Basement differences control granitoid compositions: insights from zircon Hf isotopic mapping of Paleozoic granitoids in the northern Beishan orogenic collage, NW China

ABSTRACT

The source of granitoids in Phanerozoic accretionary orogens is debatable. Paleozoic granitoids are widespread in the southern Central Asian Orogenic Belt (CAOB) and are considered the most eloquent witness to continental crustal growth during the Phanerozoic. This study presents a comprehensive analysis of zircon U-Pb and Lu-Hf isotopic and geochemical data from six Paleozoic granitic plutons in the northern Beishan Orogenic Collage (NBOC). Zircon U-Pb data reveal that these plutons recorded a long-lasting magmatism from the Late Silurian to the Late Carboniferous. The elemental and isotopic data show a major contribution from the Precambrian crustal basement as the source of the Late Silurian to Carboniferous granitoids in the Mingshui – Hanshan massif (MHM). In contrast, the source compositions of the Carboniferous granitoids in the Heiyingshan arc (HYA) indicate a dominant role of juvenile materials. Combined with published data, three magmatic pulses from the Ordovician to Carboniferous were identified in the NBOC: Stage I magmatism (Early Ordovician to Late Silurian) formed in a subduction-related compressional setting, Stage II magmatism (Late Silurian to Early Devonian) occurred in an extensional setting, and Stage III (Carboniferous) formed in a compressional setting. For the MHM, the zircon Hf isotopic mapping results show that the eastern segment was predominantly composed of a Paleoproterozoic basement, whereas the western segment mainly consisted of a young Mesoproterozoic – Neoproterozoic basement. The Heiyingshan magmatic rocks were probably formed as a continental arc during the Mesoproterozoic – Neoproterozoic and accreted to the MHM during the closure of the Paleo-Asian Ocean. Overall, these data indicate that the NBOC had remnants of the ancient Precambrian basement during the Paleozoic. Accordingly, numerous Phanerozoic granitic rocks in the NBOC have mostly resulted from the recycling of ancient crustal materials along with the addition of minor new juvenile materials. Our study has highlighted that systematic basement differences can exert a major influence on the nature of granitoids.

Graphical abstract

KEYWORDS:

• Ordovician to Carboniferous
• granitoids
• zircon hf isotopic mapping
• crustal growth
• northern Beishan orogenic collage

Acknowledgments

We thank Lei Xu, Bin Liu and Yufan Yang of Geological Survey of Gansu Province for their help in the fieldwork. We thank Dr. Guokun Zhang for the constructive suggestions and corrections to our manuscript. Constructive comments and language polishing by the Editor-in-Chief Prof. Robert J. Stern and two anonymous reviewers significantly improve the quality of our manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00206814.2023.2246063

Additional information

Funding

This study was supported by the National Key Research and Development Project of China (2022YFC2903302; 2019YFA0708503), and Research Fund of Hebei Provincial Bureau of Geology and Mineral Resources (454-0601-YBN-DXXP).