Abstract
The role of the Cathaysia Block, South China, and its linkage with orogenesis in the Rodinia and Gondwana supercontinents remain unresolved because of uncertainties in its paleoposition in supercontinental reconstructions. The lithostratigraphic, geochronologic, geochemical (including isotopic), and paleocurrent data on late Neoproterozoic to early Paleozoic sub-basins in the Cathaysia Block reveal spatio-temporal, tectono-sedimentary, and provenance diversity that show linkages with previously adjacent terranes and orogens in East Gondwana. An abundance of siliceous and conglomeratic rocks, local unconformities, and pinch-out in certain layers indicate a late Cryogenian proximal deposition, late Ediacaran transgression, and Middle Cambrian uplift. Cryogenian to early Ordovician strata contain predominantly 1000–900 Ma (late Grenvillian age) detrital zircon population, whereas 1300–1050 Ma (early Grenvillian age) zircons are only dominant in strata earlier than late Ediacaran. Besides, 850–700 Ma zircons are the most prominent group in the Middle Cambrian strata along with an occasional increase in the 650–500 Ma (Pan-African age) zircons.
The Grenvillian age zircon groups exhibit significant sediment input from the eastern Indian terrane (990–950 Ma) and western Australia (1300–1050 Ma), underlining the fact that the Cathaysia Block was located between these two terranes in the northern part of East Gondwana. The diminishing contribution of early Grenvillian components in the late Ediacaran strata can be linked to the Pinjarra Orogeny (550–520 Ma), which led to uplift that blocked the transport of detritus from Australia. Middle Cambrian provenance variation with high abundance of 850–700 Ma components indicates the presence of intrinsic sediment from the Wuyishan terrane of South China. Given that the Cathaysia Block was a passive continental margin, this change was caused by the uplift of the southeastern Cathaysia Block, which was related to the far-field stress effects of the late phase of the Kuunga Orogeny (530–480 Ma). The decrease in abundance of early Grenvillian and Pan-African zircons in space implies that they were transported into the basins through independent drainage systems. This is consistent with the local and temporal variations in paleocurrent orientations during the Cambrian, further implying diverse and complex drainage systems in the southwestern Cathaysia Block during this period.
Surface Chlorophyll-a Concentration Spatio-Temporal Variations in the Northern South China Sea Detected Using MODIS Data