Genetically meaningful decomposition of grain-size distributions

Weltje, Gert Jan; Prins, Maarten A.

doi:10.1016/j.sedgeo.2007.03.007

Cited by 257 publications

(169 citation statements)

References 23 publications

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“…Furthermore the best-possible parametrisation of an end-member model is given with an optimal weight quantile (l opt ), which resulted in the highest explained variance compared to all other l and an optimal number of EM (q opt ) at the inflection point within the Q-R 2 mean plot of the l opt model in consensus with previous works (Weltje and Prins, 2007). Table 3.…”

Section: End-member Modelling Analysis (Emma)supporting

confidence: 59%

“…Adding the set of modern lake surface samples to the Donggi Cona data Example how boundary parameters were defined for all similarly-likely model runs using the Nam Co core grain-size data set. (a) Q−R 2 mean plot after Dietze et al (2012) for selected weight quantiles (l) and numbers of end members (q) (q opt at the inflection point after Weltje and Prins (2007); q max at the first local maximum); (b) a 3-D pattern of the Q − R 2 mean plot including an example sequence of 10 l between 0 ( * after Miesch, 1976, corresponds here to l opt ) and the numerical maximum of l and the first 20 q that resulted in different end-member models, for which (c) shows the number of overlapping modes (only zero overlaps were taken into account for robust similarly-likely model runs).…”

Section: Robust End-member Loadingsmentioning

confidence: 99%

“…EMMA has been successfully applied to the multimodal grain-size distributions of marine, lacustrine, and aeolian sediments mainly in the Atlantic ocean and the Asian continent (e.g. Stuut et al, 2002;Vriend and Prins, 2005;Weltje and Prins, 2007;IJmker et al, 2012;Dietze et al, 2012, where different end members were interpreted as proxies of sediment transport processes.…”

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confidence: 99%

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Sediment transport processes across the Tibetan Plateau inferred from robust grain-size end members in lake sediments

et al. 2014

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Abstract. Grain-size distributions offer powerful proxies of past environmental conditions that are related to sediment sorting processes. However, they are often of multimodal character because sediments can get mixed during deposition. To facilitate the use of grain size as palaeoenvironmental proxy, this study aims to distinguish the main detrital processes that contribute to lacustrine sedimentation across the Tibetan Plateau using grain-size end-member modelling analysis. Between three and five robust grain-size end-member subpopulations were distinguished at different sites from similarly-likely end-member model runs. Their main modes were grouped and linked to common sediment transport and depositional processes that can be associated with contemporary Tibetan climate (precipitation patterns and lake ice phenology, gridded wind and shear stress data from the High Asia Reanalysis) and local catchment configurations. The coarse sands and clays with grain-size modes > 250 µm and < 2 µm were probably transported by fluvial processes. Aeolian sands (∼ 200 µm) and coarse local dust (∼ 60 µm), transported by saltation and in near-surface suspension clouds, are probably related to occasional westerly storms in winter and spring. Coarse regional dust with modes ∼ 25 µm may derive from near-by sources that keep in longer term suspension. The continuous background dust is differentiated into two robust end members (modes: 5-10 and 2-5 µm) that may represent different sources, wind directions and/or sediment trapping dynamics from long-range, upperlevel westerly and episodic northerly wind transport. According to this study grain-size end members of only fluvial origin contribute small amounts to mean Tibetan lake sedimentation (19 ± 5 %), whereas local to regional aeolian transport and background dust deposition dominate the clastic sedimentation in Tibetan lakes (contributions: 42 ± 14 % and 51 ± 11 %). However, fluvial and alluvial reworking of aeolian material from nearby slopes during summer seems to limit end-member interpretation and should be crosschecked with other proxy information. If not considered as a stand-alone proxy, a high transferability to other regions and sediment archives allows helpful reconstructions of past sedimentation history.

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Section: End-member Modelling Analysis (Emma)supporting

confidence: 59%

Section: Robust End-member Loadingsmentioning

confidence: 99%

mentioning

confidence: 99%

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Sediment transport processes across the Tibetan Plateau inferred from robust grain-size end members in lake sediments

et al. 2014

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“…The grain-size 321 distribution of the samples was measured during 90 seconds and the arithmetic mean was 322 calculated from the 92 size classes. Downcore grain-size distributions were unmixed using 323 the end-member modeling algorithm of Weltje and Prins (2007). 324…”

Section: Biogenic Opal 301mentioning

confidence: 99%

Late Holocene covariability of the southern westerlies and sea surface temperature in northern Chilean Patagonia

Bertrand

Hughen

Sepúlveda

et al. 2014

Quaternary Science Reviews

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18The climate of Chilean Patagonia is strongly influenced by the southern westerlies, which 19 control the amount and latitudinal distribution of precipitation in the southern Andes. In 20 austral summer, the Southern Westerly Wind Belt (SWWB) is restricted to the high latitudes. 21It expands northward in winter, which results in a strong precipitation seasonality between 22 ~35 and 45°S. Here, we present a new precipitation seasonality proxy record from Quitralco 23 fjord (46°S), where relatively small latitudinal shifts in the SWWB result in large changes in 24 precipitation seasonality. Our 1400 yr record is based on sedimentological and geochemical 25 data obtained on a sediment core collected in front of a small river that drains the 26 2 Patagonian Andes, which makes this site particularly sensitive to changes in river discharge. 27Our results indicate Fe/Al and Ti/Al values that are low between 600 and 1200 CE, increasing 28 at 1200-1500 CE, and high between 1500 and 1950 CE. Increasing Fe/Al and Ti/Al values 29 reflect a decrease in mean sediment grain-size from 30 to 20 µm, which is interpreted as a 30 decrease in seasonal floods resulting from an equatorward shift of the SWWB. Our results 31 suggest that, compared to present-day conditions, the SWWB was located in a more 32 poleward position before 1200 CE. It gradually shifted towards the equator in 1200-1500 CE, 33where it remained in a sustained position until 1950 CE. This pattern is consistent with most 34 precipitation records from central and southern Chile. The comparison of our record with 35 published regional sea surface temperature (SST) reconstructions for the late Holocene 36shows that equatorward shifts in the SWWB are systematically coeval with decreasing SSTs 37 and vice versa, which resembles fluctuations over glacial-interglacial timescales. We argue 38 that the synchronicity between SST and SWWB changes during the last 1400 years 39 represents the response of the SWWB to temperature changes in the Southern Hemisphere. 40 41 Keywords 42Southern westerlies, inorganic geochemistry, paleohydrology, paleohydroclimatology, fjord 43 sediments, southern South America, Chilean Patagonia 44 45 Introduction 46The southern westerlies are the prevailing winds at the mid latitudes of the Southern 47Hemisphere, blowing between the subtropical anticyclone and the cyclonic subpolar air 48 masses. The Southern Westerly Wind Belt (SWWB) extends roughly between 30 and 60ºS, 49and it exhibits latitudinal variations at seasonal to glacial-interglacial timescales. Due to the 50 3 absence of continental barriers in the Southern Ocean, the SWWB directly controls the 51 strength of the Antarctic Circumpolar Current (ACC), which in turn affects the release of CO 2 52 from the deep ocean up to the atmosphere, particularly on glacial-interglacial timescales 53 (Anderson et al., 2009). In addition to modulating the strength of the ACC, the SWWB also 54 controls the amount of precipitation on the windward side of the mountain ranges located 55 along its ...

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“…The supplementary material contains the grain-size data set and the R-script used for EMMA. EMMA introduces artificial modes, usually in classes where other EM have their primary modes or where other end-members overlap Weltje and Prins (2007); Dietze et al (2012a). This is due to the constraint that the model aims to produce extreme EM in order to describe most of the variability of the data set.…”

Section: Field Workmentioning

confidence: 99%

Environmental history recorded in aeolian deposits under stone pavements, Mojave Desert, USA

Dietze

Lomax

et al. 2016

Quat. res.

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Reconstructing the evolution of arid landscapes is challenged by limited availability of appropriate environmental archives. A wide-spread surface feature -stone pavement -traps aeolian fines and forms a special accretionary archive. Seven stone pavement-covered sections on basalt flows in the eastern Mojave Desert are condensed to a composite section, comprising five sedimentological units, supported by an OSL-based chronology. Three of the units are of accretionary nature and each is covered by a stone pavement. They were deposited >50.9-36.6 ka, <36.6-14.2 ka and <14.2 ka and are intimately coupled with the history of nearby Lake Mojave, which advances the current picture of regional aeolian activity. End-member modelling analysis of grain-size distributions yielded seven sediment transport regimes. The accretionary system operates in two modes: A) episodic formation of a stone pavement by lateral processes once a vesicular horizon has formed on a barren surface and B) accretion of dust and eventually burial of the clast layer. These findings improve current concepts about stone pavement evolution and their environmental proxy function in arid landscapes. Stone pavement-covered accretionary deposits are a new key archive that allows quantifying the relative importance of dust accretion, slope processes, soil formation and vegetation cover.

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Genetically meaningful decomposition of grain-size distributions

Cited by 257 publications

References 23 publications

Sediment transport processes across the Tibetan Plateau inferred from robust grain-size end members in lake sediments

Sediment transport processes across the Tibetan Plateau inferred from robust grain-size end members in lake sediments

Late Holocene covariability of the southern westerlies and sea surface temperature in northern Chilean Patagonia

Environmental history recorded in aeolian deposits under stone pavements, Mojave Desert, USA

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