+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

Chromitites from the Fiskenaesset anorthositic complex, West Greenland; clues to late Archaean mantle processes

, : Chromitites from the Fiskenaesset anorthositic complex, West Greenland; clues to late Archaean mantle processes. Geological Society Special Publications 338: 197-212

Chromitites in the late Archaean Fiskenaesset anorthosite complex are characterized by a most unusual mineral assemblage: highly calcic plagioclase, iron-rich aluminous chromites and primary amphibole. In particular, the chromite compositions are atypical of chromitites in layered igneous intrusions. However, rare occurrences of this mineral assemblage are found in modern arcs and it is proposed here that the late Archaean calcic anorthositic chromitites formed by the partial melting of unusually aluminous harzburgite in a mantle wedge above a subduction zone. This melting process produced a hydrous, aluminous basalt, which fractionated at depth in the crust to produce a variety of high-alumina basalt compositions, from which the anorthosite complex with its chromitite horizons formed as a cumulate within the continental crust. The principal trigger for the late precipitation of chromite is thought to have been the removal of Al from the basaltic melt through plagioclase crystallization, and the build-up of Cr through an absence of clinopyroxene. It is proposed that the aluminous mantle source of the parent magma was produced by the melting of a harzburgitic mantle refertilized by small-volume, aluminous slab melts. This process ceased at the end of the Archaean because the dominant mechanism of crust generation changed such that melt production shifted from the slab into the mantle wedge, thus explaining why highly calcic anorthosites are almost totally restricted to the Archaean.


DOI: 10.1144/sp338.10

Other references

Northcutt, R.Glenn., 2011: Cladistic analysis reveals brainless urbilateria. Brain, Behavior and Evolution 76(1): 1-2

Antonelli, A.L.; Mayer, D.F., 1992: Fungus gnats. In this revised illustrated leaflet from Washington State, notes are provided on the host plants, injuriousness, recognition, monitoring and control (with insecticides and microbial pesticides in home gardens, homes and commercial greenhouses) of...

Ownby, R.L.; Acevedo, A.; Waldrop-Valverde, D.; Jacobs, R.J.; Caballero, J., 2015: Abilities, skills and knowledge in measures of health literacy. Health literacy has been recognized as an important factor in patients' health status and outcomes, but the relative contribution of demographic variables, cognitive abilities, academic skills, and health knowledge to performance on tests of...

Kusstatscher S.; Nagy L.; Morales R.E.; Szabo S., 1992: Release and activation of cathepsins b h and l are common mediators of chemically induced gastric mucosal lesions. Gastroenterology 102(4 PART 2): A104

Popova, E.; Gorbachev, V., 1983: Ecological peculiarities and nitrogen fund of soils in the southern taiga of the Angara basin. Lesovedenie (4) 15-23

Kumar, A.; Grimes, B.; Logan, M.; Wedgwood, S.; Williamson, H.; Hayward, R.S., 1995: A hybrid sigma subunit directs RNA polymerase to a hybrid promoter in Escherichia coli. Most of the sigma (transcriptional initiation specificity) subunits of RNA polymerase, from a wide range of eubacteria, show strong elements of amino acid sequence similarity. There is evidence that two of the "conserved" regions, 2.4 an...

Pursch, M.; Sun, K.; Winniford, B.; Cortes, H.; Weber, A.; McCabe, T.; Luong, J., 2002: Modulation techniques and applications in comprehensive two-dimensional gas chromatography (GC x GC). More than a decade after Phillips' first published work this article reviews recent developments in comprehensive two-dimensional gas chromatography (GC X GC). Special attention is devoted to the further development and diversity of modulatio...

Temtamy, S.A.; Loutfi, A.H., 1970: Some genetic and surgical aspects of the cleft lip-cleft palate problem in Egypt. Cleft Palate Journal 7: 578-594

DeSantis, P.; Palleschi, A.; Savino, M.; Scipioni, A., 1992: Theoretical prediction of the gel electrophoretic retardation changes due to point mutations in a tract of SV40 DNA. The changes of gel electrophoretic retardation due to single base substitutions in a 173 bp fragment of Sv40 DNA were predicted by using a theoretical model based on conformational energy calculations. As described in previous papers, this model a...

Morita S.; Nemoto K.; H.D.X.; Haruki Y.; Yamazaki K., 1989: A rapid method for estimating stem diameter in rice plants. Japanese Journal of Crop Science 58(1): 143-144