تکامل ساختاری، گرمایی و مکانیکی گسل‌های راستا لغز در توده‌ی تونالیتی ده نو، غرب مشهد، شمال شرقی ایران

نویسندگان

دانشگاه فردوسی مشهد

چکیده

 توده­ی تونالیتی ده نو درغرب مشهد (شمال شرقی ایران)، یکی از قدیمی­ترین توده­های نفوذی در مجموعه­ی گرانیتوئیدهای مشهد است. این توده با چهار دسته شکستگی منظم قطع شده است. از میان آن­ها دو دسته ویژگی­های گسل با جدایش راستایی راست رو را نشان می­دهند. دسته­ی A شامل گسل­های راستا لغز راست رو با اندک مولفه­ی شیب لغز وارون و دسته­ی B گسل­های راستا لغز راست رو با مولفه­ی کوچک شیب لغز بهنجارند. تونالیت در هسته­ی گسل­ها به میلونیت تغییر یافته است. بررسی ریز ساختارها و بازتبلور دینامیکی دردانه­های کوارتز در این میلونیت­ها نشان می­دهد که تشکیل میلونیت­ها در دمای 410-430 درجه­ی سانتی­گراد و تنش تفاضلی (Mpa)31/59-54/42 و تنش برشی بیشینه­ی (Mpa)65/29- 27/21 روی داده است. نرخ کرنش در این تغییر ساختاری- بوده است. پی­جویی­های صحرایی و بررسی ریز ساختارها نشان داد که این دسته­های گسلی در نتیجه­ی لغزش دوباره روی درزهای کششی و درزه­های نامتقارن حاشیه­ای آن­ها تشکیل شده­اند.

کلیدواژه‌ها


عنوان مقاله [English]

Structural, thermal, mechanical evulotion of strike slip faults in Dehnow tonalite pluton, west of Mashhad, Northeast Iran

چکیده [English]

Dehnow tonalite in west of Mashhad, NE Iran, is one of the oldest pluton in Mashhad Granitoied Complexes. This pluton cut by four systematic fracture sets. Among them, two sets show right lateral strike separation. Set A consists of parallel right lateral strike slip faults with a minor reverse slip component and Set B includes right lateral strike slip faults with a small component of normal slip. Other set is formed between faults in set A. Tonalite is deformed into mylonite in fault cores. Study of microstructures and dynamic recrystallization of quartz grains in these mylonites indicates that the formation of mylonites have taken place under 410-430 (ºC), 42.54 - 59.31(Mpa) differential stress and 21.27-29.65(Mpa) maximum shear stress. The strain rate in this deformation is-. Field observations and study of microstructures revealed that these fault sets have formed during renewed slip on the earlier formed extensional joints and their asymmetric fringe joints probably during Late Cimmerian orogeny.

کلیدواژه‌ها [English]

  • Strike-slip fault
  • Mashhad
  • strain rate
  • stress
  • dynamic recrystallization
  • quartz
[1] Alavi M., "Sedimentary and structural characteristics of the Paleo-Tethys remnants in northeastern Iran", Geological Society of America Bulletin, 103(1991): 983-992.

[2] Majidi B., "The geochemistry of ultra basic and basic lava flows occurrences in northeastern Iran, In Geodynamic project in Iran", Geological Survey of Iran, 51(1983), 463-477.

[3] Karimpour M.H., Farmer L., Ashori C., Saadat S, "Major, Trace and REE geochemistry of Paleo-Tethys Collision-Related Granitoids from Mashhad, Iran", Journal of Science,Islamic Republic of Iran,17(2006),127-145.

[4] Karimpour M.H., Stern C.R., Farmer G.L., "Zircon U–Pb geochronology, Sr–Nd isotope analyses, and petrogenetic study of the Dehnow diorite and Kuhsangi granodiorite (Paleo-Tethys), NE Iran", Journal of Asian Earth Sciences, 37( 2010), 384-393.

[5] Segall P., Pollard D.D., "Nucleation and growth of strike slip faults in granite", Journal of Geophysical Research, 88(1983), 555-568.

]6[ Martel S.J., "Development of simple strike-slip fault zones,Mount Abbot Quadrangle,Sierra Nevada,California.", Geological society of America Bulletin, 100(1988), 1451-1465.

]7[ Myers R., Aydin A., "The evolution of faults formed by shearing across joint zone in sandstone", Journal of structural geology, 26(2004), 947-966.

]8[ Flodin E., Aydin A., "Fault with asymmetric damage zones in sandstone,Vally of Fire State Park, southern Nevada", Journal of structural geology,26(2004)983-988.

[9] Pennacchioni G., "Control of the geometry of precursor brittle structures on the type of ductile shear zone in the Adamello tonalites, Southern Alps (Italy)", Journal of Structural Geology 27(2005), 627-644.

[10] Isik V., "The ductile shear zone in granitoid of the Central Anatolian Crystalline Complex, Turkey: Implications for the origins of the Tuzgölü basin during the Late Cretaceous extensional deformation",Journal of Asian Earth Sciences, 34(2008), 507-521.

]11[Pollard D.D., Aydin A., "Progress in understanding jointing over past century.", Geological society of America Bulletin, 100(1988), 1181-1204.

[12] Hirth G, Tullis J., "Dislocation creep regimes in quartz aggregates", Journal of Structural Geology, 14 (1992), 145–159.

]13[ Stipp M., Tullis J., "The recrystallized grain size piezometer for quartz.", Geophysical Research Letters 30(2003), 2088, doi: 10.1029/2003GL018444.

]14[ Stipp M., Tullis J., Behrens H., "Effect of water on dislocation creep microstructure and flow stress of quartz and implications for the recrystallized grain size piezometer", Journal of Geophysical Research 111(2006), B04201, doi: 10.1029/2005JB003852.

]15[ Dunlap W. J., Hirth G., Teyssier C., "Thermomechanical evolution of a ductile duplex", Tectonics, 16(1997), 983-100.

]16[ Stockert B., Brix M. R., Kleinschrodt R., Hurford A. J., Wirth R., "Thermochronometry and microstructures of quartz – a comparison with experimental flow laws and predictions on the temperature of the brittle-plasticTransition", Journal of Structural Geologv, 21(1999), 351-369.

]17[ Zulauf G., "Structural style, deformation mechanisms and paleodifferential stress along an exposed crustal section; constraints on the rheology of quartzofeldspathic rocks at supra- and infrastructural levels (Bohemian Massif)", Tectonophysics, 332(2001), 211-237.

[18] Stipp M., Stünitz H., Heilbronner R., Schmid S.M., "The eastern Tonale fault zone: a ‘‘natural laboratory” for crystal plastic deformation of quartz over a temperature range from 250° to 700°C ", Journal of Structural Geology 24(2002a), 1861–1884.

]19[ Stipp M., Kunze K., "Dynamic recrystallization near the brittle-plastic transitionin naturally and experimentally deformed quartz aggregates", Tectonophysics, (2008) doi:10.1016/j.tectono.2007.11.041.

]20[ Stipp M., Stunitz H., Heilbronner R., Schmid S.M., "Dynamic recrystallization of quartz: correlation between natural and experimental conditions.In: De Meer, D., Drury, M.R., De Bresser, J.H.P., Pennock, G.M. (Eds.), Deformation Mechanisms, Rheology and Tectonics: Current Status and Future Perspectives. Geological Society of London, Special Publication", (2002b), 170–190.

[21] Passchier C.W., Trouw R.A.J., "Microtectonics", second ed., Springer, Berlin (2005).

]22[ Goetze C., Kohlstedt D. L., "Laboratory study of dislocation climb and diffusion in olivine,Journal of Geophysical Research", 78 (1973), 5961-5971.

]23[ Twiss R. J., "Static theory of size variation with stress for subgrains and dynamically recrystallized grains. In: USGS (ed) Proceedings of the IX. Conference,Magnitude of Deviatoric Stresses in the Earth's Crust and Upper Mantle", Open File Report, 80-625. Menlo Park, California. (1980) 665-683.

]24[ Twiss R. J., "Theory and applicability of a recrystallized grain size paleopiezometer", Pure and Applied Geophysics, 115(1977), 227-244.

]25[ Koch P. S., "Rheology and Microstructures of Experimentally Deformed Quartz Aggregates.", PhD thesis, University of California,Los Angeles(1983).

]26[ Heard H. C., Carte N. L., "Experimentally induced 'natural intragranular flow in quartz and quartzite", American Journal of Science, 266 (1968), 1-42.

]27[ Parrish D. K., Krivz A. L., Carter N. L., "Finite-element folds of similar geometry", Tectonophysics, 32(1976), 183-207.

]28 [Kronenberg A., Tullis J., "Flow strengths of quartz aggregates: grain size and pressure effects due to hydrolytic weakening", Journal of Geophvsical Research, 89(1984), 4281-4297.

]29[ Luan F. C., Paterson M. S., "Preparation and deformation of synthetic aggregates of quartz", Journal of Geophysical Research, 97(1992), 301-320.

]30[ Paterson M. S., Luan F. C., "Quartzite rheology under geological conditions. In: KNIPE, R. J. & RUTTER, E. H. (eds) Deformation mechanisms, rheology and tectonics.", Geological Society London, Special Publication, 54 (1990), 299-307.

]31[ Hirth G., Teyssier C., Dunlap W. J., "An evaluation of quartzite flow laws based on comparisons between experimentally and naturally deformed rocks", International Journal of Earth Sciences, 90(2001), 77-87.

]32[ Ord A., Christie J. M., "Flow stresses from microstructures in mylonitic quartzites of the Moine Thrust zone, Assynt area", Scotland.Journal of Structural Geology, 6 (1984) 639-654.

]33[ Hacker B. R., Yin. A., Christie J. M., Davis G. A., "Stress magnitude, strain rate, and rheology of extended middle continental crust inferred from quartz grain sizes in the Whipple Mountains, California", Tectonics, 11 (1992) 36-46.