|
| << vorige | volgende >> |
Tijdschrift beschrijving
Alle jaargangen van het bijbehorende tijdschrift
Alle afleveringen van het bijbehorende jaargang
Alle artikelen van de bijbehorende aflevering
Details van artikel 6 van 11 gevonden artikelen
| Titel: |
Polycrystalline amphibole aggregates (clots) in granites as potential I-type restite: an ion microprobe study of rare-earth distributions |
| Auteur: |
Stephens, W. E. |
| Verschenen in: |
Australian journal of earth sciences |
| Paginering: | Jaargang 48 (2001) nr. 4 pagina's 591-601 |
| Jaar: |
2001-08 |
| Inhoud: |
Aggregates of polycrystalline grains of amphibole (clots) occur widely in the granodiorites of the Strontian pluton, Scotland. These clots are complex structures with numerous small grains in the interior exhibiting zonation from actinolite cores to hornblende rims. Amphiboles in the outer parts of these clots are indistinguishable from hornblendes that have crystallised from the melt. A rare-earth element (REE) study of individual amphibole and pyroxene grains using an ion microprobe has also shown a marked difference in REE abundances, with clots generally being depleted in their interiors. Modelling of the compositions shows that the clots are consistent with being derived from pyroxene + plagioclase ± amphibole precursors. These granular precursors are recognised as being consistent with the residual crystalline material encountered in dehydration melting experiments of amphibolitic starting materials. It is suggested that these features could represent restite in I-type granodiorites and tonalites. Extensive, but incomplete equilibration of the clot material provides an explanation for the infrequent identification of restite (other than grain cores) in I-type granites, in marked contrast with S-types. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 6 van 11 gevonden artikelen
| << vorige | volgende >> |