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 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 (6) Citing Articles via Google Scholar Google Scholar Articles by Feenstra, A. Articles by Wiedenbeck, M. Search for Related Content GeoRef GeoRef Citation

Li-rich zincostaurolite and its decompression-related breakdown products in a diaspore-bearing metabauxite from East Samos (Greece): An EMP and SIMS study

¹ GeoForschungsZentrum Potsdam, Division 4, Telegrafenberg, D-14473 Potsdam, Germany
² Institut für Geowissenschaften der Technischen Universität Braunschweig, Abteilung für Mineralogie, Gausstrasse 28/29, D-38106 Braunschweig, Germany

Correspondence: ^* E-mail: feenstra{at}gfz-potsdam.de

Li-H-rich zincostaurolite locally formed at a metabauxite-marble contact along the eastern coast of Samos during early Alpine high-P, low-T metamorphism. The staurolite, which probably grew from gahnite, cookeite, kaolinite/pyrophyllite, diaspore, and minor Fe-oxide, occurs as prismatic crystals (up to several mm long) in a calcite matrix. It has an unusual composition with 7.5–12.9 wt% ZnO, 1.0–4.9 wt% FeO, 0.66–0.82 wt% Li₂O, up to 2.6 wt% NiO and 0.59 wt% CoO, and 0.32 wt% MgO. Calculated structural formulae point to high H₂O contents (4.14 H atoms per 48 oxygen atoms). During late-Alpine uplift of the Samos rocks, the staurolite was, at greenschist-facies conditions, variably replaced by bluish cobaltoan gahnite (X_Zn > 0.82), white Na-Ca-Li mica, Ni-rich chlorite (X_Ni = 0.42–0.59), zincohögbomite (X_Zn = 0.68–0.80), diaspore, and Fe-(hydr)oxide. Detailed EMP work and determination of Li in staurolite and mica by SIMS indicates systematic Zn-Fe-Mg-Ni-Co-Li partitioning between staurolite and its decomposition products, implying local-scale chemical equilibrium. Balanced reaction equations based on mineral-chemical data indicate that the breakdown of staurolite occurred largely isochemically with only introduction of water, Na, and Ca into the reacting system. The breakdown of high-P staurolite during uplift and decompression is thought to be related to the sensitivity of its complex crystal chemistry to changes in physico-chemical conditions.

This article has been cited by other articles:

				M. N. Taran, M. Koch-Muller, and A. Feenstra Optical spectroscopic study of tetrahedrally coordinated Co2+ in natural spinel and staurolite at different temperatures and pressures American Mineralogist, November 1, 2009; 94(11-12): 1647 - 1652. [Abstract] [Full Text] [PDF]

				A. Feenstra, D. Rhede, M. Koch-Muller, M. Wiedenbeck, and W. Heinrich Hydrogen zoning in zinc-bearing staurolite from a high-P, low-T diasporite (Samos, Greece): A combined EMP-SIMS-FIB-FTIR study American Mineralogist, May 1, 2009; 94(5-6): 737 - 745. [Abstract] [Full Text] [PDF]

				B. R. Frost, S. M. Swapp, and R. W. Gregory PROLONGED EXISTENCE OF SULFIDE MELT IN THE BROKEN HILL OREBODY, NEW SOUTH WALES, AUSTRALIA Can Mineral, February 1, 2005; 43(1): 479 - 493. [Abstract] [Full Text] [PDF]

				T. ARMBRUSTER and A. FEENSTRA Lithium in nigerite-group minerals European Journal of Mineralogy, April 1, 2004; 16(2): 247 - 254. [Abstract] [Full Text] [PDF]