Magmatic and phreatomagmatic volcanic activity at Mt. Takahe, West Antarctica, based on tephra layers in the Byrd ice core and field observations at Mt. Takahe

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doi: 10.1016/0377-0273(88)90025-X
Authors:Palais, Julie M.; Kyle, Philip R.; McIntosh, William C.; Seward, Diane
Author Affiliations:Primary:
Ohio State Univ., Inst. Polar Stud., Columbus, OH, United States
N.M. Inst. Min. and Technol., United States
Volume Title:Journal of Volcanology and Geothermal Research
Source:Journal of Volcanology and Geothermal Research, 35(4), p.295-317. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0377-0273
Publication Date:1988
Note:In English. 52 refs.; illus. incl. 6 tables, sketch maps
Summary:The morphology, grain size characteristics and composition of ash particles in 30 ka to 150 ka tephra layers from the Byrd ice core were examined to characterize the eruptions which produced them and to test the suggestion that they were erupted from Mt. Takahe, a shield volcano in Marie Byrd Land, West Antarctica. Volcanic deposits at Mt. Takahe were examined for evidence of recent activity which could correlate with the tephra layers in the ice core. Coarse- and fine-ash layers have been recognized in the Byrd ice core. The coarse-ash layers have a higher mass concentration than the fine-ash layers and are characterized by fresh glass shards 50 mm diameter, many containing elongate pipe vesicles. The fine-ash layers have a lower mass concentration and contain a greater variety of particles, typically 20 mm diameter. Many of these particles are aggregate grains composed of glass and crystal fragments showing S and Cl surface alteration. The grain-size distributions of the coarse and fine-ash layers overlap, in part because of the aggregate nature of grains in the fine-ash layers. The coarse-ash layers are interpreted as having formed by magmatic eruption whereas the fine-ash layers are believed to be hydrovolcanic in origin. Mt. Takahe is the favored source for the tephra because: (a) chemical analyses of samples from the volcano are distinctive, being peralkaline trachyte, and similar in composition to the analyzed tephra; (b) Mt. Takahe is a young volcano (0.3 Ma); (c) pyroclastic deposits on Mt. Takahe indicate styles of eruption similar to that inferred for the ice core tephra; and (d) Mt. Takahe is only about 350 km from the calculated site of tephra deposition. A speculative eruptive history for Mt. Takahe is established by combining observations from Mt. Takahe and the Byrd ice core tephra. Initial eruptions at Mt. Takahe were subglacial and then graded into alternating subaerial and subglacial activity. The tephra suggest alternating subaerial magmatic and hydrovolcanic eruptions from 30 to 20 ka BP, followed by a sustained period of hydrovolcanic eruptions from 20 to 14 ka BP, which peaked at 18 ka BP. [R.E.S.]
Subjects:Ash; Clastic sediments; Field studies; Genesis; Magmas; Petrology; Phreatomagmatism; Sediments; Volcaniclastics; Volcanism; Volcanoes; Volcanology; Antarctica; Marie Byrd Land; West Antarctica; Mount Takahe; Volcanoclastics
Abstract Numbers:89M/3781
Record ID:1989017137
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by Institute of Geological and Nuclear Sciences Limited (GNS Science), Lower Hutt, New Zealand
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