scholarly journals Fire-induced rock spalling as a mechanism of weathering responsible for flared slope and inselberg development

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Solomon Buckman ◽  
Rowena H. Morris ◽  
Robert P. Bourman
Keyword(s):  
Arid Regions ◽  
Chemical Weathering ◽  
Ground Level ◽  
Physical Weathering ◽  
Weathering Processes ◽  
Central Australia ◽  
In Fire ◽  
New Hypothesis ◽  
Primary Agent ◽  
Semi Arid

AbstractInselbergs, such as Uluru in central Australia, are iconic landscape features of semi-arid and deeply denuded continental interiors. These islands of rock are commonly skirted by steep, overhanging cliffs (flared slopes) at ground level. The weathering processes responsible for formation of flared slopes and steep-sided inselbergs in flat, planated landscapes are enigmatic. One model emphasizes sub-surface weathering followed by denudation and excavation of saprolite to expose the unweathered bedrock while other models advocate slope development under subaerial conditions at ground level. We present a new hypothesis that identifies wildfire as a primary agent of flared slope development via fire-induced rock spalling around the periphery of inselbergs. Widespread fire-spalling following the 2019–2020 Australian fires illustrates that this is a common form of physical weathering in fire-prone environments but its effects are particularly evident in semi-arid regions where lateral fire-spalling dominates over fluvial and chemical weathering to create flared slopes and steep-sided inselbergs.

scholarly journals The Effect of Weathering on Salt Release from Coal Mine Spoils

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 760
Author(s):  
Melinda Hilton ◽  
Mandana Shaygan ◽  
Neil McIntyre ◽  
Thomas Baumgartl ◽  
Mansour Edraki
Keyword(s):  
Particle Size ◽  
Coal Mine ◽  
Chemical Weathering ◽  
Physical Weathering ◽  
Particle Size Fractions ◽  
Mine Spoils ◽  
Weathering Processes ◽  
Three Samples ◽  
Two Samples ◽  
Physical And Chemical

Coal mine spoils have the potential to create environmental impacts, such as salt load to surrounding environments, particularly when exposed to weathering processes. This study was conducted to understand the effect of physical and chemical weathering on the magnitude, rate, and dynamics of salt release from different coal mine spoils. Five spoil samples from three mines in Queensland were sieved to three different particle size fractions (<2 mm, 2–6 mm, and >6 mm). Two samples were dispersive spoils, and three samples were nondispersive spoils. The spoils were subjected to seven wet–dry cycles, where the samples were periodically leached with deionised water. The rate, magnitude, and dynamics of solutes released from spoils were spoil specific. One set of spoils did not show any evidence of weathering, but initially had higher accumulation of salts. In contrast, broad oxidative weathering occurred in another set of spoils; this led to acid generation and resulted in physical weathering, promoting adsorption–desorption and dissolution and, thus, a greater release of salts. This study indicated that the rate and magnitude of salt release decreased with increasing particle size. Nevertheless, when the spoil is dispersive, the degree of weathering manages salt release irrespective of initial particle size. This study revealed that the long-term salt release from spoils is not only governed by geochemistry, weathering degree, and particle size but also controlled by the water/rock ratio and hydrological conditions of spoils.

scholarly journals Arctic–alpine blockfields in the northern Swedish Scandes: late Quaternary – not Neogene

2014 ◽  
Vol 2 (2) ◽  
pp. 383-401 ◽  
Author(s):  
B. W. Goodfellow ◽  
A. P. Stroeven ◽  
D. Fabel ◽  
O. Fredin ◽  
M.-H. Derron ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Late Quaternary ◽  
Time Frame ◽  
Temporal Variations ◽  
Early Pleistocene ◽  
Slope Position ◽  
Physical Weathering ◽  
Weathering Processes ◽  
Erosion Rates ◽  
Surrounding Landscape

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.

scholarly journals Localization and Surface Characterization by Zhurong Mars Rover at Utopia Planitia

2021 ◽  
Author(s):  
Liang Ding ◽  
Ruyi Zhou ◽  
Tianyi Yu ◽  
Haibo Gao ◽  
Huaiguang Yang ◽  
...  
Keyword(s):  
Surface Characterization ◽  
Chemical Weathering ◽  
Friction Angle ◽  
Parameter Analysis ◽  
Mars Rover ◽  
Slip Ratio ◽  
Physical Weathering ◽  
Weathering Processes ◽  
Primary Localization

Abstract China’s first Mars rover, Zhurong, has successfully touched down on the southern Utopia Planitia of Mars at 109.925° E, 25.066° N, and since performed cooperative multiscale investigations with the Tianwen-1 orbiter. Here we present primary localization and surface characterization results based on complementary data of the first 60 sols. The Zhurong rover has traversed 450.9 m southwards over a flat surface with mild wheel slippage (less than 0.2 in slip ratio). The encountered crescent-shaped sand dune indicates a NE-SW local wind direction, consistent with larger-range remote-sensing observations. Soil parameter analysis based on terramechanics indicates that the topsoil has high bearing strength and cohesion, and its equivalent stiffness and internal friction angle are ~1390-5872 kPa∙m-n and ~21°-34° respectively. Rocks observed strewn with dense pits, or showing layered and flaky structures, are presumed to be involved in physical weathering like severe wind erosion and potential chemical weathering processes. These preliminary observations suggest great potential of in-situ investigations by the scientific payload suite of the Zhurong rover in obtaining new clues of the region’s aeolian and aqueous history. Cooperative investigations using the related payloads on both the rover and the obiter could peek into the habitability evolution of the northern lowlands on Mars.

Morphological and genetic variation within the widespread species Acacia victoriae (Mimosaceae)

2007 ◽  
Vol 20 (1) ◽  
pp. 54 ◽  
Author(s):  
Siti R. Ariati ◽  
Daniel J. Murphy ◽  
Stuart Gardner ◽  
Pauline Y. Ladiges
Keyword(s):  
Genetic Variation ◽  
Morphological Variation ◽  
Genetic Divergence ◽  
Arid Regions ◽  
Nuclear Dna ◽  
Northern Australia ◽  
Parsimony Analysis ◽  
Widespread Species ◽  
Central Australia ◽  
Semi Arid

Morphological variation in Acacia victoriae, a species widespread in arid and semi-arid regions of Australia, was analysed by phenetic methods of classification and ordination. Three morphological groups were identified on the basis of phyllode characters and are treated as subspecies. Populations with short, elliptic and tomentose phyllodes are confirmed as A. victoriae subsp. arida Pedley; this form occurs mainly in central Australia. Populations with linear to oblong, non-tomentose phyllodes are referred to subsp. victoriae; this subspecies is the most variable and widely distributed across Australia. Populations with very long, narrow phyllodes, distributed in northern Australia from the Kimberley to Queensland, are described as fasciaria subsp. nov. A small number of non-tomentose specimens with broad elliptic phyllodes from central Australia require further assessment. Thirteen accessions previously sequenced for internal spacer regions and external spacer regions of ribosomal nuclear DNA showed genetic divergence. Six accessions of subsp. fasciaria formed a clade in a parsimony analysis, confirming that the long phyllode form is genetically distinct.

scholarly journals Landslides as geological hotspots of CO<sub>2</sub> to the atmosphere: clues from the instrumented Séchilienne landslide, Western European Alps

2020 ◽  
Author(s):  
Pierre Nevers ◽  
Julien Bouchez ◽  
Jérôme Gaillardet ◽  
Christophe Thomazo ◽  
Laeticia Faure ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Pyrite Oxidation ◽  
Major Elements ◽  
European Alps ◽  
Geological Time ◽  
Geological Time Scale ◽  
Gypsum Dissolution ◽  
Physical Weathering ◽  
Mountain Ranges ◽  
Weathering Processes

Abstract. This study makes use of a highly instrumented active landslide observatory (9 years of data) in the French Alps, the Séchilienne slope. Using a combination of major element chemistry and isotopes ratios (87Sr / 86Sr, δ34S) measured in different water types of the stable and unstable part of the Séchilienne instability to assess the contribution of the different lithologies of the slope and the chemical weathering mechanisms. Chemical and isotopic ratios appear useful to characterize weathering processes and the origin of waters and their flowpaths through the massif. A mixing model allows us to allocate the different major elements to different sources and quantify the involvement sulfuric and carbonic acids as a source of protons. As a consequence of the model, we are able to show that the instability creates favorable and sustained conditions for the production of sulfuric acid by pyrite oxidation by supplying reactive surfaces. We clearly identify the contribution of gypsum dissolution to the sulfate budget in the landslide. We are also able to refine the pre-existing hydrogeological views on the local water circulation and water flow paths in the instability but showing the hydrological connectivity of the different zones. Overall, our results show that the Séchilienne landslide, despite its role in accelerating rock chemical and physical weathering, acts, at a geological time scale (i.e. at timescales longer that carbonate precipitation in the ocean) as a source of CO2 to the atmosphere. If generalizable to other instable zones in mountain ranges, this study illustrates the complex coupling between physical and chemical erosion and climate. The study also highlights the importance of deciphering between sulfite oxidation and gypsum dissolution as a source of sulfate ions to rivers, particularly in mountain ranges.

Adalaj Stepwell: A Magical Resonance of Architectural Ingenuity

2021 ◽  
Vol 7 (2) ◽  
pp. 275-304
Author(s):  
Unni Sriparvathy ◽  
T.N. Salahsha
Keyword(s):  
Cultural Heritage ◽  
Arid Regions ◽  
Ground Level ◽  
Cultural Relevance ◽  
Evaporation Process ◽  
Slow Evaporation ◽  
Islamic Architecture ◽  
Cultural Legacy ◽  
Indian Architecture ◽  
Semi Arid

The term Stepwell defined as "Well with Stairs" is a window to the ethnicity of forgotten civilizations. Stepwells are structures up to 3 to 5 storeys down from ground level, many of which are artistically designed with exquisite workmanship. These stepwells collect water during seasonal monsoons and in the deeper part of the ground with shadows around, such water bodies undergo slow evaporation process. In India, stepwells have been around since the age of Harappa and Mohenjo-Daro, about 4,500 years ago. During this period, bath wells with steps were created, with rooms surrounding the well-pit for resting. Such stepwells were once integral to the semi-arid regions of India, as they provided water for basic amenities for subsistence. These wells were also venues for colourful festivals and sacred rituals, paving the way for a rich cultural legacy. One such unique stepwell is located in Adalaj village in Gujarat, India, initiated by Raja Veer Singh in 1499 and completed by King Mohammed Begada for Rani Rudabai, wife of the Raja. The cultural and architectural representations in the stepwell at various levels are a tribute to the history, built initially by Hindus and subsequently ornamented and blended with Islamic architecture during the Muslim rule. But present-day perception, nurtured by technological advancements, has shifted. The paper focuses on the effects of the changing urbanscape on the architectural and visual connectivity with the cultural heritage of Adalaj so that adequate conservation measures can be proposed to preserve this icon of Indian architecture. Understanding the cultural relevance of such structures is crucial for their continued appreciation and protection.

scholarly journals Geochemical and glacio-geomorphic implications of basalt weathering in the Queen Maud Mountains, Antarctica

1982 ◽  
Vol 119 (6) ◽  
pp. 553-566 ◽  
Author(s):  
R. W. Talkington ◽  
P. A. Mayewski ◽  
H. E. Gaudette
Keyword(s):  
Air Temperature ◽  
Chemical Weathering ◽  
Surface Air Temperature ◽  
Rock Surface ◽  
Basaltic Glass ◽  
Mass Wasting ◽  
Physical Weathering ◽  
Weathering Processes ◽  
Heating And Cooling ◽  
Basalt Weathering

SummaryThe weathering of a suite of basalt clasts, that have been transported by mass wasting downslope in the Cumulus Hills region of the Queen Maud Mountains, Antarctica, is examined from both geochemical and glacio-geomorphic viewpoints. Chemical weathering, predominantly oxidation and hydration, increases in severity from clast core to rim for the suite. These weathering processes and concomitant formation of a weathering rind are suggested to be an accumulative process, culminating in the disaggregation of the rock due in part both to the chemical breakdown of the interstitial and intersertal basaltic glass and to physical weathering processes.Mass wasting rates in the range of 1.4 × 10−3−1.13 × 10−1 cm. y−1 are estimated, assuming that the style of transport is dry creep. These transport rates suggest that the rock-surface/air-temperature differences in the study area may have been as little as 0.5 °C and heating and cooling cycles as few as 1 cy. y−1 for the last 4.2 Ma.

scholarly journals Arctic-alpine blockfields in northern Sweden: Quaternary not Neogene

2014 ◽  
Vol 2 (1) ◽  
pp. 47-93 ◽  
Author(s):  
B. W. Goodfellow ◽  
A. P. Stroeven ◽  
D. Fabel ◽  
O. Fredin ◽  
M.-H. Derron ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Late Quaternary ◽  
Temporal Variations ◽  
Slope Position ◽  
Northern Sweden ◽  
Physical Weathering ◽  
Weathering Processes ◽  
Erosion Rates ◽  
Elevation Changes ◽  
Cosmogenic 10Be

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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