Journal ArticleDOI
Speed limit for oceanic transform faults
David F. Naar,Richard Hey +1 more
TLDR
In this article, a relative motion model for the Pacific and Nazca plates is proposed and the authors show that transform faults with slip rates greater than ∼145 km/m.y. do not currently exist along the East Pacific Rise.Abstract:
Oceanic transform faults with slip rates greater than ∼145 km/m.y. do not currently exist along the East Pacific Rise where sea-floor spreading rates range from 145 to 160 km/m.y. Instead, offsets of the the very fast spreading East Pacific Rise are accommodated by microplates, propogating rifts, or overlapping spreading centers. This suggests that there might be a speed limit above which transform faults do not exist. A physical reason for a speed limit is not known, but it might be related to unstable stress fields near the rifts tips, causing them to episodically propagate and prevent a transform fault from being formed. The spreading rates quoted are from our new (0-0.73 Ma) relative-motion model for the Pacific and Nazca plates.read more
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Journal ArticleDOI
Global marine gravity from retracked Geosat and ERS‐1 altimetry: Ridge segmentation versus spreading rate
TL;DR: In this article, three approaches are used to reduce the error in the satellite-derived marine gravity anomalies: retracking the raw waveforms from the ERS-1 and Geosat/GM missions resulting in improvements in range precision of 40% and 27%, respectively.
Journal ArticleDOI
Axial summit trough of the East Pacific Rice 9°–10°N: Geological characteristics and evolution of the axial zone on fast spreading mid‐ocean ridge
TL;DR: In this article, a four-stage model is presented for the evolution of axial summit collapse trough, as well as for other well-studied portions of the East Pacific Rise crest from 21°N to ∼20°S.
Journal ArticleDOI
Rates of processes in magmatic arcs : implications for the timing and nature of pluton emplacement and wall rock deformation
TL;DR: The average rates or durations of processes in shallow to moderate level arc environments are the following: (1) crystal growth rates in magma of 10 −4 cm year −1; (2) growth rates of metamorphic porphyroblasts between 10 −5 and 10 −2 cm year−1 ; (3) long-term magma supply rates of up to 350 km 3 year − 1 ; (4) diapiric ascent rates for mafic plutons of 1 −3 m year −2 ; (5) cooling of pl
Journal ArticleDOI
Tectonic evolution of the Easter Microplate
David F. Naar,Richard Hey +1 more
TL;DR: The plate tectonic history of the Easter microplate has been reconstructed by closing the microplate in a series of steps using the Pacific-Nazca magnetic anomalies and the NUVEL 1 global plate motion model as mentioned in this paper.
Journal ArticleDOI
Uniform accretion of oceanic crust south of the Garrett transform at 14°15′S on the East Pacific Rise
Graham M. Kent,Alistair J. Harding,John A. Orcutt,Robert S. Detrick,John C. Mutter,Peter Buhl +5 more
TL;DR: In this article, the structural differences along the ultrafast spreading (150 mm/yr) East Pacific Rise south of the Garrett fracture zone are second-order, suggesting a remarkably uniform process of crustal accretion.