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Small scale RT cycles in Prebetic Lower-Middle Eocene (Alicante)

In the study of the Alicante External Prebetic Eocene platforms, ten sedimentary facies were defined in field based on lithology and fossil content observed, as follows: L1 – limestone (lmst.) with Alveolina; L2 – lmst. with small Nummulites (< 3 cm diameter); L3 – lmst. with big Nummulites (>3 cm diameter); L4 – algal lmst.; L5 – lmst. with miliolids; L6 – micritic lmst. with gastropods and bivalves; L7 – marls; L8 – greenish siltstones; L9 – dolomitized lmst. and/or dolostone; L10 – sandy lmst.

The lower interval of the Ibi section  twelve L2-L1 units were defined, after which the first dolomitized limestone (L9) occurs, changing the motif to L2-L1-L9 or L1-L9. The middle part of the succession is marked by the occurrence of facies L10, while the upper part by five units with L5-L7.

The lower interval of the Ibi section, consists of thinning-upward units, each one showing a shallowing-upward trend, indicating a decrease of accommodation in middle ramp area, ended with the basinward shift of the proximal open inner ramp. The upper interval, consisting in thickening-upward units, sedimented in lagoon-shoals of inner ramp, indicates increasing of accommodation. This interval is preceded by a period of siliciclastic supply (L10). Consequently, at the scale of the entire outcrop a regressive sequence can be defined with at least 12 smaller RT (Regressive-transgressive)  cycles, the lower 6 developed in middle ramp environments, while the upper 6 in inner ramp.

Facies L2. Ibi section.

The Prebetic Paleocene-Eocene stratigraphic succession shows a general regressive-transgressive trend. The above-presented results indicate that on the regressive interval of this trend smaller scale RT cycles are superposed.

Cite as: Miclăuș, C., Martín-Martín, M., Tosquella, J., Samsó, J.M. and Tent-Manclús, J.E. (2023): Small scale RT cycles in Lower-Middle Eocene limestones of External Prebetic Units of Betic Cordillera (Alicante Zone). Abstract Book, Fourteenth Romanian Symposium on Palaeontology, Bucharest, 14-15 September 2023 / Zoltán Csiki-Sava, Alina Floroiu, Maria-Raluca Văcărescu, Iuliana Lazăr – Bucureşti : Editura Universităţii din Bucureşti -Bucharest University Press, 2023, 83-84 p.