Premium
Sediment Characterization at the Equatorial Mid‐Atlantic Ridge From P ‐to‐ S Teleseismic Phase Conversions Recorded on the PI‐LAB Experiment
Author(s) -
Agius M. R.,
Harmon N.,
Rychert C. A.,
Tharimena S.,
Kendall J.M.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl080565
Subject(s) - geology , seafloor spreading , sediment , sedimentation , lithosphere , ridge , mid atlantic ridge , aeolian processes , oceanography , geomorphology , seismology , paleontology , tectonics
Accurate marine sediment characteristics, for example, thickness and seismic velocity, are important for constraining sedimentation rates with implications for climate variations and for seismic imaging of deeper structures using ocean bottom seismic deployments. We analyze P ‐to‐ S seismic phase conversions from the sediment‐crust boundary recorded by the Passive Imaging of the Lithosphere‐Asthenosphere Boundary (PI‐LAB) experiment to infer the sediment thickness across the Mid‐Atlantic Ridge covering 0‐ to 80‐Myr‐old seafloor. We find P d s ‐ P delay times of 0.04–0.37 s, or 5‐ to 82‐m thickness. Sediment thickness increases with age. Thickness agrees with global estimates for young (<15–20 Myr) seafloor but is thinner on older lithosphere. Our result may represent a lower limit on sediment thickness, given that several of our stations are on topographic highs. The sedimentation rate decrease observed from 5 to 1.2 mm/kyr at ∼10 Myr suggests a recent increase in productivity related to climate change, eolian dust fluxes, and/or biogenic marine activity.