Young Alkaline Magmatism in Haraz Road-Polur, Central Alborz: Evidence for the Continuation of a Rift Basin in Alborz.

Mazandaran, Ramin; Sheikhzakariaee, Sayd Jamal; Mortazavi, Seyed Mojtaba; Vosoughi Abedini, Mansour; Yazdi, Abdollah

doi:10.22034/irqua.2025.731449

Young Alkaline Magmatism in Haraz Road-Polur, Central Alborz: Evidence for the Continuation of a Rift Basin in Alborz.

Document Type : Original Article

Authors

Ramin Mazandaran ¹ ^¶

Sayd Jamal sheikhzakariaee ²

Seyed mojtaba Mortazavi ³

Mansour Vosoughi Abedini ⁴

Abdollah Yazdi ⁵

¹ PhD student, Department of Geology, Science and Research Branch, Islamic Azad University, Tehran, Iran

² Assistant Professor,Department of Geology, Science and Research Branch, Islamic Azad University, Tehran, Iran

³ Assistant Professor, Department of Geology, Savadkouh Branch, Islamic Azad University, Savadkouh, Iran

⁴ Associate Professor, Department of Geology, Shahid Beheshti University, Faculty of Earth Sciences, Tehran, Iran

⁵ Assistant Professor, Department of Geology, Kahnouj Branch, Islamic Azad University, Kahnouj, Iran

10.22034/irqua.2025.731449

Abstract

Introduction:
The Central Alborz has sedimentary rocks from Precambrian to Quaternary. This area is part of the Alborz Mountain range, located in the eastern Central Alborz Zone. It lies between longitudes 50°15’ to 50°77’ and latitudes 35°50’ to 36°15’ North. Alborz’s volcanic activity was strong during the Tertiary period, peaking in the late Eocene and Oligocene. After a calm phase, intense activity resumed in the Pliocene. Eocene and Oligocene eruptions across Alborz, including the Qazvin highlands, Takestan, and areas around Tehran, mainly produced andesite, dacite, and rhyolite. These eruptions also created many ignimbritic and tuffaceous deposits, along with pyroclastic fall deposits and pumice lahar flows (Gholami, 2001).
Sampling Method: During fieldwork, we used a systematic sampling method, collecting 70 samples. We prepared thin sections from these samples for closer examination. To analyze the major, minor, and trace elements, we selected 18 whole-rock samples. These were analyzed using Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) at Kansaran Binalood and Zar Azma companies in Iran.
Discussion:
After studying the thin sections, we identified four extrusive igneous rock groups: 1) Foliated Basaltic Trachyandesite, 2) Trachyandesite, 3) Olivine Basalt, and 4) Lamprophyres. Diagrams by Lobas et al. (1986) and Middlemost (1994) show that volcanic rock samples from Polur and the Haraz road fit within Trachybasalt, Basalt, and Trachyandesite categories. Based on the classification by Irvine & Baragar (1971), these rocks fall within the alkaline field and near the subalkaline boundary (Tchameni et al., 2006). In the Verma et al. (2006) diagram, the alkali basaltic samples are in the continental rift basalts and OIB (Ocean Island Basalt) fields. The Xu et al. (2015) diagram places these samples in the crustal contamination field, showing magma mixing with crustal components during ascent.
Some sources note that a high Ce/Pb ratio is a feature of mantle-derived ocean island basalts (OIB) (Lustrino, 2005). In the Ce/Pb diagram against Ce for the region's alkaline basalts and primary magma, samples fall within the mantle MORB/OIB range. However, some samples show continental crust characteristics due to crustal contamination and increased lead levels. In the Th/Yb diagram against Ta/Yb, the basaltic samples fit within the OIB range, indicating an asthenospheric origin with some enrichment.
Eskandari's (2016) geodynamic model for Damavand magmatism suggests that the lower crust, lithospheric mantle, and asthenospheric mantle all contribute in different amounts to forming primary magma. To determine the tectonic setting of the studied rocks, we used several diagrams. The samples indicate that these rocks have alkaline traits and formed in an intra-continental rift environment. Unlike the simple fractionation process, LREEs and some LILEs come from alkaline basalts to trachyandesites. Multi-element diagrams show that these elements and P are less in trachyandesites than in basalts. Rare element patterns in these diagrams don’t clearly show a tectonic environment. They show traits of both subduction and OIB environments. A look at some crustal contamination indicators, like elemental ratios, reveals that trachyandesites have more contamination than alkaline olivine basalts. High ratios of Ce/Pb, Nb/U, Ba/Nb, and Th/La, along with low ratios of Sm/La in alkaline olivine basalts, indicate these lavas are influenced more by crustal materials.
Conclusion
Along the Haraz road and near Polur, we find volcanic rocks ranging from alkali olivine basalt to trachyandesite. Instead of a simple differentiation trend, we observe a depletion of LREE (Light Rare Earth Elements) and some LIL (Large Ion Lithophile) elements from alkali basalts to trachyandesites. Multi-element diagrams also show a decrease in these elements and Phosphorus (P) in trachyandesites compared to basalts. The trace element patterns in these diagrams reflect characteristics typical of an OIB environment. Comparisons of crustal contamination indices suggest that trachyandesites have undergone more crustal contamination than alkali olivine basalts. Overall, these rocks show alkaline features and were formed in an intra-continental rift setting.

Keywords

Volcano

Damavand

Rift

Iran

اسکندری، الف.، 1395. بررسی تحولات ماگمایی گدازه های آتشفشان دماوند با تکیه بر ویژگیهای کانی شناسی و ژئوشیمیایی، پایان نامۀ دکتری، دانشگاه خوارزمی

اسکوئی، ب.، روحانی ، م. ج.، امیدیان، ص.، عابدی، م. 1397. تحلیل داده های مغناطیسی روی بازالتهای منطقه پلور. نشریه پژوهشهای ژئوفیزیک کاربردی. دوره 4. شماره 2. 323-337ص.

امامی ، م، ه.، ایران نژادی، م، ر.، 1372. مطالعۀ پترولوژی و ولکانولوژی آتشفشان دماوند، مجلۀ علوم زمین، شمارۀ 2.

امیدیان، ص.، 1386. تعیین جایگاه زمین ساختی آتش فشان دماوند بر اساس شواهد ساختاری و ژئوشیمیایی، پایان نامه کارشناسی ارشد پترولوژی، گروه زمین شناسی، دانشکده علوم دانشگاه تهران.

امیدی، صفیه.، 1386. تعیین جایگاه زمینساختی آتشفشان دماوند بر اساس شواهد ساختاری و ژئئوشیمیایی . پایان نامه کارشناسی ارشد، دانشگاه تهران.

پند آموز، ع.، 1377. تعیین جایگاه روانه های بازالتی در توالی آتشفشان دماوند، پایان نامه کارشناسی ارشد، دانشگاه تهران.

درویش زاده، ع.، 1383. زمین شناسی ایران نشر امیرکبیر، 343 ص.

حسن زاده، ج.، پندآموز، ع.، دیویدسون، ج.، استوکلی، د.، باشکوه، ب.، 1380. نگاهی بر تاریخ تکوبن آتشفشان دماوند بر پایه ی دادههای ژئوشیمی و سن سنجی جدید، پنجمین همایش انجمن زمین شناسی ایران .

غلامی، نسترن.، 1380. مطالعة آذرآواری جنوب شرق دماوند. پایان نامه کارشناسی ارشد، دانشگاه تهران.

معین وزیری، ح. 1377. دیباچهای بر ماگماتیسم در ایران، انتشارات دانشگاه تربیت معلم، 445 ص.

Abbassi A., Nasrabadi A., Tatar M., Yaminifard F., Abbassi M., Hatzfeld D., Priestley K., (2010). Crustal velocity structure in the southern edge of the Central Alborz (Iran), Journal of Geodynamics 49(2), pp. 68-78.

Aftabi A., Atapour H., (2002). Regional aspects of shoshonitic volcanism in Iran, Episodes 23, pp. 119-125.

Aldanmaz, E., Köprübaşı, N., Gürer, Ö.F., Kaymakçı, N. and Gourgaud, A., (2006). Geochemical constraints on the Cenozoic, OIB-type alkaline volcanic rocks of NW Turkey: implications for mantle sources and melting processes. Lithos, 86(1), pp.5076.

Allen M B., Ghassemi MR., Shahrabi M., Qorashi M., (2003). Accomodation of the late Cenozoic oblique shortening in the Alborz range, northern Iran. Journal of Struct Geolgy 25, pp. 659–672.

Allenbach P., (1966). Geologie und Petrographie des Damavand und seiner Umgebung (Zentral-Elbruz, Iran). Mitt Geol Inst ETH, Univ. Zu¨ rich 63, pp. 114.

Assereto R., (1966). The Jurassic shemshak formation in central Elburz (Iran).

Asudeh I., (1982). Seismic structure of Iran from surface and body wave data. Geophysical Journal International. 71(3) , pp. 715-730.

Berberian M., (1976). An explanatory note on the first seismotectonic map of Iran, a seismotectonic review of the country. Contribution to the seismotectonic of Iran (Part III).

Brousse R., Moine Vaziri H., (1982). La association shoshonitique du Damovand (Iran) Sonferdruck aus der Geologischen Rundschau, Band 71, pp. 687-699 .

Coban H., (2007). Basalt magma genesis and fractionation in collision- andextension-related provinces, A comparison between eastern, central and western Anatolia. Earth Science Reviews 80:219-238.

Davidson, J.P., Hassanzadeh, J., Berzins, R., Pandamouz, A., Turrin, B., and Young, A., 2000, Magmagenesis and evolution at Damavand volcano, Iran: Journal of Conference Abstracts, v. 5, p. 334.

Dehghani G., Makris J., (1984). The gravity field and crustal structure of Iran. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen. pp, 215-229.

Eskandari A., Deevsalar, R., De Rosa, R., Shinjo, R., Donato, P., Neill, I. (2019). "Geochemical and isotopic constraints on the evolution of magma plumbing system at Damavand Volcano, N Iran", LITHOS, https://doi.org/10.1016/j.lithos.2019.105274.

Fitton, J. G. ,2007- The OIB Paradox. Geological Society of America, Special Paper 430: 387-412.

Gao S., Rudnick RL., Yuan HL., Liu XM., Liu YS., Xu WL., Ling WL., Ayers J., Wang XC., Wang QH., (2004). Recycling lower continental crust in the North China craton. Nature, 43, pp. 892-897.

Hastie AR., Kerr AC., Pearce JA., Mitchell SF., (2007). Classification of altered volcanic islandarc rocks using immobile trace elements: development of the Th-Co discrimination diagram. Journal of Petrology, 48, pp. 2341-2357.

Hawkesworth C J., Gallager K., Hergt JM., McDoermott F., (1994). Destructive plate margin magmatism: Geochemistry and generation Lithos 33, pp. 169 – 188.

Hoang N., Flower M., (1998). Petrogenesis of Cenozoic basalts from Vietnam: implication for origins of a ‘diffuse igneous province, Journal of Petrology 39(3) , pp. 369-395.

Irvin T., Baragar WRA., (1971). A guide to the Chemical classification of the common volcanic rocks. Canadian Journal of earth Science Letters 8, pp. 523-548.

Jung D., Kuersten M O C., Tarkian M., (1976). Post-Mesozoic volcanism in Iran and its relation to the subduction of the Afro-Arabian under the Eurasian Plate, In: Pilger, A., Roesler, A. (Eds.), Afar between Continental and Oceanic Rifting, 2, pp. 175-181.

Le Bas MJ., Le Maitre RW., Streckeisen A., Zanettin B., (1986). A chemical classification of volcanic rocks based on the total alkali–silica diagram. Journal of Petrology, 27, pp. 745-750.

Liotard jM., Dautria j M., Bisch D., Condmines j., Mehdizade H., Ritz F., (2008). Origin of the absarokite–banakite association of the Damavand volcano (Iran): trace elements and Sr, Nd, Pb isotope constraints, International Journal of Earth Sciences, 97, pp. 89-102.

Lustrino M., (2005). How the delamination and detachment of lower crust can influence basaltic magmatism. Earth-Science Reviews, 72(1) , pp. 21-38.

Mckenzie DP., Onions RK., (1991). Partial melt distvibutions from inversion of rare earth element concentrations. Journal of Petrology, 1, pp. 1021-1091.

Mehdizadeh H., Liotard JM., Dautria JM., (2002). Geochemical characteristics of an intracontinetnal shoshonitic association: the example of the Damavand volcano, Iran, Comptes Rendus Geoscience, 334, pp. 111-117.

Middlemost, E. A. K., 1985. Magma and magmatic rocks, An Introduction to igneous petrology. Longman Group U.K., PP 73 – 86.

Mirnejad H., Hassanzadeh J., Cousens BL., Taylor BE., (2010). Geochemical evidence for deep mantle melting and lithospheric delamination as the origion of the inland Damavand volcanic rocks of northern Iran, Journal of Volcanology and Geothermal Research, 198, pp. 288-296.

Pearce JA., (1982). Trace element characteristics of lavas from destructive plate boundaries, John Wiley and Sons, U.K., pp. 525–548.

Priestley K., Baker C., Jackson J., (1994). Implications of earthquake focal mechanism data for the active tectonics of the South Caspian Basin and surrounding regions, Geophys,118, pp. 111–141.

Richards J., Wilkinson D., Ullrich T., (2006). Geology of the Sari Gunay epithermal gold. Economic Geology, 101(8), pp. 1455-1496.

Ritz JF., Nazari H., Ghassemi A., Salamati R., Shafei A., Solaymani S., Vernant P., (2006) Active transtension inside Central Alborz: a new insight into northern Iran–southern Caspian geodynamics. Geology, 34, pp. 477–480.

Shafaii Moghadam H., Stern RJ., Griffin WL., Khedr MZ., Kirchenbaur M., Ottley CJ., Whattam S., Kimura JI., Ghorbani G., Gain GS., Reilly SYO., Tamura A., (2019). Subduction initiation and back-arc opening north of Neo-Tethys: Evidence from the Late Cretaceous Torbat-e-Heydarieh ophiolite of NE Iran. Research Geological Society of America.

Sharma, j., Alimohammadian H., Bhattacharyya A., Singh Ranhotra1 P., Djamali M., Scharrer S., Angela A., Bruch, A., (2014). Exploratory palynological analysis of Quaternary lacustrine deposits around Damavand volcano, Northern Iran. JGeope, 4 (1), pp. 1-10.

Schandl ES., Gorton MP., (2002). Application of high field strength elements to discriminate tectonic settings in VMS environments. Economic Geolgy, 97, pp. 629-642.

Shervais, J.W., 1982. Ti-V plots and the petrogenesis of modern and ophiolitic lavas. Earth and planetary science letters, 59(1), pp.101-118.

Sodoudi F., Yuan X., Kind R., Heit B., Sadidkhouy A., (2009). Evidence for a missing crustal root and a thin lithosphere beneath the Central Alborz by receiver function studies. Geophys J Int, 177 (2), pp. 733–742.

Stöcklin J., (1974). Northern iran: Alborz mountains. Geological Society, London, Special Publications, 4(1) , pp. 213-234.

Tchameni R., Pouclet A., Penay J., Ganwa AA., Toteu SF., (2006). Petrography and geochemistry of the Ngaondere Pan – African granitoids in Central North Cameroon: Implication for their sources and geological setting. Journal of African Earth Sciences, 44, pp. 511 –529.

Taylor SR., McLennan SM., (1985). The continental crust: its composition and evolution.

Turner S., Arnaud N., Liu J., Rogers N., Hawkesworth C., Harris N., Vanclasteren P., Deng W., (1996). Post-collision, Shoshonitic Volcanism on the Tibetan Plateau: Implications for convective thinning of lithosphere and the Source of ocean island basalt. Journal of Petrology, 37(1):45-71.

Verma SP., Guevara M., Agrawal S., (2006). Discriminating four tectonic settings: Five new geochemical diagrams for basic and ultrabasic volcanic rocks based on log—ratio transformation of major-element data. Journal of Earth System Science, 115(5) , pp. 485-528.

Vernant P., Nilforoushan F., Chery J., Bayer R., Djamour Y., Masson F.,Tavakoli F., (2004). Deciphering oblique shortening of central Alborz in Iran using geodetic data. Earth and planetary science letters, 223(1-2) , pp. 177-185.

Wang, YN., Zhang, C. J., Xiu. SZ., 2001- Th/Hf-Ta/Hf identification of tectonic setting of basalts. Acta Petrol Sin(in Chinese)., Vol. 17(3), PP. 413-421.

Wilson M., (1989). Igneous petrogenesis A global tectonic approach. Unwin Hyman, London, 466 pp.

Xu, c., Ague, JJ., (2015). Analysis of experimental data on divalent cation diffusion kinetics in aluminosilicate garnets with application to timescales of peak Barrovian metamorphism, Scotland. Contributions to Mineralogy and Petrology 170 (2), 1-27.