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Mantle‐earthquake geothermometry of rejuvenated Proterozoic lithosphere, western Saudi Arabia
Author(s) -
Blanchette Alexander R.,
Klemperer Simon L.,
Mooney Walter D.,
Zahran Hani M.
Publication year - 2019
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.13964
Subject(s) - geology , lithosphere , proterozoic , mantle (geology) , seismology , geochemistry , tectonics
Harrat Lunayyir is a Quaternary volcanic field above a 2009 dyke intrusion located in the Arabian Shield ~100 km east of the Red Sea rift. We use 3D common conversion point stacking of P-wave receiver functions to show that the Moho is at 38 ± 2 km depth, close to the 40-km crustal thickness measured in the center of the Arabian craton, whereas the lithosphere-asthenosphere boundary is at 60 ± 5 km depth (Figure 1), far shallower than the 150 km seen further east in the Arabian shield. We re-located 64 highfrequency earthquakes with mL ≤ 2.5 at depths of 42–48 km, clearly beneath the Moho, ~30 km eastsoutheast of the 2009 dyke-intrusion beneath Harrat Lunayyir (Figure 1). These brittle-failure earthquakes, that must have nucleated at temperatures T ≤ 900°C, show that the lithosphere is not in thermal equilibrium with the underlying asthenosphere that has a petrologically calibrated potential temperature of ~1350°C at 60 km depth (Blanchette et al., 2018).