Oligocene cave sediments in Co. Cork: implications for reconstructing the Tertiary landscape of southwest Ireland
  • 【DOI】

    10.1016/S0016-7878(00)80092-9

  • 【摘要】

    Clay fill from a large fissure in Carboniferous Limestone at Ballygiblin, east of Kanturk, Co. Cork, has yielded a low diversity palynomorph assemblage indicating an Oligocene age for the sediments. T... 展开>>Clay fill from a large fissure in Carboniferous Limestone at Ballygiblin, east of Kanturk, Co. Cork, has yielded a low diversity palynomorph assemblage indicating an Oligocene age for the sediments. The configuration of this fissure indicates that it represents a series of phreatic loops developed towards the downstream end of a major cave system. Canyon-like passages developed through paragenesis, with upward dissolution of the roof occurring simultaneously with sediment deposition on the floor. Consequently, the age of the karst conduit is penecontemporaneous with the sediment infill rather than being significantly older. Similar, as yet undated, sediments fill large phreatic cave passages at Subulter Quarry, 1.5 km to the northwest and 30 m higher. The abundance of mud-flake breccias in these latter sediments suggest a closer proximity to the vadose zone. The relative abundance of Oligocene cave passages preserved in this area indicates that their survival is due to slow rates of surface lowering, perhaps as low as 3 m Ma ?1, rather than unusual depths of cave development. It can be estimated that resurgence level in the area has fallen by less than 50 m and regional surface lowering by less than 100 m since the Oligocene. Consideration of the relationship between outcrop and drainage patterns suggests that the major landscape elements in southwest Ireland have changed little since mid-Tertiary times. 收起<<

  • 【作者】

  • 【刊期】

    Proceedings of the Geologists' Association 2000年4期

  • 【语种】

    eng