thermal controls of crustal diapirism: implications for the earliest crust and sub-cratonic...
TRANSCRIPT
Thermal controls of crustal diapirism: implications for the earliest crust and sub-cratonic
lithosphere
Catherine Robin
&
Richard Bailey
Neutrino Geoscience
Sudbury, 2008
Implications:• Predominantly vertical (diapiric) crustal tectonics in the Early Earth; but also:
• Supplies metabasalts to the lower crust to form TTGs (tonalites, trondhjemites and granodiorites)
• Leaves a depleted restite which can be harzburgitic to dunitic (for komatiitic volcanism), and which can accumulate from the top-down to form the SCLM (sub-cratonic lithospheric mantle), without calling on large plumes or strong horizontal plates (but doesn’t preclude some of these)
The plausibility of vertical tectonics (and the transition to modern-day tectonics) depends on the assumed heat source distribution and mode of volcanism of the early earth, and on its evolution with time.
Thanks!