The study of hidden and appear zoning in existed garnets in metamorphic rocks of Hamadan region
Paper Details
The study of hidden and appear zoning in existed garnets in metamorphic rocks of Hamadan region
Abstract
Understudied region is located in south and south east of Hamadan and is part of the metamorphic belt named Sanandaj-Sirjan zone. Metamorphic rocks of the region include slate, phyllite, schist, migmatites and hornfels. Garnet is one of the main minerals in schist, migmatits and hornfels and sometimes it is found in some of the granites and aplitic-pegmatite. Zoning is common in most of the gernets existing in region’s metamorphic rocs. In some of the region’s garnets zoning phenomenon is observable, and this is divided in to three groups of appear, hidden (inverted and normal) and mixed groups. Appear zoning is detectable under the microscope and mostly comes along with discontinuities in crystals’ growth and in amphibole garnet; regions schist of this type of zoning are observable. Hidden zoning (chemical) are not observable by polarizing microscope, but it can be distinguished by quantitative analysis pictures. This type of zoning mostly is along with continuity in crystals’ growth, and there are chemical compounds’ changes in the environment during their growth. Hidden zoning (chemical) can be classified in to two groups of normal and inverted classes. In mixed zoning, part of the zoning relating to changes in elements’ amount is observable under the microscope, and the other part only appears in quantitative analysis pictures. This type of zoning can be the indicator of change in dominant conditions in crystals growth during multi-changing events in the understudied region. Therefore garnets zoning of understudied region has lots of varieties that can be related to multi-changing event in understudied region.
Chakraborty S. 2006. Diffusion modeling as a tool for constraining timescales of evolution of metamorphic rocks. Mineralogy and Petrology, 88, 7–27.
Dziggel A, Wulf K, Kolb J, Meyer FM, Lahaye Y. 2009. Significance of oscillatory and bell-shaped growth zoning in hydrothermal garnet:Evidence from the Navachab gold deposit, Namibia. Chemical Geology, 262, 262–276.
Harangi SZ, Downes H, Kosa L, Szabo CS, Thirlwall MF, Mason PRD Mattey D. 2002. Almandine garnet in calc-alkaline volcanic rocks of the Pannonian basin (eastern-central Europe). Geochemistry, Petrogenesis and Geodynamic Implications, Journal of Petrology, 10, 1813-1843.
Hwang SL, Yui TF, Shen P. 2001. Submicron polyphase inclusions in garnet from the Tananao metamorphice complex, Taiwan, a key to unraveling other wise unrecognized metamorphic events. J. Geol, 19, 599-605.
Klein C, Harlbut JrCS. 1985. Manual of mineralogy. 21st ed, John Wiley and Sons, 596.
Kohn MJ, Spear FS. 2000. Retrograde net transfer reaction insurance for pressure–temperature estimates. Geology journal, 28, 1127–1130.
Kretz R. 1994. Metamorphic crystallization. John Wiley and Sons, 507 p.
Kretz R.1983. Symbols for rock-forming minerals. American Mineral. 69, 277-279.
Li Li H, Kuang X, Mao A Li Y, Wang S. 2010. Study of local structures and optical spectra for octahedral Fe3+ centers in a series of garnet crystals A3B2C3O12 (A = Cd, Ca; B = Al, Ga, Sc, In; C = Ge, Si). Chemical Physics Letters, 484. 387–391.
Locock A. 2008. An Excel spreadsheet to recast analyses of garnet end-member componets, and a synopsis of the crystal chemistry of natural silicate garnets. Computers and Geosciences. 34, 1769-1780.
Robl J, Hergarten S, Stuwe K, Hauzenberger C. 2007. THERMAL HISTORY: A new software to interpret diffusive zoning profiles in garnet. Computers & Geosciences, 33, 760–772.
Russell JK, Dipple GM, Lang JR. Lueck B. 1999. Major-element discrimination of titanium andradite from magmatic and hydrothermal environments; an example from the Canadian Cordillera. European Journal of Mineral, 11, 919-935.
Schmid R, Fettes D, Harte B, Davis E, Desmons J, Silvola J. 2002. Towards a unified neomenclature in metamorphic petrology, 1. How to name a metamorphic rock- An outline no behalf of SCMR. Provisional version on SCMR website.
Sepahi AA. 2008. Typology and petrogenesis of granitic rocks in the Sanandaj-Sirjan metamorphic belt, Iran: With emphasis on the Alvand plutonic complex. N. Jb. Geol. Palaton. Abn, 247, 295-312.
Tracy RJ. 1982. Compositional zoning and inclusions in metamorphic minerals. In Ferry, J.M., (Ed). Characterization of Metamorphism through Mineral Equilibria. Review Mineralogy.
Whitney DL, Seaton NCA. 2010. Garnet polycrystals and the significance of clustered crystallization. Journal of Contribution Mineral Petrology.
Wilbur DE, Ague JJ. 2006. Chemical disequilibrium during garnet growth: Monte Carlo simulations of natural crystal morphologies. Geology journal, 34, 689–692.
Zahra Hossein mirzaee, Nafiseh Salehi Siavashani , 2015. The study of hidden and appear zoning in existed garnets in metamorphic rocks of Hamadan region. J. Biodiv. Environ. Sci., 6(1), 737-742.
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