Radiolarian Biostratigraphy of Jurassic Deep-Marine Deposits in Southwest China

Jurassic deep-marine deposits in Southwest China preserve exceptionally rich radiolarian assemblages that provide high-resolution biostratigraphic control for oceanic and basin successions. This study investigates radiolarian-bearing cherts and siliceous mudstones from key stratigraphic sections within the tectonically complex margins of the eastern Tethys realm. Through detailed taxonomic identification and quantitative analysis, multiple radiolarian biozones are established and correlated with the standard global Jurassic radiolarian zonation framework. The stratigraphic distribution of characteristic genera and species enables subdivision of the Lower, Middle, and Upper Jurassic intervals with improved temporal resolution. Evolutionary turnover patterns, first and last appearance datums, and assemblage shifts reflect both global paleoceanographic changes and regional tectonic influences. Integration with ammonite and conodont biostratigraphy, where available, strengthens chronostratigraphic calibration and enhances interregional correlation. Radiolarian assemblages indicate deposition in deep pelagic to hemipelagic environments associated with oceanic basins and accretionary complexes. Variations in species diversity and morphogroup composition suggest fluctuations in nutrient availability, ocean circulation, and water mass structure during the Jurassic.