中国科学院南京地质古生物研究所机构知识库

The Cecrops septemporatus Zone is widely applied in correlation of Valanginian to lower Hauterivian successions, but paleobiogeographic distributions of radiolarian fauna from this zone remain ambiguous. To address this issue this study compares radiolarian faunas from the Vispi Quarry section, Umbria-Marche Basin, central Italy with the Guigong section, southern Tibet. Similarity between these C. septemporatus Zone faunas suggests a close marine connection may have existed between western and eastern Tethys during Early Cretaceous time. Lithologies, depositional setting, associated fossil records, and paleomagnetic data from contemporaneous radiolarian occurrences in different areas globally are also assessed. The paleobiogeographic distribution of the C. septemporatus Zone fauna was mainly restricted to low latitudes in the Tethyan and Pacific regions, but also shows a significant migration from low latitudes in the Tethyan Realm to mid latitudes in the Boreal and Austral realms. Climatic and oceanographic conditions during the Weissert Event may have played important roles in the development of the paleobiogeographic distribution patterns observed for the C. septemporatus Zone faunas.