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South China is placed in a range of positions along the northern margin of East Gondwana in the early Paleozoic reflecting uncertainties in linking U Pb ages of detrital zircon to potential sources. Using detrital monazite U Pb ages from Cambrian sedimentary rocks, we argue for a position outboard of northeastern India. Detrital monazite yields predominantly earliest Neoproterozoic and earliest Cambrian age peaks at circa 945 Ma and 528 Ma, with minor end Mesoproterozoic and late Paleoproterozoic to early Mesoproterozoic ages. Compared with the U Pb age distribution pattern of detrital zircon from the same samples, the monazite data highlights input from earliest Cambrian metapelites. These earliest Neoproterozoic and earliest Cambrian detrital monazite grains match with ages and Th and U contents of monazite from northeastern India, but are different from those from northwestern India and northern Australia, and thus enable tighter constraints on the paleogeography of South China than detrital zircon data alone. • U Pb ages of detrital monazite from the Cambrian sandstones in the southern part of South China are analyzed. • Cambrian detrital monazite from the southern part of South China yields predominantly age peaks at circa 945 Ma and 530 Ma. • South China was linked to the northeastern India margin of East Gondwana in the Cambrian. • Detrital monazite can provide a more accurate record of provenance than detrital zircon. [ABSTRACT FROM AUTHOR]

• Mafic and intermediate rocks together with overlying tuff and carbonate rocks from the Yingyangguan Group, western Cathaysia Block, are dated at 750 Ma and 670–660 Ma, respectively. • The volcanic and volcaniclastic rocks experienced varying degrees of crustal contamination, accompanied by assimilation and fractional crystallization, and originated from older, subduction – modified, lithospheric mantle sources. • The mid-late Neoproterozoic volcaniclastic rock, argillaceous limestone and sandstone samples were derived from sources external to South China, which requires that the Cathaysia Block was accreted to North India from at least 750 Ma. • The tectonic setting of central and eastern South China transformed from an overall convergent plate margin setting into a stable within-plate siliciclastic depositional environment at ca. 750 Ma. The tectonic affinity of mid - late Neoproterozoic magmatism in the South China Block provides a first order constraint on its role in the break-up of Rodinia and the subsequent amalgamation of Gondwana. The Yingyangguan area in the western margin of Cathaysia Block preserves a magmatic and sedimentary record of this period. U-Pb zircon age data indicate magmatism at around 750 Ma, followed by accumulation of a succession of tuff and carbonate rocks at ca. 670–660 Ma. All samples show evidence for ductile deformation and metamorphism. The geochemical characteristics of mid-Neoproterozoic mafic and intermediate rocks suggest crustal assimilation and fractional crystallization play an important role in magma evolution, and they were derived from a source dominated by modified lithospheric mantle sources previously metasomatized by slab-derived fluids. Analyzed samples, as well as contemporaneous mafic rocks in neighboring areas, have high Zr/Y ratios, and plot in the within-plate basalt field at ca. 750 Ma. In addition, zircons with ages between 1200 and 950 Ma and 850–770 Ma mostly fall within the arc-related field on discriminating diagrams based on zircon trace-element compositions, whereas, most ca. 750 Ma and 700–600 Ma zircons plot in the within-plate field. This evolving tectonic record of magmatic activity suggests a transformation from a convergent plate margin setting on the periphery of Rodinia to one involving within plate extension at ca. 750 Ma. Furthermore, the detrital zircons from samples of the Yingyangguan Group present abundant late Mesoproterozoic to early Neoproterozoic (1200–950 Ma) ages. These ages match the record of North India and Indo-Antarctica, and imply a peripheral setting for South China with respect to the supercontinent and most likely adjacent to India from at least 750 Ma. Thus, we suggest that the Yangtze Block accreted to Cathaysia on the northern margin of India in the early Neoproterozoic, and that the active plate boundaries located along the northern and western margins of South China continue to ca. 750 Ma. After this time, the tectonic setting within the South China Block transformed into a stable within-plate siliciclastic depositional environment that continued to receive detritus from East Gondwana until the early Devonian. [ABSTRACT FROM AUTHOR]

• Two diamictites units are recognized on the western margin of Cathaysia Block, and correlate with the global Sturtian and Marinoan glaciations. • Late Tonian, middle Cryogenian and early Ediacaran siliciclastic rocks overlying the Cathaysia Block were derived from sources external to South China. • The Cathaysia Block was linked to North India before 720 Ma. Neoproterozoic paleogeography of the Cathaysia Block of South China is directly linked to the formation of Rodinia, its break-up, and the subsequent amalgamation of Gondwana. Two diamictite units occur in the Neoproterozoic sedimentary successions on the western margin of Cathaysia Block. In combination with our detrital zircon U-Pb dating results and corrected chemical weathering index data (CIA corr), these units coincide with the global Sturtian and Marinoan glaciations. Late Tonian to early Ediacaran sedimentary rocks from western Cathaysia contain abundant late Mesoproterozoic to early Neoproterozoic (1150–870 Ma) and some mid-Neoproterozoic (800–720) detrital zircons. Paleocurrent data indicate sediment transport to the northwest. The timing and character of the ages of detrital zircons match the records of North India and East Antarctica, indicating that the Cathaysia Block received detritus from Gondwana. Thus, South China lay adjacent to northern Gondwana since at least 720 Ma, and possibly considerably earlier. [ABSTRACT FROM AUTHOR]