SOME FIGURES FOR UNFINISHED MANUSCRIPTS (CONDENSED; FULL VERSION CAN BE REQUESTED VIA DROPBOX)

410

650

eclogiteharzburgite

cold

cold

Shear wavespeed Temperature

BL

High-T conduction geotherm

Subadiabatic geotherm

1600 C adiabat

Vs for self-compressed solid along adiabat

ObservedSeismic profile

VSH>VSV

VSV>VSH

RIDGEOIB

Tp=~1300 C

~1600 C

650 km

220 km

1

33

2

4

5

6

7

A mantle circulation model based on anisotropy, anharmonicity, absolute wavespeeds & gradients, allows for, and predicts, non adiabaticity

disconnect

LIL Sheared mélange

ridge

UPPER MANTLE

Tp

200

400kmAncient eclogite

cumulates Modern slab fragments

LVZ

TZ

LIL

THE “NEW” PARADIGM

hotspots

“the canonical box”

‘cold’

Sedimentsvolatiles

Intraplate volcanoesMidocean ridges

Residual slab components

LOWER MANTLE

*Essentially the classical model of Birch, Tatsumoto, Wilson…

200 Myr of oceanic crust accumulation

TRANSITION ZONE (TZ)

REGION BSuper-adiabatic boundary layer

Thermal max

600 km

300 km

Tp decreases with depth

600 km

Physics-Based Archimedian Paradigm*

(RIP)

(* Birch, Tatsumoto, J. Tuzo Wilson)

Shear strain

“fixed”Hawaii source

MORB source

Shear-driven magma segregation

Sources deeper than ~ 150-200 km are effectively fixed(e.g.J.T.Wilson)

OIB

(T), (V,T), TCMB(t), (V,T),U(z,t), Th(z,t)…

PebblesOld GreeksSlabs

The Eureka Solution

Archimedes & Birch

squeezing

squeezing

ISOTHERMAL

ADIA

BATI

C

ISOTHERM

ISOTHERM 100 km

HOMOGENEOUS

jet

STANDARD CONCEPTUAL MODEL (1988) No physics, no seismology

(used as reference model; Herzberg, Asimow, Humphreys, Schmandt, Victor Camp…e.g…)

No U, Th, KNo secular coolingAmbient T constrained (<1600K)

Mechanical boundary layer

Thermal boundary layer

Adiabatic interior

Lithosphere

Tp=1280o

Tp(max)~1600o

LID LLAMA subadiabat

Negative Vs gradient

0 100 200 300 Depth (km)

1600

1200

800

400

0

T (oC)

BOUNDARY LAYER

Cambridge nomenclature

UPPER MANTLE & LOWER MANTLE ARE COOLED BY LONG-LIVED FLAT (STAGNANT) SLABS

Cold slab

European, African, Asian (Changbai), Yellowstone & most continental intra-plate volcanoes (“hotspots”) are underlain by slabs

Cooled mantle

49

COLD

WARM

REGION B

TZ

Ridges & hotspots

COOL

410

650

No hotspots

LVA

STAGNANT SLABS–A FIXED REFERENCE FRAME

SLIP-FREE BOUNDARY

50There may be a concentration of CaO, Al2O3, K…U, Th…in the upper mantle…Birch

Boundary layer

Midplate

Ridge adiabat

LLAMA(shearing)

Plate (conducting)

Depth

16001400

T oC

T

Depth

B

D”

TZ

CMB

Illustrating the thermal bump and subadiabaticity

UPPER MANTLE

LOWER MANTLE

The highest potential temperature in the mantle is near 200 km. Tectonic processes (shear, delamination) are required to access this.

ridge midplate

bump

(& backarc)

400200

(Lubimova, MacDonald, Ness)

U, Th, K and other LIL are concentrated in the crust & the upper mantle boundary layer during the radial zone refining associated with accretion (Birch, Tatsumoto…). This accentuates the thermal bump.

Mesosphere (TZ)

LIDLVZ

LLAMA200

400

Intraplate (delamination, CRB, Deccan, Karoo, Siberia) magmas are shear-driven from the 200 km thick shear BL (LLAMA)

ridge

km Cold slabs

SUMMARY

OIB

Ridges are fed by broad 3D upwellings plus lateral flow along & toward ridges

subadiabatic