TY - JOUR
AU - SEYLER,, MONIQUE
AB - Abstract Major and trace element variations in an Ordovician alkaline orthogneiss (ortholeptynites) series of the Maures massif, France, suggest that the pre-metamorphic rocks were alkaline and peralkaline rhyolites derived by fractional crystallization from trachy-rhyolitic magma. Differentiation proceeded under low oxygen fugacity conditions, with the production of high-silica comendites. By comparison with unaltered alkaline and peralkaline rhyolites, it is possible to prove that the parental magma was not similar to the metatholeiites that are associated with the orthogneisses in the field. Nor were the metarhyolites derived from the alkaline to transitional metabasalts of the same age which occur elsewhere in the Maures massif. The orthogneisses have geochemical features typical of alkaline and peralkaline rhyolites occurring with basalts in continental, anorogenic, bimodal associations. This hypothesis is also supported by zircon morphology and mineral chemistry. The Maures massif was a within-plate continental volcanic province, whose crust underwent doming and thinning, but not break up, during lower Palaeozoic times. This content is only available as a PDF. Author notes Present address; Department of Geology, Queens College of the City University of New York, Rushing, N.Y. 11367, USA. © Oxford University Press
TI - Petrology and Genesis of Hercynian Alkaline Orthogneisses from Provence, France
JO - Journal of Petrology
DO - 10.1093/petrology/27.5.1229
DA - 1986-10-01
UR - https://www.deepdyve.com/lp/oxford-university-press/petrology-and-genesis-of-hercynian-alkaline-orthogneisses-from-FDwJ00CGk0
SP - 1229
EP - 1251
VL - 27
IS - 5
DP - DeepDyve
ER -