Document Type : Original Research Paper
Author
Assistant Professor, Department of Geology, Faculty of Science, Yazd University, Yazd, Iran
Abstract
Mafic dyke swarms of the Zarigan granitoid in the north of Bafq have intruded the Lower Cambrian volcanic-sedimentary sequence of central Iran. These dykes are lithologically classified as gabbro-diorite and alkali gabbro. The alkaline gabbros are younger and penetrate higher horizons. Geochemically, gabbro-diorites have a tholeiitic to transitional nature with enrichment of LILE, HREE and depletion of Nb and Ta elements. By contrast, alkali gabbros have the sodic alkaline nature, exhibiting Nb-Ta enrichment and high LREE/HREE ratio. Gabbro-diorite magmas are derived from partial melting of sub-continental lithospheric mantle affected by subduction components in equilibrium with spinel lherzolite. On the other hand, the alkali gabbros originate from greater depth and lower partial melting of enriched asthenospheric mantle in equilibrium with garnet lherzolite. These dykes are formed in an intra-arc extension setting associated with subduction of the continental margin. Geometry and mechanism of motion of Posht-e-Badam and Kuh Banan basement faults caused an anticlockwise rotation, crustal fracturing, lithospheric thinning, and stenosphere upwelling of these two faults bounded block.
Keywords
Main Subjects
Alici P., Temel A., Gourgaud A., Kieffer G. and Gundogdu M.N., 1998- Petrology and geochemistry of potassic rocks in the Go¨lcu¨k area Isparta, SW Turkey/: genesis of enriched alkaline magmas Journal of Volcanology and Geothermal Research 85,423-446. https://doi.org/10.1016/s0377-0273 (98)00065-1.
Bazoobandi, M.H., Arian, M.A., Emami, M.H., Tajbakhsh, G. and Yazdi, A., 2015- Geodynamics of Dikes in North of Saveh , Open Journal of Ecology, 5(09), 452. https://doi.org/10.4236/oje.2015.59037
Berberian, M. and King, G.C.P., 1981- Towards a paleogeography and tectonic evolution of Iran, Canadian Journal of Earth Sciences, 18, 210-265. https://doi.org/10.1139/e81-019.
Bhat, M.I., Le Fort, p. and Ahmad, T., 1994- Bafliaz volcanics, NW Himalaya: Origin of a bimodal, tholeiite and alkalibasalt suite, Chem. Geol., 114(3-4). 217-234, doi: 10.1016/0009-2541(94)90054-X. https://doi.org/10.1016/0009-2541(94)90054-x.
Bursik, M., 2009- A general model for tectonic control of magmatism: Examples from Long Valley Caldera (USA) and El Chichón (México). Geofísica internacional, 48(1), 171-183.
Cabanis, B. and Thieblemont, D., 1988- La discrimination des tholeiites continentales et des basaltes arriere-arc; proposition d'un nouveau diagramme, le triangle Th-3xTb-2xTa. Bulletin de la Société Géologique de France, 4(6), 927-935, https://doi.org/10.2113/gssgfbull.iv.6.927.
Cox, K.G., Bell, J.D. and Pankhurst, R.J., 1979- The interpretation of igneuos rocks, Allen and unwin, London, 450 P.
Ernst, R.E., Head, J.W., Parfitt, E., Grosfils, E. and Wilson, L., 1995- Giant radiating dyke swarms on Earth and Venus, Earth-Science Reviews, 39. 1-58. https://doi.org/10.1016/0012-8252(95)00017-5.
Gao, Z., Zhang, H., Yang, H., Pan, F., Luo, B., Guo, L., Xu, W., Tao, L., Zhang, L. and Wu, J., 2018- Back-arc basin development: constraints on geochronology and geochemistry of arc like and OIB-like basalts in the Central Qilian block (Northwest China), Lithos, 310- 311, 255–268. https://doi.org/10.1016/j.lithos.2018.04.002 .
Hou, G., 2012- Mechanism for three types of mafic dyke swarms. Geoscience Frontiers, 3(2), 217-223. https://doi.org/10.1016/j.gsf.2011.10.003.
Irvine, T.N. and Baragar, W.R.A., 1971- A guide to the chemical classification of the common volcanic rocks, Canadian journal of earth science, V., 8, P., 523-276. https://doi.org/10.1139/e71-055.
Jiang, H., Han, J., Chen, H., Zheng, Y., Lu, W., Deng, G. and Tan, Z., 2017- Intra-continental back-arc basin inversion and Late Carboniferous magmatism in Eastern Tianshan, NW China: constraints from the Shaquanzi magmatic suite, Geosci. Front, 8. 1447–1467. https://doi.org/10.1016/j.gsf.2017.01.008.
Kjøll, H. J., Galland, O., Labrousse, L. and Andersen, T. B., 2019- Deep section of a Neoproterozoic fossil magma rich rifted margin exposed, EGU General Assembly 2019, V., 19: Vienna.
Koglin, N., Kostopoulous, D. and Reischmann, T., 2009- Geochemistry, petrogenesis and tectonic setting of the Samothraki mafic suite, Trace-element, isotopic and zircon age constraints, Tectonophysics, NE Greece, 473. 53-68. https://doi.org/10.1016/j.tecto.2008.10.028.
Liao, F.X., Zhang, L., Chen, N.S., Sun, M., Santosh, M., Wang, Q.Y. and Mustafa, H.A., 2014- Geochronology and geochemistry of meta-mafic dykes in the Quanji Massif, Paleoproterozoic evolution of the Tarim Craton and implications for the assembly of the Columbia supercontinent, Precambr. Res., NW China, 249.33-56. https://doi.org/10.1016/j.precamres.2014.04.015.
Liu, H.C., Xia, X.P., Lai, C.K., Gan, C.S., Zhou, Y.Z. and Huangfu, P.P., 2018- Break-away of South China from Gondwana, Insights from the Silurian high-Nb basalts and associated magmatic rocks in the Diancangshan-Ailaoshan fold belt, SW China, Lithos, 318-319, 194-208. https://doi.org/10.1016/j.lithos.2018.08.014.
Masoodi, M., Yassaghi, A., Nogole Sadat, M.A.A., Neubauer, F., Bernroider, M., Friedl, G.,Genser, J. and Houshmandzadeh, A., 2013- Cimmerian evolution of the Central Iranianbasement, evidence from metamorphic units of the Kashmar–Kerman Tectonic Zone, Tectonophysics, 588, 189-208. https://doi.org/10.1016/j.tecto.2012.12.012.
Meschede, M., 1986- A method of discriminating between different types of midocean ridge basalts and continental tholeiites with the Nb-Zr-Y diagram, Chemical Geology, 56, 207-218. https://doi.org/10.1016/0009-2541(86)90004-5.
Middlemost, E.A.K., 1989- Iron oxidation ratios, norms and the classification of volcanic rocks, Chemical Geology, 77, 19-26.https://doi.org/10.1016/0009-2541 (89)90011-9.
Niu, Y.L. and O’Hara, M.J., 2003- Origin of ocean island basalts, a new perspective from petrology, geochemistry and mineral physics considerations, Journal of Geophysical Research, 108. B4 (2209), doi:10.1029/2002JB002048 .https://doi.org/10.1029/2002jb002048.
Parsons, T., Sleep, N.H., Thompson, G.A., 1992- Host rock rheology controls on the emplacement of tabular intrusions, Implications for underplating of extending crust, Tectonics, 11.1348-1356 .https://doi.org/10.1029/92tc01105.
Pearce, J.A. and Cann, J.R., 1973- Tectonic setting of basic volcanic rocks determined using trace element analyses, Earth Planet. Sci. Lett., 19, 290-300. https://doi.org/10.1016/0012-821x(73)90129-5.
Pearce, J.A. and Stern, R.J., 2006- Origin of back-arc basin magmas, trace element and isotope perspectives. In: Christie, D.M., Fisher, C.R., Lee, S.M., Givens, S. (Eds.), Geophysical Monograph Book Series, pp. 63–86. https://doi.org/10.1029/166gm06.
Pearce, J.A., 1982- Trace element characteristics of lavas from destructive plate boundaries. In: Thorpe, R.S. (Ed.), Andesites: Orogenic Andesites and Related Rocks. John Wiley and Sons, 252-548.
Pearce, J.A., Harris, N.B.W. and Tindle, A.G., 1984- Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. J. Petrol., 25, 956-983. https://doi.org/10.1093/petrology/25.4.956.
Pollard, D.D., 1987- Elementary fractures mechanics applied to the structural interpretation of dykes. In: Halls, H.C., Fahrig, W.H. (Eds.), Mafic Dyke Swarms, vol. 34. Geological Association of Canada Special Paper, pp. 524.
Rajabi, A., Canet, C., Rastad, E. and Alfonso, P., 2015- Basin evolution and stratigraphic correlation of sedimentary-exhalative Zn. Pb deposits of the Early Cambrian Zarigan. Chahmir Basi Central Iran, Ore Geology Reviews, 64. 328-353. https://doi.org/10.1016/j.oregeorev.2014.07.013.
Ramezani, J. and Tucker, R., 2003- The Saghand region, Central Iran: U/Pb geochronology, petrogenesis and implication for Gondwana tectonics. American Journal of Science 303, 622–665. https://doi.org/10.2475/ajs.303.7.622.
Sun, S. and McDonough, W.F., 1989- Chemical and isotopic systematics of oceanic basalts, Implications for mantle composition and processes, In: Saunders AD, Norry MJ, eds. Magmatism in the ocean basins. Boston, Blackwell Scientific: 313-345. https://doi.org/10.1144/gsl.sp.1989.042.01.19.
Tajbakhsh, G., Moosavizadeh, M. and Eslami Farsani, S., 2017 - Mineralogy and Geothermobarometry of Micro Gabbro-Diorite Dykes in Zarigan Acidic Pluton, The 36th National and the 3rd International Geosciences Congress of Iran.
Tao, L., Zhang, H., Yang, H., Gao, Z., Pan, F. and Luo, B., 2018- Initial back-arc extension, Evidence from petrogenesis of early Paleozoic MORB-like gabbro at the southern Central Qilian block, NW China, Lithos, 322. 166-178. https://doi.org/10.1016/j.lithos.2018.10.015.
Wang, D.Z. and Shu, L.S., 2012- Late Mesozoic basin and range tectonics and related magmatism in Southeast China, Geoscience Frontiers, 3.109-124 .https://doi.org/10.1016/j.gsf.2011.11.007.
Wang, K., Plank, T., Walker, J.D. and Smith, E.I., 2002- A mantle melting profile across the Basin and Range, Journal of Geophysical Research: Solid Earth, SW USA, 107(B1), ECV, 55-1. https://doi.org/10.1029/2001jb000209.
Wood, D.A., 1980- The application of a Th-Hf-Ta diagram to problems of tectonomagmatic classification and to establishing the nature of crustal contamination of basaltic lavas of the British tertiary volcanic province, Earth & Planetary Science Letters, 50, 11-30. https://doi.org/10.1016/0012-821x(80)90116-8.
Xia, L. and Li, X., 2019- Basalt geochemistry as a diagnostic indicator of tectonic setting, Gondwana Res, 65, 43-67. https://doi.org/10.1016/j.gr.2018.08.006.
Zhang, J. J., Zheng, Y. F., and Zhao, Z. F., 2009- Geochemical evidence for interaction between oceanic crust and lithospheric mantle in the origin of Cenozoic continental basalts in east-central China. Lithos, 110(1-4), 305-326. https://doi.org/10.1016/j.lithos.2009.06.029.
)