Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Wulff-Pedersen, E. Articles by Hansen, V. Search for Related Content GeoRef GeoRef Citation

Origin and structural character of haüyne_ss in spinel dunite xenoliths from La Palma, Canary Islands

Erik Wulff-Pedersen^1,*, Else-Ragnhild Neumann^2,, Ernst A.J. Burke³, Riccardo Vannucci⁴, Piero Bottazzi⁴, Luisa Ottolini⁴, Jon Gjønnes⁵ and Vidar Hansen⁵

¹ Mineralogical-Geological Museum, University of Oslo, Sarsgaten 1, N-0562 Oslo, Norway
² Department of Geology, P.O. Box 1047 Blindern, N-0316 Oslo, Norway
³ Faculty of Earth Sciences, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands
⁴ CNR-Centro di Studio per la Cristallochimica e la Cristallografia, via Bassi 4, I-27100 Pavia, Italy
⁵ Center of Material Science, Forskningsparken, Gaustadalleen 21, N-0371 Oslo, Norway

Correspondence: E-mail: e.r.neumann{at}toyen.uio.no

Two spinel dunite xenoliths (Fo_89.8–91.2 in olivine) from La Palma contain minor amounts (<1%) of a pale-blue sodalite-group mineral with haüyne/lazurite chemistry. Selected-area electron diffraction (SAED) patterns of this phase indicate a cubic unit cell with dimensions 9.12 ± 0.02 Å, and space group P3n. Superstructure spots along three <110> directions are common, implying commensurate or incommensurate modulations along <110> directions. Raman spectra show peaks typical of both lazurite and haüyne. It is concluded that the mineral has a structure intermediate between those of pure lazurite and pure haüyne, and it is here referred to as haüyne_ss. The haüyne_ss occurs together with strongly nepheline-normative glass in thin veinlets (<0.1 mm), in interstitial glass pockets, and as inclusions in olivine porphyroclasts. To our knowledge lazurite or haüyne has not previously been described in mantle rocks. The haüyne_ss is strongly depleted in REE and most other highly lithophile elements relative to the coexisting glass, whereas D_{mineral/glass} for Sr is 1.0, and D_Eu higher than the other REE. The haüyne_ss crystallized from a melt now present as phonolitic glass, probably in response to rapidly decreasing pressure during transport of the xenoliths to the surface. The coexistence of haüyne_ss and FeS-rich sulfide globules in some samples suggests slightly more oxidizing conditions than for samples in which the glass contains sulfide globules alone.

This article has been cited by other articles:

				A. Di Muro, E. Bonaccorsi, and C. Principe Complex colour and chemical zoning of sodalite-group phases in a hauynophyre lava from Mt. Vulture, Italy Mineralogical Magazine, August 1, 2004; 68(4): 591 - 614. [Abstract] [Full Text] [PDF]