Velocity-Temperature Conversion in the Oceanic Lithosphere: Investigating Thermal Structure and Evolution Along the African Margins

Abstract

This study investigates the relationship between seismic velocity and temperature in
the lithosphere by utilizing high-resolution shear wave velocity models, cooling models,
and heat flow data. The velocity models used in this study, primarily derived from
Fishwick (2010), provide a detailed seismic tomography framework for analysing
lithospheric temperature distribution. Comparisons were made with global models such
as Schaeffer et al. (2013) and Kustowski et al. (2008) to assess model reliability and
resolution differences. By applying both half-space and plate cooling models, the study
estimates lithospheric thickness, thermal uplift, and subsidence patterns. Velocity-to-
temperature conversion was conducted using a statistical approach as well as the
empirical parameterization of Priestley & McKenzie (2006). Results indicate that the
half-space cooling model predicts a continuously cooling lithosphere, while the plate
model shows thermal equilibrium at older ages. Temperature estimates from shear wave
velocities range from 375°C to 1746°C using the half-space model, and from 598°C to
1580°C using the plate model. The empirical parameterization by Priestley & McKenzie
(2006) predicted lower temperatures, ranging from 140°C to 1280°C, and demonstrated
better correlation with observed heat flow data. Temperature difference maps
highlight slow velocity anomalies beneath the ocean ridge, Cape Verde, and Canary
Islands, corresponding to regions of high thermal anomalies. Gravity data analysis
reveals that faster seismic velocities coincide with negative free-air gravity anomalies
and lower temperature deviations, while slower seismic velocities align with intermediate
gravity anomalies and higher thermal deviations. These findings provide a refined
understanding of lithospheric cooling patterns and contribute to geodynamic studies,
petroleum exploration, and the assessment of regional thermal models. The study
underscores the importance of integrating seismic, thermal, and gravity data for
improved lithospheric characterization and highlights the need for expanding the
analysis to the eastern margin of Africa and the Indian Ocean for a comprehensive
regional assessment.