Late Ediacaran carbonate production and REE+Y signatures tracing redox conditions in a Cadomian retroarc basin, Central Iberian Zone, Spain

Abstract

The late Ediacaran carbonate production recorded in a Cadomian retroarc basin from the Iberian Peninsula provides an excellent opportunity to evaluate the tectonic and redox factors that controlled the infill of the foredeep troughs, located between uplifted orogenic wedges and exposed forebulge transects. In the Central Iberian Zone of the Iberian massif, the carbonates of the Villarta Formation follow two geographic belts, which represent short-term mosaics of uplifted and tilted fault-bounded basement highs. These recorded the nucleation of fringing reefal (rich in Cloudina and Sinotubulites microfossils embedded in thromboid textures) and shoal and back-barrier complexes, which episodically fed slope-related megabreccia lobes and channels. REE+Y datasets from the impure carbonates reflect contamination by detrital material, hydrothermal interaction and variable redox conditions, ranging from oxic to dysoxic, the latter emphasized by the deposition of kerogenous black shales in distal parts of the foredeep trough.