Archean Crustal Evolution of the Alxa Block, Western North China Craton: Constraints from Zircon U-Pb Ages and the Hf Isotopic Composition

The Alxa Block is an important component of the North China Craton, but its metamorphic basement has been poorly studied, which hampers understanding and Craton. In this study, we conducted geochronological geochemical studies on three TTG (tonalite–trondhjemite–granodiorite) gneisses one granitic gneiss exposed in Langshan area eastern to investigate their crustal evolution. zircon U-Pb dating results revealed that protoliths were formed at 2836 ± 20 Ma, 2491 18 2540 38 2763 42 respectively, overprinted by middle–late Paleoproterozoic metamorphism (1962–1721 Ma). All samples had high Sr/Y ratios (41–274) intermediate Mg# values (44.97–55.78), with negative Nb, Ta, Ti anomalies moderately strongly fractionated REE patterns ((La/Yb)N = 10.6–107.1), slight Sr enrichment, positive Eu anomalies, displaying features typical high-SiO2 adakites Archean TTGs. magmatic zircons from 2.84 Ga 2.49 rocks low εHf(t) −1.9–1.7, −3.83–2.12 two-stage model ages (TDMC) 3.24–3.11 3.10–3.01 Ga, whereas those 2.54 rock exhibited ranging −1.1 3.46 TDMC 3.0 2.83 suggesting materials initially extracted depleted mantle during late Paleoarchean Mesoarchean era reworked Neoarchean era. By contrast, probably a relative younger evolutionary history (<3.24 Ga) than main (<3.88 Ga), Tarim (<3.9 Yangtze (<3.8 Cratons likely unique before early