Combined remote sensing analyses and landform evolution modeling reveal the terrestrial Bosumtwi impact structure as a Mars-like rampart crater

2019 ◽  
Vol 506 ◽  
pp. 209-220 ◽  
Author(s):  
G. Wulf ◽  
S. Hergarten ◽  
T. Kenkmann
Keyword(s):  
Remote Sensing ◽  
Impact Structure ◽  
Landform Evolution ◽  
Evolution Modeling

scholarly journals Rivers as linear elements in landform evolution models

2020 ◽  
Vol 8 (2) ◽  
pp. 367-377 ◽  
Author(s):  
Stefan Hergarten
Keyword(s):  
Strong Dependence ◽  
Scaling Relation ◽  
Landform Evolution ◽  
Mountain Ranges ◽  
Fluvial Erosion ◽  
Drainage Networks ◽  
Catchment Size ◽  
Linear Elements ◽  
Evolution Modeling ◽  
Hillslope Processes

Abstract. Models of detachment-limited fluvial erosion have a long history in landform evolution modeling in mountain ranges. However, they suffer from a scaling problem when coupled to models of hillslope processes due to the flux of material from the hillslopes into the rivers. This scaling problem causes a strong dependence of the resulting topographies on the spatial resolution of the grid. A few attempts based on the river width have been made in order to avoid the scaling problem, but none of them appear to be completely satisfying. Here a new scaling approach is introduced that is based on the size of the hillslope areas in relation to the river network. An analysis of several simulated drainage networks yields a power-law scaling relation for the fluvial incision term involving the threshold catchment size where fluvial erosion starts and the mesh width. The obtained scaling relation is consistent with the concept of the steepness index and does not rely on any specific properties of the model for the hillslope processes.

scholarly journals Rivers as linear elements in landform evolution models

2020 ◽  
Author(s):  
Stefan Hergarten
Keyword(s):  
Strong Dependence ◽  
Scaling Relation ◽  
Landform Evolution ◽  
Mountain Ranges ◽  
Fluvial Erosion ◽  
Drainage Networks ◽  
Catchment Size ◽  
Linear Elements ◽  
Evolution Modeling ◽  
Hillslope Processes

Abstract. Models of detachment-limited fluvial erosion have a long history in landform evolution modeling in mountain ranges. However, they suffer from a scaling problem when coupled to models of hillslope processes due to the flux of material from the hillslopes into the rivers. This scaling problem causes a strong dependence of the resulting topographies on the spatial resolution of the grid. A few attempts based on the river width have been made in order to avoid the scaling problem, but none of them appears to be completely satisfying. Here a new scaling approach is introduced that is based on the size of the hillslope areas in relation to the river network. An analysis of several simulated drainage networks yields a power-law scaling relation for the fluvial incision term involving the threshold catchment size where fluvial erosion starts and the mesh width. The obtained scaling relation is consistent with the concept of the steepness index and does not rely on any specific properties of the model for the hillslope processes.

scholarly journals Clarketal_2021.zip

2021 ◽  
Author(s):  
Martin Clark
Keyword(s):  
South Africa ◽  
Remote Sensing ◽  
Impact Structure ◽  
Aerial Photo ◽  
Special Issue ◽  
Still Images ◽  
Spatial Expression ◽  
Post Impact

This dataset is supplementary to a submitted manuscript to MDPI: Geosciences, "Making an Impact" special issue.<div><br></div><div>Manuscript title: Post-impact faulting of the Holfontein Granophyre Dike of the Vredefort Impact Structure, South Africa, inferred from remote sensing, geophysics, and geochemistry.</div><div>Authors: Clark, M.D., Kovaleva, E., Huber, M.S., Fourie, F., Harris, C.<br><div><br></div><div>The file contains an aerial photo and videos acquired via a drone which document the spatial expression of the geological dike.</div></div><div><br></div><div>Resolution of video is 4k (3840x2160 pix). Resolution of still images is 5472x3648 pix.</div>

scholarly journals Clarketal_2021.zip

2021 ◽  
Author(s):  
Martin Clark
Keyword(s):  
South Africa ◽  
Remote Sensing ◽  
Impact Structure ◽  
Aerial Photo ◽  
Special Issue ◽  
Still Images ◽  
Spatial Expression ◽  
Post Impact

This dataset is supplementary to a submitted manuscript to MDPI: Geosciences, "Making an Impact" special issue.<div><br></div><div>Manuscript title: Post-impact faulting of the Holfontein Granophyre Dike of the Vredefort Impact Structure, South Africa, inferred from remote sensing, geophysics, and geochemistry.</div><div>Authors: Clark, M.D., Kovaleva, E., Huber, M.S., Fourie, F., Harris, C.<br><div><br></div><div>The file contains an aerial photo and videos acquired via a drone which document the spatial expression of the geological dike.</div></div><div><br></div><div>Resolution of video is 4k (3840x2160 pix). Resolution of still images is 5472x3648 pix.</div>

The Cleanskin impact structure, Northern Territory and Queensland, Australia: A reconnaissance study

2021 ◽  
Author(s):  
T. Kenkmann ◽  
P.W. Haines ◽  
I.P. Sweet ◽  
K. Mitchell
Keyword(s):  
Remote Sensing ◽  
Northern Territory ◽  
Impact Structure ◽  
Impact Event ◽  
Deformation Features ◽  
Apparent Diameter ◽  
The Impact ◽  
Planar Deformation Features ◽  
Impact Origin ◽  
Quartz Grains

ABSTRACT We report on the Cleanskin structure (18°10′00″S, 137°56′30″E), situated at the border between the Northern Territory and Queensland, Australia, and present results of preliminary geological fieldwork, microscopic analyses, and remote sensing. The Cleanskin structure is an eroded complex impact structure of ~15 km apparent diameter with a polygonal outline caused by two preexisting regional fault sets. The structure has a central uplift of ~6 km diameter surrounded by a rather shallow ring syncline. Based on stratigraphy, the uplift in the center may not exceed ~1000 m. The documentation of planar deformation features (PDFs), planar fractures (PFs), and feather features (FFs) in quartz grains from sandstone members of the Mesoproterozoic Constance Sandstone confirms the impact origin of the Cleanskin structure, as proposed earlier. The crater was most likely eroded before the Cambrian and later became buried beneath Cretaceous strata. We infer a late Mesoproterozoic to Neoproterozoic age of the impact event. In this chapter, the Cleanskin structure is compared with other midsized crater structures on Earth. Those with sandstone-dominated targets show structural similarities to the Cleanskin structure.

scholarly journals Post-Impact Faulting of the Holfontein Granophyre Dike of the Vredefort Impact Structure, South Africa, Inferred from Remote Sensing, Geophysics, and Geochemistry

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 96
Author(s):  
Martin D. Clark ◽  
Elizaveta Kovaleva ◽  
Matthew S. Huber ◽  
Francois Fourie ◽  
Chris Harris
Keyword(s):  
South Africa ◽  
Remote Sensing ◽  
Crater Floor ◽  
Impact Structure ◽  
Impact Melt ◽  
Geophysical Modeling ◽  
Tectonic Events ◽  
Post Impact ◽  
The Impact

Better characterization features borne from long-term crustal modification processes is essential for understanding the dynamics of large basin-forming impact structures on Earth. Within the deeply eroded 2.02 Ga Vredefort Impact Structure in South Africa, impact melt dikes are exposed at the surface. In this study, we utilized a combination of field, remote sensing, electrical resistivity, magnetic, petrographical, and geochemical techniques to characterize one such impact melt dike, namely, the Holfontein Granophyre Dike (HGD), along with the host granites. The HGD is split into two seemingly disconnected segments. Geophysical modeling of both segments suggests that the melt rock does not penetrate below the modern surface deeper than 5 m, which was confirmed by a later transecting construction trench. Even though the textures and clast content are different in two segments, the major element, trace element, and O isotope compositions of each segment are indistinguishable. Structural measurements of the tectonic foliations in the granites, as well as the spatial expression of the dike, suggest that the dike was segmented by an ENE–WSW trending sinistral strike-slip fault zone. Such an offset must have occurred after the dike solidified. However, the Vredefort structure has not been affected by any major tectonic events after the impact occurred. Therefore, the inferred segmentation of the HGD is consistent with long-term crustal processes occurring in the post-impact environment. These crustal processes may have involved progressive uplift of the crater floor, which is consistent with post-impact long-term crustal adjustment that has been inferred for craters on the Moon.

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