Cambrian intermediate-felsic rocks in Central Pamir: Insights into source heterogeneity and subduction initiation in the Proto-Tethys Ocean
Odinaev S. Aminov J. Kallistov G. Ma X. Tang G.-R. Azamdzhon M. Stepanov A.S. Oimuhammadzoda I. Gadoev M. Ashuraliev S. Dan W. Tang G.-J.
1 December 2025Elsevier B.V.
Lithos
2025#516-517
The Early Paleozoic magmatic rocks in the Central Pamir provide insights into the tectonic evolution of the Proto-Tethys Ocean. This study integrates zircon U[sbnd]Pb ages, in situ Hf[sbnd]O isotopes, whole-rock elemental and Sr[sbnd]Nd isotopic data of the intermediate and felsic rocks from the Zorburulyuk, Panghazjilga, and Taxkorgan complexes in the eastern segment of the Central Pamir to constrain their magma sources and tectonic implications. Zircon U[sbnd]Pb ages reveal these magmatic rocks formed at Early Cambrian (pegmatite: 527.0 ± 5.4 Ma; gneiss-granite: 524.3 ± 3.6 Ma; monzodiorite mafic microgranular enclaves (MMEs): 524.1 ± 1.6 Ma; quartz diorite: 517.3 ± 1.1 and 520.3 ± 2.2 Ma and biotite granite: 512.1 ± 3.5 Ma). The intermediate rocks exhibit enriched isotopic compositions (εHf(t) = −5.78 to +6.93; εNd(t) = −5.56 to −4.02; 87Sr/86Sr = 0.70212–0.70844), indicating mainly derivation from a metasomatized subcontinental lithospheric mantle source that was enriched by subduction-derived sediments, and involved magma fractionation of mantle-derived mafic melts to produce intermediate rocks. The felsic rocks exhibit variable isotopic compositions: pegmatites (εHf(t) = −2.41 to +0.95; εNd(t) = −4.02 to −5.15), biotite granites (εNd(t) = −1.54 to −0.94; δ18O = 7.87–9.17 ‰), which are similar to coeval mafic-intermediate rocks, indicating that they were derived from melting of hybrid lower crustal sources represented by the latter. Our results propose that the Cambrian intermediate-felsic rocks record the early stages of southward subduction of the Proto-Tethys Ocean with arc magmatism peaking in the Early Cambrian (ca. 524–527 Ma). In this process, slab rollback facilitated magma underplating and crustal hybridization, leading to the formation of intermediate-felsic rocks through melting of metasomatized subcontinental lithospheric mantle and lower crustal sources.
Cambrian intermediate/felsic melts , Eastern Central Pamir , Fractional crystallization/crustal contamination , Proto-Tethys Ocean subduction , Subducted sediments
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State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
Institute of Geology, Earthquake Engineering and Seismology of National Academy of Sciences of Tajikistan, Dushanbe, 734063, Tajikistan
School of Mining and Geosciences, Nazarbayev University, Astana, 010000, Kazakhstan
Zavaritsky Institute of Geology and Geochemistry, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, 620002, Russian Federation
School of Geography and Tourism, Qilu Normal University, Jinan, 250200, China
State Key Laboratory of Geological Processes and Mineral Resources, Collaborative Innovation Center for Exploration of Strategic Mineral Resources, School of Earth Resources, China University of Geosciences, Wuhan, 430074, China
Main Department of Geology under the Government of the Republic of Tajikistan, Dushanbe, 734025, Tajikistan
State Key Laboratory of Deep Earth Processes and Resources
College of Earth and Planetary Sciences
Institute of Geology
School of Mining and Geosciences
Zavaritsky Institute of Geology and Geochemistry
School of Geography and Tourism
State Key Laboratory of Geological Processes and Mineral Resources
Main Department of Geology under the Government of the Republic of Tajikistan
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