Sedimentary architecture of the Santo André transverse dunes (Portugal) interpreted from ground-penetrating radar

The sedimentary architecture of Santo André transverse dunes was analyzed applying Ground Penetrating Radar, using a shielded 100 MHz frequency antenna. GPR data were collected along two W-E orientated lines, in two different ridges (western ridge - profile STA10 and eastern ridge - profile STA9). B...

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Bibliographic Details
Published in:Journal of coastal research 2011-01, Vol.SI (64), p.303-307
Main Authors: Ramos, R., Freitas, M. C., Bristow, C.S., Andrade, C., Hermozilha, H., Grangeia, C., Matias, M. Senos
Format: Article
Language:English
Subjects:
Architecture
Coastal Dunes
Coastal zone management
Deposition
Dunes
Ground penetrating radar
Migration
Radar
Reflection
Ridges
Sedimentation & deposition
Water table
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Summary:The sedimentary architecture of Santo André transverse dunes was analyzed applying Ground Penetrating Radar, using a shielded 100 MHz frequency antenna. GPR data were collected along two W-E orientated lines, in two different ridges (western ridge - profile STA10 and eastern ridge - profile STA9). Both profiles show clear images of the internal architecture of the transverse dunes, with sets of cross-stratification dipping eastward, indicating dune migration from W to E inland from the coast. At the bottom of both images lies a high amplitude and continuous reflection corresponding to water table. Reflections within the dunes indicate west to east (inland) dune migration with sets of cross-strata and bounding surfaces. The identification of seven stratigraphic units in the eastern profile and two in the western profile suggests a more complex depositional history in the landward (eastern) dune ridge. In the eastern profile a bounding surface (high-amplitude and irregular reflection) was identified as a period of dune stabilization. The geometry resembles an ancient topographic surface, interpreted as a period that may have favored soil development. After this phase, a new migration episode occurred covering the soil. Correlation with several boreholes indicates that the reflections found on the radargrams seem to be related with changes in water, organic matter and Fe content and grain size. The western dune (STA10) is interpreted to be younger than the eastern dune (STA9) which is further inland. The older dune appears to have a more complex history of stabilization and reworking commensurate with its greater age.
ISSN:0749-0208
1551-5036