A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Post-wildfire denudation assessed from compositional features of river sediments (Central Portugal)
https://orcid.org/0000-0001-7558-7369
https://orcid.org/0000-0002-7297-8863
Abstract The wildfires of 2017 were responsible for vegetation clearance in a wide area of central Portugal, leaving the weathering profiles more exposed to erosive action. In the present research, suspended loads from a set of catchment areas affected by these fires with diverse geological and orographic features were periodically sampled to evaluate spatial and seasonal variability in sediment production. Bulk mineralogy reflected the geology of the source areas, but displayed high variability even for a single sampling site, which can be partially linked to the grain-size control on sediment composition. Clay mineralogy provided a better picture of the denudation at catchment scale. The predominance of detrital illite with low I5/I10 (ratio of the intensities at 5 Å (002) and 10 Å (001)) indicated very shallow weathering profiles. Chlorite was usually the second most common mineral, more common in metasedimentary-derived sediments, whilst kaolinite was detected only in less steep catchment areas with a predominance of granitic basement rocks or where previous-cycle depositional units are also present. Year-long shifts in clay assemblages were attributed to different spatial patterns of denudation. A depletion of kaolinite occurred in sampling sites mainly sourced by granitoids. An opposite trend was observed where areas with Meso-Cenozoic deposits, less affected by the wildfires than those with basement units, occupy significant proportions of the drainage basins. This trend was ascribed to the wearing out of the weathering profiles covering the basement. Regolith denudation was also testified by a progressive decrease in I5/I10. Shifts in clay mineralogy linked with progressive surface denudation were found to be limited in areas with shallow soils, but may complicate any paleoenvironmental reconstructions based on sediment composition when more evolved weathering profiles have been eroded.
Highlights Sediment composition influenced by yields from areas with different geology. Proxies of land surface denudation in the mineralogy of the clay fraction Denudation led to depletion in minerals associated with more intense weathering. Shifts in source area can promote opposing trends of clay mineralogy.
Post-wildfire denudation assessed from compositional features of river sediments (Central Portugal)
https://orcid.org/0000-0001-7558-7369
https://orcid.org/0000-0002-7297-8863
Abstract The wildfires of 2017 were responsible for vegetation clearance in a wide area of central Portugal, leaving the weathering profiles more exposed to erosive action. In the present research, suspended loads from a set of catchment areas affected by these fires with diverse geological and orographic features were periodically sampled to evaluate spatial and seasonal variability in sediment production. Bulk mineralogy reflected the geology of the source areas, but displayed high variability even for a single sampling site, which can be partially linked to the grain-size control on sediment composition. Clay mineralogy provided a better picture of the denudation at catchment scale. The predominance of detrital illite with low I5/I10 (ratio of the intensities at 5 Å (002) and 10 Å (001)) indicated very shallow weathering profiles. Chlorite was usually the second most common mineral, more common in metasedimentary-derived sediments, whilst kaolinite was detected only in less steep catchment areas with a predominance of granitic basement rocks or where previous-cycle depositional units are also present. Year-long shifts in clay assemblages were attributed to different spatial patterns of denudation. A depletion of kaolinite occurred in sampling sites mainly sourced by granitoids. An opposite trend was observed where areas with Meso-Cenozoic deposits, less affected by the wildfires than those with basement units, occupy significant proportions of the drainage basins. This trend was ascribed to the wearing out of the weathering profiles covering the basement. Regolith denudation was also testified by a progressive decrease in I5/I10. Shifts in clay mineralogy linked with progressive surface denudation were found to be limited in areas with shallow soils, but may complicate any paleoenvironmental reconstructions based on sediment composition when more evolved weathering profiles have been eroded.
Highlights Sediment composition influenced by yields from areas with different geology. Proxies of land surface denudation in the mineralogy of the clay fraction Denudation led to depletion in minerals associated with more intense weathering. Shifts in source area can promote opposing trends of clay mineralogy.
Post-wildfire denudation assessed from compositional features of river sediments (Central Portugal)
https://orcid.org/0000-0001-7558-7369
https://orcid.org/0000-0002-7297-8863
Abstract The wildfires of 2017 were responsible for vegetation clearance in a wide area of central Portugal, leaving the weathering profiles more exposed to erosive action. In the present research, suspended loads from a set of catchment areas affected by these fires with diverse geological and orographic features were periodically sampled to evaluate spatial and seasonal variability in sediment production. Bulk mineralogy reflected the geology of the source areas, but displayed high variability even for a single sampling site, which can be partially linked to the grain-size control on sediment composition. Clay mineralogy provided a better picture of the denudation at catchment scale. The predominance of detrital illite with low I5/I10 (ratio of the intensities at 5 Å (002) and 10 Å (001)) indicated very shallow weathering profiles. Chlorite was usually the second most common mineral, more common in metasedimentary-derived sediments, whilst kaolinite was detected only in less steep catchment areas with a predominance of granitic basement rocks or where previous-cycle depositional units are also present. Year-long shifts in clay assemblages were attributed to different spatial patterns of denudation. A depletion of kaolinite occurred in sampling sites mainly sourced by granitoids. An opposite trend was observed where areas with Meso-Cenozoic deposits, less affected by the wildfires than those with basement units, occupy significant proportions of the drainage basins. This trend was ascribed to the wearing out of the weathering profiles covering the basement. Regolith denudation was also testified by a progressive decrease in I5/I10. Shifts in clay mineralogy linked with progressive surface denudation were found to be limited in areas with shallow soils, but may complicate any paleoenvironmental reconstructions based on sediment composition when more evolved weathering profiles have been eroded.
Highlights Sediment composition influenced by yields from areas with different geology. Proxies of land surface denudation in the mineralogy of the clay fraction Denudation led to depletion in minerals associated with more intense weathering. Shifts in source area can promote opposing trends of clay mineralogy.
Post-wildfire denudation assessed from compositional features of river sediments (Central Portugal)
Dinis, Pedro A. (author) / Sequeira, Mário (author) / Tavares, Alexandre O. (author) / Carvalho, Joel (author) / Castilho, Ana (author) / Cabral Pinto, Marina (author)
Applied Clay Science ; 193
2020-05-13
Article (Journal)
Electronic Resource
English
Hydrocarbons in particulate samples from wildfire events in central Portugal in summer 2010
| Online Contents | 2017
Hydrocarbons in particulate samples from wildfire events in central Portugal in summer 2010
| Online Contents | 2016
Assessing Wildfire Hazard in the Wildland–Urban Interfaces (WUIs) of Central Portugal
| DOAJ | 2023
Distribution of Selected Heavy Metals in Sediments of the Águeda River (Central Portugal)
| Online Contents | 2005
Distribution of Selected Heavy Metals in Sediments of the Águeda River (Central Portugal)*
| Online Contents | 2005