Paleoenvironmental evolution of the Vinchina formation (Miocene) along the sierra de los Colorados, La Rioja, Argentina
The Vinchina Formation was deposited between 16 and 8 My in a broken foreland basin, recording sedimentation in continental environments, reaching a huge thickness (around 6 km). Thirteen sedimentary facies were defined along the Sierra de Los Colorados representing fluvial, eolian-fluvial interacti...
Guardado en:
| Autores principales: | , , |
|---|---|
| Formato: | JOUR |
| Materias: | |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00044822_v75_n1_p17_Schencman |
| Aporte de: |
| Sumario: | The Vinchina Formation was deposited between 16 and 8 My in a broken foreland basin, recording sedimentation in continental environments, reaching a huge thickness (around 6 km). Thirteen sedimentary facies were defined along the Sierra de Los Colorados representing fluvial, eolian-fluvial interaction, alluvial, lacustrine and eolian environments. The lateral distribution of the facies allowed to distinguish three sectors: north, center and south. The northern area shows the greatest abundance of conglomerates and the largest size clasts. The central sector comprises sandstones and mudstones in similar proportions, whereas in the south mudstones predominate. This lithological variation allows supposing that sediments distribution pattern was north-south. The vertical evolution of sedimentary paleoenvironments can be synthesized in four stages. Stage 1 comprises the basal deposits (basal part of the Lower Member): the sediment was transported by ephemeral braided systems and later reworked by wind processes (eolian-fluvial systems). Stage 2 comprises the maining part of the Lower Member and it is characterized by fluvial transport by anastomosed rivers and terminal lobes systems. The region continued in a distal position respect to the nearest elevated area (Sierra de Toro Negro), which experienced coeval rising. The lower third of the Upper Member corresponds to stage 3 when river systems were sand-gravel braided (north), were sand-gravel braided and meandering (central region), and anastomosed that engage with eolian systems (south). During stage 4 (upper portion of the Upper Member) meandering systems were developed (middle sector), which provided an important amount of fine-grained sediment to ephemeral lacustrine systems (south). © 2018, Taylor and Francis Ltd. All rights reserved. |
|---|