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The volcano‐sedimentary sequences from the Weixi belt provide significance for the Sanjiang Paleo‐Tethys evolution. This manuscript constrains the ages of volcano‐sedimentary sequences by LA‐ICPMS U–Pb, including bimodal volcanics (245.0–244.0 Ma) from Pantiange Formation, trachyandesite–basaltic andesite (234 ± 2.0 Ma) from Cuiyibi Formation, high silica subalkaline rhyolite (221 ± 1.4 Ma) from Waigucun Formation and Early Jurassic high silica subalkaline rhyolite (184 ± 2.2 Ma). The volcanics show various Hf isotopic composition, which includes Middle Triassic dacite (εHf[t] = −15.7 to −8.5, TDM2 = 2,006–1,613 Ma), Late Triassic rhyolite (εHf(t) = −9.8 to +1.9, TDM2 = 1,667–1,021 Ma), Late Triassic trachyandesite (εHf(t) = +2.6 to +5.7, TDM2 = 990–816 Ma) and Early Jurassic rhyolite (εHf(t) = −2.7 to +1.1, TDM2 = 1,250–1,145 Ma). The Middle–Late Triassic volcanics exhibit similar characteristics, the content of SiO2 exerts positive correlation with K2O and negative correlation with oxide of Ti, Fe, Al, Mg, Ca, Mn and P. The Hf isotopic and geochemical features indicate that the Middle Triassic basalt and rhyolite derived from mantle and crust by crystal fractionation, respectively. The absence of Lower Jurassic strata and existence of Triassic bimodal volcanic sequences suggest that the middle Sanjiang Tethys Orogen experienced collision during the Middle Triassic with local extension resulting from oblique convergence. Late Triassic–Early Jurassic rhyolite exhibit high SiO2 (77.12–77.81 wt%), K2O (4.35–6.10 wt%), Na2O (1.91–3.15 wt%) content, and a negative Eu anomaly. Together with the sedimentary sequence, the middle Sanjiang Tethys Orogen evolved into post‐collision phase during Late Triassic – Early Jurassic. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Biluoxueshan Pluton included three phases of 231 Ma, 227 Ma, and 227–217 Ma. • The Late Triassic Biluoxueshan Pluton was emplaced in a post-collisional setting. • The closure of the Paleo-Tethys Ocean occurred in a northward-propagating manner. The Sanjiang Orogen is important for us to better understand the tectonic evolution of the Paleo-Tethys Ocean. However, the petrogenesis and tectonic setting of the Late Triassic igneous rocks in the central part of the orogen are poorly understood. In this study, we present new whole-rock elemental and isotopic compositions for the Biluoxueshan Pluton, which consists of quartz diorite, granodiorite, and alkali-feldspar granite. Zircon U-Pb dating yields crystallisation ages of 231 ± 1 Ma for the quartz diorite, 227 ± 1 Ma for the granodiorite, and 227 ± 2, 224 ± 2, 222 ± 1, and 217 ± 3 Ma for alkali-feldspar granites, indicating a prolonged emplacement of the pluton. Quartz diorites are metaluminous, high-potassium calc-alkaline, and magnesian in composition. Granodiorites are characterized by peraluminous composition and the existence of normative-corundum, resembling S-type granite. They have negative zircon ε Hf (t) values (−13 to −10.8) and old Hf crustal model ages (2060–1920 Ma), indicating a Paleoproterozoic crustal source. Alkali-feldspar granites are metaluminous to weakly peraluminous, have higher SiO 2 content, FeO T /MgO ratio and differentiation index (DI) than other samples, and pronouncedly negative Eu anomalies, which are characteristics of highly fractionated granites. They have narrow ε Hf (t) values of −2.7 to +2.6 with corresponding Hf crustal model ages of 1410–1060 Ma, indicating a Mesoproterozoic juvenile crustal source modified by mantle-derived magma. By combining previous and the new data, we proposed a new tectonic evolution model of a Late Triassic northward scissor-like post-collisional extension during ca. 235–223 Ma in the Changning-Menglian Suture Zone. [ABSTRACT FROM AUTHOR]

• Zircon U-Pb ages of 2776–2771 Ma mark a major phase of crust building. • Paleoproterozoic metamorphism dated as 1922–1915 Ma. • Amphibolite derived from partial melting of a metasomatic mantle source. • TTG gneiss derived from partial melting of juvenile lower crust. • Archean-Paleoproterozoic crustal accretion and reworking in the southern margin of the NCC. The North China Craton (NCC) preserves important records of Archean-Paleoproterozoic crustal evolution. Here we present results from petrology, geochemistry, zircon U-Pb dating and Lu-Hf isotopes of the Taihua Complex (THC) from the southern part of the NCC. Zircon U-Pb dating of the amphibolite yields the ages of 2776–2771 Ma representing the formation age, marking a major phase of late Archean crustal growth in the NCC. The 1922–1915 Ma ages represent the Paleoproterozoic metamorphism associated with the collisional assembly between the Eastern and Western Blocks. The amphibolites are characterized by low SiO 2 , Na 2 O + K 2 O, and Nb/Y, indicating a sub-alkaline basaltic protolith. These rocks show relatively high LILE/HFSE and LREE/HREE ratios, similar to E-MORB, low [Nb/La] PM , negative Nb-Ta anomalies and positive ε Hf (t) values indicating partial melting of a metasomatic mantle source. The TTG gneisses are characterized by high SiO 2 , Sr/Y, (La/Yb) N , Nb/Ta, Zr/Sm and Zr/Hf ratios, and low MgO, Cr, Ni, Y, Gd/Yb and Dy/Yb ratios, with positive Eu anomalies, indicating partial melting of juvenile lower crust with garnet-amphibolite residue. Our data are consistent with a tectonic setting within a volcanic arc in a convergent margin. Our study on the THC contributes to the Archean-Paleoproterozoic crustal accretion and reworking history along the southern margin of the NCC. [ABSTRACT FROM AUTHOR]