CONTRASTING LATE MIOCENE TO PRESENT LANDSCAPE EVOLUTION ACROSS MONGOLIA’S KHANGAY MOUNTAINS THROUGH THE LENS OF CHEMICAL AND PHYSICAL WEATHERING PROCESSES

2017 ◽  
Author(s):  
Gantulga Bayasgalan ◽  
◽  
Karl W. Wegmann ◽  
R.V. Fodor ◽  
Bayasgalan Amgalan
Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 760
Author(s):  
Melinda Hilton ◽  
Mandana Shaygan ◽  
Neil McIntyre ◽  
Thomas Baumgartl ◽  
Mansour Edraki

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.


Geomorphology ◽  
2020 ◽  
Vol 371 ◽  
pp. 107433
Author(s):  
Markus Egli ◽  
Dennis Dahms ◽  
Mike Dumitrescu ◽  
Farzaneh Derakhshan-Babaei ◽  
Marcus Christl ◽  
...  

2014 ◽  
Vol 2 (2) ◽  
pp. 383-401 ◽  
Author(s):  
B. W. Goodfellow ◽  
A. P. Stroeven ◽  
D. Fabel ◽  
O. Fredin ◽  
M.-H. Derron ◽  
...  

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.


2021 ◽  
Author(s):  
Liang Ding ◽  
Ruyi Zhou ◽  
Tianyi Yu ◽  
Haibo Gao ◽  
Huaiguang Yang ◽  
...  

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.


Geosphere ◽  
2020 ◽  
Vol 16 (6) ◽  
pp. 1508-1537
Author(s):  
Kenneth S. Edgett ◽  
Steven G. Banham ◽  
Kristen A. Bennett ◽  
Lauren A. Edgar ◽  
Christopher S. Edwards ◽  
...  

Abstract Extraformational sediment recycling (old sedimentary rock to new sedimentary rock) is a fundamental aspect of Earth’s geological record; tectonism exposes sedimentary rock, whereupon it is weathered and eroded to form new sediment that later becomes lithified. On Mars, tectonism has been minor, but two decades of orbiter instrument–based studies show that some sedimentary rocks previously buried to depths of kilometers have been exposed, by erosion, at the surface. Four locations in Gale crater, explored using the National Aeronautics and Space Administration’s Curiosity rover, exhibit sedimentary lithoclasts in sedimentary rock: At Marias Pass, they are mudstone fragments in sandstone derived from strata below an erosional unconformity; at Bimbe, they are pebble-sized sandstone and, possibly, laminated, intraclast-bearing, chemical (calcium sulfate) sediment fragments in conglomerates; at Cooperstown, they are pebble-sized fragments of sandstone within coarse sandstone; at Dingo Gap, they are cobble-sized, stratified sandstone fragments in conglomerate derived from an immediately underlying sandstone. Mars orbiter images show lithified sediment fans at the termini of canyons that incise sedimentary rock in Gale crater; these, too, consist of recycled, extraformational sediment. The recycled sediments in Gale crater are compositionally immature, indicating the dominance of physical weathering processes during the second known cycle. The observations at Marias Pass indicate that sediment eroded and removed from craters such as Gale crater during the Martian Hesperian Period could have been recycled to form new rock elsewhere. Our results permit prediction that lithified deltaic sediments at the Perseverance (landing in 2021) and Rosalind Franklin (landing in 2023) rover field sites could contain extraformational recycled sediment.


2013 ◽  
Vol 387 ◽  
pp. 76-90 ◽  
Author(s):  
Naomi E. Kirk-Lawlor ◽  
Teresa E. Jordan ◽  
Jason A. Rech ◽  
Sophie B. Lehmann

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Solomon Buckman ◽  
Rowena H. Morris ◽  
Robert P. Bourman

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.


2020 ◽  
Author(s):  
Pierre Nevers ◽  
Julien Bouchez ◽  
Jérôme Gaillardet ◽  
Christophe Thomazo ◽  
Laeticia Faure ◽  
...  

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.


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