1. Continental growth spurts were all before 1 Ga This plus ophiolites, kimberlites, komatiites, TTG,UHPT…suggest that modern plate tectonics was not occurring before Late Precambrian Today, delamination equals arc and plateau addition

2. Can we bridge geophysics,geochemistry & geodynamics? Continents; the missing link The lower crust is transient It is recycled 6 times faster than upper crust Recent arc growth estimates are 5X previous estimates! Therefore, a huge previously unaccounted for flux Mantle convection controlled from the top; episodicity is plate reorganization, not mantle avalanches!

4. TRI-CYCLING THROUGH THE EARTH RIDGE-TRENCH ‘CYCLE’ (the escalator) SUPERCONTINENT CYCLE (the trolley) SLAB-PLUME ‘CYCLE’ (the tube) SUBTERRANEAN CYCLE (delamination, orogenic cycle; the elevator)

5. Modes of advection TUBES CIRCUITS, BOUNDARY LAYERS ELEVATOR HEAT EXCHANGER

6. Estimating mantle sources & sinks, continental addition & loss, through time, depends critically on when deep subduction, got underway David Scholl 1 Gyr of oceanic crust subduction=70 km of eclogite According to Stern, deep subduction started at 1 Ga

7. Ringwood& Green, 1966

8. New parameters Scale (size) Homologous temperature Stress Buoyancy parameter Architecture Fertility Entrainability

9. What triggered this new understanding? The upper crust paradox Recognition of true arc growth rates The need to get rid of enormous amounts of lower crust Appreciation of role of Eclogite Appreciation of SCALE

10. Recent workers who are, or are almost onto this, once they leave the crust or MORB Bob & Suzanne Kay Roberta Rudnick Sobolov, Green, Scholl, Elliott, Natland, Presnall, Cin-Ty Lee

11. MASS BALANCE km 3 /yr TOTAL MIDPLATE MAGMA VOLUMES 3-6 Growth rate of arc garnet pyroxenite cumulates 1.5-6 Underside erosion & delamination of continents 4-6 Production rate of magmas in arcs 4-5 LOWER CRUSTAL LOSS = ‘HOTSPOT’ MAGMATISM CYCLE TIME 40-80 MYR 10-30 KM CHUNKS

12. dense roots fall off warm up in ambient mantle rise possible mechanism for Atlantic & Indian ocean plateaus & DUPAL anomaly Delamination cycle