Llsvp

(2010) argued that kimberlite eruptions, and thus diamond deposits, occur preferentially within 15° of the edge of the African LLSVP, defined as the –1% ΔVS contour in the deep mantle. They claim that ~80% (1112 out of 1395) kimberlites and related volcanics erupted since ca. 320 Ma lie within this zone, and therefore propose that, in addition to causing hotspots and LIPs, deep-mantle plumes cause this distinctive style of volcanic activity, comprising clusters of pipes, dikes, and sills.

The global distribution of sources and permanent seismic stations limits the resolution of velocity gradients and total extent of the LLSVPs under Africa (Figure 9) and the Pacific, so deployments of portable instruments have been important for detailed differential traveltime analyses and waveform modeling used to improve resolution of LLSVP structure. Ritsema et al. (1998) and Ni and Helmberger (2003a,b) find that low-shear-velocity structure under southern Africa involves 3% ...

At a more regional scale, Farnetani et al. [2012] point out that 208Pb*/206Pb* increases from Hawaiʻi southward to Samoa. Their modeling results demonstrate that such large-scale latitudinal variations in isotopic signatures do not obscure bilateral asymmetry in the Hawaiian plume, but only add azimuthal and radial variations within the compositional hemispheres. Thus, whereas it may not be possible to characterize the geochemical properties of the LLSVP precisely at this time, ...