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 Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by CARRARO, A. Search for Related Content GeoRef GeoRef Citation

Crystal chemistry of Cr-spinels from a suite of spinel peridotite mantle xenoliths from the Predazzo Area (Dolomites, Northern Italy)

Dipartimento di Mineralogia e Petrologia, Università di Padova, C.so Garibaldi, 37, 1–35137 Padova, Italy

^* E-mail: carraro{at}dmp.unipd.it

The crystal chemistry of ten Cr-spinels enclosed in protogranular to weakly porphyroclastic spinel peridotite mantle xenoliths from the Predazzo Area (Dolomites, Northern Italy) was studied by single-crystal X-ray diffraction and electron microprobe. Within the suite, unit cell parameter a₀ increases from 8.1358 to 8.2201 Å, with increasing Cr content, from 0.205 to 0.812 a.f.u., whereas the oxygen coordinate u remains virtually constant (u = 0.2627–0.2630), therefore giving a quite constant ratio of octahedral (M-O) and tetrahedral (T-O) bond distances. The cation distribution, obtained from structural and chemical data, shows that, with increasing Cr³⁺ within the suite, the Al (T) content decreases from 0.144 to 0.056 a.f.u. Data from the Predazzo spinels were compared with those of spinel suites from well-defined mantle rocks (Newer Victoria, Australia; NE Brazil; Assab, Ethiopia; Balmuccia, Italy) from different petrological environments. Estimation of the intracrystalline closure temperature for the investigated spinels gives a mean value of 769°C. This indicates a cooling rate intermediate between that of a slowly cooled peridotitic massif and that of very fast cooled mantle xenoliths hosted by volcanics, which is consistent with the origin of the Predazzo spinels from mantle xenoliths hosted in subvolcanic dykes.

Key-words: Cr-spinel, crystal chemistry, intra-crystalline temperature, Dolomites, NE Italy..

This article has been cited by other articles:

				D. Lenaz, R. Braidotti, F. Princivalle, G. Garuti, and F. Zaccarini Crystal chemistry and structural refinement of chromites from different chromitite layers and xenoliths of the Bushveld Complex European Journal of Mineralogy, July 1, 2007; 19(4): 599 - 609. [Abstract] [Full Text] [PDF]

				H. Uchida, B. Lavina, R. T. Downs, and J. Chesley Single-crystal X-ray diffraction of spinels from the San Carlos Volcanic Field, Arizona: Spinel as a geothermometer American Mineralogist, November 1, 2005; 90(11-12): 1900 - 1908. [Abstract] [Full Text] [PDF]

				D. Lenaz and F. Princivalle THE CRYSTAL CHEMISTRY OF DETRITAL CHROMIAN SPINEL FROM THE SOUTHEASTERN ALPS AND OUTER DINARIDES: THE DISCRIMINATION OF SUPPLIES FROM AREAS OF SIMILAR TECTONIC SETTING? Can Mineral, August 1, 2005; 43(4): 1305 - 1314. [Abstract] [Full Text] [PDF]