Waning magmatic activity along the Southern Explorer Ridge revealed through fault restoration of rift topography
We combine high‐resolution bathymetry acquired using the Autonomous Underwater Vehicle ABE with digital seafloor imagery collected using the remotely operated vehicle ROPOS across the axial valley of the Southern Explorer Ridge (SER) to infer the recent volcanic and tectonic processes. The SER is an...
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Published in | Geochemistry, geophysics, geosystems : G3 Vol. 14; no. 5; pp. 1609 - 1625 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Washington
Blackwell Publishing Ltd
01.05.2013
John Wiley & Sons, Inc AGU and the Geochemical Society |
Subjects | |
Online Access | Get full text |
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Summary: | We combine high‐resolution bathymetry acquired using the Autonomous Underwater Vehicle ABE with digital seafloor imagery collected using the remotely operated vehicle ROPOS across the axial valley of the Southern Explorer Ridge (SER) to infer the recent volcanic and tectonic processes. The SER is an intermediate spreading ridge located in the northeast Pacific. It hosts the Magic Mountain hydrothermal vent. We reconstruct the unfaulted seafloor terrain at SER based on calculations of the vertical displacement field and fault parameters. The vertical changes between the initial and the restored topographies reflect the integrated effects of volcanism and tectonism on relief‐forming processes over the last 11,000–14,000 years. The restored topography indicates that the axial morphology evolved from a smooth constructional dome >500 m in diameter, to a fault‐bounded graben, ~500 m wide and 30–70 m deep. This evolution has been accompanied by changes in eruptive rate, with deposition of voluminous lobate and sheet flows when the SER had a domed morphology, and limited‐extent low‐effusion rate pillow eruptions during graben development. Most of the faults shaping the present axial valley postdate the construction of the dome. Our study supports a model of cyclic volcanism at the SER with periods of effusive eruptions flooding the axial rift, centered on the broad plateau at the summit of the ridge, followed by a decrease in eruptive activity and a subsequent dominance of tectonic processes, with minor low‐effusion rate eruptions confined to the axial graben. The asymmetric shape of the axial graben supports an increasing role of extensional processes, with a component of simple shear in the spreading processes.
Key Points
High‐resolution bathymetry on the Explorer RidgeRidge topography reconstructionModel of cyclic volcanism |
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Bibliography: | istex:24E7BE5E825C0CA6EC3E098B3AB91304DC14900D ark:/67375/WNG-N50RDXJ7-D ArticleID:GGGE20110 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1525-2027 1525-2027 |
DOI: | 10.1002/ggge.20110 |