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This paper summarizes the new results on the petrogenesis of Mesozoic granitoids and volcanic rocks in South China. The authors propose that these rocks were formed in time and space as a response to regional tectonic regime change from the continent-continent collision of the Indosinian orogeny within the broad Tethyan orogenic domain in the Early Mesozoic (T 1-T 3) (Period I) to the largely extensional setting as a result of the Yanshanian orogeny genetically associated with the NW-WNW-ward subduction of the paleo-Pacific oceanic lithosphere in the Late Mesozoic (J 2-K 2) (Period II). Of the Period I Indosinian granitoids, the early (T 1-T 2 1) ones are syn-collisional, and formed in a compressional setting; the late (T 2 2-T 3) ones are latecollisional, and formed in a locally extensional environment. During the Period II Yanshanian magmatism, the Early Yanshanian (J 2-J 3) granitoid-volcanic rocks, which are distributed mainly in the Nanling Range and in the interior of the South China tectonic block (SCB), are characteristic of rift-type intraplate magmatism, whereas the Late Yanshanian K 1 granitoid-volcanic rocks are interpreted as genetically representing active continental margin magmatism. The K 2 tholeiitic basalts interlayered with red beds are interpreted as genetically associated with the development of back-arc extensional basins in the interior of the SCB. The Yanshanian granitoid-volcanic rocks are distributed widely in South China, reflecting extensional tectonics within much of the SCB. The extension-induced deep crustal melting and underplating of mantle-derived basaltic melts are suggested as the two principal driving mechanisms for the Yanshanian granitic magmatism in South China.

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This paper provides some new evidences on stratigraphic sequence, zircon SHRIMP dating from ophiolite, granitoids, and fold-and-thrust tectonic styles in the South China Block (SCB). Stratigraphic studies suggest that the eastern and central parts of the SCB show a SWdipping palaeoslope framework during the Late Palaeozoic-Early Mesozoic. These areas were not in a deep-sea environment, but in a shallow-sea or littoral one. Coeval volcanic rocks are missing. Deep-water deposits and submarine volcanism only took place in the western part of the SCB. The three ophiolitic mélanges of the eastern SCB formed in the Neoproterozoic, but not in the Permian or the Triassic. The sedimentary rocks associated with the Neoproterozoic oceanic relics contain abundant Proterozoic acritarchs, but no radiolarians. The Early Mesozoic granitoids (235-205 Ma) belong to the post-collision peraluminous S-type granites; they are widely exposed in the central-western SCB, and rare in the eastern SCB. The foldand-thrust belt developed in the eastern SCB shows a top-to-the-south displacement, whereas the Xuefengshan Belt of central SCB indicates a north-or northwest-directed shearing. The geodynamic settings of the different parts of the SCB during the Triassic are discussed. Résumé Cet article fournit des données nouvelles sur le bloc Chine du Sud (BSC) en matière de séquence stratigraphique, de datation SHRIMP sur zircon dans des ophiolites et granitoïdes et à propos de styles de déformation tectonique. Des études stratigraphiques suggèrent que les parties orientale et centrale du BSC correspondaient à une paléopente à pendage sud-ouest pendant la période allant de la fin du Paléozoïque au début du Mésozoïque. L'environnement n'était pas du type mer profonde, mais de type peu profond ou littoral, et le volcanisme en était absent. Les sédiments profonds et le volcanisme sous-marin ne concernent que la partie occidentale de la Chine du Sud. Les trois mélanges ophiolitiques présents dans la partie orientale se sont formés au Néoprotérozoïque, et nullement au Permien ou au Trias. Les roches sédimentaires associées à ces reliques de l'océan protérozoïque contiennent d'abondants Acritarches protérozoïques, mais pas de Radiolaires. Les granites du début du Mésozoïque (235-205 Ma) appartiennent à la catégorie des granites hyperalumineux postcollisionnels de type S et sont largement représentés dans la partie centre-occidentale du BSC, rarement dans la partie orientale. La chaîne plissée et chevauchante qui se développe dans l'Est de la Chine du Sud montre une vergence vers le sud, tandis que la ceinture chevauchante de Xuefengshan indique un cisaillement vers le nord ou le nord-ouest. Le cadre géodynamique au Trias des différentes parties de la Chine du Sud est discuté.