The origin of Na-alkaline lavas revisited: new constraints from experimental melting of amphibole-rich metasomes + lherzolite at uppermost mantle pressureOpen Access

Grützner, T; Prelevic, D; Berndt, J; Klemme, S

Forschungsartikel (Zeitschrift) | Peer reviewed

Zusammenfassung

We present a new experimental dataset for reaction experiments between natural amphibole-clinopyroxene metasomes (hornblendite) and synthetic lherzolite that produced Na-rich alkaline melts. Experiments were conducted at 1, 3 and 4 GPa and 1000 to 1300 °C. The generated melts range from foidite over basanite to phonotephrite. At 1 GPa between 1000 and 1100 °C amphibole decompression-breakdown products generate phonotephritic melt. Among the breakdown components rhönite was found to be stable up to 1100 °C and 1 GPa. At 3 and 4 GPa the melt compositions are additionally influenced by phlogopite melting and shift to more foiditic composition. We find that the melting of metasome produces wehrlitic residue. The reaction of the melt with the lherzolite produces again a wehrlitic residue with different olivine : clinopyroxene ratios. Therefore, wehrlite formation does not always require separate metasomatic processes, but can be a direct by-product of alkaline volcanism. We applied a metasome melting model to the magmas of the Kula volcanic province, Turkey, and show that at 1 GPa basanite melts and phonotephrite melts cover the whole range of known Kula lava compositions. The Kula lava compositional trend can be therefore generated not by differentiation of basanite but by basanite-phonotephrite melt mixing. A comparison of high-pressure (3-4 GPa) melts with natural nephelinite data shows overlap with many major, minor, and trace elements but differences in SiO2, FeO, and TiO2 argue that the natural nephelinite data do not represent primary metasome melts.

Details zur Publikation

FachzeitschriftContributions to Mineralogy and Petrology
Jahrgang / Bandnr. / Volume178
Seitenbereich73null
StatusVeröffentlicht
Veröffentlichungsjahr2023
Sprache, in der die Publikation verfasst istEnglisch
DOI10.1007/s00410-023-02052-6
Stichwörteralkaline volcanism; experimental petrology; kaersutite; Kula volcanic province; mantle metasomatism; wehrlitization

Autor*innen der Universität Münster

Gerdes, Jasper
Professur für Petrologie (Prof. Klemme)
Grützner, Tobias
Professur für Petrologie (Prof. Klemme)
Klemme, Stephan
Professur für Petrologie (Prof. Klemme)

Projekte, aus denen die Publikation entstanden ist

Laufzeit: 01.01.2016 - 31.12.2019 | 1. Förderperiode
Gefördert durch: DFG - Sonderforschungsbereich
Art des Projekts: Teilprojekt in DFG-Verbund koordiniert außerhalb der Universität Münster

Promotionen, aus denen die Publikation resultiert

An experimental study on fluorine in nominally fluorine free minerals and humite group minerals in the Earth's upper mantle and transition zone
Promovend*in: Grützner, Tobias | Betreuer*innen: Klemme, Stephan
Zeitraum: 01.04.2013 - 02.12.2016
Promotionsverfahren erfolgt(e) an: Promotionsverfahren an der Universität Münster