
doi: 10.1007/bf01829361
A new estimate of the bulk continental crust is reported consisting of 57 percent lower crust (60% felsic and 40% mafic granulites) and 43 percent upper crust. The proportions of crustal units are based on petrological observations (Bohlen &Mezger, 1989). The estimate of a bulk composition is intermediate between andesite and tonalite and is higher in Si, K, Rb, Sr, Zr, Nb, Ba, LREE, Pb, Th concentrations and lower in Mg, Ca, Sc, Mn, Fe than the crustal abundances reported byTaylor &McLennan (1985). Equal chemical composition between the upper crust and the felsic part of the lower crust is attained in balance computations if one restores a fraction of 12.5 percent S-type granite from the upper into the lower crust. An example of water-undersaturated partial melting and separation of a fraction of about 35 percent granitic magma at the conversion from amphibolite-into granulite-facies metasediments has been balanced bySchnetger (1988) in the Ivrea area (N. Italy). The worldwide observed discrepancy between a larger negative Eu anomaly in the upper crust compared with the half as large positive anomaly of the lower crust increasing from the early Precambrian to present has been explained by recycling of Ca-rich restite into the upper mantle. The composition of the Archean crust (example: Greenland) does not differ systematically from the post-Archean crust.
550.geology, Article
550.geology, Article
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 146 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Top 1% | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Top 1% | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Top 10% |
