Source areas and paleoenvironmental reconstruction of the Serra d'Almenara loess (NE Ebro Valley, Iberian Peninsula) from grain-size and heavy mineral signatures
The northeastern part of the Ebro Basin (NE Spain) features loess that cover an area of about 40 km2 on the northern slopes of the Serra d'Almenara anticline. The deposits and soils developed from them were mapped, described, and dated by luminescence. Additionally, grain size, percentage of he...
| Autores: | , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universitat de Lleida (UdL) |
| Repositorio: | Repositori Obert UdL |
| OAI Identifier: | oai:repositori.udl.cat:10459.1/465223 |
| Acceso en línea: | https://doi.org/10.1016/j.geomorph.2024.109085 https://hdl.handle.net/10459.1/465223 |
| Access Level: | acceso abierto |
| Palabra clave: | Aeolian processes Iberia Palaeoclimatology Quaternary |
| Sumario: | The northeastern part of the Ebro Basin (NE Spain) features loess that cover an area of about 40 km2 on the northern slopes of the Serra d'Almenara anticline. The deposits and soils developed from them were mapped, described, and dated by luminescence. Additionally, grain size, percentage of heavy minerals (>2.8 g/cm3), and the mineralogical composition of the heaviest fraction (>3.2 g/cm3) were analysed. The coarse textures of the deposits indicate a very proximal origin. Therefore, potential source areas of the sands and silts were analysed with special attention given to the extensive river floodplains and alluvial fans close by, as well as gypsum-rich rocky outcrops. The mineral signature of the loess shows that it mainly originates from the alluvial plain of the Segre River, located about 10–30 km to the west. In some places, the loess also received particles from the alluvial fans of the Ondara and Corb rivers located south of the Almenara reliefs. In addition, the gypsum present in the loess is apparently derived from Eocene deposits. The loess in the study area was deposited during cold phases of the last two glacial cycles when the topographic obstacle of the Serra d'Almenara blocked the dominant winds from the southwest. Analysis of the almost 4-meter-thick profile of Pilar d'Almenara shows initial but limited accumulation phases in Marine Isotope Stages (MIS) 6, followed by the formation of a red soil during MIS 5e. Accumulation resumed during MIS3, with more energetic and powerful wind transport during the final phase of MIS 3 (ca. 34–30 ka) and early MIS 2, but prior to the Last Glacial Maximum. Our data highlights the prominent role of large rivers and alluvial fans as the sources of particles that are later reworked by the wind. |
|---|