COMPOSITION OF WIDESPREAD VOLCANIC GLASS IN DEEP-SEA SEDIMENTS OF THE SOUTHERN PACIFIC-OCEAN - AN ANTARCTIC SOURCE INFERRED

被引:28
作者
SHANE, PAR
FROGGATT, PC
机构
[1] Research School of Earth Sciences, Victoria University of Wellington, Wellington
关键词
D O I
10.1007/BF00569943
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
Widespread Plio-Pleistocene (2.43-0.06 Ma) tephra zones recognised in deep-sea cores from high latitudes (> 60-degrees) in the Southern Pacific Ocean were thought to have originated from calc-alkaline rhyolitic eruptions in New Zealand, some 5000 km distant. Electron microprobe analyses of the glasses reveal a wide diversity of alkalic felsic compositions, as well as minor components of basic and intermediate glasses, incompatible with a New Zealand Neogene source but similar to contemporaneous eruptives from the Antarctic region. Most tephra zones are trachytic; seven zones are peralkaline rhyolite. The rhyolitic zones represent a deep-sea record of widespread silicic eruptions from continental Antarctica, possibly Marie Byrd Land. The extent of these rhyolitic zones suggest a greater frequency of large explosive eruptions in Antarctica than previously documented. The coarse grain size of some of the shards (up to 3 mm), their great distance from the closest sources (> 1600 km for some cores), and the presence of nonvolcanic ice-rafted debris indicate some of the glasses, especially the more basic compositions, may have been ice-rafted, contrary to previous suggestions of a fallout origin.
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页码:595 / 601
页数:7
相关论文
共 22 条
[11]  
Johnson G.L., Kyle P.R., Vanney J.R., Campsie J., Geology of Scott and Balleny Islands, Ross Sea, Antarctica, and morphology of the adjacent seafloor, NZJ Geol Geophys, 25, pp. 427-436, (1982)
[12]  
Kyle P.R., Seward D., Dispersed rhyolitic tephra from New Zealand in deep sea sediments of the Southern Ocean, Geology, 12, pp. 487-490, (1984)
[13]  
La Bas M.J., Le Maitre R.W., Streckeisen A., Zanettin B., A chemical classification of volcanic rocks based on the total alkali-silica diagram, J Petrol, 27, pp. 745-750, (1986)
[14]  
Nelson C.S., Froggatt P.C., Gosson G.J., Von der Borch C.C., Et al., Nature, chemistry and origin of late Cenozoic megascopic tephras in Leg 90 cores from the southwest Pacific, Initial reports of the Deep Sea Drilling Project, 90, pp. 1161-1173, (1986)
[15]  
Nielsen C.H., Sigurdsson H., Quantitative methods for electron microprobe analysis of sodium in natural and synthetic glasses, Am Mineral, 66, pp. 547-552, (1981)
[16]  
Palais J.M., Kyle P.R., McIntosh W.C., Seward D., 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, J Vol Geoth Res, 35, pp. 295-317, (1988)
[17]  
Ruddiman W.F., Glover K.L., Vertical mixing of ice-rafted volcanic ash in North Atlantic sediment, Geol Soc Am Bull, 83, pp. 2817-2836, (1972)
[18]  
Shane P.A.R., Remobilised silicic tuffs in middle Pleistocene fluvial sediments, southern North Island, New Zealand, NZJ Geol Geophys, 34, pp. 489-499, (1991)
[19]  
Shane P.A.R., Froggatt P.C., Glass chemistry, paleomagnetism and correlation of middle Pleistocene tuffs in southern North Island, New Zealand and Western Pacific, NZJ Geol Geophys, 34, pp. 203-211, (1991)
[20]  
Shaw D.M., Watkins N.D., Huang T.C., Atmospherically transported volcanic glass in deep-sea sediments: theoretical considerations, J Geophys Res, 7, pp. 3087-3084, (1974)