Receiver function imaging of mantle transition zone discontinuities and the origin of volcanism beneath Libya

Abstract

The origin of magma at Libya’s volcanic provinces is still poorly understood. In order to constrain these sources we report results of the first P-to-S receiver function investigation of the 410 km and 660 km depth discontinuities bounding the mantle transition zone (MTZ) beneath Libya. The dataset used by this study is a combination of eighteen seismic stations belonging to the Libyan Center for Remote Sensing and Space Science and the Incorporated Research Institutions for Seismology Data Management Center. The average thickness of the MTZ is found to be 249 ± 14 km, which is similar to the global average. A 10 km thinning of the MTZ was observed beneath the Miocene – Holocene volcanic provinces in central Libya, suggesting higher-than-normal temperatures in those parts of the MTZ. Our preferred model suggests that the origin of volcanism in Libya is due to higher temperatures in the MTZ beneath this region. However, in Eastern Libya, the thickness of the MTZ increases from 249 km to 270 km which indicates a colder-than-normal MTZ which may relate to ancient subducted slabs due to the Africa-Europe convergence since the late Mesozoic.