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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 9. (September)

First Page: 1670

Last Page: 1670

Title: Phenomena of Pulsation Tectonics Related to Early Rifting of Eastern North American Continental Margin: ABSTRACT

Author(s): Robert E. Sheridan

Article Type: Meeting abstract


New data from the recent IPOD drilling of DSDP Site 534 in the Blake-Bahama Basin give a definitive age for the spreading-center shift involved in the early rifting of the North American Atlantic margin. A basal Callovian age (~155 m.y.) is determined for the Blake Spur magnetic anomaly marking this spreading-center shift that signals the birth of the modern North Atlantic Ocean. This is some 20 m.y. younger than previously thought. One implication of this surprising result is that this spreading-center shift starting North Atlantic rifting is now of an age which could be assigned to the spreading-center shift needed to end the rifting in the Gulf of Mexico. It is suggested that this might be one and the same event. Another implication of this surprisingly young age for t e Blake Spur event is that very high spreading rates are now required for the Jurassic outer magnetic quiet zone along the North American margin. This association of a high spreading rate with a magnetic quiet zone is similar to that for the middle Cretaceous and implies a link between the processes controlling plate spreading, which are in the upper mantle, and the processes controlling the magnetic field, which are in the outer core. A theory of pulsation tectonics involving the cyclic eruption of plumes of hot mantle material from the lowermost mantle could explain the correlation. Plumes carrying the heat away from the core/mantle boundary later reach the asthenosphere and lithosphere to induce faster spreading. The pulse of fast spreading in the Jurassic apparently caused the riftin of the North Atlantic. Other pulses of fast spreading appear to correlate with major ocean openings on various parts of the globe, implying that this may be a consistent process. Rifting of passive margins may be controlled by the more fundamental global processes described by the theory of pulsation tectonics.

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Copyright 1997 American Association of Petroleum Geologists