###### Abstract  
We report information on the protolith, the Triassic retrograde metamorphism, and anatexis recorded in zircons extracted from granitic gneiss and biotite schist in the Sulu orogenic zone, central China. The schist is enclosed within the granitic gneiss in the form of a lens. Zircon grains from the schist sample indicate anatexis occurred at 214.6 \(\pm\) 3.6 Ma (MSWD = 5.1), with \(\epsilon_{\rm Hf}\) (t) values ranging from \(-\)22.6 to \(-\)18.3, corresponding to T\({}_{\rm DM}\) \({}^{\rm C}\)(Hf) ages between 2675 Ma and 2407 Ma. The granitic gneiss originated from magmatic rock formed at 774 \(\pm\) 32 Ma (MSWD = 5.7) and subsequently underwent metamorphism at \(\sim\)211 Ma. Three zircon cores from the granitic gneiss exhibit \(\epsilon_{\rm Hf}\) (t) values ranging from \(-\)13.6 to \(-\)6.3, with T\({}_{\rm DM}\) \({}^{\rm C}\)(Hf) ages spanning 2487-2075 Ma. Six zircon rims from the gneiss yield \(\epsilon_{\rm Hf}\) (t) values of \(-\)14.7 to \(-\)13.3, and T\({}_{\rm DM}\) \({}^{\rm C}\)(Hf) ages ranging from 2176 to 2092 Ma. We believe that the protolith of granitic gneiss is the Neoproterozoic magmatic rock, whose tectonic affinity is the northern margin of the Yangtze craton. The granitic gneiss experienced Triassic collisional orogeny-related metamorphism and subsequent retrograde metamorphism, with the timing of retrograde overprinting consistent with zircon-recorded anatexis in the schist. In addition, the protoliths of both the gneiss and schist exhibit close affinity to Archean-Paleoproterozoic crustal sources. Art  
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(1) The metamorphic stage of HP quartz eclogite facies (246-244 Ma), with the metamorphic _P-T_ conditions of 1.7-2.1 GPa and 570-690 \({}^{\circ}\)C, is characterized by the association of quartz eclogite facies inclusions preserved in zircons [13; 14; 15; 16]; (2) The peak metamorphic stage of the UHP eclogite facies (240-225 Ma), with the metamorphic _P-T_ conditions are 3.0-5.9 GPa and 750-900 \({}^{\circ}\)C, and the typical characteristics are the UHP metamorphic indicator minerals such as coesite or diamond preserved by the host minerals in the metamorphic rocks [6; 9; 10; 15; 16]; (3) The retrometamorphic stage of quartz eclogite facies (225-215 Ma), with the metamorphic _P-T_ conditions are 1.5-2.5 GPa and 600-750 \({}^{\circ}\)C, and the representative mineral assemblage is garnet + ombacite + quartz, while the content of coesite obviously decreases or disappears [17; 18; 19]; (4) The amphibolite facies retrometamorphic stage (215-205 Ma), with the metamorphic _P-T_ conditions of 06-1.0 GPa and 450-600 \({}^{\circ}\)C, are characterized by amphibolite facies retrometamorphic products (such as plagioclase + amphibolite) developed around such as garnet and ombacite [9; 10; 16; 19]. The Sulu UHP metamorphic zone predominantly comprises orthognesses, with minor amounts of eclogites, speisses, granulites, and ultramafic rocks, which have Paleoproterozoic protolithic or metamorphic ages and appear as enclaves embedded within the orthogneses [20; 21; 22; 23; 24]. The Northern Sulu orogenic zone, which delineates the northern extent of the YC, is central to studies of the Sulu zone and deciphering the tectonic evolutionary history of the YC. Decades of multidisciplinary research have systematically explored UHP metamorphism, unraveling the petrological and geodynamic controls on deep subduction and exhumation of continental material [5; 14; 18; 19; 25; 26; 27]. However, there have been fewer studies of retrograde metamorphism and ananexis. This greatly limits our complete understanding of the collisional orogen process. This study offers valuable insights that stem from the study of retrogressed biotite schist within the Sulu zone into the tectonic evolution of the Sulu orogenic belt and the northern margin of the YC. We investigated the biotite schist--an important but retrograde component of the Sulu zone and its surrounding rock, granitic gneiss, that have undergone retrograde metamorphism in northeast Sulu.