Инд. авторы:	Seryotkin Y.V., Sokol E.V., Kokh S.N.
Заглавие:	Natural pseudowollastonite: Crystal structure, associated minerals, and geological context
Библ. ссылка:	Seryotkin Y.V., Sokol E.V., Kokh S.N. Natural pseudowollastonite: Crystal structure, associated minerals, and geological context // Lithos. - 2012. - Vol.134-135. - P.75-90. - ISSN 0024-4937. - EISSN 1872-6143.
Внешние системы:	DOI: 10.1016/j.lithos.2011.12.010; SCOPUS: 2-s2.0-84855801736;
Реферат:	eng: Pseudowollastonite, an extremely rare constituent of ultrahigh-temperature combustion metamorphic and igneous rocks, has been found as a rock-forming mineral in Ca-rich paralava veins of Nabi Musa fossil mud volcano (Dead Sea area). Pseudowollastonite-bearing paralavas are the products of combustion metamorphism associated with spontaneous burning of methane. The melt began to crystallize at 1480-1500°C about the ambient pressure. Pseudowollastonite enters two mineral assemblages: (1) rankinite, larnite, nagelschmidtite, wollastonite (1T), gehlenite-rich melilite, Ti-rich andradite, cuspidine, and fluorapatite; (2) parawollastonite (2M), wollastonite (1T), gehlenite-rich melilite, Ti-rich andradite, fluorellestadite. In this study we present the first single-crystal structure determination of natural pseudowollastonite. Pseudowollastonite from Nabi Musa dome is stoichiometric CaSiO 3 and belongs to the most widespread four-layer polytype: a=6.83556(10) Å, b=11.86962(18) Å, c=19.6255(3) Å, β=90.6805(13)°, V=1592.21(4) Å 3, space group C2/c. We argue that pseudowollastonite is so scarce in nature because its formation requires joint action of several uncommon factors: availability of hot melts of T>1200°C that bear free calcium but are poor in Mg and Fe (mostly as Fe 3+) and their crystallization in the shallow crust followed by quenching. © 2011 Elsevier B.V..
Ключевые слова:	Dead Sea; wollastonite; vein (geology); ultrahigh temperature metamorphism; stoichiometry; pressure effect; melting; lava; crystallization; Musa; crust; combustion; calcium; Wollastonite; Pseudowollastonite; Parawollastonite; Mottled Zone; Combustion metamorphism; crystal structure;
Издано:	2012
Физ. характеристика:	с.75-90