Radiolarian Successional Sequences and Rare Earth Element Variations in Late Paleozoic Chert Sequences of South China: An Integrated Approach for Study of the Evolution of Paleo-Ocean Basins
Abstract:Radiolarian ecological diagnoses and rare earth element (REE) criteria are sensitive indicators of the evolution of paleo-ocean basins. We examined the radiolarian succession and biozonation, as well as the ΣREE, Lan/Cen and Ce/Ce* of chert samples from the Early Carboniferous to Middle Permian chert sequences in South China. Six radiolarian ecological facies (REFs) are distinguished: (1) a clear pelagic REF,with eupelagic radiolarians assemblage and the lowest Ce/Ce* (0.33–0.60, average 0.45); (2) a transitional REF containing mixed radiolarian assemblage of eupelagic and bathyal taxa and a moderate Ce/Ce* (0.67–0.76, average 0.73); (3) a convergent continental margin REF containing bathyal radiolarians and a higher Ce/Ce* (0.73–0.79, average 0.76); (4) a divergent bathyal REF containing bathyal radiolarians and a variable Ce/Ce* (0.52–0.97, average 0.75); (5) a rifted-trough REF, with monotonous radiolarians and the highest Ce/Ce* (0.77–0.85, average 0.81); and (6) a crisis event REF containing mutated radiolarians as well as extreme and variation Ce/Ce* values. Stacking of genesis-related REFs allowed for analysis of a radiolarian successional sequence (RSS) corresponding to an evolutionary cycle in a paleo-ocean basin. The complete RSS consisted of a basal rifted trough REF underlain by a crisis event REF, a lower divergent bathyal REF, a middle clear pelagic REF, and an upper transitional, possibly a convergent continental margin REF.
Document Type: Research Article
Publication date: 2002-07-01