Large igneous province locations and their connections with the core–mantle boundary - Volcanism and Global Environmental Change - page 30

3

Large igneous province locations and their connections
with the core - mantle boundary

trond h. torsvik and kevin burke

3.1 Introduction
In 2004, Burke and Torsvik demonstrated for the

first time that reconstructed large
igneous provinces (LIPs) of the past 200 Myr overlie the edges of two equatorial,
antipodal large low shear-wave velocity provinces (LLSVPs) in the lowermost
mantle beneath Africa (Tuzo, named for Tuzo Wilson) and the Paci c Ocean

(Jason, named for Jason Morgan). In that work, palaeomagnetic data were used
to reconstruct the continents, and their contained LIPs were compared with the
seismic tomography of the lowermost mantle (at 2800 km) using the S20RTS
(Ritsema et al ., 1999 ) and SMEAN models (Becker and Boschi, 2002 ). Because
the pattern of LIPs correlating with present-day core

-

mantle boundary (CMB)
tomography was recognizable for times back to 200 Ma, we concluded that
LIPs originated above plumes from the edges on CMB of the two LLSVPs, and
also that the LLSVPs have been stable for the past 200 Myr.
This first documented stability extending back to 200 Ma was ignored or received
with sceptism by the geodynamic modelling community who considered that there was
no physical basis for stationary structures in the lowermost mantle because they could
not model this stability nor produce plumes from the margins of such stable features.
Nowadays, many modellers accept stability back to about 200 Ma but not before that
time. Some argue that the formation of the African LLSVP (Tuzo) is intimately linked
to the Pangea supercontinent formation and destruction (e.g. Zhang et al ., 2010 ).
Here we ning them from their

distinguishing characters and emphasizing current ideas about their provenance
including their origin at depth, and distinguish oceanic plateau LIPs from intra-
continental LIPs. Next, we outline the reconstruction methods that we have used
to rotate LIP outcrops from their present locations to the locations in which they

first review LIPs of the past 300 Myr, de