Abstract
A continuous flow method, by a combination of thermal conversion elemental analyzer (TC/EA) with isotope ratio mass spectrometry (MS), was developed to determine both H isotope composition and H2O concentration of ultrahigh-pressure (UHP) metamorphic rocks in the Dabie-Sulu orogenic belt. By using the developed step-heating technique, we have studied H2O concentration and H isotope composition of the different forms of water (structural OH and molecular H2O) in garnet. The quantitative measurements of H2O concentration and H isotope composition of minerals in UHP metamorphic rocks from several typical outcrops indicate that the gneisses can release more amounts of water than the eclogites during exhumation of the deeply subducted continental crust. Therefore, by decompression dehydration at the contact between eclogite and gneiss, the released water could flow from the gneiss to the eclogite and result in significant hydration of the eclogite adjacent to the gneiss. The measured maximum water contents of minerals in eclogites indicate that garnet and omphacite have the maximum water solubilities of 2500 and 3500 ppm, respectively, under the peak UHP metamorphic conditions.
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Zheng Y-F. Metamorphic chemical geodynamics in continental subduction zones. Chem Geol, 2012, 328: 5–48
Zheng Y-F, Xia Q-X, Chen R-X, et al. Partial melting, fluid supercriticality and element mobility in ultrahigh-pressure metamorphic rocks during continental collision. Earth Sci Rev, 2011, 107: 342–374
Zheng Y-F. Fluid regime in continental subduction zones: Petrological insights from ultrahigh-pressure metamorphic rocks. J Geol Soc London, 2009, 166: 763–782
Xiao Y L, Hoefs J, van den Kerkhof A M, et al. Fluid history of UHP metamorphism in Dabie Shan, China: A fluid inclusion and oxygen isotope study on the coesite-bearing eclogite from Bixiling. Contrib Mineral Petrol, 2000, 139: 1–16
Fu B, Touret J L R, Zheng Y-F. Fluid inclusions in coesite-bearing eclogites and jadeite quartzites at Schuanghe, Dabie Shan, China. J Metamorph Geol, 2001, 19: 531–548
Su W, You Z-D, Cong B-L, et al. Cluster of water molecules in garnet from ultrahigh-pressure eclogite. Geology, 2002, 30: 611–614
Meng D W, Wu X L, Fan X Y, et al. Submicron-sized fluid inclusions and distribution of hydrous components in jadeite, quartz and symplectite-forming minerals from UHP jadeite-quartzite in the Dabie Mountains, China: TEM and FTIR investigation. Appl Geochem, 2009, 24: 517–526
Johnson E A. Water in nominally anhydrous crustal minerals: Speciation, concentration, and geologic significance. Rev Mineral Geochem, 2006, 62: 117–154
Fukuda J, Yokoyama T, Kirino Y. Characterization of the states and diffusicity of intergranular water in a chalcedonic quartz by high-temperature in situ infrared spectroscopy. Mineral Mag, 2009, 73: 825–835
Chen R-X, Zheng Y-F, Gong B, et al. Origin of retrograde fluid in ultrahigh-pressure metamorphic rocks: Constraints from mineral hydrogen isotope and water content changes in eclogite-gneiss transitions in the Sulu orogen. Geochim Cosmochim Acta, 2007, 71: 2299–2325
Gong B, Zheng Y-F, Chen R-X. TC/EA-MS online determination of hydrogen isotope composition and water concentration in eclogitic garnet. Phys Chem Minerals, 2007, 34: 687–698
Hirschmann M, Kohlstedt D. Water in Earth’s mantle. Physics Today, 2012, 65: 40–45
Zhang J F, Jin Z M, Green H W, et al. Hydroxyl in continental deep subduction zone: evidence from UHP eclogites of the Dabie mountains. Chin Sci Bull, 2001, 46: 592–595
Zhang J F, Green H W, Bozhilov K, et al. Faulting induced by precipitation of water at grain boundaries in hot subducting oceanic crust. Nature, 2004, 428: 633–636
Katayama I, Nakashima. Hydroxyl in clinopyroxene from the deep subducted crust: Evidence for H2O transport into the mantle. Am Mineral, 2003, 88: 229–234
Katayama I, Nakashima S, Yurimoto H. Water content in natural eclogite and implication for water transport into the deep upper mantle. Lithos, 2006, 86: 245–259
Xia Q K, Sheng Y M, Yang X Z, et al. Heterogeneity of water in garnets from UHP eclogites, eastern Dabieshan, China. Chem Geol, 2005, 224: 237–246
Sheng Y M, Xia Q K, Yang X Z, et al. H2O contents and D/H ratios of nominally anhydrous minerals from ultrahigh-pressure eclogites of the Dabie orogen, eastern China. Geochim Cosmochim Acta, 2007, 71: 2079–2103
Zhao Z-F, Chen B, Zheng Y-F, et al. Mineral oxygen isotope and hydroxyl content changes in ultrahigh-pressure eclogite-gneiss contacts from Chinese Continental Scientific Drilling Project cores. J Metamorph Geol, 2007, 25: 165–186
Zheng Y-F, Fu B, Gong B, et al. Stable isotope geochemistry of ultrahigh pressure metamorphic rocks from the Dabie-Sulu orogen in China: implications for geodynamics and fluid regime. Earth Sci Rev, 2003, 62: 105–161
Zheng Y-F, Chen R-X, Zhao Z-F. Chemical geodynamics of continental subduction-zone metamorphism: Insights from studies of the Chinese Continental Scientific Drilling (CCSD) core samples. Tectonophysics, 2009, 475: 327–358
Gong B, Zheng Y-F, Chen R-X. An online method combining a thermal conversion elemental analyzer with isotope ratio mass spectrometry for determination of hydrogen isotope composition and water concentration in geological samples. Rapid Commun Mass Spectrom, 2007, 21: 1386–1392
Chen R-X, Zheng Y-F, Gong B. Mineral hydrogen isotopes and water contents in ultrahigh-pressure metabasite and metagranite: Constraints on fluid flow during continental subduction-zone metamorphism. Chem Geol, 2011, 281: 103–124
Gong B, Zheng Y-F, Wu Y-B, et al. Geochronology and stable isotope geochemistry of UHP metamorphic rocks at Taohang in the Sulu orogen, east-central China. Intern Geol Rev, 2007, 49: 259–286
Hauri E H, Gaetani G A, Green T H. Partitioning of water during melting of the Earth’s upper mantle at H2O-undersaturated conditions. Earth Planet Sci Lett, 2006, 248: 715–734
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Gong, B., Chen, R. & Zheng, Y. Water contents and hydrogen isotopes in nominally anhydrous minerals from UHP metamorphic rocks in the Dabie-Sulu orogenic belt. Chin. Sci. Bull. 58, 4384–4389 (2013). https://doi.org/10.1007/s11434-013-6069-7
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DOI: https://doi.org/10.1007/s11434-013-6069-7