Rudist reef structure : Insights from orientation of hippuritids at l'Espà (Campanian, southern Pyrenees)
Boix, C. (Universidad de Alcalá. Departamento de Geología)
Vicens, Enric (Universitat Autònoma de Barcelona. Departament de Geologia)
Riera, V. (Centro de Estudios y Experimentación de Obras Públicas)
Oms, O (Universitat Autònoma de Barcelona. Departament de Geologia)

Date:	2023
Abstract:	Rudist were common Mesozoic reef builders, but rare examples exist to evaluate reef structure. The l'Espà locality (southern Pyrenees) is approached to study rudist reef structure by a quantitative assessment of the individuals' position (growing vs reworked) and its sedimentary context. This late Campanian reef is exposed along some 20 × 6 m outcrop. Builders are mainly Hippurites radiosus, although other rudists, such as Hippuritella lapeirousei, Hippuritella sp. and Mitrocaprina sp. are also present together with corals. The orientation of 325 specimens of mainly H. radiosus was plotted in stereographic and cartesian projections. Orientations and microfacies permit to differentiate 5 vertically stacked intervals (settings) along the outcrop: (1) Distal reef setting (reef-talus slope), with rudists reworked as large bunches of grouped specimens, with scarce erosion and preserving both valves articulated; (2) Halfway distal-proximal reef setting (close cluster reef), with abundant reworked, isolated, and flat-lying specimens. In this zone, endo-epibiont colonization on rudist shells is common, together with the presence of large (up to 1 m) branching and massive corals; (3) Proximal reef setting (frame/close cluster reef), where specimens are in life position; (4) A proximal back reef unit (spaced cluster reef) with few highly reworked specimens; (5) Distal back reef setting (very spaced cluster reef), with hardly any rudist fragments. This succession provides a reef tract model resembling that of most coral reefs and differs from smaller rudist reefs. The structure of the studied reef is well preserved as a result of high accommodation space related to thrust emplacement.
Grants:	Agencia Estatal de Investigación PGC2018-101575-B-I00 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1666
Note:	Altres ajuts: acords transformatius de la UAB
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Carbonates ; Foreland basin ; Hippuritids ; Microfacies ; Paleoecology
Published in:	Cretaceous research, Vol. 147 (July 2023) , art. 105507, ISSN 1095-998X

DOI: 10.1016/j.cretres.2023.105507

13 p, 9.7 MB

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