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Unravelling the patterns of alluvial fan development using mineral magnetic analysis: examples from the Sparta Basin, Lakonia, southern Greece
Author(s) -
Pope Richard J. J.,
Millington Andrew C.
Publication year - 2000
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/1096-9837(200006)25:6<601::aid-esp94>3.0.co;2-m
Subject(s) - alluvial fan , sedimentary depositional environment , geology , geochemistry , structural basin , holocene , paleontology , paleosol , geomorphology , loess
Mineral magnetic analysis of B‐horizons of soils developing upon the surfaces of alluvial fans was undertaken in order to: (i) differentiate and rank discrete fan surfaces by order of formation; (ii) establish whether fan surfaces formed simultaneously in adjacent fan systems; and (iii) deduce probable patterns of fan development. The results of the analysis indicate that the greatest concentration of ferrimagnetic and anti‐ferromagnetic minerals occurs within soils which have developed upon the proximal fan surfaces with a progressive reduction in magnetic minerals in soils associated with medial and distal surfaces. The build‐up of magnetic minerals in the proximal fan soils suggests that these surfaces formed first followed by the medial and distal surfaces. With the exception of the Kalivia Sokas fan, the majority of depositional events responsible for fan surface formation occurred simultaneously, suggesting that adjacent fan systems share broadly similar depositional histories. Although the precise timing of depositional events is uncertain, it is probable that by the end of the late Pleistocene, small, largely undissected fans comprising two to three surfaces had formed. At the start of the Holocene, fan systems experienced significant fanhead incision. A net distal extension of the fan trench coupled with a progressive basinward shift of the locus of deposition during the middle and late Holocene resulted in formation of medial and distal fan surfaces. Changes in climate are deemed to be the major control of fanhead incision, fan trenching and fan surface formation. However, the likely effects of long‐term tectonic activity and approximately five thousand years of human occupation upon fan development in the Sparta Basin remain unclear. Copyright © 2000 John Wiley & Sons, Ltd.