Stratigraphy and sedimentology of distal-alluvial and lacustrine deposits of the western-central Ebro Basin (NE Iberia) reflecting the onset of the middle Miocene Climatic Optimum

Authors

  • Z. Larena University of the Basque Country/EHU
  • C. Arenas Universidad de Zaragoza http://orcid.org/0000-0002-4212-0524
  • J.I. Baceta University of the Basque Country/EHU
  • X. Murelaga University of the Basque Country/EHU
  • O. Suarez-Hernando University of the Basque Country/EHU

DOI:

https://doi.org/10.1344/GeologicaActa2020.18.7

Keywords:

Miocene stratigraphy, Palustrine-lacustrine facies model, Ebro Basin, Middle Miocene Climatic Optimum.

Abstract

Stratigraphic and sedimentological study of distal alluvial and lacustrine deposits in the Plana de la Negra-Sancho Abarca area (western-central Ebro Basin, NE Iberia) within the early and middle Miocene allows five main lithofacies to be characterized and mapped within two tectosedimentary units, construction of a sedimentary facies model and discussion on allogenic controls on sedimentation. In this area, the boundary between tectosedimentary units T5 and T6 appears to be conformable and is marked by the change from dominant clastics to carbonates. Correlation of the studied outcrops with nearby sections that already had magnetostratigraphic and biostratigraphic data allows the studied succession to be dated from C5Dr to C5Cn (Burdigalian-Langhian), placing the boundary T5/T6 at ca. 16.1-16.05Ma. Seven vertical facies sequences document deposition of distal alluvial clastics and palustrine and lacustrine carbonates. Sandstones and mudstones represent low-sinuosity channels and lateral and terminal splays by unconfined flows runnig across the alluvial plain, associated to the Pyrenean-derived Luna fluvial system. The carbonates contain charophytes, ostracods, bivalves and gastropods, indicating deposition in 2-4m deep lakes. Laminated carbonate facies record reworking of shore carbonates and the influx fine-siliciclastic sediment offshore. Abundant bioturbation and desiccation features indicate episodic submergence and subaerial exposure. Four main episodes of alluvial and associated palustrine/lacustrine facies belt shifts are identified. Alluvial deposition in the studied T5 unit is related to low lake level conditions, rather than to a Pyrenean uplift. The maximum extent of the freshwater carbonates occur at the base of unit T6. This is consistent with conditions of increasing humidity of the Middle Miocene Climatic Optimum.

Author Biographies

Z. Larena, University of the Basque Country/EHU

Department of Stratigraphy and Paleontology. Science and Tecnology Faculty.

 

Master Degree in Geology

C. Arenas, Universidad de Zaragoza

Stratigraphy Division. Department of Earth Sciencies

 

PhD

J.I. Baceta, University of the Basque Country/EHU

Department of Stratigraphy and Paleontology. Science and Tecnology Faculty.

 

PhD

X. Murelaga, University of the Basque Country/EHU

Department of Stratigraphy and Paleontology. Science and Tecnology Faculty.

 

PhD

O. Suarez-Hernando, University of the Basque Country/EHU

Department of Stratigraphy and Paleontology. Science and Tecnology Faculty.

 

PhD

Downloads

Published

2020-05-20

How to Cite

1.
Larena Z, Arenas C, Baceta J, Murelaga X, Suarez-Hernando O. Stratigraphy and sedimentology of distal-alluvial and lacustrine deposits of the western-central Ebro Basin (NE Iberia) reflecting the onset of the middle Miocene Climatic Optimum. GeA [Internet]. 2020May20 [cited 2021Jul.30];18:1-26, I. Available from: https://revistes.ub.edu/index.php/GEOACTA/article/view/GeologicaActa2020.18.7

Issue

Section

Articles