Skip to Main Content
Book Chapter

Recent Research on Passive Continental Margins

By
Robert E. Sheridan
Robert E. Sheridan
Department of Geology, University of Delaware
Newark, Delaware 19711 U.S.A.
The JOIDES Passive Margin Panel
Search for other works by this author on:
Published:
January 01, 1981

Abstract

Recently available multichannel-seismic data have provided a detailed look at many Atlantic passive margins. DSDP holes and COST (Continental Offshore Stratigraphic Test) wells have provided geologic calibration. Reefal-carbonate bank underpinnings were involved in continental slope migration seaward of the original continental edge, especially in the Jurassic-Early Cretaceous. Tertiary erosion has caused a large landward retreat of the continental slope. These erosional events are nearly coeval on both sides of the Atlantic Ocean, indicating that they were caused by some basin- wide oceanographic change

Deeper crustal layers are identified on the modern reflection and refraction data. Intermediate seismic velocity layers, 7.1 km/sec, near the continental edge on both sides of the Atlantic might be characteristic of transitional-type crusts, or merely continuations of Layer 3 under the slope and shelf.

Deep, listric normal faults are observed where the soles of the faults merge into a lower crustal layer (6.3 km/sec velocity). Thinning with listric faulting of apparent continental crust has brought the mantle (8.2 km/sec) to within 14 km depths of the surface. Viscous creep in the lower continental crust appears necessary to account for the measured crustal thinning.

Detailed analysis of the multichannel reflection data permits sequence identification within the thick margin sediments. Sealevel cycles can be identified, and correlations reveal the configuration of genetically related stratigraphic units. Such analyses define the subsidence history and paleobathymetry of the margins. Some passive margins start with an uplift and rifting phase, whereas others are rifted through previous deepbasins without uplift or volcanism. Other margins are dominated by volcanism in the early stages, and outer ridge structures have formed. Others have been involved in ridge-jump early in the seafloor spreading history which isolated transitional crusts of dispersed volcanism and continental slivers.

You do not currently have access to this article.

Figures & Tables

Contents

SEPM Special Publication

The Deep Sea Drilling Project: A Decade of Progress

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

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal