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 Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by EL-SHAZLY, A. K. Articles by SISSON, V. B. Search for Related Content

Fluid inclusions in carpholite-bearing metasediments and blueschists from NE Oman

¹ Department of Geology, Geography and Physics, University of Tennessee, Martin, TN 38238, USA e-mail: aelshazly{at}utm.edu
² Department of Earth Science, Rice University, Houston TX 77005–1892, USA

Thrust sheets of the upper plate of the Saih Hatat window, NE Oman contain metasediments formed under lawsonite albite facies conditions. Quartz and Fe-Mg carpholite in these metasediments contain several types of fluid inclusions; most are two-phase at room T with an aqueous NaCl - H₂O or NaCl - MgCl₂ - H₂O solution. Texturally early fluid inclusions display a wide range of final melting (Tm_f) and homogenization (T_h) temperatures. The lowest Tm_f and T_h values were recorded for moderately sized inclusions occurring in clusters. Some of the highest Tm_f and T_h values (> 320°C) are recorded for isolated inclusions in Fe-Mg carpholite and quartz. In the lower plate epidote-blueschist facies metasediments, many fluid inclusions in quartz are decrepitated, with most of the surviving inclusions being 3-phase, CO₂-bearing, filled with a low salinity fluid with XCO₂ < 0.05. For all samples from both plates, isochores calculated for the few texturally early inclusions with low T_h values are consistent with their respective P-T estimates.

We conclude that inclusions with high T_h experienced post-entrapment stretching ± loss of H₂O during exhumation. Larger inclusions and inclusions in Fe-Mg carpholite were more strongly affected by these changes. Small isolated inclusions in relatively unstrained quartz have escaped these modifications and are useful for constraining peak conditions.

Key-words: fluid inclusions, microthermometry, carpholite, high P metamorphism.

Abbreviations: Ab: albite • Act: actinolite • Alln: allanite • Ap: apatite • Cc: calcite • Chil: chlorite • Car: Fe-Mg carpholite • Crs: crossite • Czo: clinozoisite • Ctd: chloritoid • Dap: daphnite (Fe-chlorite) • Ep: epidote • Fcar: Fe-carpholite • Fctd: Fe-chloritoid • Fgln: ferroglaucophane • Gln: glaucophane • Hm: hematite • III: illite • Jd: jadeite • Kln: kaolinite • Ky: kyanite • Mcar: Mg-carpholite • Musc: muscovite • Opq: opaque phase • Oxychl: oxychlorite • Pg: paragonite • Ph: phengite • Prl: pyrophyllite • Qz: quartz • Rt: rutile • S.F.: shape factor • Sud: sudoite • Tm: tourmaline • T_h: homogenization temperature • Tm_f: final melting temperature • Ttn: titanite • VESR: volume equivalent spherical radius • WM: white mica • Zrn: zircon

This article has been cited by other articles:

				B. A. Zoheir, A. K. El-Shazly, H. Helba, K. I. Khalil, and R. J. Bodnar Origin and Evolution of the Um Egat and Dungash Orogenic Gold Deposits, Egyptian Eastern Desert: Evidence from Fluid Inclusions in Quartz Economic Geology, March 1, 2008; 103(2): 405 - 424. [Abstract] [Full Text] [PDF]