East Pacific Rise at 21 °N: The volcanic, tectonic, and hydrothermal processes of the central axis

Earth and Planetary Science Letters
By: , and 



Photographs obtained by the ANGUS survey system at 21°N reveal many similarities to the geological processes delineated at other spreading centers and in particular those observed in the Galapagos Rift at 86°W. The region of recent volcanism is restricted to a narrow zone (Zone l) approximately l km wide. This suggests that the width of the magma chamber feeding these flows is also narrow at the top. Variations in sediment cover are used to subdivide the flows within Zone 1 into three sheet-flow/pillow-flow pairs. The youngest pair appears to have erupted form a linear fissure 8 km long running parallel to the valley axis. This fissure is part of a larger en echelon pattern of eruptive fissures. Active hydrothermal vents associated with the youngest flows are situated directly above the apparent eruptive fissure. The high (350°C) temperature for some of the fluids exiting from the vents suggests a highly restricted circulation system involving, at times, little to no mixing with cold seawater. The lava terrain in the remainder of Zone l and bordering regions is characterized by extensive fracturing, further suggesting a narrow upper dimension to the magma chamber and also that subsurface hydrothermal deposition of massive sulfides may lead to a reduction in the mixing processes.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title East Pacific Rise at 21 °N: The volcanic, tectonic, and hydrothermal processes of the central axis
Series title Earth and Planetary Science Letters
DOI 10.1016/0012-821X(81)90081-9
Volume 55
Year Published 1981
Language English
Publisher Elsevier
Contributing office(s) Woods Hole Coastal and Marine Science Center
Description 10 p.
First page 1
Last page 10
Country Mexico
Other Geospatial Baja California
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