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Book Chapter

Structure and Sediments

Published:
January 01, 1981

Abstract

The Deep Sea Drilling Project drilled a substantial number of sites that bear on the origin of linear island and seamount chains, aseismic ridges and other more regional expressions of intraplate volcanism. Drilling in the Emperor Seamounts during Leg 55 was particularly successful. Results from this leg include: 1) the volcanoes of the Hawaiian- Emperor chain continue to increase in age away from Kilauea as predicted. 2) Suiko Seamount formed at a paleolatitide of 26.9 ± 3.5°N, 7° north of present-day Hawaii, but far south of its present latitude of 44.8°N. 3) the volcanic rock types recovered include hawaiite, mugearite, alkalic basalt and tholeiitic basalt in the sequence and relative volume expected for Hawaiian volcanoes. 4) the tholeiitic and alkalic basalts recovered are geochemically similar to those in the Hawaiian Islands, only the ratio of 87Sr/86Sr appears to change through time. All the lavas appear to be derived from a source that has small-scale heterogeneities, but is homogeneous on a large scale. 4) The Emperor Seamounts were once volcanic islands that underwent subaerial and shallow marine erosion, and deposition of shallow-water biogenic carbonate sediments that capped all or most of each volcano

Drilling in other regions has yielded less conclusive results. For example, it is uncertain if the Line Islands are an age progressive chain (hot-spot trace) or result from some other type of intraplate volcanism. The mid-Pacific Mountains also show evidence of originating from a regional episode of volcanism in the mid-Cretaceous. Drilling in the Nauru Basin encountered a voluminous mid-Cretaceous volcanic flow-sill complex that overlies Jurassic .magnetic anomalies, yet is composed of depleted tholeiite. In the Indian Ocean, drilling on the Ninety-East Ridge established that it 1) is volcanic in origin; 2) is older to the north; 3) formed in shallow water, and 4) formed further south and has moved northward. It appears that the Ninety-East Ridge, like the Hawaiian-Emperor chain, is a hot spot trace. In the Atlantic Ocean, drilling on the Iceland-Faeroe Ridge and the Rio Grande Rise-Walvis Ridge suggests that all the se aseismic ridges are hot spot traces generated by the Iceland and Tristan de Cunha hot-spots.

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SEPM Special Publication

The Deep Sea Drilling Project: A Decade of Progress

John E. Warme
John E. Warme
Colorado School of Mines, Golden Colorado.
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Robert G. Douglas
Robert G. Douglas
University of Southern California, Los Angeles California
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Edward L. Winterer
Edward L. Winterer
Scripps Institution of Oceanography, La Jolla California
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SEPM Society for Sedimentary Geology
Volume
32
ISBN electronic:
9781565761629
Publication date:
January 01, 1981

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