Terreneuvian skeletonized microfossils from the Central Iberian Zone (Spain) and correlation of the Fortunian Stage throughout southwestern Europe

Abstract

During the Ediacaran–Cambrian boundary interval, the Iberian margin of West Gondwana recorded oceanic upwelling and phosphogenesis favouring the preservation of originally phosphatic and diagenetically phosphatized shells. In the Abenójar Dome and the Alcudia Anticline of the Central Iberian Zone, the Fuentepizarra Formation comprises several phosphorite and phosphatic limestone interbeds that yield a microfossil assemblage rich in the helcionellid Anabarella plana, the halkieriid Halkieria sacciformis, the hyolith Conotheca subcurvata and chancelloriid debris. The assemblage is correlatable with the Purella antiqua Zone of the Aldan-Lena region and the Purella cristata Zone of the Anabar Uplift (Siberian Platform), slightly predating the Watsonella Zone of the Siberian Platform and the Watsonella crosbyi–Oelandiella korobkovi Zone of the northern Montagne Noire (France), both close to the (not yet globally defined) base of Cambrian Age 2. Despite the intra-Terreneuvian collapse of the Cadomian Orogen, stratigraphically associated with the onset of diachronous gaps, the base and top of the Fortunian Stage is well constrained throughout southwestern Europe based on radiometric ages and the micro- and ichnofossil record.