Archean geodynamics: Similar to or different from modern geodynamics?

摘要: There is a wealth of geologic, geochemical, structural, volcanologic, and sedimentologic data that are consistent with Archean plate tectonics, especially after 3.0 Ga. Neither the eruption submarine basalts onto thinned continental crust nor existence ductile or viscous diapirism precludes tectonics during Archean. Some "missing indicators" found in terranes (probable oceanic crust, melange, possible passive margin sequences, boninite), whereas absence others (such as blueschists) can be explained by higher mantle geotherm. Bimodal magmatism not limited to but occurs several modem tectonic settings. The relative abundance komatiites reflects hotter possibly widespread plume activity. Any viable model for geodynamics must accommodate following 10 constraints: During Archean, was than it today; there two styles crustal deformation Archean; komatiite proportionally more abundant greenstones younger greenstones; tonalite-trondhjemite-granodiorite depleted heavy rare earth elements afterwards; thick lithosphere underlies many cratons; portions were strongly large ion lithophile comprise arc-like rock assemblages; significant proportion contain volcanic rocks geochemical characteristics similar plume-derived basalts; paleomagnetic indicate apparent polar wandering occurred volume produced about 2.7