Chilled margins and commingling of magmas in the Bressanone (Brixen) Hercynian granodiorites (Eastern Alps, northern Italy)
1986; Elsevier BV; Volume: 56; Issue: 1-2 Linguagem: Inglês
10.1016/0009-2541(86)90108-7
ISSN1872-6836
Autores Tópico(s)Mineralogy and Gemology Studies
ResumoThe Brixen Hercynian pluton is the result of a multiple intrusion of crustal anatectic magma (granodiorite-granites and two-mica cordierite-bearing leucogranites) and subcrustal magma (gabbro-diorites and fayalite-bearing leucogranites). Some adjacent granodioritic stocks show chilled margins containing globular inclusions in the size of several centimetres of a coarse-grained leucogranite. The granodiorite margins also show narrow zoning with more acidic external borders. This phenomenon is correlated to differentiated processes such as filter pressing and the Soret effect, which were active during the rise of these stocks. The strong petrographic and chemical analogies between the globular inclusions of (some) chilled margins and the fayalite leucogranites suggest their common subcrustal origin. The granodiorite containing these inclusions is of crustal origin: the occurrence of globular inclusions inside it thus indicates only mechanical mingling between crustal anatectic and subcrustal magmas, as shown by the absence of hybrids and chemical interactions.
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