首页|Gastropod-rich lacustrine carbonate deposits in N Iberia: a depositional, climatic and ecological record of the Late Miocene

Gastropod-rich lacustrine carbonate deposits in N Iberia: a depositional, climatic and ecological record of the Late Miocene

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  • NSTL
  • Elsevier
The Tortonian Pena Adrian Formation represents the youngest depositional unit of the Miranda-Trebino basin (Basque-Cantabrian Pyrenees), which developed on the Southern Basque-Cantabrian Pyrenees from late Eocene to Late Miocene times. The formation is a 50-160 m thick succession of alluvial detrital grading to lacustrine carbonates that contain rich and varied calcareous fossil biota (gastropods, ostracods and charophytes). The fossil association characterizes warm temperate, shallow lakes with vegetated bottoms and well-oxygenated and alkaline fresh waters. Integration of stratigraphic, sedimentological, paleontological and C-O stable isotopic data allows the differentiation of a wide range of sedimentary facies, the construction of a depositional model and the definition of distinct evolutionary phases and relation to allogenic processes. Up to 3 metre-thick facies sequences record repetitive water-level changes, likely reflecting short-term climate changes. Overall, the succession outlines an asymmetric cycle of gradual expansion and faster contraction of a shallow ramp-like lake system evolving under oscillating climatic conditions. C and O stable isotopes are consistent with decreasing salinity and increasing precipitation/evaporation balance trough time. Excellent preservation of aragonitic and bimineralic gastropods characterizes the open lacustrine deposits, whereas shell dissolution and neomorphism are distinct in the palustrine ones. This contrasting degree of preservation of calcareous biota clearly reflects changes in the physico-chemical conditions that prevailed during sedimentation and early burial. The findings add to the knowledge of carbonate lake basins, help discern the factors that controlled their evolution and highlight specific depositional and preservation conditions for gastropod-rich carbonate records.

Carbonate faciesLacustrinePalustrineFreshwater gastropodsLate MioceneLIMESTONE LATE EOCENEISLE-OF-WIGHTMADRID BASINEBRO BASINPALUSTRINE FACIESDRAINAGE REORGANIZATIONENVIRONMENTAL CONTROLSISOTOPE FRACTIONATIONSYNTHETIC ARAGONITESEDIMENTARY CYCLES

Larena, Zurine、Arenas, Concha、Sanjuan, Josep、Pascual, Ana、Larraz, Mariano、Murelaga, Xabier、Baceta, Juan Ignacio

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Univ Basque Country UPV EHU||Univ Zaragoza

Fac Ciencias Tierra Marti & Franques

Univ Navarra

2025

10.1016/j.sedgeo.2025.106899

Sedimentary geology

Sedimentary geology

ISSN：0037-0738
年,卷(期)：2025.483(Jun.)
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