000019030 001__ 19030
000019030 005__ 20131002113919.0
000019030 0248_ $$aoai:doc.rero.ch:20100608110841-BM$$punifr$$ppostprint$$prero_explore$$zcdu34$$zthesis_urn$$zreport$$zthesis$$zbook$$zjournal$$zcdu549$$zcdu16$$zpreprint$$zcdu1$$zdissertation
000019030 041__ $$aeng
000019030 080__ $$a549
000019030 100__ $$aWiedenmann, Daniel$$uDepartment of Geosciences, University of Fribourg, Switzerland - EMPA, Swiss Federal Laboratories for Materials Testing and Research, Hydrogen and Energy, Dübendorf, Switzerland
000019030 245__ $$9eng$$aMelilite-group minerals at Oldoinyo Lengai, Tanzania
000019030 269__ $$c2010-04-13
000019030 520__ $$9eng$$aOldoinyo Lengai and the volcanic centres of the Lake Natron–Engaruka province contain melilite as a widespread mineral. Extraordinarily Na–Al-rich melilites (up to 6 wt.% Na₂O and 9 wt.% Al₂O₃) from recent explosive eruptions are among the most Na-rich ever reported. Their unusual mineral composition leads to optical properties with vivid birefringence colours of 2nd order. The continuous variation in mineral composition from common åkermanite to Na–Al–melilite (<i>alumoåkermanite</i>) is documented and reflects the whole peralkaline trend of Oldoinyo Lengai. The data presented allow the volcano's evolution from primitive olivine melilitites to highly evolved and peralkaline combeite–wollastonite nephelinites to be traced. Melilite compositions of Oldoinyo Lengai extend the magmatic field in the Ca₂Fe(Si₂O₇)–Ca₂Mg(Si₂O₇)–(CaNa)Al(Si₂O₇) end-member ternary compositional diagram.
000019030 695__ $$9eng$$aAlumoåkermanite ; Åkermanite ; Melilite ; Melilitites ; Nephelinites ; Volcanic rock ; Oldoinyo Lengai ; Tanzania
000019030 700__ $$aKeller, Jörg$$uInstitut für Geowissenschaften, Mineralogie-Geochemie, Universität Freiburg, Germany
000019030 700__ $$aZaitsev, Anatoly N.$$uDepartment of Mineralogy, St. Petersburg State University, Russia - Department of Mineralogy, The Natural History Museum, London, UK
000019030 773__ $$g2010///-$$tLithos
000019030 775__ $$gPublished version$$ohttp://dx.doi.org/10.1016/j.lithos.2010.04.002
000019030 8564_ $$fwie_mgm.pdf$$qapplication/pdf$$s1694573$$uhttp://doc.rero.ch/record/19030/files/wie_mgm.pdf$$yorder:1$$zpdf
000019030 918__ $$aFaculté des sciences$$bDécanat, Ch. du Musée 6A, 1700 Fribourg$$cGéosciences
000019030 919__ $$aUniversité de Fribourg$$bFribourg$$ddoc.support@rero.ch
000019030 980__ $$aPOSTPRINT$$bUNIFR$$fART_JOURNAL
000019030 990__ $$a20100608110841-BM