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Upper Crustal Structure of Superfast-Spread Oceanic Crust Exposed at the Pito Deep Rift: Implications for Seafloor Spreading

Publication ,  Journal Article
Karson, JA; Chutas, LA; Hayman, NW; Hey, RN; Horst, AJ; Hurst, SD; Klein, EM; Naar, DF; Varga, RJ
Published in: Geochemistry, Geophysics, Geosystems
March 1, 2023

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.

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Published In

Geochemistry, Geophysics, Geosystems

DOI

EISSN

1525-2027

Publication Date

March 1, 2023

Volume

24

Issue

3

Related Subject Headings

  • Geochemistry & Geophysics
  • 51 Physical sciences
  • 37 Earth sciences
  • 04 Earth Sciences
  • 02 Physical Sciences
 

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Karson, J. A., Chutas, L. A., Hayman, N. W., Hey, R. N., Horst, A. J., Hurst, S. D., … Varga, R. J. (2023). Upper Crustal Structure of Superfast-Spread Oceanic Crust Exposed at the Pito Deep Rift: Implications for Seafloor Spreading. Geochemistry, Geophysics, Geosystems, 24(3). https://doi.org/10.1029/2022GC010527
Karson, J. A., L. A. Chutas, N. W. Hayman, R. N. Hey, A. J. Horst, S. D. Hurst, E. M. Klein, D. F. Naar, and R. J. Varga. “Upper Crustal Structure of Superfast-Spread Oceanic Crust Exposed at the Pito Deep Rift: Implications for Seafloor Spreading.” Geochemistry, Geophysics, Geosystems 24, no. 3 (March 1, 2023). https://doi.org/10.1029/2022GC010527.
Karson JA, Chutas LA, Hayman NW, Hey RN, Horst AJ, Hurst SD, et al. Upper Crustal Structure of Superfast-Spread Oceanic Crust Exposed at the Pito Deep Rift: Implications for Seafloor Spreading. Geochemistry, Geophysics, Geosystems. 2023 Mar 1;24(3).
Karson, J. A., et al. “Upper Crustal Structure of Superfast-Spread Oceanic Crust Exposed at the Pito Deep Rift: Implications for Seafloor Spreading.” Geochemistry, Geophysics, Geosystems, vol. 24, no. 3, Mar. 2023. Scopus, doi:10.1029/2022GC010527.
Karson JA, Chutas LA, Hayman NW, Hey RN, Horst AJ, Hurst SD, Klein EM, Naar DF, Varga RJ. Upper Crustal Structure of Superfast-Spread Oceanic Crust Exposed at the Pito Deep Rift: Implications for Seafloor Spreading. Geochemistry, Geophysics, Geosystems. 2023 Mar 1;24(3).
Journal cover image

Published In

Geochemistry, Geophysics, Geosystems

DOI

EISSN

1525-2027

Publication Date

March 1, 2023

Volume

24

Issue

3

Related Subject Headings

  • Geochemistry & Geophysics
  • 51 Physical sciences
  • 37 Earth sciences
  • 04 Earth Sciences
  • 02 Physical Sciences