Archaean plate tectonics revisited; 1, Heat flow, spreading rate, and the age of subducting oceanic lithosphere and their effects on the origin and evolution of continents

Tectonics(August 1984), 3(4):429-448

Index Terms/Descriptors: age; Archean; continents; crust; erosion; evolution; heat flow; igneous activity; mid-ocean ridges; oceanic crust; plate tectonics; Precambrian; rates; sea-floor spreading; subduction; subduction zones; tectonophysics

Abstract:

A simple model has been derived using the following parameters: (1) the spreading rate at mid-ocean ridges; (2) the age of the oceanic lithosphere at the time of subduction; (3) the area-age distribution of the seafloor; (4) the continental surface area as a fraction of the total surface area of the Earth; and (5) the erosion rate of continents as a function of continental surface area and the total number of continental masses. If the subduction of old oceanic lithosphere results in an 8-10 times greater volume of subduction zone magmatism, our model predicts or explains all of the following observed features of earth history: (1) Archean terranes appear to record two periods of rapid continental accretion, between 3.8 and 3.5 b.y. ago and between 3.1 and 2.6 b.y. ago; (2) there are very few differences and many marked similarities between between rocks from Archean terranes and equivalent rocks from Phanerozoic terranes; (3) the total continental area appears to have remained essentially constant for the past 2 b.y. (4) Archean andesites are comparatively rare: (5) plutonic tonalites and trondhjemites appear to have been relatively much more abundant during the Archean.--Modified journal abstract.