Journal articles on the topic 'Landscape regolith'
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1
Ott, Richard F., Sean F. Gallen, and Darryl E. Granger. "Cosmogenic nuclide weathering biases: corrections and potential for denudation and weathering rate measurements." Geochronology 4, no. 2 (July 6, 2022): 455–70. http://dx.doi.org/10.5194/gchron-4-455-2022.
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Abstract. Cosmogenic radionuclides (CRNs) are the standard tool to derive centennial-to-millennial timescale denudation rates; however, it has been demonstrated that chemical weathering in some settings can bias CRNs as a proxy for landscape denudation. Currently, studies investigating CRN weathering biases have mostly focused on the largely insoluble target mineral quartz in felsic lithologies. Here, we examine the response of CRN build-up for both soluble and insoluble target minerals under different weathering scenarios. We assume a simple box model in which bedrock is converted to a well-mixed regolith at a constant rate, and denudation occurs by regolith erosion and weathering either in the regolith or along the regolith–bedrock interface, as is common in carbonate bedrock. We show that weathering along the regolith–bedrock interface increases CRN concentrations compared to a no-weathering case and how independently derived weathering rates or degrees can be used to correct for this bias. If weathering is concentrated within the regolith, insoluble target minerals will have a longer regolith residence time and higher nuclide concentration than soluble target minerals. This bias can be identified and corrected using paired-nuclide measurements of minerals with different solubility coupled with knowledge of either the bedrock or regolith mineralogy to derive denudation and long-term weathering rates. Similarly, single-nuclide measurements on soluble or insoluble minerals can be corrected to determine denudation rates if a weathering rate and compositional data are available. Our model highlights that for soluble target minerals, the relationship between nuclide accumulation and denudation is not monotonic. We use this understanding to map the conditions of regolith mass, weathering, and denudation rates at which weathering corrections for cosmogenic nuclides become large and ambiguous, as well as identify environments in which the bias is mostly negligible and CRN concentrations reliably reflect landscape denudation. We highlight how measurements of CRNs from soluble target minerals, coupled with bedrock and regolith mineralogy, can help to expand the range of landscapes for which centennial-to-millennial timescale denudation and weathering rates can be obtained.
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Ollier, C. D. "Evolution of the Australian landscape." Marine and Freshwater Research 52, no. 1 (2001): 13. http://dx.doi.org/10.1071/mf00032.
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Landscape evolution of Australia is on the same time scale as global tectonics and biological evolution. In places, actual landforms and deep weathering products are hundreds of millions of years old. Much of Australia has a landscape resulting from stripping of weathered rock after an earlier period of very deep weathering. Other regions have sequential landforms that provide a natural laboratory where we can work out the biogeochemistry of the past. Landforms and regolith reveal the long evolution of groundwater in Australia. Lateral movement of groundwater is of paramount importance. The effects of past climates are stored in the landscape. They show that the present is not the key to the past, and former environments must be worked out from consistent internal evidence rather than the application of models based on present-day conditions. Inorganic chemistry alone is inadequate to explain many earth materials, and biology, especially microbiology, has a very significant role. Recent and present-day processes also affect the landscape, and it cannot be assumed that because the landscape and regolith are old the soils are old. Many regions have a complex regolith cover that shows modern processes working on inherited materials.
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Grundy, M. J., R. A. Viscarra Rossel, R. D. Searle, P. L. Wilson, C. Chen, and L. J. Gregory. "Soil and Landscape Grid of Australia." Soil Research 53, no. 8 (2015): 835. http://dx.doi.org/10.1071/sr15191.
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The Soil and Landscape Grid of Australia (SLGA) is the first continental version of the GlobalSoilMap concept and the first nationally consistent, fine spatial resolution set of continuous soil attributes with Australia-wide coverage. The SLGA relies on digital soil mapping methods and integrates historical soil data, new measurement with spectroscopic sensors, novel spatial modelling and a web-service delivery architecture. The SLGA provides soil, regolith and landscape estimates at the centre point of 3 arcsecond grid cells (~90 × 90 m) across Australia. At each point, there are estimates of 11 soil attributes and confidence intervals for each estimate to a depth of 2 m or less, depth of regolith and a set of terrain descriptors. The information system also includes a library of mid-infrared spectra, an inference engine that allows estimation of additional soil parameters and an information model that enables users to access the system via web services. The explicit mapping of depth, bulk density and coarse fragments allows estimation of material stores and fluxes on a volumetric basis. The SLGA therefore has immediate applications in carbon, nitrogen and water process modelling. The map of regolith depth will find immediate application to studies of vadose zone processes, including solute transport, groundwater and nutrient fluxes beyond the root zone. Landscape attributes at 1 and 3 arcseconds are useful for a wide spectrum of ecological, hydrological and broader environmental applications. The SLGA can be accessed at no cost from www.csiro.au/soil-and-landscape-grid. It is managed and delivered as part of the Australian Soil Resource Information System (ASRIS).
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Depicker, Arthur, Gerard Govers, Liesbet Jacobs, Benjamin Campforts, Judith Uwihirwe, and Olivier Dewitte. "Interactions between deforestation, landscape rejuvenation, and shallow landslides in the North Tanganyika–Kivu rift region, Africa." Earth Surface Dynamics 9, no. 3 (May 31, 2021): 445–62. http://dx.doi.org/10.5194/esurf-9-445-2021.
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Abstract. Deforestation is associated with a decrease in slope stability through the alteration of hydrological and geotechnical conditions. As such, deforestation increases landslide activity over short, decadal timescales. However, over longer timescales (0.1–10 Myr) the location and timing of landsliding is controlled by the interaction between uplift and fluvial incision. Yet, the interaction between (human-induced) deforestation and landscape evolution has hitherto not been explicitly considered. We address this issue in the North Tanganyika–Kivu rift region (East African Rift). In recent decades, the regional population has grown exponentially, and the associated expansion of cultivated and urban land has resulted in widespread deforestation. In the past 11 Myr, active continental rifting and tectonic processes have forged two parallel mountainous rift shoulders that are continuously rejuvenated (i.e., actively incised) through knickpoint retreat, enforcing topographic steepening. In order to link deforestation and rejuvenation to landslide erosion, we compiled an inventory of nearly 8000 recent shallow landslides in © Google Earth imagery from 2000–2019. To accurately calculate landslide erosion rates, we developed a new methodology to remediate inventory biases linked to the spatial and temporal inconsistency of this satellite imagery. Moreover, to account for the impact of rock strength on both landslide occurrence and knickpoint retreat, we limit our analysis to rock types with threshold angles of 24–28∘. Rejuvenated landscapes were defined as the areas draining towards Lake Kivu or Lake Tanganyika and downstream of retreating knickpoints. We find that shallow landslide erosion rates in these rejuvenated landscapes are roughly 40 % higher than in the surrounding relict landscapes. In contrast, we find that slope exerts a stronger control on landslide erosion in relict landscapes. These two results are reconciled by the observation that landslide erosion generally increases with slope gradient and that the relief is on average steeper in rejuvenated landscapes. The weaker effect of slope steepness on landslide erosion rates in the rejuvenated landscapes could be the result of three factors: the absence of earthquake-induced landslide events in our landslide inventory, a thinner regolith mantle, and a drier climate. More frequent extreme rainfall events in the relict landscapes, and the presence of a thicker regolith, may explain a stronger landslide response to deforestation compared to rejuvenated landscapes. Overall, deforestation initiates a landslide peak that lasts approximately 15 years and increases landslide erosion by a factor 2 to 8. Eventually, landslide erosion in deforested land falls back to a level similar to that observed under forest conditions, most likely due to the depletion of the most unstable regolith. Landslides are not only more abundant in rejuvenated landscapes but are also smaller in size, which may again be a consequence of a thinner regolith mantle and/or seismic activity that fractures the bedrock and reduces the minimal critical area for slope failure. With this paper, we highlight the importance of considering the geomorphological context when studying the impact of recent land use changes on landslide activity.
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EMILIA YOLANDA AGUILERA, AGUSTINA REATO, OSCAR MARTÍNEZ, EUGENIO ARAGÓN, and JORGE RABASSA. "GRANITIC LANDSCAPE IN THE MUNRO PLUTON (TAPERA DE BURGOS), PROVINCE OF CHUBUT, PATAGONIA, ARGENTINA." William Morris Davis – Revista de Geomorfologia 1, no. 1 (August 14, 2020): 47–74. http://dx.doi.org/10.48025/issn2675-6900.v1n1.p47-74.2020.
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The Munro Pluton is located in the extra-Andean region of the province of Chubut, Argentina, in northern Patagonia, northeast of the Sierra de Tecka and northwest of the Sierra de Languineo. It is a sub-volcanic pluton with a SHRIMP age of 60 Ma (Paleocene?). Studies of fission tracks on apatites of the studied region suggest that the exhumation of the region took place during the Paleogene, indicating that the lapse since its emplacement until its exhumation, took less than 35 Ma, and that the pluton has been exposed to weathering at least since the Miocene until present times. This pluton has ellipsoidal shape and a surface of 25 km2 and it is intruded by two dyke systems. The Munro Pluton develops a landscape whose weathering front exposes fresh rocks, regolith zones and boulders immersed in regolith. Granitic landforms have been recognized at different scales. Among the bigger landforms of the granitic landscape, the following have been identified: domes (bornhardts), nubbins, koppies and smaller landforms such as boulders, flared slopes, gnammas, rills/gutters/gullies, tafoni and pseudo-bedding. Structural and textural observations allowed the inference that many of the identified landforms are generated in the sub-soil, being followed by the regolith mobilization thus exposing the paleo-weathering front. Other landforms have a tectonic component associated for their development, such as pseudo-bedding, as well as the endogenous deformations, related to the emplacement type of the Munro pluton. In general, most of the landforms are convergent as they evolve along different pathways.
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Marshall, Jill A., Joshua J. Roering, Patrick J. Bartlein, Daniel G. Gavin, Darryl E. Granger, Alan W. Rempel, Sarah J. Praskievicz, and Tristram C. Hales. "Frost for the trees: Did climate increase erosion in unglaciated landscapes during the late Pleistocene?" Science Advances 1, no. 10 (November 2015): e1500715. http://dx.doi.org/10.1126/sciadv.1500715.
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Understanding climatic influences on the rates and mechanisms of landscape erosion is an unresolved problem in Earth science that is important for quantifying soil formation rates, sediment and solute fluxes to oceans, and atmospheric CO2regulation by silicate weathering. Glaciated landscapes record the erosional legacy of glacial intervals through moraine deposits and U-shaped valleys, whereas more widespread unglaciated hillslopes and rivers lack obvious climate signatures, hampering mechanistic theory for how climate sets fluxes and form. Today, periglacial processes in high-elevation settings promote vigorous bedrock-to-regolith conversion and regolith transport, but the extent to which frost processes shaped vast swaths of low- to moderate-elevation terrain during past climate regimes is not well established. By combining a mechanistic frost weathering model with a regional Last Glacial Maximum (LGM) climate reconstruction derived from a paleo-Earth System Model, paleovegetation data, and a paleoerosion archive, we propose that frost-driven sediment production was pervasive during the LGM in our unglaciated Pacific Northwest study site, coincident with a 2.5 times increase in erosion relative to modern rates. Our findings provide a novel framework to quantify how climate modulates sediment production over glacial-interglacial cycles in mid-latitude unglaciated terrain.
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Mcfarlane, DJ, and RJ George. "Factors affecting dryland salinity in two wheat belt catchments in Western Australia." Soil Research 30, no. 1 (1992): 85. http://dx.doi.org/10.1071/sr9920085.
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We investigated why the Wallatin Creek Catchment in the Western Australian wheatbelt had an appreciable area of secondary salinity whereas the adjoining North Baandee Catchment had almost none. The Wallatin Creek Catchment, which is long and narrow, had a shallow regolith over granite bedrock. Although this catchment had less salt stored in the regolith than the wider North Baandee Catchment, the groundwaters came close to the ground surface because the regolith was thin and the valley cross-section narrow. Management practices which increase recharge (e.g. using level banks to control runoff), are likely to result in increased salinity in the short term in the Wallatin Creek Catchment. We also investigated whether retaining areas of remnant vegetation had reduced the amount of secondary salinity in a sub-catchment of the Wallatin Creek Catchment. At comparable positions in the landscape, groundwater levels were up to 7 m lower under the remnant vegetation. The vegetation appears to have delayed, if not prevented, the development of salinity in nearby and downslope areas.
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King, Andrew, and Ignacio Gonzalez-Alvarez. "Constraining Airborne Electromagnetic Interpretation with Regolith Stratigraphy and Landscape Evolution Processes." ASEG Extended Abstracts 2018, no. 1 (December 2018): 1–5. http://dx.doi.org/10.1071/aseg2018abp041.
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Chan, R. A. "Evolution of the Girilambone regolith landscape, central-western New South Wales." Australian Journal of Earth Sciences 56, sup1 (July 2009): S105—S123. http://dx.doi.org/10.1080/08120090902871135.
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Dosseto, Anthony, Heather L. Buss, and P. O. Suresh. "Rapid regolith formation over volcanic bedrock and implications for landscape evolution." Earth and Planetary Science Letters 337-338 (July 2012): 47–55. http://dx.doi.org/10.1016/j.epsl.2012.05.008.
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Schmidt, Amanda H., Thomas B. Neilson, Paul R. Bierman, Dylan H. Rood, William B. Ouimet, and Veronica Sosa Gonzalez. "Influence of topography and human activity on apparent in situ <sup>10</sup>Be-derived erosion rates in Yunnan, SW China." Earth Surface Dynamics 4, no. 4 (November 4, 2016): 819–30. http://dx.doi.org/10.5194/esurf-4-819-2016.
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Abstract. In order to understand better if and where erosion rates calculated using in situ 10Be are affected by contemporary changes in land use and attendant deep regolith erosion, we calculated erosion rates using measurements of in situ 10Be in quartz from 52 samples of river sediment collected from three tributaries of the Mekong River (median basin area = 46.5 km2). Erosion rates range from 12 to 209 mm kyr−1 with an area-weighted mean of 117 ± 49 mm kyr−1 (1 standard deviation) and median of 74 mm kyr−1. We observed a decrease in the relative influence of human activity from our steepest and least altered watershed in the north to the most heavily altered landscapes in the south. In the areas of the landscape least disturbed by humans, erosion rates correlate best with measures of topographic steepness. In the most heavily altered landscapes, measures of modern land use correlate with 10Be-estimated erosion rates but topographic steepness parameters cease to correlate with erosion rates. We conclude that, in some small watersheds with high rates and intensity of agricultural land use that we sampled, tillage and resultant erosion has excavated deeply enough into the regolith to deliver subsurface sediment to streams and thus raise apparent in situ 10Be-derived erosion rates by as much as 2.5 times over background rates had the watersheds not been disturbed.
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Moore, C. L., B. R. Jenkins, A. L. Cowood, A. Nicholson, R. Muller, A. Wooldridge, W. Cook, et al. "Hydrogeological Landscapes framework: a biophysical approach to landscape characterisation and salinity hazard assessment." Soil Research 56, no. 1 (2018): 1. http://dx.doi.org/10.1071/sr16183.
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In Australia, salinity has the potential to affect up to 17million hectares of agricultural and pastoral land. For many degraded sites, biophysical hazards are often poorly understood and consequently poorly managed. Attempts to remediate areas affected by salinity have met with varying degrees of success. The New South Wales (NSW) Office of Environment and Heritage, NSW Department of Primary Industries, University of Canberra and Geoscience Australia have collaborated to develop a biophysical expert-based approach for the assessment and management of salinity within landscapes. The Hydrogeological Landscape (HGL) framework provides a structure for understanding how salinity manifests in the landscape, how differences in salinity are expressed across the landscape and how salinity may best be managed. The HGL framework merges the flow dynamics of the groundwater flow system with the landscape elements of the soil landscape or regolith landform approaches. This is the first approach to specifically address all three manifestations of salinity: land salinity, in-stream salt load and in-stream salt concentration. The HGL framework methodology recognises the interplay between surface and subsurface flow systems, as well as the capacity for water to interact with salt stores in the landscape, and identifies biophysical landscape characteristics (e.g. amount and type of vegetation cover, typical land use practice) that affect these interactions. The HGL framework is an expert system that integrates the spatial variability of landscape characteristics and salinity processes to produce a salinity hazard assessment for any given area.
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Ramos, Maria Angélica, Marcelo Dantas, Maria Adelaide Maia, Iris Bandeira, José Barros, Vivian Fernandes, Pedro Pfaltzgraff, and Carlos Eduardo Ferreira. "Mapping of superficial formations: a methodological proposal for systematic cartography of the Brazilian territory." Journal of the Geological Survey of Brazil 3, no. 3 (December 2020): 169–88. http://dx.doi.org/10.29396/jgsb.2020.v3.n3.3.
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We present a methodological proposal for the systematic mapping of superficial formations applicable on a national scale. The importance of such a proposition stems from the fact that a large part of the Brazilian territory is located in a humid or semi-humid tropical zone, where deeply weathered and sometimes tens of meters thick lateritized regolith mantles develop. The methodological approach consists of a geological-geomorphological-pedological compartmentalization of the terrains, together with elements of morphostratigraphic analysis and of the intrinsic properties of saprolites and soils. This approach, structured in a GIS environment, was applied in two different areas in Brazil: The Federal District and the São Luis island in the state of Maranhão, where the complex geodiversity of the regolith landscape stands out in both areas. The results highlight the diversity of horizons in the regolith profile, in addition to its anisotropy. The recognition of the complexity of these superficial formations is, therefore, of great importance for a more detailed analysis of various themes, such as for civil works; susceptibility to erosion and mass movements; potential for aquifer recharge; and mineral potential. Finally, the importance of the study of superficial formations is emphasized for the improvement of geological mapping and for the multi-thematic analysis of the physical environment applied to land management.
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Goodfellow, B. W., A. P. Stroeven, D. Fabel, O. Fredin, M. H. Derron, R. Bintanja, and M. W. Caffee. "Arctic-alpine blockfields in northern Sweden: Quaternary not Neogene." Earth Surface Dynamics Discussions 2, no. 1 (February 10, 2014): 47–93. http://dx.doi.org/10.5194/esurfd-2-47-2014.
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Abstract. Slowly-eroding, blockfield-mantled, non-glacial surface remnants may serve as markers against which to determine Quaternary glacial erosion volumes in high latitude mountain settings. To investigate this potential utility of these surfaces, chemical weathering, erosion rates, and origins of mountain blockfields are investigated in northern Sweden. This is done, firstly, by assessing the intensity of regolith chemical weathering along altitudinal transects descending from three blockfield-mantled summits. Clay/silt ratios, secondary mineral assemblages determined through X-ray diffraction, and the presence of chemically weathered grains visible on scanning electron microscopy, in fine matrix samples collected from pits excavated along the transects are each used for this purpose. Secondly, erosion rates and total surface histories of two of the summits are inferred from concentrations of in situ-produced cosmogenic 10Be and 26Al in quartz at the blockfield surface. An interpretative model is adopted that includes temporal variations in nuclide production rates through surface burial by glacial ice and glacial isostasy-induced elevation changes of the blockfield surfaces. Together, our data indicate that these blockfields are not derived from remnants of intensely weathered Neogene weathering profiles, as is commonly considered. Evidence for this interpretation includes minor chemical weathering in each of the three examined blockfields, despite some differences according to slope position. In addition, average erosion rates of ∼16.2 mm ka−1 and ∼6.7 mm ka−1, calculated for two blockfield-mantled summits, are low but of sufficient magnitude to remove present blockfield mantles, of up to a few meters in thickness, within a late-Quaternary timeframe. Hence, blockfield mantles appear to be replenished by regolith formation through, primarily physical, weathering processes that have operated during the Quaternary. Erosion rates remain low enough, however, for blockfield-mantled, non-glacial surface remnants to provide reasonable landscape markers against which to contrast Quaternary erosion volumes in surrounding glacial landscape elements. The persistence of blockfield mantles over a number of glacial-interglacial cycles and an apparently low likelihood that they can re-establish on glacially eroded bedrock, also discounts the operation of a "glacial buzz-saw" on surface remnants that are presently perceived as non-glacial. These interpretations are tempered though by outstanding questions concerning the composition of preceding Neogene regoliths and why they have apparently been comprehensively removed from these remnant non-glacial surfaces. It remains possible that periglacial erosion of perhaps more intensely weathered Neogene regoliths was high during the Pliocene–Pleistocene transition to colder conditions and that periglacial processes reshaped non-glacial surface remnants largely before the formation of blockfield armours.
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Williams, B., J. Walker, and J. Anderson. "Spatial variability of regolith leaching and salinity in relation to Whole Farm Planning." Australian Journal of Experimental Agriculture 46, no. 10 (2006): 1271. http://dx.doi.org/10.1071/ea04110.
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An electromagnetic induction (EM31) survey was carried out on a 700-ha property in the western basalt plains of Victoria. The apparent electrical conductivity (ECa) was interpreted in terms of the inferred salt content and, hence, the degree of leaching or recharge through the upper 5 m of the regolith. The focus of the survey was to determine the spatial variability of ECa across a landscape of low relief which included salt lakes. The area mapped is subject to regional groundwater discharge. All parts of the property exhibited hydrological ‘sinks’ and ‘trenches’ of relatively low ECa values, interpreted as areas of preferential recharge or leaching through the regolith. They ranged in size from 200 to 500 m in diameter and/or length and were not related to relief. This apparent hydrological ‘holeyness’ of the upper regolith suggests local recharge into the regional groundwater system. This finding has important implications for Whole Farm Planning and Environmental Management Strategies as local recharge can be reduced by manipulating ground cover and land-use practices. Both the mean and standard deviation of ECa values across the property provide a rational basis for planning land management practices. The location of hydrological ‘holes’ can be built in as significant layers in Whole Farm Plans to minimise water entering the water table and/or salt lakes.
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Petts, Anna E., and Steven M. Hill. "Reading the Regolith: Mapping the Landscape and Developing an Understanding of the Contribution of Soil Biota to Regolith Formation in Northern Australia." ASEG Extended Abstracts 2006, no. 1 (December 2006): 1–6. http://dx.doi.org/10.1071/aseg2006ab131.
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Goodfellow, B. W., A. P. Stroeven, D. Fabel, O. Fredin, M. H. Derron, R. Bintanja, and M. W. Caffee. "Arctic–alpine blockfields in the northern Swedish Scandes: late Quaternary – not Neogene." Earth Surface Dynamics 2, no. 2 (July 21, 2014): 383–401. http://dx.doi.org/10.5194/esurf-2-383-2014.
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Abstract. Autochthonous blockfield mantles may indicate alpine surfaces that have not been glacially eroded. These surfaces may therefore serve as markers against which to determine Quaternary erosion volumes in adjacent glacially eroded sectors. To explore these potential utilities, chemical weathering features, erosion rates, and regolith residence durations of mountain blockfields are investigated in the northern Swedish Scandes. This is done, firstly, by assessing the intensity of regolith chemical weathering along altitudinal transects descending from three blockfield-mantled summits. Clay / silt ratios, secondary mineral assemblages, and imaging of chemical etching of primary mineral grains in fine matrix are each used for this purpose. Secondly, erosion rates and regolith residence durations of two of the summits are inferred from concentrations of in situ-produced cosmogenic 10Be and 26Al in quartz at the blockfield surfaces. An interpretative model is adopted that includes temporal variations in nuclide production rates through surface burial by glacial ice and glacial isostasy-induced elevation changes of the blockfield surfaces. Together, our data indicate that these blockfields are not derived from remnants of intensely weathered Neogene weathering profiles, as is commonly considered. Evidence for this interpretation includes minor chemical weathering in each of the three examined blockfields, despite consistent variability according to slope position. In addition, average erosion rates of ~16.2 and ~6.7 mm ka−1, calculated for the two blockfield-mantled summits, are low but of sufficient magnitude to remove present blockfield mantles, of up to a few metres in thickness, within a late Quaternary time frame. Hence, blockfield mantles appear to be replenished by regolith formation through, primarily physical, weathering processes that have operated during the Quaternary. The persistence of autochthonous blockfields over multiple glacial–interglacial cycles confirms their importance as key markers of surfaces that were not glacially eroded through, at least, the late Quaternary. However, presently blockfield-mantled surfaces may potentially be subjected to large spatial variations in erosion rates, and their Neogene regolith mantles may have been comprehensively eroded during the late Pliocene and early Pleistocene. Their role as markers by which to estimate glacial erosion volumes in surrounding landscape elements therefore remains uncertain.
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Furze, Shane, Antóin M. O’Sullivan, Serge Allard, Toon Pronk, and R. Allen Curry. "A High-Resolution, Random Forest Approach to Mapping Depth-to-Bedrock across Shallow Overburden and Post-Glacial Terrain." Remote Sensing 13, no. 21 (October 20, 2021): 4210. http://dx.doi.org/10.3390/rs13214210.
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Regolith, or unconsolidated materials overlying bedrock, exists as an active zone for many geological, geomorphological, hydrological and ecological processes. This zone and its processes are foundational to wide-ranging human needs and activities such as water supply, mineral exploration, forest harvesting, agriculture, and engineered structures. Regolith thickness, or depth-to-bedrock (DTB), is typically unavailable or restricted to finer scale assessments because of the technical and cost limitations of traditional drilling, seismic, and ground-penetrating radar surveys. The objective of this study was to derive a high-resolution (10 m2) DTB model for the province of New Brunswick, Canada as a case study. This was accomplished by developing a DTB database from publicly available soil profiles, boreholes, drill holes, well logs, and outcrop transects (n = 203,238). A Random Forest model was produced by modeling the relationships between DTB measurements in the database to gridded datasets derived from both a LiDAR-derived digital elevation model and photo-interpreted surficial geology delineations. In developing the Random Forest model, DTB measurements were split 70:30 for model development and validation, respectively. The DTB model produced an R2 = 92.8%, MAE = 0.18 m, and RMSE = 0.61 m for the training, and an R2 = 80.3%, MAE = 0.18 m, and RMSE = 0.66 m for the validation data. This model provides an unprecedented resolution of DTB variance at a landscape scale. Additionally, the presented framework provides a fundamental understanding of regolith thickness across a post-glacial terrain, with potential application at the global scale.
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Fu, Wei, Yangyang Feng, Peng Luo, Yinmeng Zhang, Xiaorong Huang, Xiangwei Zeng, Qian Cai, and Yongzhang Zhou. "Weathering of Ophiolite Remnant and Formation of Ni Laterite in a Strong Uplifted Tectonic Region (Yuanjiang, Southwest China)." Minerals 9, no. 1 (January 16, 2019): 51. http://dx.doi.org/10.3390/min9010051.
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The Yuanjiang Ni deposit in southwestern margin of the Yunnan Plateau is the only economically important lateritic Ni deposit in China. It contains 21.2 Mt ore with an average grade of 1.05 wt % Ni and has been recognized as the second largest Ni producer in China following the Jinchuan super-large magmatic Ni–Cu deposit. This Ni deposit is hosted within the lateritic regolith derived from serpentinite within the regional Paleo-Tethyan Ophiolite remnants. Local landscape controls the distribution of the Ni mineralized regolith, and spatially it is characterized by developing on several stepped planation surfaces. Three types of lateritic Ni ores are identified based on Ni-hosting minerals, namely oxide ore, oxide-silicate mixed ore and silicate ore. In the dominant silicate ore, two phyllosilicate minerals (serpentine and talc) are the Ni-host minerals. Their Ni compositions, however, are remarkably different. Serpentine (0.34–1.2 wt % Ni) has a higher Ni concentration than talc (0.18–0.26 wt % Ni), indicating that the serpentine is more significantly enriched in Ni during weathering process compared to talc. This explains why talc veining reduces Ni grade. The geochemical index (S/SAF value = 0.33–0.81, UMIA values = 17–60) indicates that the serpentinite-derived regolith has experienced, at least, weak to moderate lateritization. Based on several lines of paleoclimate evidence, the history of lateritization at Yuanjiang area probably dates to the Oligocene-Miocene boundary and has extended to the present. With a hydrology-controlled lateritization process ongoing, continuous operation of Ni migration from the serpentinite-forming minerals to weathered minerals (goethite and serpentine) gave rise to the development of three types of Ni ore in the regolith. Notably, the formation and preservation of the Yuanjiang lateritic Ni deposit has been strongly impacted by regional multi-staged tectonic uplift during the development of Yunnan Plateau. This active tectonic setting has promoted weathering of serpentinite and supergene Ni enrichment, but is also responsible for its partial erosion.
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Crawford, M. H., K. M. Williams, A. J. W. Biggs, and E. Dafny. "Salinity risk assessment of an irrigation development using treated coal seam gas water in the Condamine River catchment." Soil Research 59, no. 1 (2021): 44. http://dx.doi.org/10.1071/sr19375.
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All irrigation developments inherently carry a salinity risk, due to an unavoidable change in the water and salt balance. The time frame in which either land or water salinity will develop is driven by the ability of the landscape to absorb the change of water and salt supplied. Factors that influence this are landscape attributes, such as the size of the unsaturated zone and its properties (permeability and drainage), management considerations (land-use changes, water application rate and crop water use) and climate variability (temperature and rainfall). This study assessed the risk of secondary salinity expression occurring in an irrigation area in the Condamine-Balonne catchment in southern inland Queensland, Australia. The objectives were to (1) define the depth, size and properties of the unsaturated zone and regolith, (2) define deep drainage rates for past, present and future land uses and (3) assess this information to calculate the risk that groundwater table rise may result in surface salinity expression. Data collected during field investigations was used to conceptualise the regolith architecture, undertake hydrogeological modelling, estimate the available moisture storage capacity of the unsaturated zone and model paddock deep drainage characteristics. The work identified that irrigation-induced deep drainage had started to mobilise salt stores in the unsaturated zone. It also identified connectivity between land management and salt discharges into the Condamine River. As the water supply for the scheme is scheduled to continue until 2030, there is a clear risk of the unsaturated zone moisture storage capacity being exceeded, leading to both land and surface water salt expressions.
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Rovey, Charles W., and Greg Balco. "Periglacial Climate at the 2.5 Ma Onset of Northern Hemisphere Glaciation Inferred from the Whippoorwill Formation, Northern Missouri, USA." Quaternary Research 73, no. 1 (January 2010): 151–61. http://dx.doi.org/10.1016/j.yqres.2009.09.002.
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The Whippoorwill Formation is a gleyed diamicton that is present locally within bedrock depressions beneath the oldest glacial till in northern Missouri, USA. Stratigraphy, paleomagnetism, and cosmogenic–nuclide burial ages show that it was deposited between the Matuyama–Gauss magnetostratigraphic boundary at 2.58 Ma and the first advance of the Laurentide ice sheet into Missouri at 2.47 ± 0.19 Ma. High cosmogenic–nuclide concentrations also show that the constituents of the Whippoorwill Formation experienced long exposure at a stable landscape surface with erosion rates of 1–2 m/Ma. However, cosmogenic–nuclide concentrations are invariant with depth below the Whippoorwill Formation surface, indicating active mixing of the soil profile shortly before burial by till. The Whippoorwill Formation retains numerous features indicative of cryoturbation. Therefore, we interpret it as a buried Gelisol, a soil formed under periglacial conditions in the presence of permafrost. At the onset of Northern Hemisphere glaciation, climate cooling established permafrost conditions and accelerated erosion by inducing landscape instability. Thus, weathered regolith materials were mobilized and redeposited by gelifluction shortly before the ice sheet overrode the landscape.
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Worrall, L., T. J. Munday, and A. A. Green. "Airborne electromagnetics — Providing new perspectives on geomorphic process and landscape development in regolith-dominated terrains." Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy 24, no. 10 (January 1999): 855–60. http://dx.doi.org/10.1016/s1464-1895(99)00127-1.
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Egholm, D. L., J. L. Andersen, M. F. Knudsen, J. D. Jansen, and S. B. Nielsen. "The periglacial engine of mountain erosion – Part 2: Modelling large-scale landscape evolution." Earth Surface Dynamics 3, no. 4 (October 6, 2015): 463–82. http://dx.doi.org/10.5194/esurf-3-463-2015.
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Abstract. There is growing recognition of strong periglacial control on bedrock erosion in mountain landscapes, including the shaping of low-relief surfaces at high elevations (summit flats). But, as yet, the hypothesis that frost action was crucial to the assumed Late Cenozoic rise in erosion rates remains compelling and untested. Here we present a landscape evolution model incorporating two key periglacial processes – regolith production via frost cracking and sediment transport via frost creep – which together are harnessed to variations in temperature and the evolving thickness of sediment cover. Our computational experiments time-integrate the contribution of frost action to shaping mountain topography over million-year timescales, with the primary and highly reproducible outcome being the development of flattish or gently convex summit flats. A simple scaling of temperature to marine δ18O records spanning the past 14 Myr indicates that the highest summit flats in mid- to high-latitude mountains may have formed via frost action prior to the Quaternary. We suggest that deep cooling in the Quaternary accelerated mechanical weathering globally by significantly expanding the area subject to frost. Further, the inclusion of subglacial erosion alongside periglacial processes in our computational experiments points to alpine glaciers increasing the long-term efficiency of frost-driven erosion by steepening hillslopes.
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Cowood, A. L., J. Young, T. I. Dowling, C. L. Moore, R. Muller, J. MacKenzie, M. Littleboy, and A. T. Nicholson. "Assessing wetland climate change vulnerability for wetland management decision support using the hydrogeological landscape framework: application in the Australian Capital Territory." Marine and Freshwater Research 70, no. 2 (2019): 225. http://dx.doi.org/10.1071/mf17302.
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The hydrogeological landscape (HGL) framework provides a landscape characterisation method that identifies areas of similar physical, hydrogeological, hydrological, chemical and biological properties, referred to as HGL units. The underlying principle of the HGL framework is that water distribution and movement is controlled by climate, landform, geology, regolith, soil and vegetation properties. By understanding the patterns of variability in the setting and controls of atmospheric, surface and groundwater systems for a given landscape, the developed HGL units, and associated landscape element-based management areas, can be used for hazard assessment and natural resource management centred on water availability, quality, sustainability and associated ecological systems. Existing wetland frameworks also demonstrate that it is the hydrogeomorphological or hydrogeological characteristics of the landscape that will determine the variability in water inputs and outputs for a wetland water balance, a principle shared with the HGL framework. It is therefore logical that HGL units and management areas can be used as planning units for wetland hazard assessment and management. This paper presents an assessment of climate change vulnerability for 1296 wetlands across the Australian Capital Territory using indicators representing current anthropogenic pressure, future ecological change and future hydrological change. The use of management areas for the hazard assessment allows understanding of the patterns of variability in the chosen indicators and hazard assessment outcomes specifically for the areas to be managed. This approach allows consideration of the landscape setting when identifying suitable locations to undertake on-ground management actions to address the hazards identified.
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Bock, Michael, Olaf Conrad, Andreas Günther, Ernst Gehrt, Rainer Baritz, and Jürgen Böhner. "SaLEM (v1.0) – the Soil and Landscape Evolution Model (SaLEM) for simulation of regolith depth in periglacial environments." Geoscientific Model Development 11, no. 4 (April 27, 2018): 1641–52. http://dx.doi.org/10.5194/gmd-11-1641-2018.
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Abstract. We propose the implementation of the Soil and Landscape Evolution Model (SaLEM) for the spatiotemporal investigation of soil parent material evolution following a lithologically differentiated approach. Relevant parts of the established Geomorphic/Orogenic Landscape Evolution Model (GOLEM) have been adapted for an operational Geographical Information System (GIS) tool within the open-source software framework System for Automated Geoscientific Analyses (SAGA), thus taking advantage of SAGA's capabilities for geomorphometric analyses. The model is driven by palaeoclimatic data (temperature, precipitation) representative of periglacial areas in northern Germany over the last 50 000 years. The initial conditions have been determined for a test site by a digital terrain model and a geological model. Weathering, erosion and transport functions are calibrated using extrinsic (climatic) and intrinsic (lithologic) parameter data. First results indicate that our differentiated SaLEM approach shows some evidence for the spatiotemporal prediction of important soil parental material properties (particularly its depth). Future research will focus on the validation of the results against field data, and the influence of discrete events (mass movements, floods) on soil parent material formation has to be evaluated.
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Thomas, M., R. W. Fitzpatrick, and G. S. Heinson. "Distribution and causes of intricate saline - sodic soil patterns in an upland South Australian hillslope." Soil Research 47, no. 3 (2009): 328. http://dx.doi.org/10.1071/sr07191.
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We describe a soil–landscape investigation conducted in a South Australian upland hillslope (128 ha) to understand the distribution and causes of saline–sodic soil patterns using convenient, ground-based geophysical surveys of the hillslope. These surveys included: (i) EM31 for deep (~6 m) apparent electrical conductivity (ECa) patterns, (ii) EM38 for shallow (>1.5 m) ECa patterns, and (iii) Bartington MS2-D loop sensor for surface volume magnetic susceptibility (κ) patterns. From these surveys we inferred hillslope distributions of: (i) deep (~6 m) concentrations of salinity associated with deep groundwater systems and deposits of magnetic gravels (dominated by maghemite and hematite) (EM31 sensor); (ii) shallow (<1.5 m) soil salinity (EM38 sensor); and (iii) preservation of pedogenic magnetic materials (e.g. maghemite and hematite) (MS2-D loop sensor). We also describe terrain analysis to locate near-surface hydropedological patterns using topographic wetness index. When combined in 3D geographic information system, strong visual matches were identified between patterns in: (i) geophysical surveys, (ii) terrain, and (iii) soil survey data, thus allowing integrated interpretations of soil–landscape pedogenic processes to be made on a whole-of-landscape basis. Such mechanistic interpretations of soil–landscape processes reveal and map intricate saline and sodic soil–regolith patterns and groundwater and fresh surface water flow paths that were not revealed during a previous traditional soil survey.
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PRENDERGAST, M. D. "LANDSCAPE EVOLUTION, REGOLITH FORMATION AND NICKEL LATERITE DEVELOPMENT IN THE NORTHERN PART OF THE GREAT DYKE, ZIMBABWE." South African Journal of Geology 116, no. 2 (December 1, 2013): 219–40. http://dx.doi.org/10.2113/gssajg.116.2.219.
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George, Richard, Jonathan Clarke, and Pauline English. "Modern and palaeogeographic trends in the salinisation of the Western Australian wheatbelt: a review." Soil Research 46, no. 8 (2008): 751. http://dx.doi.org/10.1071/sr08066.
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The Western Australian wheatbelt contains vast areas of agricultural land underlayed by saline and deeply weathered regolith derived from Archaean rocks and recent sediments. The region has been geologically stable since the late Permian, although the Archaean basement sustained some movement during the break-up of Gondwanaland and the northward drift of Australia from Antarctica. During the Early Cretaceous, Eocene and more recently, the wheatbelt region’s weathered mantle has been successively eroded by rivers. The palaeovalleys have been infilled with terrestrial and marine sediments, and subjected to ongoing deep weathering. During the Pliocene and Quaternary the region experienced alternating arid and wetter climates. These cyclic episodes influenced regolith development, affected vegetation species and catchment water balances, and also promoted the accumulation of massive volumes of salt. In more recent times, these salt stores have interacted with vegetation, soils, surface water bodies, and groundwater systems and left a distinctive and pervasive legacy in the landscape. Salinisation was manifest in the wheatbelt from as long ago as 2.8 Ma, concentrating in valley floors as arid and wetter cycles prevailed and while the continent migrated northwards. Today, agricultural development has altered the water balance on 20 Mha of cleared farmland. As a result, salinity is spreading, further degrading 300 000 ha of variably saline landscape that existed before the arrival of Europeans, and affecting an additional 1.1 Mha of formerly arable land. Unchecked by reduced rainfall or human-induced changes to the water balance, salinity may expand even further, potentially affecting 1.7–3.4 Mha of the wheatbelt’s agricultural land and its unique natural resources. This paper reviews the palaeogeography and palaeoclimates of the region and its hydrogeology and examines the nature of its susceptibility to salinisation. It poses questions about the relationship between palaeo-salinity and contemporary salinity, seeking geomorphic evidence to indicate whether salinity is likely to expand beyond extant palaeo-salinity markers. Finally, it considers the likely timeframes involved in salinisation and whether clearing-induced salinity will follow patterns similar to those observed from past saline episodes in the region.
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Salama, Walid, Ignacio González-Álvarez, and Ravi R. Anand. "Significance of weathering and regolith/landscape evolution for mineral exploration in the NE Albany-Fraser Orogen, Western Australia." Ore Geology Reviews 73 (March 2016): 500–521. http://dx.doi.org/10.1016/j.oregeorev.2015.07.024.
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McQueen, K. G., O. R. Gonzalez, I. C. Roach, B. J. Pillans, W. J. Dunlap, and M. L. Smith. "Landscape and regolith features related to Miocene leucitite lava flows, El Capitan northeast of Cobar, New South Wales." Australian Journal of Earth Sciences 54, no. 1 (February 2007): 1–17. http://dx.doi.org/10.1080/08120090600923311.
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Hurst, M. D., M. A. Ellis, K. R. Royse, K. A. Lee, and K. Freeborough. "Controls on the magnitude-frequency scaling of an inventory of secular landslides." Earth Surface Dynamics Discussions 1, no. 1 (July 1, 2013): 113–39. http://dx.doi.org/10.5194/esurfd-1-113-2013.
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Abstract. Linking landslide size and frequency is important at both human and geological time-scales for quantifying both landslide hazards and the effectiveness of landslides in the removal of sediment from evolving landscapes. Landslide inventories are usually compiled following a particular triggering event such as an earthquake or storm, and their statistical behavior is typically characterized by an inflected power-law relationship. The occurrence of landslides is expected to be influenced by the material properties of rock and/or regolith in which failure occurs. Here we explore the statistical behavior and the controls of a secular landslide inventory (SLI) (i.e. events occurring over an indefinite time period) consisting of mapped landslide deposits and their underlying lithology (bedrock or superficial) across the United Kingdom. The magnitude-frequency distribution of this secular inventory exhibits an inflected power law relationship, well approximated by an inverse Gamma or double Pareto model. The scaling exponent for the power-law relationship is α = −1.76. The small-event rollover occurs at a significantly higher magnitude than observed in single-event landslide records, which we interpret as evidence of “landscape annealing” at these relatively short length-scales, noting the corollary that a secular dataset will tend to underestimate the frequency of small landslides. This is supported by a subset of data where a complete landslide inventory was recently mapped. Large landslides also appear to be under-represented relative to model predictions, which we interpret as a non-linear or transient landscape response as the UK emerged from the last glacial maximum and through relatively volatile conditions toward a generally more stable late Holocene climate.
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Hurst, M. D., M. A. Ellis, K. R. Royse, K. A. Lee, and K. Freeborough. "Controls on the magnitude-frequency scaling of an inventory of secular landslides." Earth Surface Dynamics 1, no. 1 (December 11, 2013): 67–78. http://dx.doi.org/10.5194/esurf-1-67-2013.
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Abstract. Linking landslide size and frequency is important at both human and geological timescales for quantifying both landslide hazards and the effectiveness of landslides in the removal of sediment from evolving landscapes. The statistical behaviour of the magnitude-frequency of landslide inventories is usually compiled following a particular triggering event such as an earthquake or storm, and their statistical behaviour is often characterised by a power-law relationship with a small landslide rollover. The occurrence of landslides is expected to be influenced by the material properties of rock and/or regolith in which failure occurs. Here we explore the statistical behaviour and the controls of a secular landslide inventory (SLI) (i.e. events occurring over an indefinite geological time period) consisting of mapped landslide deposits and their underlying lithology (bedrock or superficial) across the United Kingdom. The magnitude-frequency distribution of this secular inventory exhibits an inflected power-law relationship, well approximated by either an inverse gamma or double Pareto model. The scaling exponent for the power-law scaling of medium to large landslides is α = −1.71 ± 0.02. The small-event rollover occurs at a significantly higher magnitude (1.0–7.0 × 10−3 km2) than observed in single-event landslide records (~ 4 × 10−3 km2). We interpret this as evidence of landscape annealing, from which we infer that the SLI underestimates the frequency of small landslides. This is supported by a subset of data where a complete landslide inventory was recently mapped. Large landslides also appear to be under-represented relative to model predictions. There are several possible reasons for this, including an incomplete data set, an incomplete landscape (i.e. relatively steep slopes are under-represented), and/or temporal transience in landslide activity during emergence from the last glacial maximum toward a generally more stable late-Holocene state. The proposed process of landscape annealing and the possibility of a transient hillslope response have the consequence that it is not possible to use the statistical properties of the current SLI database to rigorously constrain probabilities of future landslides in the UK.
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Cracknell, M. J., and A. L. Cowood. "Construction and analysis of Hydrogeological Landscape units using Self-Organising Maps." Soil Research 54, no. 3 (2016): 328. http://dx.doi.org/10.1071/sr15016.
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The Hydrogeological Landscape (HGL) framework divides geographic space into regions with similar landscape characteristics. HGL regions or units are used to facilitate appropriate management actions tailored to individual HGL units for specific applications such as dryland salinity and climate-change hazard assessment. HGL units are typically constructed by integrating data including geology, regolith, soils, rainfall, vegetation and landscape morphology, and manually defining boundaries in a GIS environment. In this study, we automatically construct spatially contiguous regions from standard HGL data using Self-Organising Maps (SOM), an unsupervised statistical learning algorithm. We compare the resulting SOM-HGL units with manually interpreted HGL units in terms of their spatial distributions and attribute characteristics. Our results show that multiple SOM-HGL units successfully emulate the spatial distributions of individual HGL units. SOM-HGL units are shown to define subregions of larger HGL units, indicating subtle variations in attribute characteristics and representing landscape complexities not mapped during manual interpretation. We also show that SOM-HGL units with similar attributes can be selected using Boolean logic. Selected SOM-HGL units form regions that closely conform to multiple HGL units not necessarily connected in geographic space. These SOM-HGL units can be used to establish generalised land management strategies for areas with common physical characteristics. The use of SOM for the construction of HGL units reduces the subjectivity with which these units are defined and will be especially useful over large and/or inaccessible regions, where conducting field-based validation is either logistically or economically impractical. The methodology presented here has the potential to contribute significantly to land-management decision-support systems based on the HGL framework.
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Wakelin-King, Gresley. "Using geomorphology to assess contour furrowing in western New South Wales, Australia." Rangeland Journal 33, no. 2 (2011): 153. http://dx.doi.org/10.1071/rj10080.
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This study examines landscape rehabilitation treatments installed 20–40 years ago in the Western Catchment of NSW. Treatment outcomes were assessed using geomorphic criteria, because geomorphic processes are fundamental to ecological permanence. Contour furrowing creates artificial runoff-runon sets which intercept runoff (resistance to flow by windrows microrelief and surface roughness) and promote infiltration (artificial permeability by ripping). As originally conceived, after windrows subside, flow resistance would be afforded by surface roughness under belts of vegetation. This study shows that rehabilitation treatments have a more complex relationship with the landscape than this would suggest, and that the final effect of the treatment depends on the geomorphic processes natural to the site. Treatment design should therefore be site-specific. The relevant aspects of treatment design are site location, runoff : runon ratio (expressed as furrow spacing and furrow length), furrow placement, and post-treatment management. Some long-term successes are documented. In ironstone ridge country affected by impermeable hard-setting soils, furrowing creates artificial permeability, allowing plant germination; plant material in the soil reverses hard-setting and establishes self-sustaining permeability. In stony gilgai country furrowing through vegetated patches can aid in re-establishing vegetation, but furrowing through stony runoff patches only diminishes, rather than improves, landscape function. Other landscape types will have different key attributes. In all cases, selection of appropriate sites for rehabilitation treatment is of primary importance. The 1990s NSW Soil Conservation Service best-practice included a specialised furrower, surveying techniques for accurate furrow placement along the contour, staggered gaps along each furrow line to reduce risks of gullying by windrow breakthrough, and post-treatment management of total grazing pressure. New guidelines for treatment design developed from this study include determining for each site the optimum runoff:runon ratio (which varies according to climate, gradient, vegetation, and regolith), and matching furrow spacing and furrow/gap length to local runoff:runon ratios. In stony gilgai country, furrow placement should be along the contour but within non-stony patches; elsewhere, placement should be rigorously along the contour. In ironstone ridge country, a greater runoff:runon ratio, commensurate with the area’s apparently larger patch scale, can be achieved by having more gap than furrow along each furrow line. No single rehabilitation technique will fit all landscape types, and these guidelines will ideally be developed further with investigation of other landscapes.
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Hill, S. M., R. A. Eggleton, and G. Taylor. "Neotectonic disruption of silicified palaeovalley systems in an intraplate, cratonic landscape: regolith and landscape evolution of the Mulculca range-front, Broken Hill Domain, New South Wales." Australian Journal of Earth Sciences 50, no. 5 (October 2003): 691–707. http://dx.doi.org/10.1111/j.1440-0952.2003.01020.x.
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Campbell, Mae Kate, Paul R. Bierman, Amanda H. Schmidt, Rita Sibello Hernández, Alejandro García-Moya, Lee B. Corbett, Alan J. Hidy, et al. "Cosmogenic nuclide and solute flux data from central Cuban rivers emphasize the importance of both physical and chemical mass loss from tropical landscapes." Geochronology 4, no. 2 (July 5, 2022): 435–53. http://dx.doi.org/10.5194/gchron-4-435-2022.
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Abstract. We use 25 new measurements of in situ produced cosmogenic 26Al and 10Be in river sand, paired with estimates of dissolved load flux in river water, to characterize the processes and pace of landscape change in central Cuba. Long-term erosion rates inferred from 10Be concentrations in quartz extracted from central Cuban river sand range from 3.4–189 Mg km−2 yr−1 (mean 59, median 45). Dissolved loads (10–176 Mg km−2 yr−1; mean 92, median 97), calculated from stream solute concentrations and modeled runoff, exceed measured cosmogenic-10Be-derived erosion rates in 18 of 23 basins. This disparity mandates that in this environment landscape-scale mass loss is not fully represented by the cosmogenic nuclide measurements. The 26Al / 10Be ratios are lower than expected for steady-state exposure or erosion in 16 of 24 samples. Depressed 26Al / 10Be ratios occur in many of the basins that have the greatest disparity between dissolved loads (high) and erosion rates inferred from cosmogenic nuclide concentrations (low). Depressed 26Al / 10Be ratios are consistent with the presence of a deep, mixed, regolith layer providing extended storage times on slopes and/or burial and extended storage during fluvial transport. River water chemical analyses indicate that many basins with lower 26Al / 10Be ratios and high 10Be concentrations are underlain at least in part by evaporitic rocks that rapidly dissolve. Our data show that when assessing mass loss in humid tropical landscapes, accounting for the contribution of rock dissolution at depth is particularly important. In such warm, wet climates, mineral dissolution can occur many meters below the surface, beyond the penetration depth of most cosmic rays and thus the production of most cosmogenic nuclides. Our data suggest the importance of estimating solute fluxes and measuring paired cosmogenic nuclides to better understand the processes and rates of mass transfer at a basin scale.
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Marc, Odin, André Stumpf, Jean-Philippe Malet, Marielle Gosset, Taro Uchida, and Shou-Hao Chiang. "Initial insights from a global database of rainfall-induced landslide inventories: the weak influence of slope and strong influence of total storm rainfall." Earth Surface Dynamics 6, no. 4 (October 10, 2018): 903–22. http://dx.doi.org/10.5194/esurf-6-903-2018.
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Abstract. Rainfall-induced landslides are a common and significant source of damages and fatalities worldwide. Still, we have little understanding of the quantity and properties of landsliding that can be expected for a given storm and a given landscape, mostly because we have few inventories of rainfall-induced landslides caused by single storms. Here we present six new comprehensive landslide event inventories coincident with well identified rainfall events. Combining these datasets, with two previously published datasets, we study their statistical properties and their relations to topographic slope distribution and storm properties. Landslide metrics (such as total landsliding, peak landslide density, or landslide distribution area) vary across 2 to 3 orders of magnitude but strongly correlate with the storm total rainfall, varying over almost 2 orders of magnitude for these events. Applying a normalization on the landslide run-out distances increases these correlations and also reveals a positive influence of total rainfall on the proportion of large landslides. The nonlinear scaling of landslide density with total rainfall should be further constrained with additional cases and incorporation of landscape properties such as regolith depth, typical strength or permeability estimates. We also observe that rainfall-induced landslides do not occur preferentially on the steepest slopes of the landscape, contrary to observations from earthquake-induced landslides. This may be due to the preferential failures of larger drainage area patches with intermediate slopes or due to the lower pore-water pressure accumulation in fast-draining steep slopes. The database could be used for further comparison with spatially resolved rainfall estimates and with empirical or mechanistic landslide event modeling.
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Webb, T. H., B. D. Fahey, K. M. Giddens, S. Harris, C. C. Pruden, and J. S. Whitton. "Soil-landscape and soil-hydrological relationships in the Glendhu Experimental Catchments, East Otago Uplands, New Zealand." Soil Research 37, no. 4 (1999): 761. http://dx.doi.org/10.1071/sr98102.
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Soil-landscape relationships were investigated in a first-order catchment and a fifth-order catchment of the Waipori River. The soils are formed mainly from loess and loess−colluvium derived fromschist, with limited inclusions of rock material from under lying schist bedrock. Five soil series are identified primarilyon the basis of differences in soil drainage. Occurrence of soil series within the landscape is related to a combination of aspect and slope angle while the depth of regolith is related to a combination of landform element and slope angle. Five soil profiles within a first-order catchment were analysed for chemical, mineralogical, and hydrological properties. Allsoils are acidic, strongly leached, and moderately weathered. Pedogenesis and geomorphology are discussed in relation to glacial history, climate, and vegetation. Evidence is presented to indicate that the change from forest to tussock grassland vegetation, 700−1000 years ago, has had a major impact on the development of a perch-gley profile morphology. Permeable conditions are largely confined to the upper 0·10−0·15 m depth and to underlying very stony horizons below 0·50 m depth. All profiles have one or more horizons with very slow permeability. Under high or prolonged rainfall conditions, water will perch above slowly permeable horizons and flow laterally within more permeable surface horizons. This conclusion is in agreement with previous water-flow measurements in the catchment.
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Balks, M. R., and T. A. O’Neill. "Soil and permafrost in the Ross Sea region of Antarctica: stable or dynamic?" Cuadernos de Investigación Geográfica 42, no. 2 (September 13, 2016): 415. http://dx.doi.org/10.18172/cig.2923.
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Soils in the Ross Sea Region of Antarctica generally comprise a surface desert pavement and a seasonally thawed active layer over permafrost. Most soils are formed on regolith such as glacial till or colluvium. Mean annual air temperatures range from -18°C to -24°C with low precipitation. The active layer ranges in depth from minimal in higher altitude, colder sites, to near 1 m deep at warmer coastal sites in the northern part of the region. Underlying permafrost may be ice-cemented, or dry with no ice cement. In some areas ice-cored moraine occurs where there is a large body of ice within the subsoil permafrost. Two examples of active gully/fan -forming events, one at Cape Evans and one at Lake Vanda are described. At the Cape Evans event water from a small lake thawed and came into contact with the ice in the underlying patterned ground ice-wedge causing the ice-wedge to melt and extensive gully erosion to occur. A fan-building event near Lake Vanda in the Wright Valley resulted in erosive and depositional features covering a horizontal distance of about 3 km and an altitudinal range of about 1400 m. Such occasional events, can be attributed to warmer than average summers, and were first described in the Ross Sea Region in the 1970s. The Cape Evans and Lake Vanda events are examples of active, rapid, landscape processes and show that landscapes are not as static as is often assumed.
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Smedberg, E., C. Humborg, M. Jakobsson, and C. M. Mörth. "Landscape elements and river chemistry as affected by river regulation – a 3-D perspective." Hydrology and Earth System Sciences 13, no. 9 (September 9, 2009): 1597–606. http://dx.doi.org/10.5194/hess-13-1597-2009.
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Abstract. We tested the hypothesis whether individual land classes within a river catchment contribute equally to river loading with dissolved constituents or whether some land classes act as "hot spots" to river loading and if so, are these land classes especially affected by hydrological alterations. The amount of land covered by forests and wetlands and the average soil depth (throughout this paper soil refers to everything overlying bedrock i.e. regolith) of a river catchment explain 58–93% of the variability in total organic carbon (TOC) and dissolved silicate (DSi) concentrations for 22 river catchments in Northern Sweden. For the heavily regulated Luleälven, with 7 studied sub-catchments, only 3% of the headwater areas have been inundated by reservoirs, some 10% of the soils and aggregated forest and wetland areas have been lost due to damming and further hydrological alteration such as bypassing entire sub-catchments by headrace tunnels. However, looking at individual forest classes, our estimates indicate that some 37% of the deciduous forests have been inundated by the four major reservoirs built in the Luleälven headwaters. These deciduous forest and wetlands formerly growing on top of alluvial deposits along the river corridors forming the riparian zone play a vital role in loading river water with dissolved constituents, especially DSi. A digital elevation model draped with land classes and soil depths which highlights that topography of various land classes acting as hot spots is critical in determining water residence time in soils and biogeochemical fluxes. Thus, headwater areas of the Luleälven appear to be most sensitive to hydrological alterations due to the thin soil cover (on average 2.7–4.5 m) and only patchy appearance of forest and wetlands that were significantly perturbed. Hydrological alterations of these relatively small headwater areas significantly impacts downstream flux of dissolved constituents and their delivery to receiving water bodies.
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Clarke, C. J., R. J. George, R. W. Bell, and R. J. Hobbs. "Major faults and the development of dryland salinity in the western wheatbelt of Western Australia." Hydrology and Earth System Sciences 2, no. 1 (March 31, 1998): 77–91. http://dx.doi.org/10.5194/hess-2-77-1998.
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Abstract. Dryland salinity poses a major threat to agricultural production in the wheatbelt of Western Australia and much time and effort is expended on understanding the mechanisms which cause it and on developing techniques to halt or reverse its development. Whilst the location of much dryland salinity can be explained by its topographic position, a significant proportion of it cannot. This study investigated the hypothesis that major faults in the Yilgarn Craton represented in aeromagnetic data by intense curvilinear lows explained the location of areas of dryland salinity not explained by topography. Moreover, the causal mechanisms that might underpin a spatial relationship between major faults and dryland salinity were sought. In one fourth order catchment, nearly 85% of the salinity that was not explained topographically was within 2km of the centre line of a major fault, the remaining 15% being in the other 12km of the catchment. Three groups of similar third order catchments in the western wheatbelt of Western Australia were also investigated; in each case the catchment that was underlain by a major fault had dryland salinity an order of magnitude more than the unfaulted catchment(s). This evidence demonstrates a strong spatial association between major faults and the development of dryland salinity. Other evidence suggests that the underlying mechanism is hydraulic conductivity 5.2 to 2.9 times higher inside the fault zone compared to outside it and shows that geomorphology, salt store, regolith thickness, and degree of clearing are not the underlying mechanisms. In one of the groups of catchments, it has been calculated that an amount of recharge, significant in relation to recharge from rainfall, was entering from an adjacent catchment along a major fault. The paper concludes that geological features such as major faults affect the development of dryland salinity in the wheatbelt of Western Australia because of permeability differences in the regolith and therefore computer models of salinity risk need to take these differences into account. Techniques need to be developed to map, quickly and relatively cheaply, the geology-related permeability differences over wide areas of the landscape.
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Basharat, Muhammad, Masood Qasim, Muhammad Shafique, Nasir Hameed, Muhammad Tayyib Riaz, and Muhammad Rustam Khan. "Regolith thickness modeling using a GIS approach for landslide distribution analysis, NW Himalayas." Journal of Mountain Science 15, no. 11 (November 2018): 2466–79. http://dx.doi.org/10.1007/s11629-018-4840-6.
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Cattle, Stephen R., Richard S. B. Greene, and Andrew A. McPherson. "The role of climate and local regolith–landscape processes in determining the pedological characteristics of æolian dust deposits across south-eastern Australia." Quaternary International 209, no. 1-2 (November 2009): 95–106. http://dx.doi.org/10.1016/j.quaint.2008.12.017.
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Basher, L. R. "Is pedology dead and buried?" Soil Research 35, no. 5 (1997): 979. http://dx.doi.org/10.1071/s96110.
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Pedology, the field study of soils as natural landscape bodies, has suffered serious cutbacks in stang and funding in many developed countries. Soil survey, a strong focus for pedology, has been most affected by this recession. The cutbacks to pedology reflect the reduction in funding for general purpose soil resource inventories and a decline in central government planning and land development, as well as changing needs for soil information and perceived failure of soil survey to respond by delivering relevant, timely information at affordable cost. A refocusing of research effort in pedology is required to contribute to research into environmental issues of sustainable land management, and global change processes and impacts. The adoption of modern, ecient approaches to collecting, analysing, interpreting and presenting field soil data will improve the fund-raising capability of pedology and enhance its institutional stature. The general purpose paper soil map and soil survey report has largely been superseded as a medium for presenting soil information. Increasingly, it will be replaced by computer-generated, special purpose, interpretive soil maps that are based on soil–landscape models and include more objective, statistically estimated information on soil variability. There is a continuing role for pedology to define the extent, distribution, properties, suitability, and vulnerability of soils as a basis for sustainable land management. There is a need for increasing focus on temporal changes in soil properties, greater attention to soil properties that determine soil functioning and influence soil use, and interpretation of the environmental record contained in soils and regolith.
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Triantafilis, J., V. Wong, F. A. Monteiro Santos, D. Page, and R. Wege. "Modeling the electrical conductivity of hydrogeological strata using joint-inversion of loop-loop electromagnetic data." GEOPHYSICS 77, no. 4 (July 1, 2012): WB99—WB107. http://dx.doi.org/10.1190/geo2011-0507.1.
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In coastal-estuarine agricultural landscapes that are inherently rich in sulfidic sediments and saline water-tables, natural resource management data need to be collected to describe the heterogeneous nature of the soil, underlying regolith, and interactions with groundwater. Geophysical methods, such as electromagnetic (EM) induction instruments, are increasingly being used. This is because they measure apparent soil electrical conductivity [Formula: see text], which has previously been successfully used to map the areal distribution of soil (e.g., salinity) and hydrological (e.g., water-table depth) properties. We explored the potential of a next-generation DUALEM-421 and EM34 to be used independently and in conjunction with each other to provide information we can use to represent the pedological and hydrogeological setting of alluvial and estuarine sediments. A 1D laterally constrained joint-inversion algorithm can account for the nonlinearity of large [Formula: see text] (i.e., [Formula: see text]). We applied this algorithm to develop 2D cross sections of electrical conductivity ([Formula: see text]) from DUALEM-421 and EM34 [Formula: see text] data acquired across an estuarine landscape and situated within Quaternary fluvial sediments adjacent to Rocky Mouth Creek on the far north coast of New South Wales, Australia. We compared this joint-inversion model with inversions of the DUALEM-421 and EM34 [Formula: see text] data independently of each other. For the most part, the general patterns of the inverted models of [Formula: see text] compare favorably with existing pedological and hydrogeological interpretations, based on results achieved during a previous geoelectrical survey. However, the joint-inversion provides a more realistic model of the location and extent of a saline water-table and associated with the location of sulfidic sediments.
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Losekamm, Martin J., Janos Biswas, Thibaud Chupin, Michael Deiml, Matthieu Deremetz, Anthony M. Evagora, Guillaume Fau, et al. "Assessing the Distribution of Water Ice and Other Volatiles at the Lunar South Pole with LUVMI-X: A Mission Concept." Planetary Science Journal 3, no. 10 (October 1, 2022): 229. http://dx.doi.org/10.3847/psj/ac8cfd.
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Abstract The search for exploitable deposits of water and other volatiles at the Moon’s poles has intensified considerably in recent years, due to the renewed strong interest in lunar exploration. With the return of humans to the lunar surface on the horizon, the use of locally available resources to support long-term and sustainable exploration programs, encompassing both robotic and crewed elements, has moved into focus of public and private actors alike. Our current knowledge about the distribution and concentration of water and other volatiles in the lunar rocks and regolith is, however, too limited to assess the feasibility and economic viability of resource-extraction efforts. On a more fundamental level, we currently lack sufficiently detailed data to fully understand the origins of lunar water and its migration to the polar regions. In this paper, we present LUVMI-X, a mission concept intended to address the shortage of in situ data on volatiles on the Moon that results from a recently concluded design study. Its central element is a compact rover equipped with complementary instrumentation capable of investigating both the surface and shallow subsurface of illuminated and shadowed areas at the lunar south pole. We describe the rover and instrument design, the mission’s operational concept, and a preliminary landing-site analysis. We also discuss how LUVMI-X fits into the diverse landscape of lunar missions under development.
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Cockburn, Hermione A. P., and Michael A. Summerfield. "Geomorphological applications of cosmogenic isotope analysis." Progress in Physical Geography: Earth and Environment 28, no. 1 (March 2004): 1–42. http://dx.doi.org/10.1191/0309133304pp395oa.
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Cosmogenic isotope analysis involves the measurement of cosmogenic nuclides that have accumulated in the upper few metres of the Earth’s surface as a result of interactions between cosmic rays and target elements. The concentrations of these cosmogenic nuclides can provide quantitative estimates of the timing and rate of geomorphic processes. In dating applications the concentration of cosmogenic nuclides is interpreted as reflecting the time elapsed since a surface exposure event. However, over most of the Earth’s surface for most of the time the landsurface experiences incremental denudation and in these circumstances cosmogenic nuclide concentrations are related to the rate of denudation. Applications of event dating using cosmogenic isotopes include constructional landforms such as volcanic and depositional features, fault displacement, meteorite impacts, rapid mass movement, bedrock surfaces rapidly eroded by fluvial or wave action or exposed by glacial retreat, and the burial of sediment or ice. Strategies for quantifying rates of incremental change include estimates of denudation rates from site-specific samples and from fluvial sediment samples reflecting catchment-wide rates, and measurements of cosmogenic nuclide concentrations in soils and regolith to quantify rates of rock weathering. The past decade has seen a rapid growth in applications of cosmogenic isotope analysis to a wide range of geomorphological problems, and the technique is now playing a major role in dating and quantifying rates of landscape change over timescales of several thousands to several millions of years.
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Jibson, Randall W. "Types and Areal Distribution of Ground Failure Associated with the 2019 Ridgecrest, California, Earthquake Sequence." Bulletin of the Seismological Society of America 110, no. 4 (May 5, 2020): 1567–78. http://dx.doi.org/10.1785/0120200001.
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ABSTRACT The July 2019 Ridgecrest, California, earthquake sequence included the largest earthquake (M 7.1) to strike the conterminous United States in the past 20 yr. To characterize the types, numbers, and areal distributions of different types of ground failure (landslides, liquefaction, and ground cracking), I conducted a field investigation of ground failure triggered by the sequence around the periphery of the epicentral area (which had limited access). The earthquake sequence triggered sparse and widely scattered landslides over an area of ∼22,000 km2 and at a maximum epicentral distance of 114 km; these metrics are within the upper bounds as compared with global averages for earthquakes of similar size. Some rock falls blocked primary and secondary roads, but no other landslide damage was reported. Almost all of the landslides in the peripheral area were small rock falls (∼1–10 m3), but a few larger (∼100 m3) rock slides also occurred. Though there are only informal reports about ground failure in the immediate epicentral area and we lack a detailed survey there, the small number (hundreds) and size of the landslides still seems to be far below global averages for M 7.1. This could be a result of the arid landscape and lack of a deeply weathered zone of soil and regolith. Liquefaction occurred along part of the western margin of Searles Valley. One large (∼0.4 km2) lateral spread caused by liquefaction severely damaged parts of Trona. Minor liquefaction also occurred in a ∼100-m-wide band along the fault-rupture zone in some places.
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Khalaf, Fikry Ibrahim, Médard Thiry, Anthony Milnes, and Rehab Alnaqi. "Characterization of chert in the Dammam Formation (Eocene), Kuwait: Clues to groundwater silicification processes." Journal of Sedimentary Research 90, no. 3 (March 26, 2020): 297–312. http://dx.doi.org/10.2110/jsr.2020.18.
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ABSTRACT Conspicuous chert horizons occur as discontinuous bands and isolated nodules in dolostones in the Eocene Dammam Formation, which is exposed in the southeast of Kuwait. The Formation has never been deeply buried, and so chert formation is likely to have resulted from silicification processes at or near the land surface. Erosional reworking of the chert constrains its formation to a time period between the late Eocene and the Mio-Pliocene. As there is no significant source of silica in the dolostones, the chert was formed from silica imported from other sources. This process, together with the specificity of chert to particular non-bedding horizons, suggests that silicification is related to discrete locations of the groundwater table during landscape incision and resultant groundwater discharge in the region. Detailed petrographical studies demonstrate that “chertification” was initiated by precipitation of nanoglobules of silica (opal-A) from supersaturated groundwater solutions flowing through voids formed concomitantly by dissolution of dolomite. Subsequently, silica was precipitated as more crystalline forms of chalcedony, microquartz, and megaquartz from successively less saturated groundwater. The most likely mechanism for triggering the precipitation of silica is considered to be significant cooling of the groundwater as it neared the landsurface and came into contact with a cold regolith terrain. Precipitation of disordered forms of silica (opal-A) occurred at the cold front: progressively more crystalline phases formed as the host rock was warmed by the inflowing groundwater and its degree of supersaturation diminished. If our interpretation is correct, this “chertification” process could have been initiated during global cooling related to one of the glaciations recorded during Oligocene and Miocene times.
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Clapuyt, François, Veerle Vanacker, Marcus Christl, Kristof Van Oost, and Fritz Schlunegger. "Spatio-temporal dynamics of sediment transfer systems in landslide-prone Alpine catchments." Solid Earth 10, no. 5 (September 3, 2019): 1489–503. http://dx.doi.org/10.5194/se-10-1489-2019.
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Abstract. Tectonic and geomorphic processes drive landscape evolution over different spatial and temporal scales. In mountainous environments, river incision sets the pace of landscape evolution, and hillslopes respond to channel incision by, e.g., gully retreat, bank erosion, and landslides. Sediment produced during stochastic landslide events leads to mobilization of soil and regolith on the slopes that can later be transported by gravity and water to the river network during phases of hillslope–channel geomorphic coupling. The mechanisms and scales of sediment connectivity mitigate the propagation of sediment pulses throughout the landscape and eventually drive the contribution of landslides to the overall sediment budget of mountainous catchments. However, to constrain the timing of the sediment cascade, the inherent stochastic nature of sediment and transport through landsliding requires an integrated approach accounting for different space scales and timescales. In this paper, we examine the sediment production on hillslopes and evacuation to the river network of one landslide, i.e. the Schimbrig earthflow, affecting the Entle River catchment located in the foothills of the Central Swiss Alps. We quantified sediment fluxes over annual, decadal, and millennial timescales using respectively unmanned aerial vehicle (UAV)–structure-from-motion (SfM) techniques, classic photogrammetry, and in situ produced cosmogenic radionuclides. At the decadal scale, sediment fluxes quantified for the period 1962–1998 are highly variable and are not directly linked to the intensity of sediment redistribution on the hillslope. At the millennial scale, landslide occurrence perturbs the regional positive linear relationship between sediment fluxes and downstream distance as the landslide-affected Schimbrig catchment is characterized by a decrease in sediment fluxes and a strong variability. Importantly, the average decadal sediment flux of the Schimbrig catchment is 2 orders of magnitude higher than millennial sediment fluxes computed over the same spatial extent. The discrepancy between decadal and millennial sediment fluxes, combined to the highly variable annual sediment evacuation from the hillslopes to the channel network suggest that phases of hillslope–channel geomorphic coupling are short and intermittent. During most of the time, the first-order catchments are transport-limited and sediment dynamics in the headwaters are uncoupled from the fluvial systems. In addition, our unique spatio-temporal database of sediment fluxes highlights the transient character of the intense geomorphic activity of the Schimbrig catchment in a regional context. Its decadal sediment flux is of the same order of magnitude as the background sediment flux going out of the entire Entle River catchment. Over the last 50 years, the Schimbrig catchment, which represents ca. 1 % of the entire study area, provides 65 % of the sediments that the entire Entle catchment will supply over the millennial scale. These results suggest that episodic supply of sediment from landslides during intermittent phases of hillslope–channel geomorphic coupling are averaged out when considering sediment fluxes at longer timescales and larger spatial scales.