coastal dune soils in oregon, usa, forming allophane and gibbsite by
DESCRIPTION
Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by. Georg H. Grathoff Curt D. Peterson Darren L. Beckstrand. Funded by:. Objective. Determine the age and mechanism of dune emplacement Determine whether soil/paleosol mineralogy can constrain age of emplacement. Study Area. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/1.jpg)
Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite
by
Georg H. GrathoffCurt D. Peterson
Darren L. Beckstrand
Funded by:
![Page 2: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/2.jpg)
Objective
• Determine the age and mechanism of dune emplacement
• Determine whether soil/paleosol mineralogy can constrain age of emplacement
![Page 3: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/3.jpg)
0 100 200 300 Kilometers
####
#############
#############################################################
##################################################################################################
#####
##
#### #
#################################################################################
#
#######
###########
######
#
####
##
##
S
N
EW
Dunesheets
Sample Locations#
Figure 1. Study area dune sheets in Oregon, SW Washington and N. California, and context map.Sample locations are where dune characteristics have already been collected by this research group, funding provided by Seagrant and USGS.Bathymetry shows 20 meter contours.
Columbia River
Oregon
Washington
Pac
ific
Oce
an
CLAT
NEHA
PACI
LINC
NEWP
FLOR
COOS
BAND
GOLD
LONG
GRAYNORT
CRESCalifornia
Study Area
![Page 4: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/4.jpg)
Importance of the paleosols
• Influence stability
• Control groundwater chemistry and flow
• Indicate age
![Page 6: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/6.jpg)
“Weeping sands”
![Page 8: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/8.jpg)
0 100 200 300 Kilometers
####
#############
#############################################################
##################################################################################################
#####
##
#### #
#################################################################################
#
#######
###########
######
#
####
##
##
S
N
EW
Dunesheets
Sample Locations#
Figure 1. Study area dune sheets in Oregon, SW Washington and N. California, and context map.Sample locations are where dune characteristics have already been collected by this research group, funding provided by Seagrant and USGS.Bathymetry shows 20 meter contours.
Columbia River
Oregon
Washington
Pac
ific
Oce
an
CLAT
NEHA
PACI
LINC
NEWP
FLOR
COOS
BAND
GOLD
LONG
GRAYNORT
CRESCalifornia
Study Area
![Page 9: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/9.jpg)
Map of TL and 14C dates in ka BP. Core names are in parentheses. (from Beckstrand 2001)
![Page 10: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/10.jpg)
Eustatic sea level fluctuations and absolute elevations. Chappell and Shackleton (1986) (A), Shackleton (1987) (B), and Bloom and Yonekura (1985) (C). Boxes indicated probable errors of age and height related to curve C. Modified from Pirazzoli (1993). From Beckstrand; 2001
![Page 11: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/11.jpg)
Results:Minerals in Dunal Soils
1) Gibbsite: Al(OH)3
2) Allophane/Imogolite: amorphous Al-Silicate
3) Vermiculite and/or chlorite
4) Fe oxides/hydroxides
![Page 12: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/12.jpg)
1) Gibbsite
![Page 13: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/13.jpg)
![Page 14: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/14.jpg)
X-ray Diffraction results
Gibbsite002
Gibbsite110
Gibbsite
5.35 Å 200
![Page 15: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/15.jpg)
![Page 16: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/16.jpg)
2) Allophane replacing tree roots
Seal Rock State Park
![Page 17: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/17.jpg)
Allophane/Imogolite replacing whole pieces of tree
![Page 18: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/18.jpg)
![Page 19: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/19.jpg)
Allophane replacing woodBlue: Allophane
Green: Opal-a
X-ray Diffraction
![Page 20: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/20.jpg)
X-ray Diffraction
![Page 21: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/21.jpg)
XRD data from Wada (1989)
![Page 22: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/22.jpg)
Chemistry
Si:Al ratio
This study (microprobe):1: 1.3 to 1:1.8
Wada (1989):allophane 1:1 to 1:1.5imogolite 1:1.7 to 1:1.8
![Page 23: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/23.jpg)
TGA analysis of tree replacement
Temperature (°C)50 900
Weight loss
Derivative of weight loss
![Page 24: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/24.jpg)
TGA and DTA data forallophane and imogolite(Wada 1989)
![Page 25: Coastal Dune Soils in Oregon, USA, Forming Allophane and Gibbsite by](https://reader035.vdocuments.us/reader035/viewer/2022081603/5681474b550346895db48e52/html5/thumbnails/25.jpg)
Conclusion
• Gibbsite – forms under highly permeable conditions (change in pH)
– Fills cavities not replacing minerals
• Allophane/imogolite – Replaces woody material
– One phase or two phases
• Indication of high Al mobility• Where does the silica go (kinetics?)