Early Paleozoic orogenesis along Gondwana's northern margin constrained by provenance data from South China

The Cambrian-Ordovician boundary unconformity in the southern part of the South China Craton is spatially and temporally related to coeval orogenic activity along the Indian margin of east Gondwana. Detrital zircon age spectra from strata above and below the unconformity range in age from 3580-450 Ma, with peaks in the late Mesoproterozoic and Neoproterozoic. The patterns are similar to time equivalent sequences elsewhere in South China and together with regional facies relationships and paleocurrent data indicate derivation from a Gondwana source. The disconformity at the base of the Ordovician succession forms part of a regional break that has also been documented in the Himalaya, Qiangtang, Lhasa, Sibumasu, and Western Australia. All these successions have similar detrital zircon age spectra suggesting derivation from common source(s). In South China the effects of this tectonic event are relatively mild and are represented by a local disconformity at the base of the Ordovician succession, but elsewhere in north Gondwana this event is marked by an angular unconformity with metamorphism of older units and relatively widespread magmatic activity. South China was likely located in a distal location to the northeast of the pulse of tectonic activity, which was focused in the Himalaya region, and was close to the continent-ocean boundary between northern Gondwana and the proto-Tethys.