La influencia glaciomanna en la sedimentación hirnatiense (Ordovicico terminal) de las Cadenas Ibéricas y Hespéricas (NE de España)

• J.J. Álvaro ^[2] ; E. Vennin ^[3] ; E. Villas ^[1]
  1. [1] Universidad de Zaragoza

     Universidad de Zaragoza

     Zaragoza, España

     
  2. [2] Université des Sciences et Technologies de Lille
  3. [3] Muséum national d’Histoire naturelle

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• Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 6, 2, 2004 (Ejemplar dedicado a: IV Congreso Geológico de España), págs. 17-18
• Idioma: español
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• Resumen

  • Hirnantian grounded ice covered parts o f the northern Gondwana margin. A belt o f Hirnantian glaciomarine deposits has been envisaged surrounding the North-Gondwana grounded ice, as described in the Hesperian Chains, the Armorican Massif, eastern Avalonia, Turkey, etc. As theglaciogenic sedimentation depended upon the hydrodynamic regime, frequency and intensity o fwaves, currents, tides, as well as the depth and geometry o f the platforms, the Hirnantian deposition recorded in the Iberian and Hesperian Chains (NE Spain) is somewhat unique when compared with other neighbouring basins because both platforms were located in temperate latitudes,recorded dropstone and glaciomarine deposits, and faced the same margin o f Gondwana. H ow ever, they differ in their platform geometries (Iberian intra-shelf ramp vs. Hesperian horst-and-depression-related platform), and thus recorded different local hydrodynamics and thicknesses. Asa result, offshore ice rafting yielded a special signature in mixed (glaciomarine vs background)facies, such as in diamictites bearing chaotic silts to blocks, tectonically breccia levels related tosynsedimentary faults in the Hesperian platform, and fine-grained shales related to background-dominated conditions, and contorted and slumped beds in the Iberian platform.