Various ideas about the main controlling factors for terrace formation in the Lower Miño River basin are proposed, but no consensus exists. Absence of fossils and other chronostratigraphical markers make long-distance correlations between the terraces remnants along the river profile tentative. The most accepted view is that the terrace remnants tread parallel to the current river bed, because terraces are found at similar altitudes above river level throughout the Lower Miño region. This in turn, would favour an interglacial origin for the terrace deposits. Precise mapping of terrace distribution and the weathering state of quartzite pebbles in the fluvial terraces however, suggests that the terraces do not tread parallel to the current river bed. This is confirmed by a numerical modelling evaluation with the FLUVER2 model of the development of the Miño longitudinal profile for the past 450 ka. The results indicate that the proximity of a steep and narrow passive margin in combination with eccentricity-induced eustatic changes are the main controlling factors for valley incision and terrace formation. They cause a strong lowering in base level, which results in a much steeper river profile gradient of approximately 1 m km-1 during periods of low sea level.
|Title of host publication||VII Symposium on the Atlantic Iberian Margin, 16-20 december 2012, Lisboa|
|Place of Publication||Universidade de Lisboa, Portugal|
|Publication status||Published - 2012|
|Event||VII Symposium on the Atlantic Iberian Margin, 16-20 december 2012 - |
Duration: 16 Dec 2012 → 20 Dec 2012
|Conference||VII Symposium on the Atlantic Iberian Margin, 16-20 december 2012|
|Period||16/12/12 → 20/12/12|