratory findings are supplemented by field investigations of two recent rock avalanche deposits on glaciers in the Southern Alps of New Zealand. This work demonstrates that the rock avalanche deposits are very thick (10 m at Aoraki/Mt. Cook and 7m at Mt. Beatrice) and almost stopped the ablation of the overlying ice. This resulted in the formation of an ice-platform more than 30 m high. This led to a reduction of the existing negative mass balance of the affected Tasman and Hooker Glaciers. There was little noticeable alteration of the overall glacial regime due to the small scale of the debris covered area (4 and 1% of the ablation zones for the Tasman and Hooker Glaciers, respectively) but there is a significant contribution to supraglacial debris, which is passively transported toward the terminus. A conceptual model of the response of mountain valley glaciers to emplacement of extensive rock avalanche debris on the ablation zone has been proposed for the effect of this type of debris on terminal moraine formation based on enhanced ‘dumping’ of supraglacial sediments. A new technique has been developed to distinguish rock-avalanche-derived sediment from sediment of glacial origin, based on the sedimentary characteristics of the finest fraction. Examination of rock avalanche sediment under the Scanning Electron Microscope showed that finer particles tend to form strong clumps, which comprise many smaller (down to nanometre-scale) clasts, named here ‘agglomerates’. These agglomerates are present in the fine fraction of all examined rock avalanche deposits and absent in known…

Subjects/Keywords: Rock avalanche; supraglacial rock avalanche; comminution; glacier; moraine; glacial sediment; ablation; debris-cover; glacial mass balance; advance; retreat; glacial regime; glacial geomorphology; aclimatic advance; microsedimentology; agglomerates; palaeoclimate; moraine chronology; rock-avalanche-driven advance; the Southern Alps of New Zealand; Norway

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Reznichenko, N. (2012). Rock Avalanches on Glaciers: Processes and Implications. (Doctoral Dissertation). University of Canterbury. Retrieved from http://dx.doi.org/10.26021/9139

Chicago Manual of Style (16th Edition):

Reznichenko, Natalya. “Rock Avalanches on Glaciers: Processes and Implications.” 2012. Doctoral Dissertation, University of Canterbury. Accessed April 12, 2021. http://dx.doi.org/10.26021/9139.

MLA Handbook (7th Edition):

Reznichenko, Natalya. “Rock Avalanches on Glaciers: Processes and Implications.” 2012. Web. 12 Apr 2021.

Vancouver:

Reznichenko N. Rock Avalanches on Glaciers: Processes and Implications. [Internet] [Doctoral dissertation]. University of Canterbury; 2012. [cited 2021 Apr 12]. Available from: http://dx.doi.org/10.26021/9139.

Council of Science Editors:

Reznichenko N. Rock Avalanches on Glaciers: Processes and Implications. [Doctoral Dissertation]. University of Canterbury; 2012. Available from: http://dx.doi.org/10.26021/9139


McMaster University

2. Eggertson, E. Bruce. The Espanola Formation: A Proterozoic Carbonate North of Lake Huron, Ontario.

Degree: 1975, McMaster University

The Proterozoic Espanola Formation (Huronian Sequence) was studied at Geneva Lake, Ontario, 45 miles north-west of Sudbury. A major lithological change exists in the Espanola Formation between this area and the type section on the north shore of Lake Huron, 75 miles to the south. Unusually pure (95 percent) microcrystalline limestones and dolostones occur in almost equal abundance to the calcareous siltstones which are the characteristic lithology of the formation in its type section. The existence and position of a fine grained deposit such as the Espanola in a stratigraphic sequence which consists mostly of glacial and periglacial deposits is unusual. It is suggested that this fine-grained deposit was an integral part of a cycle of deposition resulting from glacial advance and retreat and that its sedimentary basin was created by marine transgression in response to a glacial retreat. Spatial distribution of the Espanola Formation suggests that its sedimentary basin may have consisted of at least three environmental zones. At least one of these zones may represent a glacial melt-water lake. A microfossil search was carried out with negative results. This made speculation necessary in determining the origin of the calcareous fraction of the Espanola Formation. A mechanism is suggested whereby calcium carbonate is precipitated inorganically, as a result of photosynthesis by anaerobic bacteria. This mechanism can be observed in the present. If it is true, then the Espanola Formation may represent a time marker for the first presence of free oxygen in the atmosphere.

Thesis

Bachelor of Science (BSc)

Advisors/Committee Members: Risk, M. J., Clifford, P. M., Geology.

Subjects/Keywords: Proterozoic Espanola Formation; Huronian Sequence; Geneva Lake; lithology; Espanola; cycle of deposition; glacial advance and retreat; calcium carbonate precipitation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Eggertson, E. B. (1975). The Espanola Formation: A Proterozoic Carbonate North of Lake Huron, Ontario. (Thesis). McMaster University. Retrieved from http://hdl.handle.net/11375/17756

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Eggertson, E Bruce. “The Espanola Formation: A Proterozoic Carbonate North of Lake Huron, Ontario.” 1975. Thesis, McMaster University. Accessed April 12, 2021. http://hdl.handle.net/11375/17756.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Eggertson, E Bruce. “The Espanola Formation: A Proterozoic Carbonate North of Lake Huron, Ontario.” 1975. Web. 12 Apr 2021.

Vancouver:

Eggertson EB. The Espanola Formation: A Proterozoic Carbonate North of Lake Huron, Ontario. [Internet] [Thesis]. McMaster University; 1975. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/11375/17756.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Eggertson EB. The Espanola Formation: A Proterozoic Carbonate North of Lake Huron, Ontario. [Thesis]. McMaster University; 1975. Available from: http://hdl.handle.net/11375/17756

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.