Universität zu Köln

Ballhaus, Chris, Fonseca, Raul O. C. ORCID: 0000-0002-0897-4884, Muenker, Carsten, Kirchenbaur, Maria and Zirner, Aurelia (2015). Spheroidal textures in igneous rocks - Textural consequences of H2O saturation in basaltic melts. Geochim. Cosmochim. Acta, 167. S. 241 - 253. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 1872-9533

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Abstract

When melts reach H2O saturation before they are emplaced at the Earth's surface, they exsolve a hydrous fluid phase. At elevated pressure and high temperature, a hydrous fluid is not pure H2O but can contain some quantities of silicate and metal oxide solute, notably if fluid saturation occurs at high pressure. Chemically and physically, fluid-saturated basalts behave like any other system with liquid immiscibility. Textures that can result after solidification are globules of former fluid dispersed in a former silicate melt, or silicate melt orbs embedded in a former fluid matrix. The Troodos ophiolite on the island of Cyprus, generated in a back arc basin above a wet intra oceanic subduction zone, carries in its magmatic stratigraphy lithologies distinctly orbicular and globular in shape. Many melt compositions parental to the ophiolite were H2O-saturated near their liquidus temperatures before they reached their depths of emplacement within the ophiolite sequence. Spheroids are not uncommon in magmatic rocks but still debated as to how they form. We propose that globular and orbicular textures in igneous worldwide may result when melts reach H2O saturation and exsolve an immiscible solute-bearing H2O-dominated fluid phase at elevated temperature and pressure, before or while they are emplaced. (C) 2015 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Ballhaus, Chris UNSPECIFIED UNSPECIFIED UNSPECIFIED Fonseca, Raul O. C. UNSPECIFIED orcid.org/0000-0002-0897-4884 UNSPECIFIED Muenker, Carsten UNSPECIFIED UNSPECIFIED UNSPECIFIED Kirchenbaur, Maria UNSPECIFIED UNSPECIFIED UNSPECIFIED Zirner, Aurelia UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-389771
DOI:	10.1016/j.gca.2015.07.029
Journal or Publication Title:	Geochim. Cosmochim. Acta
Volume:	167
Page Range:	S. 241 - 253
Date:	2015
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
Place of Publication:	OXFORD
ISSN:	1872-9533
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language TROODOS OPHIOLITE; LIQUID IMMISCIBILITY; COMPLETE MISCIBILITY; SILICATE MELTS; UPPER-MANTLE; HYDROUS FLUIDS; WATER; ORIGIN; MAGMAS; LAVAS Multiple languages Geochemistry & Geophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/38977