Aggradation and dissection sequences on spanish alluvial fans: Influence on morphological development |
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| Authors: | AM Harvey |
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| Institution: | Dept. of Geography, University of Liverpool, PO Box 147, Liverpool, L 69 3BX England |
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| Abstract: | Similarities in Quaternary alluvial fan development are identified throughout southeast Spain. Pre-Wurm aggradation phases culminate in calcrete crusted upper fan surfaces, which are followed by Wurm dissection phases producing deep fanhead or through trenches. Deposits of the aggradation phases reflect source area size, relief and geology and in addition to proximal/distal facies variations show vertical decreases in debris flow and increases in gravel deposition. The dissection phases were complicated by cut and fill sequences forming within-trench terraces which show a southward decrease in complexity. The sequences are expressed in progressive changes in fan, terrace, and channel slopes and intersection point location. Fan morphological development during the Quaternary reflects long term progressive change, complicated by short term responses to climatic fluctuations and further comolicated by the locally variable effectiveness of trenching thresholds. |
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