Análisis preliminar de los ostrácodos del Mioceno Inferior de las Bardenas Reales de Navarra: (Cuenca del Ebro)

• Murelaga, X. ^[1] ; Caballero, F. ^[1] ; Rodriguez-Lázaro, J. ^[1] ; Astibia, H. ^[1] ; Pereda-Suberbiola, X. ^[1]
  1. [1] Universidad del País Vasco/Euskal Herriko Unibertsitatea

     Universidad del País Vasco/Euskal Herriko Unibertsitatea

     Leioa, España

     
• Localización: Geogaceta, ISSN 0213-683X, Nº. 22, 1997 (Ejemplar dedicado a: 22ª Sesión Científica, Bilbao 1997), págs. 129-132
• Idioma: español
• Títulos paralelos:
  • Preliminary report on the Lower Miocene ostracodes from Las Bardenas Reales of Navarra: (Ebro Basin)
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• Resumen

  • The outcrops of the Tudela Formation, Lower Miocene (Ramblian), in the Bardenas Reales of Navarra (western area of the Ebro Basin) are very rich on vertebrate remains (fishes, amphibians, reptiles, birds and mammals), gastropods and microfauna of ostracodes and charas. Lithologies are composed by silts, marls and limestones, with sporadic levels of sandstones, deposited in a distal alluvial and lacustrine environment. Ostracode assemblages that have been studied from nine sections of this formation, show a dominance of the genera Nannocandona, Heterocypris, lIyocypris and limnocytherids, which are characteristics of a shallow lacustrifle environment, with fresh to oligohalyne and vegetated waters. The analysis of the assemblages, salinity and other ecologic ranges of these ostracode faunas allow to differentiate two phases in the lake evolution: the first phase (biozone "Z", Daams and Freudenthal, 1989) with a fresh water, carbonated and warm climate lake, and a second phase (biozone «A», Daams and Freudenthal, 1989) with bicarbonated, alcaline waters in aclimate context where seasonality was more evident. The transition between both phases was marked by several euryhaline intervals, indicators of the environmental instability that affected those microfaunas during the water chemistry transition.