Continental crust formation

Another approach is to follow a genetic model for continental crust formation, for example in island arcs, oceanic plateaus or Archean granite-greenstone terrains. For example, the full vertical crustal sequence of a mature island-arc has been reconstructed in the Hidaka belt in Hokkaido, Japan over a total thickness of 30 km. This arc contains high-grade metamorphic rocks representative of lower crustal material and its average rate of crustal heat generation is 0.83 p.W m (Furukawa and Uyeda, 1989 Furukawa and Shinjoe, 1997). 

Tatsumi Y. (2000) Continental crust formation by delamination in subduction zones and complementary accumulation of the enriched mantle I component in the mantle. Geochem. Geophys. Geosys. (G-cubed) 1, 1-17. 

Kramers, J. D. 1988. An open-system fractional crystallization model for very early continental crust formation. Precambrian Research, 38, 281-295. 

Fig. 2. Reservoirs and fluxes used in previous and present modelling work (not to scale). Rectangles used for reservoirs ellipses for loci of fractionation by melt processes, m-f, depleted mantle melting, oceanic crust (MORB) formation s-f, subduction zone melting leading to continental crust formation c-f, intracrustal fractionation leading to upper and lower crust formation. Bold arrows, fluxes involving trace element fractionation line arrows flirxes without trace element fractionation stippled arrows, fluxes operating only during accretion and core formation.

Magma types 2006). A significant part in formation of magmatic complexes accompaning riftogenesis belongs to the sources of different nature and to characteristics of the continental crust contaminated by those complexes. These very data accounted for the formation of a contrasting volcanism which is widely developed in the zone of the Central-Asian fold belt. The paper considers a bimodal volcano-plutonic complex of the end of the Late Cretaceous. It is spatially located within the continuation of the formations with similar composition which compose the Central-Asian fold belt. 

Sims, K.W.W., Newsom, H.E. and Gladney, E.S. (1990) Chemical fractionation during formation of the Earth s core and continental crust clues from As, Sb, W, and Mo, in Origin of the Earth (eds H.E. Newson and J.H. Jones), Oxford University Press, New York Lunar and Planetary Institute, Houston, pp. 291-317. 

Conditions of rock weathering, sediment formation and therefore geochemical processes as a whole were different in the geological past (Veizer, 1973) oxygen and carbon dioxide partial pressures were different and there were more basic rocks available for weathering. The Precambrian sediments of the Canadian and Scottish shields are discussed by J. G. Holland and Lambert (1973) in relation to the composition of the continental crust. 

Kramers J. D. and Tolstikhin I. N. (1997) Two terrestrial lead isotope paradoxes, forward transport modeling, core formation and the history of the continental crust. Chem. Geol. 139, 75-110. 

The principal division of the Earth into core, mantle, and crust is the result of two fundamental processes, (i) The formation of a metal core very early in the history of the Earth. Core formation ended at —30 million years after the beginning of the solar system (Kleine et aL, 2002). (ii) The formation of the continental crust by partial melting of the silicate mantle. This process has... 

Campbell I. H. (2002) Implications of Nb/U, ThAJ and Sm/Nd in plume magmas for the relationship between continental and oceanic crust formation and the development of the depleted mantle. Geochim. Cosmochim. Acta 66, 1651-1662. 

The above explanation does not account for the elevated ° Pb/ °" Pb ratios of continental rocks and their sedimentary derivatives relative to mantle-derived basalts (Figures 5(a) and 21). This special feature can be explained by a more complex evolution of continents subsequent to their formation. New continental crust formed during Archean time by subduction and accretion processes must have initially possessed a U/Pb ratio slightly higher than that of the mantle. At that time, the terrestrial ratio was signifi-... 

Sylvester P. J., Campbell 1. H., and Bowyer D. A. (1997) Niobium/Uranium evidence for early formation of the continental crust. Science 275, 521-523. 

This chapter reviews the present-day composition of the continental crust, the methods employed to derive these estimates, and the implications of the continental crust composition for the formation of the continents. Earth differentiation, and its geochemical inventories. 

Bohlen S. R. and Mezger K. (1989) Origin of granulite terranes and the formation of the lowermost continental crust. 

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