Benmoreite Explained

Benmoreite is a volcanic rock of intermediate composition. It is a silica-undersaturated sodium-rich variety of trachyandesite (the other kind is latite) and belongs to the alkaline suite of igneous rocks. It was named after Ben More, a mountain on the Isle of Mull, Scotland.

Benmoreite has been found, for example, on Ascension Island and Easter Island, at Mount Berlin in Antarctica, and in Atakor volcanic field, Algeria. Benmoreite lava was erupted during the 2010 eruptions of Eyjafjallajökull.^[1]

An origin by fractionation from basanite through nepheline hawaiite to nepheline benmoreite has been demonstrated for a volcanic suite in the McMurdo Volcanic Group of late Cenozoic age in McMurdo Sound area of Antarctica.^[2] Nepheline benmoreite magmas derived from mantle sources, containing lherzolite xenoliths, display similarities to some plutonic nepheline syenites.^[3]

Notes and References

1. Subglacial lava propagation, ice melting and heat transfer during emplacement of an intermediate lava flow in the 2010 Eyjafjallajökull eruption . B. . Oddsson . M.T. . Gudmundsson . B.R. . Edwards . T. . Thordarson . E. . Magnússon . G. . Sigurðsson . Bulletin of Volcanology . 2016 . 78 . 7 . 48 . 10.1007/s00445-016-1041-4. 2016BVol...78...48O . 54939869 .
2. Kyle. P. R.. Adams. J.. Rankin. P. C.. Geology and petrology of the McMurdo Volcanic Group at Rainbow Ridge, Brown Peninsula, Antarctica. Geological Society of America Bulletin. 1979. 90. 7. 676–688. 10.1130/0016-7606(1979)90<676:GAPOTM>2.0.CO;2. 1979GSAB...90..676K.
3. Green. D. H.. Edgar. A. D.. Beasley. P.. Kiss. E.. Ware. N. G.. Upper mantle source for some hawaiites, mugearites and benmoreites. Contributions to Mineralogy and Petrology. 1974. 48. 1. 33–43. 10.1007/BF00399108. 1974CoMP...48...33G. 129511256 .