Marine Science Faculty Publications
Document Type
Article
Publication Date
2023
Keywords
seafloor spreading, oceanic crust, sheeted dikes, ophiolites, faulting
Digital Object Identifier (DOI)
https://doi.org/10.1029/2022GC010527
Abstract
A tectonic window into the upper 2,000 m of oceanic crust generated at the superfast spreading (∼142 mm/yr) southern East Pacific Rise exposes a continuous layered structure of basaltic lavas and sheeted dikes over gabbroic rocks. This relatively simple structure is in accord with expectations for crustal accretion at a very fast spreading rate and high magma budget where magmatic construction keeps pace with plate separation. Detailed observations show that basaltic lava flows dip progressively more steeply inward (toward the spreading axis where they were erupted). Underlying sheeted dikes are faulted and tectonically rotated to dip steeply outward. These structures are interpreted in terms of subsidence beneath the axis of the southern East Pacific Rise during crustal construction that allowed the lava unit to thicken to >400 m without creating comparable relief at the spreading center. Transitional units above and below the sheeted dike complex show that the thickness of upper crustal rock units is modified by tectonic and intrusive processes during accretion. The crustal structure shows that even approaching the superfast spreading end-member of seafloor spreading, crustal accretion involves dramatic tectonic processes that are not obvious from the surface geology of spreading centers.
Rights Information
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Was this content written or created while at USF?
Yes
Citation / Publisher Attribution
Geochemistry, Geophysics, Geosystems, v. 24, issue 3, art. e2022GC010527
Scholar Commons Citation
Karson, J. A.; Chutas, L. A.; Hayman, N. W.; Hey, R. N.; Horst, A. J.; Hurst, S. D.; Klein, E. M.; Naar, D. F.; and Varga, R. J., "Upper Crustal Structure of Superfast-Spread Oceanic Crust Exposed at the Pito Deep Rift: Implications for Seafloor Spreading" (2023). Marine Science Faculty Publications. 2589.
https://digitalcommons.usf.edu/msc_facpub/2589
