بررسی رفتار زمین‌شیمیایی عناصر اصلی و کمیاب خاکی در گارنت‌های پگماتیت‌های دره ولی (شمال شرق بروجرد، پهنه سنندج- سیرجان)
محورهای موضوعی :سمیه رحمانی جوانمرد 1 , زهرا طهماسبی 2 , زینک دینک 3 , احمد احمدی خلجی 4
1 - دانشگاه لرستان، خرم¬آباد
2 - دانشگاه لرستان
3 - اکادمی علوم چین، گوانجو
4 - دانشگاه لرستان، خرم¬آباد
کلید واژه: بروجرد پگماتيت دره ولی زمین‌شیمی عناصر کمیاب خاکی گارنت ماگمایی,
چکیده مقاله :
پگماتیت‌های منطقه دره ولی در شمال شرق بروجرد و در پهنه ساختاری سنندج- سیرجان واقع شده‌اند. این پگماتیت‌ها به‌صورت دایک‌هایی با روند شمال‌غرب- جنوب‌شرق، واحدهای گرانودیوریتی منطقه مورد مطالعه را قطع کرده‌اند. این سنگ‌ها از نظر کانی‌شناسی شامل کانی‌های کوارتز، فلدسپار‌های آلکالن (ارتوکلاز و میکروکلین)، پلاژیوکلاز، مسکوویت، گارنت (آلماندین- اسپسارتین)، آندالوزیت، تورمالین و آپاتیت هستند. الگو‌های REE بهنجار‌شده نسبت به كندريت در پگماتیت‌های دره ولی، بیانگر غنی‌شدگی اندک LREE نسبت به HREE )04/4-76/1(LaN/YbN=، الگوی نسبتاً مسطح HREE و بی‌هنجاری منفی شدید Eu (54/0-20/0 (Eu/Eu*= است. بررسی شيمي عناصر اصلي گارنت‌هاي درون اين پگماتيت‌ها بيانگر منطقه‌بندی ترکیبی با افزایش FeO و کاهش MnO از مرکز به حاشیه است. مقادیر بسيار بالاي منگنزwt.%) 18/13-27/10 (MnO= و مقدار کم کلسيمwt.%) 29/0-15/0(CaO= گارنت‌هاي موجود در پگماتيت دره ولی، مشابه گارنت‌هاي ماگمايي درون مذاب‌هاي پگماتيتي است. ترکیب بلور‌های گارنت بر روی نمودار MnO+CaO در مقابل FeO+MgO (برحسب درصد وزنی)، بیانگر تبلور آنها در بخش حاشیه‌ای رگه پگماتیتی و از مذاب‌های کم‌تر تفریق‌یافته است. نتایج LA-ICP-MS حاکی از غنی‌شدگی گارنت‌های مورد مطالعه از عناصر کمیاب خاکی سنگین (HREE)، تهی‌شدگی از عناصر کمیاب خاکی سبک (LREE) و بی‌هنجاری منفی شدید Euدر مرکز )41/0-0(Eu/Eu*= و مثبتEu )22/3-0(Eu/Eu*= در حاشیه‌ها است. عناصر Y، HREE، Ti، Zr، Nb، Ta، Hf، U و Mn از مرکز به سمت حاشیه کاهش نشان می‌دهند. این تغییرات از مرکز به حاشیه، به افزایش فاز سیال و اکتیویته H2O در ماگما و افزایش تفریق ماگمایی نسبت داده شده است. الگوی REE و بی‌هنجاری‌های Eu در گارنت‌های دارای منطقه‌بندی، بیانگر تبلور آنها در شرایط احیایی تا اکسیدان است.
The pegmatites of Darreh Vali region is located in the north-east of Boroujerd which is a part of Sanandaj-Sirjan zone. In the Darreh Vali area, granodiorite bodies are cut by small pegmatitic dykes with NW–SE trend. The mineralogy of studied pegmatites consists of quartz, alkali-feldspar (orthoclase and microcline), plagioclase, muscovite, garnet (almandine-spessartin), andalusite, tourmaline, and apatite. Chondrite-normalized patterns of the Darreh Vali pegmatite are characterized by low enrichments of LREE relative to HREE (LaN/YbN=1.76-4.04), with a relatively flat HREE distribution, and a strong negative Eu anomaly (Eu/Eu* =0.20-0.54). Major element chemistry of garnets in these pegmatites indicates a compositional zoning with decreasing MnO and increasing FeO from core towards the rim. In the case of the Darreh Vali pegmatites, all garnet crystals contain low CaO (0.15 to 0.29 wt.%) and high MnO (10.27 to 13.18 wt.%), which are similar to magmatic garnets from pegmatitic melts. On the MnO+CaO versus FeO+MgO (in wt. %) diagram, the composition of garnets shows that they probably crystallised in contact zones of pegmatite vein and from less evolved melts. LA-ICP-MS analyses show that analysed garnets have a high HREE, low LREE contents, and strong negative Eu anomaly (Eu/Eu*=0-0.41) in the core along with positive Eu anomaly (Eu/Eu*=0-3.22) at the rim. Y, HREE, Ti, Zr, Nb, Ta, Hf, U and Mn decrease from core to rim. These core-to-rim elemental variations are attributed to increasing fluid-phase and H2O activity in magma, along with increasing magma fractionation. REE patterns and Eu anomalies in zoned garnets suggest that they probably formed in reducing to oxidizing conditions.
حاج ملاعلی، ا. و سهندی، م.ر.، 1371. نقشه زمین‌شناسی 1:250000 خرم‌آباد. سازمان زمین‌شناسی و اکتشافات معدنی کشور.
- Abbott Jr., R.N., 1981. AFM liquidus projection for granitic magmas, with special reference to hornblende, biotite and garnet. The Canadian Mineralogist, 19, 103–110.
- Ahmadi-Khalaji, A., Esmaeily, D., Valizadeh, M.V. and Rahimpour-Bonab, H., 2007. Petrology and geochemistry of the granitoid complex of Boroujerd, Sanandaj-Sirjan zone, Western Iran. Journal of Asian Earth Sciences, 29, 859-877.
- Aldanmaz, E., Pearce, J. A., Thirlwall, M.F. and Mitchell, J.G., 2000. Petrogenetic evolution of late Cenozoic, post-collision volcanism in western Anatolia, Turkey. Journal of Volcanology and Geothermal Research, 102, 67-95.
- Allan, B.D. and Clarke, D.B., 1981. Occurrence and origin of garnets in the South Mountain batholith, Nova Scotia. Canadian Mineralogist, 19, 19–24.
- Anczkiewicz, R., Thirlwall, M., Alard, O., Rogers, N.W. and Clark, C., 2012. Diffusional homogenization of light REE in garnet from the Day Nui Con Voi Massif in N-Vietnam: Implications for Sm–Nd geochronology and timing of metamorphism in the Red River shear zone. Chemical Geology, 318–319, 16-30.
- Arredondo, E.H., Rossman, G.R. and Lumpkin, G.R., 2001. Hydrogen in spessartine–almandine garnets as a tracer of granitic pegmatite evolution. American Mineralogist, 86, 485–490.
- Baldwin, J.R. and Von Knorring, O., 1983. Compositional range of Mn-garnet in zoned granitic pegmatites. Canadian Mineralogist, 21, 683–688.
- Bau, M., 1991. Rare-earth element mobility during hydrothermal and metamorphic fluid–rock interaction and the significance of the oxidation state of europium. Chemical Geology, 93, 219–230.
- Bau, M., Usui, A., Pracejus, B., Mita, N., Kanai, Y., Irber, W. and Dulski, P., 1998. Geochemistry of low-temperature water–rock interaction: evidence from natural waters, andesite, and iron-oxyhydroxide precipitates at Nishiki-numa iron-spring, Hokkaido, Japan. Chemical Geology, 151, 293–307.
- Černý, P., Meintzer, R.E. and Anderson, A.J., 1985. Extreme fractionation in rare-element granitic pegmatites: selected examples of data and mechanism. The Canadian Mineralogist, 23, 381-421.
- Chappell, B.W. and White, A.J.R., 1992. I- and S-type granites in the Lachlan Fold Belt. Transactions of the Royal Society of Edinburgh Earth Sciences, 83, 1–26.
- Clemens, J.D. and Wall, V.J., 1981. Origin and crystallization of some peraluminous (S-type) granitic magmas. Canadian Mineralogist, 10, 111-131.
- Coleman, R.G., Lee, D.E., Beatty, L.B. and Brannock, W.W., 1965. Eclogites and eclogites: Their differences and similarities. Geological Society of America Bulletin, 76, 483-508.
- Dahlquist, J.A., Galindo, C., Pankhurst, R.J., Rapela, C.W., Alasino, P. H., Saavedra, J. and Fanning, C.M., 2007. Magmatic evolution of the Peñón Rosado granite: Petrogenesis of garnet-bearing granitoids. Lithos, 95, 177–207.
- Deer, W.A., Howie, R.A. and Zussman, J., 1982. Rock-Forming Minerals. 1A Orthosilicates. Longmans, 2nd edition, 919.
- Dorais, M.J. and Tubrett, M., 2012. Detecting peritectic garnet in the peraluminous Cardigan Pluton, New Hampshire. Journal of Petrology, 53, 299–324.
- Droop, G.T.R., 1987. A general equation for estimating Fe3+ concentrations in ferromagnesian silicates and oxides from microprobe analyses, using stoichiometric data. Mineralogical Magazine, 51, 431-435.
- Gaspar, M., Knaack, C., Meinert, L. and Moretti, D., 2008. REE in skarn systems: A LA-ICP-MS study of garnets from the Crown Jewel gold deposit. Geochimica Cosmochimica Acta, 72, 185–205.
- Gramaccioli, C.M. and Pezzotta, F., 2000. Geochemistry of yttrium with respect to rare-earth elements in pegmatities. Memorie della Società Italiana di Scienze naturali e del Museo Civico di Storia Naturale di Milano, 30, 111-115.
- Green, D.H. and Ringwood, A.E., 1968. Origin of the garnet phenocrysts in calc-alkaline rocks. Contributions to Mineralogy and Petrology, 18, 163–174
- Green, T.H., 1977. Garnet in silicic liquids and its possible use as a P–T indicator. Contributions to Mineralogy and Petrology, 65, 59–67.
- Green, T.H., 1992. Experimental phase equilibrium studies of garnet-bearing I-type volcanic and high-level intrusive from Northland, New Zealand. Transactions of the Royal Society of Edinburgh Earth Sciences, 83, 429–438.
- Harangi, S.Z., Downes, H., Ko´sa, L., Szabo´, C.S., Thirlwall, M.F. and Mason, P.R.D., 2001. Almandine garnet in calc-alkaline volcanic rocks of the Northern Pannonian Basin (Eastern-Central Europe): geochemistry, petrogenesis and geodynamic implications. Journal of Petrology, 42, 1813–1843.
- Heimann, A., 2015. The chemical composition of gahnite and garnet as exploration guides to and indicators of rare element (Li) granitic pegmatites. U.S. Geological Survey, Open-File Report 1–24.
- Heimann, A., Spry, P.G., Teale, G.S., Conor, C.H.H. and Pearson, N.J., 2011. The composition of garnet in garnet-rich rocks in the southern Proterozoic Curnamona Province, Australia: an indicator of the premetamorphic physicochemical conditions of formation. Mineralogy and Petrology, 101, 49–74.
- Hönig S., Čopjaková R., Škoda R., Novák M., Dolejš D., Leichmann, J. and Vašinová Galiová, M., 2014. Garnet as a major carrier of the Y and REE in the granitic rocks: An example from the layered anorogenic granite in the Brno Batholith, Czech Republic. American Mineralogist, 99, 1922–1941.
- Hsu, L.C., 1968, Selected phase relationships in the system Al-Mn-Fe-Si-O-H, a model for garnet equilibria. Journal of Petrology, 9, 40-83.
- Leake, B.E., 1967. Zoned garnets from the Galway granite and its aplite. Earth and Planetary Science Letters, 3, 311–315.
- London, D., 2008. Pegmatites. Canadian Mineralogist Special Publication, 10, 1–347.
- Lottermoser, B.G., 1988. Rare earth element composition of garnets from the Broken Hill Pb-Zn-Ag orebodies, Australia. Neues Jahrbuch Mineral Monatsh, 9, 423–431.
- Lottermoser, B.G., 1992. Rare earth elements and hydrothermal ore formation processes. Ore Geology Reviews, 7, 25–41.
- Macleod, G., 1992. Zoned manganiferous garnets of magmatic origin from the Southern Uplands of Scotland. Mineralogical Magazine, 56, 115–116.
- Manning, D.A.C., 1983. Chemical variations in garnets from aplites and pegmatites, peninsular Thailand. Mineralogical Magazine, 47, 353-358.
- McDonough, W.F. and Sun, S.S., 1995. The composition of the Earth. Chemical Geology, 120, 223–253.
- Miller, C.F. and Stoddard, E.F., 1981. The role of manganese in the paragenesis of magmatic garnet: an example from the Old Woman Piute Range, California. The Journal of Geology, 89, 233-246.
- Moretz, L., Heimann, A., Bitner, J., Wise, M., Rodrigues Soares, D. and Mousinho Ferreira, A., 2013. The composition of garnet as indicator of rare metal (Li) mineralization in granitic pegmatites. Proceeding of The 6th International Symposium on Granitic Pegmatites, 94–95.
- Müller, A., Kaersley, A., Spratt, J. and Seltmann, R., 2012. Petrogenetic implications of magmatic garnet in granitic pegmatites from southern Norway. Canadian Mineralogist, 50, 1095–1115.
- Nakano, T. and Ishikawa, Y., 1997. Chemical zoning of pegmatite garnets from the Ishikawa and Yamanoo areas, northeastern Japan. Geochemical Journal, 31, 105-118.
- Peng, T., Wang, Y., Zhao, G., Fan, W. and Peng, B., 2007. Arc-like volcanic rocks from the Southern Lancangtion Zone, SW china: Geochronological and geochemical constraint on their petrogenesis and tectonic implication. Lithos, 102, 358-373.
- Rollinson, H., 1993. Using Geochemical Data: Evaluation, Presentation, Interpretation. Longman Group UK Ltd., London, U.K, 352.
- Samadi, R., Miller, N., Mirnejad, H., Hariss, C., Kawabata, H. and Shirdashtzadeh, N., 2014. Origin of garnet in aplite and pegmatite from Khajeh Morad of NE Iran: a major, trace element, and oxygen isotope approach. Lithos, 208-209, 378-392.
- Schwandt, C.S., Papike, J.J., Shearer, C.K. and Brearley, A.J., 1993. A SIMS investigation of REE chemistry of garnet in garnetite associated with the Broken Hill Pb-Zn-Ag orebodies, Australia. Canadian Mineralogist, 31, 371–379.
- Smeds, S.A., 1994. Zoning and fractionation trends of a peraluminous NYF granitic pegmatite field at Falun, south-central Sweden. Journal of the Geological Society of Sweden, 116(3), 175–184.
- Sölva, H., Thöni, M. and Habler, G., 2003. Dating a single garnet crystal with very high Sm/Nd ratios (Campo basement unit, Eastern Alps). European Journal of Mineralogy, 15, 35–42.
- Sverjensky, D.A., 1984. Europium equilibria in aqueous solution. Earth and Planetary Science Letters, 67, 70–78.
- Thöni, M. and Miller, C., 2000. Permo-Triassic pegmatites in the eo-Alpine eclogite-facies Koralpe complex, Austria: age and magma source constraints from mineral chemical, Rb–Sr and Sm–Nd isotope data. Schweizerische Mineralogische und Petrographische Mitteilungen, 80(2), 169–186.
- Thöni, M. and Miller, C., 2004. Ordovician meta-pegmatite garnet (NW Ötztal basement, Tyrol, Eastern Alps): preservation of magmatic garnet chemistry and Sm-Nd age during mylonitization. Chemical Geology, 209, 1-26.
- Tsygankov, A.A. and Vrublevskaya, T.T., 1988. The Continental Crust: Its Composition and Evolution. Blackwell Scientific Publications, 312.
- Van Westrenen, W., Blundy, J. and Wood, B., 1999. Crystal-chemical controls on trace element partitioning between garnet and anhydrous silicate melt. American Mineralogist, 84, 838–847.
- Wang, R.C., Fontan, F., Chen, X.M., Hu, H., Liu, C.S., Xu, S.J. and de Parseval, P., 2003. Accessory minerals in the Xihuashan Y-enriched granitic complex, southern China: A record of magmatic and hydrothermal stages of evolution. Canadian Mineralogist, 41, 727–748.
- Weisbrod, A., 1974. Étude experimentale de l'équilibre grenat-cordiérite dans le système Mn–Fe–Al–Si–O–H, à 750 °C. Implications thermodynamiques et pétrologiques. Bulletin de la Société Française Minéralogie et de Cristallographie, 97, 261–270.
- Whitney, D.L. and Evans, B.W., 2010. Abbreviations for names of rock-forming minerals. American Mineralogist, 95,185–187.
- Whitworth, M.P., 1992. Petrogenetic implications of garnets associated with lithium pegmatites from SE Ireland. Mineralogical Magazine, 56, 75-83.
- Whitworth, M.P. and Feely, M., 1994. The compositional range of magmatic Mn-garnets in Galway Granite, Connemara, Ireland. Mineralogical Magazine, 58, 163–168.
- Wilson, M., 1989. Igneous Petrogenesis. Chapman and Hall, Londen, UK, 452.
- Wu, F.Y., Jahn, B.M., Wilde, S.A., Lo, C.H., Yui, T.Z., Lin, Q., Ge, W.C. and Sun, D.Y., 2003. Highly fractionated I-type granites in NE China (I): geochronology and petrogenesis. Lithos, 66, 241-273.