Skip to main content

Serpentinites and their tectonic signature along the Northwest Zagros Thrust Zone, Kurdistan Region, Iraq

السربنتينات وبصمتها التكتونية بمحاذاة نطاق صدع دسرى شمال غرب زجروس، منطقة كردستان، العراق

Abstract

Two types of serpentinized peridotites are distinguished within the Northwest Zagros Thrust Zone (NW-ZTZ) in Kurdistan region of Iraq. One is found as lower members of ophiolite sequences, such as the Mawat and Penjwin ophiolites of the upper Cretaceous age. The other is represented by intraformational isolated serpentinite bodies in Betwat, Qaladeza, and Qalander areas within the Walash–Naopurdan volcano-sedimentary unit of the Paleocene to Eocene paleo-arc tectonic setting. Serpentinites within the NW-ZTZ consist mainly of lizardite and chrysotile, with subordinate amounts of syn-serpentinization magnetite, carbonates, chromium chlorite, tremolite, and talc as secondary minerals, and olivine, clinopyroxene, and chromian spinel as primary minerals. Minor antigorite is also found in the sheared serpentinites often found in ophiolite sequences. Petrological and geochemical studies of serpentinites from the NW-ZTZ show that, of the original protoliths of serpentinites, those associated with ophiolites are residual depleted harzburgite and dunite. The \( {\text{Cr}}\# \left( {{{ = {\text{ Cr}}} \mathord{\left/ {\vphantom {{ = {\text{ Cr}}} {\left( {{\text{Cr}} + {\text{Al}}} \right){\text{ atomic ratio}}}}} \right. \kern-\nulldelimiterspace} {\left( {{\text{Cr}} + {\text{Al}}} \right){\text{ atomic ratio}}}}} \right) \) of chromian spinel is more than 0.6, and the forsterite content of olivine is 91–92. On the other hand, the original protolith of isolated serpentinite bodies is less depleted harzburgite or depleted lherzolite, which has spinel with Cr# less than 0.6 and olivine with 90–91 forsterite contents. Whole rock chemistry of major, trace, and rare earth elements shows that the serpentinites of ophiolite sequences are depleted in CaO, Al2O3, and SiO2, Sr, and Zr, and are enriched in MgO, Ni, and Cr, in comparison with the isolated serpentinites. Cr# of the disseminated unaltered chromian spinels indicates that the serpentinites of both types had been originated from the supra-subduction zone tectonic setting; the serpentinites of ophiolite sequences obducted and thrusted over the continental margin during the obduction of the Tethyth oceanic crust onto the Arabian continental margin during the upper Cretaceous period. Isolated serpentinite bodies represent serpentinized forearc mantle wedge peridotites emplaced by diapiric upwelling into non-accretionary forearc tectonic settings during the Paleocene to Eocene age.

Abstract

تم التعرف على نوعين من البريدوتايت السربنتينى فى نطاق صدع دسرى شمال غرب زجروس بمنطقة كردستان العراق. يتواجد احد هذين النوعين كعضو سفلى لتتابع الافيوليت، مثل افيوليت الماوات والبنجوين لعصر الكريتاوى العلوى. ويتمثل الاخر بأجسام سربنتينية معزولة داخل البتوات، والكالاديزا والكالندر فى وحدة الوالاش- نيوبوردان الرسوبية البركانية، والممثلة للقوس التكتونى القديم فى عصر الباليوسين الى الايوسين. وتتكون السربنتينات فى منطقة الدراسة بصفة رئيسية من الليزردايت والكريسوتيل ومصحوبة بكميات قليلة من معادن الماجنيتيت والكربونات وكلوريد الكروم والتريموليت والتلك كمعادن ثانوية تكونت اثناء عملية السربنتنة وكذلك الاولوفين والكلينوبيروكسين والاسبنيل الكرومى كمعادن اولية. ويتواجد ايضا قليلا من الانتيجوريت فى السربنتين القصى فى تتابع الافيوليت. اوضحت الدراسات البترولوجية والجيوكيميائية للسربنتينات فى منطقة الدراسة ان الاصل الصخرى للسربنتين الذى يرتبط مع الافيوليت عبارة عن بواقى مستنفذة للهارزبرجيت والدونيت. وتبلغ نسبة الكروم Cr#{= Cr/(Cr + Al) atomic ratio}اكثر من 6و0 ومحتوى الفروشتيريت فى الاولوفين من 91–92. ويتكون الصخر الاصلى للاجسام المعزولة من الهارزبرجيت او الهرزوليت الاقل استنفاذا وذات اسبينل بنسبة للـ Cr# اقل من 6و0 ومحتوى للفوروشتوريت 90–91 فى الاولوفين. وتوضح كيميائية الصخور من عناصر اساسية وشحيحة وعناصر ارضية نادرة ان سربنتينات التتابع الافيوليتى تكون مستنفذة فى CaO, Al2O3, and SiO2, Sr, and Zr وتكون غنية بـ MgO, Ni, and Cr بالمقارنة بالسربنتينات المعزولة. دلت نسبة الكروم للاسبينلات الكرومية للغير متحولة والمبعثرة ان سربينتينات كلا النوعين قد تكونت فى وضع تكتونى ممثل بنطاق غوص. وقد انتقلت سربينتينات التتابع الافيوليتى (القشرة المحيطية للتيثس) بصدوع دوسرية فوق الحافة القارية للوح العربى خلال العصر الكريتاوى العلوى. وتمثل الاجسام السربنتينية المعزولة ببيرودايت وشاحى امام قوسى انبثق لاعلى فى وضع تكتونى امام قوسى خلال عصر الباليوسين الى الايوسين.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Fig. 14

References

  • Alavi M (1980) Tectonostratigraphic evolution of Zagrosides of Iran. Geology 8:144–149

    Article  Google Scholar 

  • Al-Gare JS (1984) Petrochemistry, petrogenesis and metamorphism of mafic and ultramafic rocks of Penjwin ophiolite, northeast Iraq. Master thesis, University of Mousl, pp 150

  • Al-Hashimi AR, Al-Mehidi H (1975) Cu, Ni, Cr dispersion in Mawat ophiolite complex, northeast Iraq. Iraqi Journal of Geological Society: Special issue

  • Al-Hassan MI (1975) Comparative petrological study between Mawat and Pejwin igneous complexes, northeastern Iraq.Unpublished M. Sc thesis, University of Baghdad, pp 120

  • Al-Hassan MI (1982) Petrology, mineralogy and geochemistry of Penjwin igneouse complex, northeastern Iraq. Doctoral thesis, University of Dunde, pp 250

  • Al-Jawadi MR (1980) Petrology and geochemistry of Bardi-I-Zard serpentinites and associated chromite occurring around Rayat northeast Iraq. Master thesis, University of Mousl, pp 130

  • Al-Mehidi HM (1975) Tertiary nappe in Mawat range. Iraqi Journal of Geological Society VIII:31–44

    Google Scholar 

  • Al-Samman AH (1983) Mineralogy and geochemistry of ultramafic rocks in the west Norway basement gneiss terrane. Doctorla thesis, Sheffield University, pp 220

  • Alt JC, Shanks WC (1998) Sulfur in serpentinized oceanic peridotite: serpentinization process and microbial sulfate reduction. J Geophys Res 103:9917–9929

    Article  Google Scholar 

  • Alt JC, Shanks WC (2003) Serpentinization of abyssal peridotite from the Mark area, Mid-Atlantic ridge: sulfur geochemistry and reaction modeling. Geochemica et Cosmochemica Acta 67:641–653

    Article  Google Scholar 

  • Aqrawi AM (1990) Petrochemistry, Petrogenesis of ultramafic and gabbroic around Route mountain (Mawat ophiolite complex). Master thesis, University of Mousl, pp 230

  • Aqrawi AM (2000) Preparation and study of forsterite and cordierite from Iraqi serpentinite. Ph.D Thesis, University of Baghdad, Iraq

  • Azer MK, Khalil AES (2005) Petrological and mineralogical studies of Pan-African serpentinites at Bir Al-Edeid area, central Eastern Desert, Egypt. Journal of African earth Science 43:525–536

    Article  Google Scholar 

  • Beard JS, Hopkinson L (2000) A fossil, serpentinization-related hydrothermal vent, Oceanic Drilling Program Leg 173, Site 1068 (Iberia Abyssal Plain): some aspects of mineral and fluid chemistry. J Geophys Res 105:16527–16539

    Article  Google Scholar 

  • Berberian M, King GCP (1981) Towards a paleogeography and tectonic evolution of Iran. Can J Earth Sci 18:210–265

    Article  Google Scholar 

  • Buday T, Jassim SZ (1987) The regional geology of Iraq, Tectonism, magmatism and metamorphism, Volume 2. Geological Survey Minerals Investigation Library, Baghdad

    Google Scholar 

  • Cannat M, Seyler M (1995) Transform tectonics, metamorphic plagioclase and amphibolitization in ultramafic rocks of the Verma transform fault (Atlantic Ocean). Earth Planet Sci Lett 133:283–289

    Article  Google Scholar 

  • Charlou JL, Fouquet Y, Bougault H, Donval JP, Etoubleau JP, Jean-Baptist P, Dapoigny A, Appriou P, Rona PA (1998) Intense CH4 plumes generated by serpentinization of ultramafic rocks at intersection of 15° 20′ N fracture zone and the Mid-Atlantic Ridge. Geochemica and Cosmochemica Acta 62:2323–2333

    Article  Google Scholar 

  • Coish RA, Gardner P (2004) Supra-subduction-zone peridotite in the northern USA Appalachians: evidence from mineral composition. Mineral Mag 68:699–708

    Article  Google Scholar 

  • Coleman RG (1971) Plate tectonic emplacement of upper mantle peridotite along continental edges. J Geophys Res 76:1212–1222

    Article  Google Scholar 

  • Dick HJB (1977) Partial melting in the Josephine Peridotite I, the effect on the mineral compositions and its consequence for geobarometry and geotherometry. Am J Sci 277:801–832

    Article  Google Scholar 

  • Dick HB, Bullen T (1984) Chromian spinel as a petrogenetic indicator in abyssal and Alpine-type peridotites and spatially associated lavas. Contribution to Mineralogy and Petrology 86:54–76

    Article  Google Scholar 

  • Dubińska E, Bylina P, Kozłowski A, Dörr W, Nejbert K, Schastok J, Kulicki C (2004) U-Pb dating of serpentinization: Hydrothermal zircon from metasomatic rodingite shell (Sudetic ophiolite, SW Poland). Chem Geol 203:183–203

    Article  Google Scholar 

  • Dungan MA (1979) A microprobe study of antigorite and some serpentine pseudomorphs. Can Mineral 17:711–784

    Google Scholar 

  • Fryer P (2002) Recent studies of serpentinites occurrences in the oceans: mantel-ocean interactions in the plate tectonic cycle. Chemie der Erde Geochemistry 62:257–302

    Article  Google Scholar 

  • Fryer P, Ambos EL, Hussong DM (1985) Origin and emplacement of Mariana forearc seamounts. Geology 13:774–777

    Article  Google Scholar 

  • Gruau G, Griffiths JB, Lecuyer C (1998) The origin of the U-shaped rare patterns in ophiolite peridotite: Assessing the role of secondary rock alteration and melt/rock reaction. Geochim Cosmochim Acta 62:3545–3560

    Article  Google Scholar 

  • Kamenetsky V, Crawford AJ, Meffre S (2001) Factor controlling chemistry of magmatic spinel: an empirical study of associated olivine. Cr-Spinel and melt inclusions from primitive rocks. J Petrol 42:655–671

    Article  Google Scholar 

  • Karson JA (1999) Geological investigation of a lineated massif at the Kane Transform fault: implications for oceanic core complex. Phil Trans Roy Soc London 357:713–740

    Article  Google Scholar 

  • Koyi H (1988) Experimental modeling of role of gravity and lateral shortening in Zagros mountain belt. AAPG 72:1381–1394

    Google Scholar 

  • Leblance M (1987) Chromite in oceanic arc environments: New Caledonian. In: Stome CW (ed) Evolution of chromium ore fields. Van Nostrand Rienhold, New York, pp 265–297

    Google Scholar 

  • Li XP, Rahn M, Bucher K (2004) Serpentinization of the Zermatt-Saas ophiolite complex and their texture evolution. J Metamorph Geol 22:159–177

    Article  Google Scholar 

  • Mahmmod LA (1978) Petrology and geochemistry of ultramafics around Penjwin, northeast Iraq with special reference to the genesis of the chromites associated with them. Unpublished M. Sc thesis, University of Mosul, Iraq

  • Melcher F, Meisel T, Puhl J, Koller F (2002) Petrogenesis and geotectonic setting of ultramafic in the Eastern Alps: constraints from geochemistry. Lithos 65:69–112

    Article  Google Scholar 

  • Mevél C (2003) Serpentinization of abyssal peridotite at mid-ocean ridges. Geoscience 335:5–852

    Article  Google Scholar 

  • Mitchell NC, Tivey MA, Gente P (2000) Seafloor slopes at mid-ocean ridges from submersible observations and implication for interpreting geology from seafloor topography. Earth Planet Sci Lett 183:543–555

    Article  Google Scholar 

  • Mohammad YO (2004) Petrology and geochemistry of serpentinite and associated rocks in Mawat and Penjwin areas, Kurdistan region, Northeastern Iraq. Unpublished M. Sc thesis, University of Sulaimani, Iraq

  • Mohammad YO, Maekawa H (2008) Origin of titanite in metarodingite from the Zagros Thrust Zone, Iraq. Am Mineral 93:1133–1141

    Article  Google Scholar 

  • Mohammad YO, Mekawa H, Lawa FA (2007) Mineralogy and origin of Mlakawa albitite from Kurdistan region, northeastern Iraq. Geosphere 3:624–645

    Article  Google Scholar 

  • Moody JB (1976) Serpentinization: a review. Lithos 9:125–138

    Article  Google Scholar 

  • Numan NM (2001) Discussion on “Dextral transpression in late Cretaceous continental collision, Sanadaj-Sirjan, western Iran”. J Struct Geol 23:2033–2034

    Article  Google Scholar 

  • O’Hanley DS (1996) Serpentinites: Records of tectonics and petrological history. Oxford University Press, Oxford, p 269

    Google Scholar 

  • Pichard HM (1979) A petrographic study of serpentinisation in ophiolite and oceanic crust. Contribution to Mineralogy and Petrology 68:231–241

    Article  Google Scholar 

  • Pusching AR (2002) Metasomatic alteration at mafic-ultramafic contacts in Valmalenco (Rhetic Alps, N-Italy). Schweiz Mineral Perograph Mitt 82:515–536

    Google Scholar 

  • Savov IP, Ryan JG, D’Antonio M, Kelley K, Mattie P (2005) Geochemistry of serpentinized peridotites from the Mariana Forearc Conical Seamount, ODP Leg 125: Implication for the elemental recycling at subduction zones. Geochemistry Geophysics Geosystems 6:1–24

    Article  Google Scholar 

  • Seifert K, Brunotte D (1996) Geochemistry of serpentinized peridotite from site 897 in the Iberia Abyssal Plain. Proceeding Oceanic Drilling Program Science Results 149:413–424

    Google Scholar 

  • Sengör C (1990) A new model for the late Palaeozoic-Mesozoic tectonic evolution of Iran and implications for Oman. Geol Soc London Spec Pub 49:797–831

    Article  Google Scholar 

  • Sharma M, Wasserburge GJ (1996) The neodymium isotopic compositions and rare earth pattern in highly depleted ultramafic rocks. Geochemica and Cosmochemica Acta 60:4537–4550

    Article  Google Scholar 

  • Shervais JW, Kolesar P, Andreasen K (2005) A field and chemical study of serpentinization Stonyford, California: chemical flux and mass balance. Int Geol Rev 47:1–23

    Article  Google Scholar 

  • Takin M (1972) Iranian geology and continental drift in the Middle East. Nature 235:147–150

    Article  Google Scholar 

  • Wicks FJ, Plant AG (1979) Electron microprobe and X-ray microbeam studies of serpentine textures. Can Mineral 17:785–830

    Google Scholar 

Download references

Acknowledgments

The author is grateful to two anonymous reviewers for critical reading and valuable comments on the manuscript. Y.O. Mohammad is grateful to H. Maekawa for helpful and fruitful discussion.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Yousif Osman Mohammad.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Mohammad, Y.O. Serpentinites and their tectonic signature along the Northwest Zagros Thrust Zone, Kurdistan Region, Iraq. Arab J Geosci 4, 69–83 (2011). https://doi.org/10.1007/s12517-009-0080-y

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s12517-009-0080-y

Keywords

  • Serpentinite
  • Northwest Zagros Thrust Zone (NW-ZTZ)
  • Penjwin ophiolite