Publication Date:
2022-03-24
Description:
Plate divergence along mid‐ocean ridges is accommodated through faulting and magmatic accretion, and, at overlapping spreading centers (OSC), is distributed across two curvilinear overlapping ridge axes. One‐meter resolution bathymetry acquired by autonomous underwater vehicles, combined with distribution and ages of lava flows, is used to: (a) analyze the spatial and temporal distribution of flows, faults, and fissures in the OSC between the distal south rift zone of Axial Seamount and the Vance Segment, (b) locate spreading axes, (c) calculate extension, and (d) determine the proportion of extension accommodated at the surface by faults and fissures versus volcanic extrusion over a period of ∼1300–1450 years. Our study reveals that in the recent history of the ridges, extension over a distance of 14 km across the Axial/Vance OSC was asymmetric in proportion and style: faults and fissures across 1–2 km of the Vance axial valley accommodated ∼3/4 of the spreading, whereas dike‐fed eruptions contributed ∼1/4 of the extension and occurred across 4 km of the south rift of Axial Seamount.
Description:
Plain Language Summary:
Along mid‐ocean ridges, oceanic plates separate through the formation and growth of faults and the emplacement of dikes supplying lava flows. Where segments overlap in a zone of separation, these processes are distributed along two spreading axes separated by 2–30 km kilometers. We combine 1‐m resolution bathymetry collected by autonomous underwater vehicles and the age of large lava flows to (a) analyze the distribution of faults and lava flows where Axial Seamount overlaps with the Vance Segment, (b) define the current plate boundary, (c) calculate the speed of plate separation, and (d) determine the proportion and locations of fault extension versus flow emplacement. Our study shows that during the last ∼1300–1450 years, fault formation and growth along the Vance Segment are the main contributor to plate separation. In contrast, the emplacement of dikes and lava flows along Axial Seamount account only for ∼1/4 of the plate separation.
Description:
Key Points:
Autonomous underwater vehicle mapping of an overlapping spreading center reveals the proportion of faulting and eruptions that occurred during the last ∼1300–1450 years.
Faulting at the Vance Segment accommodates ∼3/4 of the spreading and magmatic accretion along Axial Seamount south rift accounts for ∼1/4.
The spreading axis is 〈250 m wide along the Vance Segment but ∼4 km wide along the south rift of Axial Seamount.
Description:
David and Lucile Packard Foundation (PF)
http://dx.doi.org/10.13039/100000008
Keywords:
ddc:551.8
;
ddc:551.13
Language:
English
Type:
doc-type:article
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