Sm-Nd geochronology of the Hoxbulak Zn-Pb deposit in Xinjiang (NW China) and its link to Paleogene Mississippi Valley-type mineralization in the Tethyan domain

• 55 Ma Sm-Nd age confirms MVT origin, ruling out Permian magmatic link. • India-Asia collision triggered ore-forming fluids via extensional faults. • Crustal ε Nd (t) (−10.0) supports basinal brine source, not magmatic input. • The deposit represents the western extension of Tethyan MVT belt into Central Asia. Sediment-hosted Zn-Pb deposits are the most important global source of Pb and Zn, yet their genesis and timing remain central questions in economic geology. Direct geochronological constraints are often difficult to obtain due to the general absence of suitable datable minerals, hindering the understanding of ore-forming processes and regional metallogenic models. The Hoxbulak Zn-Pb deposit in Xinjiang, a typical sediment-hosted Zn-Pb deposit in the southwestern Tianshan Mountains of the Central Asian metallogenic domain, has long been controversial with respect to its genetic type and mineralization age, primarily focusing on whether it is related to adjacent Permian magmatism and whether it formed syngenetically or epigenetically. In this study, we conducted precise Sm-Nd isochron dating of sphalerite, galena, and associated calcite/dolomite from the main mineralization stage, yielding a mineralization age of 55 ± 2 Ma. This result indicates that the deposit formed during the Paleogene and shows no genetic relationship with the neighboring Permian Hoxbulak pluton (261.5 ± 2.7 Ma; 273.6 ± 2.0 Ma and 274.8 ± 1.5 Ma), supporting its classification as an epigenetic Mississippi Valley-type (MVT) deposit. Integrated regional structural analysis suggests that this mineralization event was likely controlled by transpression tectonics triggered during the initial India-Eurasia collision (∼60–50 Ma). Our findings demonstrate that the Hoxbulak deposit represents a critical northwestern extension of the Tethyan MVT metallogenic belt (spanning Yunnan-Tibet-Xinjiang) and serves as its easternmost component within the Central Asian metallogenic domain—linking the classic Tethyan MVT system with the interior of the Central Asian Orogenic Belt. This study provides important constraints for exploring Paleogene MVT-type Zn-Pb deposits in Late Paleozoic carbonate formations of the South Tianshan, offering significant insights into the metallogenic patterns of Zn-Pb deposits in the junction zone between the Tethyan and Central Asian orogenic belts.