The Mlindi ring structure. An example of an ultrapotassic pyroxenite to syenite differentiated complex

Petrogenesis of the Neoproterozoic Alkaline Ultrapotassic Suítes of Northeastern Brazil: Major- and Trace-Element Evidence from Pyroxene Chemistry and Numerical Modeling

“…Similar processes are described in other ultrapotassic syenitic suites, such as the Cara Suja (Paim, 1998) and Cerafma (Leahy, 1997) massifs, in southwestern Bahia State, Northeast Bra zil; the pyroxenite-syenite association of CleYicy pluton, Abitibi region, Québec; (Bourne and L'Heureux, 1991); and the pyroxenite-syenite Mlindi ring structure (Laval and Hottin, 1992).…”

The alkaline silica-saturated ultrapotassic magmatism of the Riacho do Pontal Fold Belt, NE Brazil: an example of syenite–granite Neoproterozoic association

“…Ultrapotassic syenitic magmatism associated with collisional settings is usually related to previously subduction-modified sources as discussed by Thompson and Fowler (1986), Corriveau et al (1990) and Ferreira et al (1994). The ultrapotassic rocks of the RPFB have trace element patterns comparable to those of the pyroxenitesyenite association in Mlindi, Malawi (Laval and Hottin, 1992) and the Triunfo syenite (Ferreira, 1991) Thompson et al (1982). Ta and Hf contents from engrac ¸adinha granites, Ba-Timineralised granites, as well as the syenites from triunfo and africa were not reported.…”

“…Shoshonitic and ultrapotassic saturated to oversaturated rocks, some of them with petrographic and geochemical characteristics comparable to the Casa Nova and Engrac ¸adinha suites, have been described in southeastern Papua New Guinea (Smith, 1972), in southwestern Nigeria (Oyawoye, 1976), in syenites from Scotland (Thompson and Fowler, 1986), in syenitic dykes from Sinkiang Province, China (Pognante, 1990), in the Green-ville Province, Canada (Corriveau et al, 1990), in the Little Murun ultrapotassic complex of the Aldan Shield, Russia (Mitchell and Vladykin, 1996), in the Cle ´ricy Archean ultrapotassic syenite pluton in southern Abitibi, Canada (Lafle `che et al, 1991), in syenites from western Africa (Laval and Hottin, 1992), and in the syenitic Paleoproterozoic province of Bahia, northeastern Brazil (Conceic ¸a ẽt al., 1989Conceic ¸a ˜, 1990;Rosa, 1994). The Brasiliano belts in northeastern Brazil have several syenitegranite occurrences (Fig.…”

New insights into the ultrapotassic magmatism through xenoliths from the Eğirdir area, West Anatolia, Turkey

“…We report here the mineralogy and geochemical data for a new occurrence of melilite-, leucite-, kalsilite-bearing plutonic xenoliths found in the southern part of the Potassic-Ultrapotassic Afyon Province, Turkey. Some rare occurrences of such plutonic rocks have been previously found for example in the ejectas from Alban Hills and Montefiascone volcanism, Italy (Keller 1983;Peccerillo et al 1984;Federico et al 1994;Vollmer 1989;Beccaluva et al 1991;Beccaluva et al 2012;Peccerillo 1990Peccerillo , 1992Peccerillo , 1994Di Battistini et al 2001;Stoppa 2003;Stoppa et al 2003a;Gaeta et al 2006;Conticelli et al 2013Conticelli et al , 2015, and also in the ultrapotassic volcanic series from the East African rift (Bell and Powell 1969;Mitchell and Bell 1976;Pouclet 1980;Edgar and Arima 1981;Bergman 1987;Kampunzu and Lubala 1991;Laval and Hottin 1992;Bell and Tilton 2001 et al 2003b). For a long time, authors have paid attention to the distinctive mineralogy of potassic-ultrapotassic rocks in relation with magma crystallization and differentiation (Yoder 1986;Veksler et al 1998) and their complex hypothetic mantle source and successive mantle metasomatism events in relation with a post-collision, extensional geodynamical context (Savasçin et al 1994;Yağmurlu et al 1997).…”

“…The term of autolith would be better than xenolith for these two groups of rocks as it has been used for the autoliths from the Kilombe volcano, Kenya Rift, and the Ilimaussaq autoliths, Greenland (Ridolfi et al 2006;Schönenberger et al 2006). Cumulate-type rocks are known in ultrapotassic provinces, such as the Malawi ring complexes, in particular the ultrapotassic Mlindi ring complex (Laval and Hottin 1992). Trace element patterns of pyroxenite and leucitolite also show that their bulk compositions are a direct expression of the ratio of mafic and felsic mineral.…”