Provenance, weathering conditions, and tectonic evolution history of the Cambrian meta-sediments in the Zhuguangshan area, Cathaysia Block

Abstract

Sandstones and mudstones collected from the Cambrian sedimentary sequences in the Zhuguangshan area were analyzed to trace their provenance, weathering conditions, depositional environment, and Precambrian tectonic evolution in the Cathaysia Block, South China. Detrital zircon geochronology defines at least five populations: 2658–2370 Ma, 1866–1500 Ma, 1390–1268 Ma, 1250–858 Ma, and 830–700 Ma. The 2648–2370 Ma population may correspond to the Neoarchean global continental growth. The 1816–1510 Ma population may represent a subduction event caused by the assembly of the Columbia supercontinent. The 1390–1268 Ma and 1250–858 Ma population reflect the tectono-thermal events associated with the assembly of the Rodinia supercontinent, while the 830–700 Ma population may be associated with the breakup of the Rodinia supercontinent. Detrital zircon Hf isotopic compositions indicate that the mechanism involves multiple juvenile inputs and the reworking of older crustal materials.The sandstones and mudstones display K2O enrichment, but they are moderately to extremely depleted in Na2O, CaO and Sr. The major and trace elements reveal that the sandstones and mudstones were derived from recycled felsic rocks and deposited in the passive continental margin. The compositions of the protoliths are inferred equivalent to andesite to granodiorite. The petrographic and geochemical features indicate that the sandstones and mudstones have undergone medium to intensive chemical weathering. Conversion of aluminous clay minerals to illite is inferred to be the predominant post-depositional potash metasomatism.