Hindsight Heresy

Examples of “Hindsight Heresy” in which a hypothesis is constructed after looking at a data set, and then using the same data to support and test the hypothesis, to prune the data or change parameters (Burke 2008; Torsvik at al. 2006; Lithgow-Bertelloni & Richards 1998; Courtillot et al 2003; Coutier et al. 2007; etc.).1. Courtillot, V. et al. Three distinct types of hotspots in the Earth's mantle. Earth Planet. Sci. Lett. 205, 295308 (2003).2. Torsvik, T.H. et al. 2006. Large igneous provinces generated from the margins of the large low-velocity provinces in the deep mantle. GJI 167, 1447–1460.3. Burke, K. et al. Plume generation zones at the margins of large low shear velocity provinces on the core–mantle boundary. EPSL 265, 49–60 (2008).4. Lithgow-Bertelloni, C., Richards, M.A., 1998. The dynamics of Cenozoic and Mesozoic plate motions. Rev. Geophys. 36, 27–78.5. Cottaar, S., B. Romanowicz, An unsually large ULVZ at the base of the mantle near Hawaii, EPSL, 355-356, 213-222, 2012.6. Courtier, A. M. and 14 others. Correlation of seismic and petrologic thermometers suggests deep thermal anomalies beneath hotspots. EPSL 264, 308-316.

100 km depth

Ridge, slab related

Using the same parameters as Burke, the correlation of hotspots & backtracked LIPs with tomography is higher for the uppermost than for the lowermost mantle

Slabs in TZ

11 hotspots on edges

Ridge-related LVAs

18 hotspots

Most hotspots are in broad ridge-related LVAsLIPs & some hotspots started at edges of slabs

6 ‘aberrant’ hotspots

14 ‘aberrant’ hotspots

P=1.47x10-7

Burke et al.

(“outside of plate boundary related low wavespeed areas)

true within-plate hotspots are underlain by average or fast mantle at 100 km depth.

100 km depth

Core-mantle boundary (CMB)

P<10-8

“Hotspots” correlate with upper mantle LVAs

There is a strong anticorrelation between the inferred positions of plate divergence, ridges, hotspots and LIP initiation & subduction zones over the last 250 Myrs and high wavespeed features in and just below the TZ.

Near-ridge mantle

Plates move over less dense hotter mantle as they move away from ridge

This explains seafloor flattening & residual bathymetry

anisotropy

ridges

Constrains thermal gradient

Constrains melt content

Cross-over