Magma Storage System and Hidden Hotspot Track of the Emeishan Large
Igneous Province and its Impact on the Timing of the Capitanian Mass
Extinction
Abstract
Large igneous provinces (LIPs) are often associated with mass
extinctions and are vital for life evolution on Earth. However, the
precise relation between LIPs and their impacts on biodiversity is
enigmatic as they can be asynchronous. If the environmental impacts are
primarily related to sill emplacement, the structure of LIPs’ magma
storage system becomes critical as it dictates the occurrence and timing
of mass extinction. Here we use surface wave tomography to image the
lithosphere under the Permian Emeishan Large Igneous Province (ELIP) in
SW China. We find a NE-trending zone of high shear-wave velocity (Vs)
and negative radial anisotropy (Vsv > Vsh) in the crust and
lithosphere and interpret it as a mafic-ultramafic, dike-dominated magma
storage system on the hidden hotspot track of the ELIP. An area of
less-negative radial anisotropy, on the hotspot track but away from the
eruption center, reflects an elevated proportion of sills emplaced at
the incipient stage of the ELIP. Liberation of poisonous gases and
mercury by the sills explains why the mid-Capitanian global biota crisis
preceded the peak ELIP eruption by 2-3 million years.