COMPOSITIONAL FEATURES OF THE EARLY PALEOZOIC GRANITOIDS OF THE PANGHAZJILGA COMPLEX, EASTERN PART OF THE CENTRAL PAMIR, TAJIKISTAN

The Panghazjilga igneous complex in the eastern part of the Central Pamirs is one of the few Cambrian intrusive formations in the region. In our study, we address a number of questions that contribute to understanding the nature of the rocks in the complex. The quartz diorites and granodiorites of the Panghazjilga complex, which constitute the eponymous massif, are products of crystallization from a single parent andesitic magma. The fact that mafic microgranular enclaves (MME), isotopically similar to the rocks of the complex and represented by monzodiorites, are present in quartz diorites and granodiorites, as well as the rock association itself, indicates the involvement of mafic and acid magmas in the process of magma generation. The predominance of amphibole crystals and the absence of pyroxene in the quartz diorites, granodiorites and monzodiorites from the enclaves suggest that amphibole was the principal early-crystallizing mineral, and the dominant role of amphibole and biotite in the rocks indicates a significant influence of H₂O on crystallization. The composition of the rocks from this igneous complex, as well as that of the monzodiorites from the enclaves, demonstrates their close connection with melting of a mantle source that interacted with crustal rocks (or their melts). In particular, this hybrid nature of the source explains the variable and enriched isotopic composition of Hf–Nd–Sr in the rocks that were considered earlier. We believe that the generation of magmas, which serve as a parent material for quartz diorites and granodiorites, involved heterogeneous sources: heterogeneous crustal source (predominantly subducted sedimentary material) and magmas that formed through partial melting of enriched mantle material altered during subduction. The formation of magmas, which are the source of granitoids of the Panghazjilga complex, was associated with the subduction of the oceanic crust of the Proto-Tethys beneath the northern margin of Gondwana.

1. Aminov J., Ding L., Mamadjonov Y., Dupont-Nivet G., Aminov J., Zhang L.Y., Yoqubov S., Aminov J., Abdulov S., 2017. Pamir Plateau Formation and Crustal Thickening Before the India-Asia Collision Inferred from Dating and Petrology of the 110–92 Ma Southern Pamir Volcanic Sequence. Gondwana Research 51, 310–326. https://doi.org/10.1016/j.gr.2017.08.003.

2. Aminov J., Koulakov I., Jakovlev A., Zhao J., El-Khrepy S., Aminov J., Al Arifi N., Aminov J., Mamadjanov Y., 2020. Directions of Lithosphere Interactions in the Pamir – Hindu Kush Junction Inferred from Anisotropic Tomography. Canadian Journal of Earth Sciences 57 (5), 601–616. https://doi.org/10.1139/cjes-2019-0081.

3. Aminov J., Roperch P., Dupont-Nivet G., Cordier C., Guillot S., Glodny J., Timmerman M.J., Sudo M. et al., 2023. Contractional Deformation Between Extensional Dome Exhumation in Central Pamir at 17–15 Ma Constrained by Metamorphic and Paleomagnetic Data from the Bartang Volcanic Rocks, Tajikistan. Tectonophysics 868, 230080. https://doi.org/10.1016/j.tecto.2023.230080.

4. Angiolini L., Zanchi A., Zanchetta S., Nicora A., Vezzoli G., 2013. The Cimmerian Geopuzzle: New Data from South Pamir. Terra Nova 25 (5), 352–360. https://doi.org/10.1111/ter.12042.

5. Angiolini L., Zanchi A., Zanchetta S., Nicora A., Vuolo I., Berra F., Henderson C., Malaspina N., Rettori R., Vachard D., Vezzoli G., 2015. From Rift to Drift in South Pamir (Tajikistan): Permian Evolution of a Cimmerian Terrane. Journal of Asian Earth Sciences 102, 146–169. https://doi.org/10.1016/j.jseaes.2014.08.001.

6. Ashuraliev S., Xiao W., Mao Q., Yang H., Miao S., Yogibekov D., Aminov J., Moghadam H.S., Mamadjanov Y., Odinaev Sh., 2024. Tectonic Evolution of the South Pamir Orogen: Insights from the Permian to Cretaceous Magmatism. Lithos 480–481, 107648. https://doi.org/10.1016/j.lithos.2024.107648.

7. Baratov R.B. (Ed.), 1976. Subdivision of Stratified and Intrusive Rocks of Tajikistan. Donish, Dushanbe, 207 p. (in Russian)

8. Baratov R.B., Mogarovsky V.V., Lutkov V.S. (Eds)., 1978. Petrology and Geochemistry of the Magmatic Formations in the Pamir and Gissar-Alai. Donish, Dushanbe, 343 p. (in Russian)

9. Barkhatov B.P., 1962. The Route Khorog – Viskharvi River Mouth. In: Field Excursion Guide for the II All-Union Tectonic Meeting. Publishing House of the Academy of Sciences Tajik SSR, Dushanbe, p. 23–46 (in Russian)

10. Barkhatov B.P., 1963. Tectonics of the Pamir. Leningrad State University, Leningrad, 244 p. (in Russian)

11. Burmakina G.N., Tsygankov A.A., 2013. Mafic Microgranular Enclaves in Late Paleozoic Granitoids in the Burgasy Quartz Syenite Massif, Western Transbaikalia: Composition and Petrogenesis. Petrology 21 (3), 280–303. https://doi.org/10.1134/S086959111303003X.

12. Chapman J.B., Scoggin S.H., Kapp P., Carrapa B., Ducea M.N., Worthington J., Oimahmadov I., Gadoev M., 2018. Mesozoic to Cenozoic Magmatic History of the Pamir. Earth and Planetary Science Letters 482, 181–192. https://doi.org/10.1016/j.epsl.2017.10.041.

13. Collins W.J., Richards S.R., Healy B.E., Ellison P.I., 2000. Origin of Heterogeneous Mafic Enclaves by Two-Stage Hybridization in Magma Conduits (Dykes) Below and in Granitic Magma Chambers. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 91 (1–2), 27–45. https://doi.org/10.1017/S0263593300007276.

14. Didier J., Barbarin B. (Eds), 1991. Enclaves and Granite Petrology. Developments in Petrology. Vol. 13. Elsevier, Amsterdam, 625 p.

15. Dmitriev E.A., Minaev V.E., 1972. A Scheme of Magmatism in the Eastern Part of the Central Pamir Zone. Doklady of the Academy of Sciences of the Tajik SSR XV (2), 47–50 (in Russian)

16. Dmitriev E.A., Volodin P.K., Minaev V.E., 1972. Intrusive Magmatism in the Eastern Part of the Central Pamir. Report. Dushanbe, 241 p. (in Russian)

17. Dronov V.I., 1964. Structural-Facial Subzones of the Central and Southeastern Pamir. In: Tectonics of the Pamir and Tien Shan. Proceedings of the II All-Union Tectonic Meeting in Dushanbe. Nauka, Moscow, p. 14–23 (in Russian)

18. Frost B.R., Barnes C.G., Collins W.J., Arculus R.G., Ellis D.J., Frost C.D., 2001. A Geochemical Classification for Granitic Rocks. Journal of Petrology 42 (11), 2033–2048. https://doi.org/10.1093/petrology/42.11.2033.

19. Gorokhov I.M., Dyufur M.S., Neymark L.A., Amelin Yu.V., Ovchinnikova G.V., Gorokhovsky B.M., 1993a. Early Paleozoic Fragments of Gondwana in the Covers of the Central Pamir and the Lower Himalayan Range: Geochemical and Isotopic Characteristics. Stratigraphy and Geological Correlation 1 (3), 20–34 (in Russian)

20. Gorokhov I.M., Melnikov N.N., Dyufur M.S., Kutyavin E.P., Baskakov A.V., Krylov I.N., 1993b. Rb-Sr Systems in the Rocks of the Central Pamir: The Effect of Alpine Metamorphism. Geochemistry International 10, 1457–1469 (in Russian)

21. Gubin I.E., 1943. The Pamir and Adjacent Countries (A Scheme of Tectonic Zoning). Bulletin of the Tajik Branch of the AS USSR 2, 101–117 (in Russian)

22. Gubin I.E., 1960. Regularities of Manifestation of Seismicity in Tajikistan (Geology and Seismicity). Publishing House of the USSR Academy of Sciences, Moscow, 465 p. (in Russian)

23. Harker A., 1909. The Natural History of Igneous Rocks. Methuen & Co., London, 385 p. https://doi.org/10.1017/CBO9780511920424.

24. He J., Kapp P., Chapman J.B., DeCelles P.G., Carrapa B., 2019. Structural Setting and Detrital Zircon U-Pb Geochronology of Triassic – Cenozoic Strata in the Eastern Central Pamir, Tajikistan. Geological Society of London Special Publications 483, 605–630. https://doi.org/10.1144/SP483.11.

25. Hu Y.-M., Li X.-W., Mo X.-X., Li L., Wang K., Wang B.-Zh., Gong X.-P., Dong G.-Ch., Liu Y.B., 2023. Early Paleozoic Subduction Imprints of the Proto-Tethys Ocean: Evidence from the Appinite-Diorite-Granodiorite Complex in East Kunlun, Northern Tibet. Lithos 452, 107215. https://doi.org/10.1016/j.lithos.2023.107215.

26. Kufner S.-K., Schurr B., Sippl Ch., Yuan X., Ratschbacher L., Ischuk A., Murodkulov Sh., Schneider F., Mechie J., Tilmann F., 2016. Deep India Meets Deep Asia: Lithospheric Indentation, Delamination and Break-off Under Pamir and Hindu Kush (Central Asia). Earth and Planetary Science Letters 435, 171–184. https://doi.org/10.1016/j.epsl.2015.11.046.

27. Li S., Zhao Sh., Liu X., Cao H., Yu Sh., Li X., Somerville I., Yu Sh., Suo Y., 2018. Closure of the Proto-Tethys Ocean and Early Paleozoic Amalgamation of Microcontinental Blocks in East Asia. Earth-Science Reviews 186, 37–75. https://doi.org/10.1016/j.earscirev.2017.01.011.

28. Li S.Z., Zhao Sh.-J., Yu Sh., Cao H.-H., Li X.-Y., Liu X., Guo X.-Y., Xiao W.-J. et al., 2016. Proto‐Tethys Ocean in East Asia (II): Affinity and Assembly of Early Paleozoic Micro-Continental Blocks. Acta Petrologica Sinica 32 (9), 2628–2644.

29. Li X.-H., Li Zh.-X., Wingate M.T.D., Chung S.-L., Liu Y., Lin G.-Ch., Li W.-X., 2006. Geochemistry of the 755 Ma Mundine Well Dyke Swarm, Northwestern Australia: Part of a Neoproterozoic Mantle Superplume Beneath Rodinia? Precambrian Research 146 (1–2), 1–15. https://doi.org/10.1016/j.precamres.2005.12.007.

30. Li X.-Y., Li S.-Zh., Yu Sh.-Y., Santosh M., Zhao Sh.-J., Guo X.-Y., Cao H.-H., Wang Y.-M., Huang Zh.-B., 2018. Early Paleozoic Arc–Back-Arc System in the Southeastern Margin of the North Qilian Orogen, China: Constraints from Geochronology, and Whole-Rock Elemental and Sr-Nd-Pb-Hf Isotopic Geochemistry of Volcanic Suites. Gondwana Research 59, 9–26. https://doi.org/10.1016/j.gr.2018.03.008.

31. Liu X.-Q., Zhang Ch.-L., Ye X.-T., Zou H., Hao X.-Sh., 2019. Cambrian Mafic and Granitic Intrusions in the Mazar-Tianshuihai Terrane, West Kunlun Orogenic Belt: Constraints on the Subduction Orientation of the Proto-Tethys Ocean. Lithos 350–351, 105226. https://doi.org/10.1016/J.LITHOS.2019.105226.

32. Liu X.-Q., Zhang Ch.-L., Zou H., Ye X.-T., 2023. Diverse Metavolcanic Sequences in the Cambrian Accretionary Complex at the Pamir Syntax: Implications for Tectonic Evolution from Proto-Tethys to Paleo-Tethys. Journal of Asian Earth Sciences 241, 105481. https://doi.org/10.1016/j.jseaes.2022.105481.

33. Markovsky A.P., 1936. On Interaction Between the Pamir and Tien Shan. In: Scientific Results of the Tajik-Pamir Expedition. Publishing House of the USSR Academy of Sciences, Moscow, 156–158 (in Russian)

34. Müller R.D., Flament N., Cannon J., Tetley M.G., Williams S.E., Cao X., Bodur Ӧ.F., Zahirovic S., Merdith A., 2022. A Tectonic-Rules-Based Mantle Reference Frame Since 1 Billion Years Ago – Implications for Supercontinent Cycles and Plate–Mantle System Evolution. Solid Earth 13 (7), 1127–1159. https://doi.org/10.5194/se-13-1127-2022.

35. Nalivkin D.V., 1936. Paleogeography of Middle Asia. In: Scientific Results of the Tajik-Pamir Expedition. Publishing House of the USSR Academy of Sciences, Moscow, p. 35–86 (in Russian)

36. Nikolaev V.A., 1936. Outline of Geology of Magmatic Systems in the Pamir and Darvaz. In: Scientific Results of the Tajik-Pamir Expedition. Publishing House of the USSR Academy of Sciences, Moscow, p. 329–387 (in Russian)

37. Odinaev Sh., Aminov J., Kallistov G., Ma X., Tang G.-R., Murodov A., Stepanov A.S., Oimuhammadzoda I. et al., 2025. Cambrian Intermediate-Felsic Rocks in Central Pamir: Insights Into Source Heterogeneity and Subduction Initiation in the Proto-Tethys Ocean. Lithos 516–517, 108251. https://doi.org/10.1016/j.lithos.2025.108251.

38. Pashkov B.R., Budanov V.I., 1990. Tectonics of the Junction Zone Between the Southeastern and Southwestern Pamir Mountains. Geotectonics 3, 70–79 (in Russian)

39. Pearce J.A., 2008. Geochemical Fingerprinting of Oceanic Basalts with Applications to Ophiolite Classification and the Search for Archean Oceanic Crust. Lithos 100 (1–4), 14–48. https://doi.org/10.1016/j.lithos.2007.06.016.

40. Pearce J.F., Ernst R.E., Peate D.W., Rogers C., 2021. LIP Printing: Use of Immobile Element Proxies to Characterize Large Igneous Provinces in the Geologic Record. Lithos 392–393, 106068. https://doi.org/10.1016/j.lithos.2021.106068.

41. Peccerillo A., Taylor S.R., 1976. Geochemistry of Eocene Calc-Alkaline Volcanic Rocks from the Kastamonu Area, Northern Turkey. Contributions to Mineralogy and Petrology 58 (1), 63–81. https://doi.org/10.1007/BF00384745.

42. Petrography of Tajikistan, 1988. Pamir. Vol. II. Donish, Dushanbe, 244 p. (in Russian)

43. Robinson A.C., 2015. Mesozoic Tectonics of the Gondwanan Terranes of the Pamir Plateau. Journal of Asian Earth Sciences 102, 170–179. http://dx.doi.org/10.1016/j.jseaes.2014.09.012.

44. Rutte D., Ratschbacher L., Schneider S., Stübner K., Stearns M.A., Gulzar M.A., Hacker B.R., 2017. Building the Pamir-Tibetan Plateau – Crustal Stacking, Extensional Collapse, and Lateral Extrusion in the Central Pamir: 1. Geometry and Kinematics. Tectonics 36 (3), 342–384. https://doi.org/10.1002/2016TC004293.

45. Schwab M., Ratschbacher L., Siebel W., McWilliams M., Minaev V., Lutkov V., Chen F., Stanek K., Nelson B., Frisch W., Wooden J.L., 2004. Assembly of the Pamirs: Age and Origin of Magmatic Belts from the Southern Tien Shan to the Southern Pamirs and Their Relation to Tibet. Tectonics 23 (4), TC4002. https://doi.org/10.1029/2003TC001583.

46. Slobodskoy R.M., 1969. The Origin of Gneissosity in the Pangaz-Dzhilga Quartz-Diorite Massif (Eastern Pamir) and Its Formation Mechanism. Doklady of the USSR Academy of Sciences 186 (3), 682–685 (in Russian)

47. Sun S.-S., McDonough W.F., 1989. Chemical and Isotopic Systematics of Oceanic Basalts: Implications for Mantle Composition and Processes. Geological Society of London Special Publications 42 (1), 313–345. https://doi.org/10.1144/GSL.SP.1989.042.01.19.

48. Tang G.-J., Wyman D.A., Dan W., Wang Q., Liu X.-J., Yang Y.-N., Gadoev M., Oimahmadov I., 2024. Protracted and Progressive Crustal Melting During Continental Collision in the Pamir and Plateau Growth. Journal of Petrology 65 (4), egae024. https://doi.org/10.1093/petrology/egae024.

49. Wang Sh., Tang W., Liu Yi., Liu X., Yao X., 2020. Rushan-Pshart Paleo-Tethyan Suture Deduced from Geochronological, Geochemical, and Sr-Nd-Hf Isotopic Characteristics of Granitoids in Pamir. Lithos 364–365, 105549. https://doi.org/10.1016/j.lithos.2020.105549.

50. Warr L.N., 2021. IMA–CNMNC Approved Mineral Symbols. Mineralogical Magazine 85 (3), 291–320. https://doi.org/10.1180/mgm.2021.43.

51. Weinberg R.F., Hasalová P., 2015. Water-Fluxed Melting of the Continental Crust: A Review. Lithos 212–215, 158–188. https://doi.org/10.1016/j.lithos.2014.08.021.

52. Xie Ch., Duan M., Zhan Y., Wang B., Song Y., Zhang J., Hao Y., 2024. Subduction of the Proto-Tethys Ocean Along the Northern Margin of Gondwana: Evidence from the Middle Cambrian High-Mg Dioritic Pluton in the Northern Lhasa Terrane, Tibet. Journal of Asian Earth Sciences 272, 106247. https://doi.org/10.1016/j.jseaes.2024.106247.

53. Yogibekov D., Sang M., Xiao W., Mamadjonov Y., Zhou C., Yang H., Mao Q., Aminov J., Khalimov G., Ashuraliev S., 2023. Post-Collisional Magmatism Associated with the Final Closure of the Rushan-Pshart Meso-Tethys Ocean in Pamir, Tajikistan: Inference from Cretaceous Igneous Rocks of the Pshart Accretionary Complex. Frontiers in Earth Science 10, 1090952. https://doi.org/10.3389/feart.2022.1090952.

54. Yogibekov D., Sang M., Xiao W., Windley B.F., Mamadjonov Y., Yang H., Huang P., Aminov J., Vatanbekov F., 2020. Late Palaeozoic to Late Triassic Northward Accretion and Incorporation of Seamounts Along the Northern South Pamir: Insights from the Anatomy of the Pshart Accretionary Complex. Geological Journal 55 (12), 7837–7857. https://doi.org/10.1002/gj.3906.

55. Zanchi A., Angiolini L., Zanchetta S., Nicora A., Vezzoli G., 2013. The Cimmerian Accretion of SE Pamir and Its Relationships with the Surrounding Cimmerian Blocks. In: Abstracts of the EGU General Assembly (April 7–12, 2013, Vienna, Austria). Vol. 15. EGU, EGU2013-12805.

56. Zhai Q., Li C., Wang J., Hu P., Tang Y., Wang H., 2019. The Open of the Paleo-Tethys Ocean: Inferred from the Early Paleozoic Ophiolite in the Qiangtang Area, Northern Tibetan Plateau. Acta Geologica Sinica 93 (S2), 43–43. https://doi.org/10.1111/1755-6724.14184.

57. Zhang Ch-.L., Zou H.-B., Ye X.-T., Chen X.-Y., 2019. Tectonic Evolution of the Western Kunlun Orogenic Belt Along the Northern Margin of the Tibetan Plateau: Implications for the Assembly of the Tarim Terrane to Gondwana. Geoscience Frontiers 10 (3), 973–988. https://doi.org/10.1016/j.gsf.2018.05.006.

58. Zhao Ch., Qin K.-Zh., Song G.-X., Li G.-M., Mao J.-W., 2021. The Triassic Duobaoshan Appinite-Granite Suite, NE China: Implications for a Water-Fluxed Lithospheric Mantle and an Extensional Setting Related to the Subduction of the Mongol-Okhotsk Ocean. Lithos 394–395, 106169. https://doi.org/10.1016/j.lithos.2021.106169.