Linking high-frequency lacustrine sequences to orbitally-induced cyclicity (Lower Cretaceous, Iberian Basin)

Illueca, Natalia (Universidad de Zaragoza) ; Liesa, Carlos L. (Universidad de Zaragoza) ; Soria de Miguel, Ana R. (Universidad de Zaragoza)

Resumen: The lacustrine El Castellar Formation in the Castillo de Aliaga section (Early Cretaceous Galve sub-basin, eastern Spain) features two carbonate successions of marl and limestone, separated by a mudstone and marl interval. Sequence analysis revealed small-scale (44 elementary sequences), medium-scale (ten complete and two incomplete parasequences), and large-scale (three sets of parasequences, one incomplete), high-frequency lacustrine sequences, with an average thickness of 2.9, 12.4 and 54m, respectively. These sequences start with a sudden facies change (deepening) and exhibit a shallowing-upward trend with features of subaerial exposure (bioturbation, oxidation, or brecciation) at the top, indicating phases of climate-modulated lake expansion and retraction. The temporal framework of the lacustrine sequences is further characterized by the correlation of these sequences with sedimentary-cycle periodicities of 3.3, 13.2 and 57.3m, attributed, respectively, to the long precession cycle (22.4kyr) and the short (95kyr) and long (405kyr) eccentricity cycles of the Earth’s orbit. The hierarchical stacking of sequences aligns with orbitally driven cyclicity, with thickness variations interpreted as tectonic subsidence effects (accommodation) resulting from normal fault slip in a rift system. The three sets of parasequences (SPS-1 to SPS-3) align with stages of lake system evolution. SPS-1 represents deposition in a lowenergy shallow carbonate lake. SPS-2 indicates a significant lake expansion and deepening, linked with clastic input and a mixed lake system, and correlates with a major increase in accommodation, over ~200kyr, involving fault-induced local tilting. SPS-3 represents deposition in a high-energy carbonate lake. The parasequences identified show variations in cyclic thickness tied to a >700kyr tectonic cycle. The elementary sequences, mainly corresponding to marl-limestone bundles, exhibit thickness changes probably due to shorter-term tectonic pulses. Accelerated tectonic activity resulted in increased accommodation in shorter (40-50kyr) periods, followed by longer (>100kyr) periods of progressive deceleration.

Idioma: Inglés

DOI: 10.1344/GeologicaActa2024.22.10

Año: 2024

Publicado en: Geologica Acta 22, 10 (2024), 26
ISSN: 1695-6133

Factor impacto JCR: 2.0 (2024)

Categ. JCR: GEOLOGY rank: 10 / 61 = 0.164 (2024) - Q1 - T1

Factor impacto SCIMAGO: 0.418 - Geology (Q2)

Financiación: info:eu-repo/grantAgreement/ES/AEI/PID2019-108705GB-I00
Financiación: info:eu-repo/grantAgreement/ES/DGA/E32-23R
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2023-148949NB-I00

Tipo y forma: Article (Published version)

Área (Departamento): Área Estratigrafía (Dpto. Ciencias de la Tierra)
Área (Departamento): Área Geodinámica Interna (Dpto. Ciencias de la Tierra)