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

来源：

BULLETIN OF VOLCANOLOGY | 1992年 / 54卷 / 07期

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.

引用

页码：595 / 601

页数：7

共 22 条

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