Terrestrial biomarker isotope records of late Quaternary climate and source-to-sink sediment transport processes in southwestern Taiwan

2021 ◽  
Vol 321 (4) ◽  
pp. 393-423
Author(s):  
Queenie Chang ◽  
Michael Hren ◽  
Andrew T. Lin ◽  
Clay Tabor ◽  
Shun-Wen Yu ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Late Quaternary ◽  
Transport Processes ◽  
Quaternary Climate ◽  
Source To Sink ◽  
Southwestern Taiwan

Southern African hydroclimate during the Late Quaternary: integrating source to sink and multi-archive studies

2020 ◽  
Author(s):  
Annette Hahn ◽  
Hayley Cawthra ◽  
Green Andrew ◽  
Humphries Marc ◽  
Schefuß Enno ◽  
...  
Keyword(s):  
Southern Africa ◽  
Late Quaternary ◽  
Global Climate ◽  
Climatic Variability ◽  
Environmental Indicators ◽  
Ocean Current ◽  
Temperate Climate ◽  
Small Scale ◽  
Quaternary Climate ◽  
Source To Sink

<p>Southern Africa is located at the interface of sub-tropical and temperate climate zones as well as between two major warm and cold ocean current systems (Agulhas and Benguela), respectively. This makes it a key region for understanding global climate dynamics and highly sensitive to future climatic change. A growing number of paleo-archives have revealed small-scale climatic dipoles in this region and the driving mechanisms of the complex climatic variability often in this region remain unclear. Several regional studies have suggested a synchronicity with the southern hemisphere and thus inferred a direct insolation forcing while others have observed a synchronicity with northern hemispheric climate and associated this with a teleconnection mechanism. In order to decipher the complex climatic processes affecting this region it is necessary to integrate on- and offshore paleo-archives as well as various paleo-environmental indicators (proxies). For the correct interpretation of the various proxies a source to sink approach is necessary determining the origin of the different terrestrial sedimentary components and their potential alterations during transport and deposition. With a focus on marine and lacustrine sedimentary archives along the west, south, and east coast of southern Africa we are now able to reconstruct Late Quaternary climate variability on regional scales. We propose a new conceptual model describing latitudinal shifts of rainfall zones as tropical and temperate climate systems shift over glacial and interglacial cycles. New insights allow us to resolve some of the apparent contradictions between paleoclimate records from the region. </p><p> </p>

scholarly journals Millennial-Scale Response of a Western Mediterranean River to Late Quaternary Climate Changes: A View from the Deep Sea

2014 ◽  
Vol 122 (6) ◽  
pp. 687-703 ◽  
Author(s):  
Lucile Bonneau ◽  
Stéphan J. Jorry ◽  
Samuel Toucanne ◽  
Ricardo Silva Jacinto ◽  
Laurent Emmanuel
Keyword(s):  
Deep Sea ◽  
Climate Changes ◽  
Late Quaternary ◽  
Western Mediterranean ◽  
Mediterranean River ◽  
Quaternary Climate ◽  
Scale Response ◽  
Quaternary Climate Changes ◽  
Millennial Scale

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

2014 ◽  
Vol 10 (1) ◽  
pp. 91-106 ◽  
Author(s):  
E. Dietze ◽  
F. Maussion ◽  
M. Ahlborn ◽  
B. Diekmann ◽  
K. Hartmann ◽  
...  
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Tibetan Plateau ◽  
Transport Processes ◽  
The Tibetan Plateau ◽  
Dust Deposition ◽  
Northerly Wind ◽  
Near Surface ◽  
Depositional Processes ◽  
End Members

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, upper-level 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.

scholarly journals Application of a 3D Layer Integrated Numerical Model of Flow and Sediment Transport Processes to a Reservoir

Water ◽  
2015 ◽  
Vol 7 (10) ◽  
pp. 5239-5257 ◽  
Author(s):  
Shervin Faghihirad ◽  
Binliang Lin ◽  
Roger Falconer
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Transport Processes ◽  
Flow And Sediment Transport

scholarly journals Phytogeographical patterns of dry forests sensu stricto in northern Minas Gerais State, Brazil

2013 ◽  
Vol 85 (2) ◽  
pp. 623-634 ◽  
Author(s):  
DANIEL M. ARRUDA ◽  
WALNIR G. FERREIRA-JUNIOR ◽  
REINALDO DUQUE-BRASIL ◽  
CARLOS E.R. SCHAEFER
Keyword(s):  
Late Quaternary ◽  
Sensu Stricto ◽  
Minas Gerais ◽  
Dry Forest ◽  
Floristic Similarity ◽  
Humid Forest ◽  
Quaternary Climate ◽  
Dominant Soil ◽  
Minas Gerais State ◽  
Semi Arid

The Deciduous Complex that occurs in northern Minas Gerais State, Brazil, raises questions about the floristic affinities of these formations in relation to neighboring phytogeographical domains. Little is known about the identity of the seasonal forest formations that comprise this complex, or about its relationships to abiotic components, such as soils, topography and climate. This study aimed to recognize the patterns of floristic similarity of all studied fragments of dry forest of northern Minas Gerais with soil and climate attributes, based on the available database. Cluster analysis indicated the existence of two floristic groups that had clear associations with either the Koppen's BSh (semi-arid) or Aw (seasonal tropical) climates. Likewise, the subdivisions of these groups showed clear associations with the dominant soil classes in the region. The Red-Yellow Latosol is the dominant soil classes in the BSh climatic domain, seconded by alluvial areas associated with Fluvic Neosols. The Aw domain comprised a much varied set of soils: Nitosols, Argisols, Cambisols and Litholic Neosols, most derived from the Bambuí limestone/slate formation. The ecotonal nature of northern Minas Gerais State provides a complex interaction between the flora of neighboring phytogeographical domains. This, allied to pedogeomorphological factors, allowed a better understanding of the effects of late Quaternary climate changes for the Deciduous Complex evolution. We conclude that the Latosols under present-day semi-arid climates (BSh) are relicts of former wetter climates, during which humid forest (semideciduous) expansion took place. Later, these semideciduous forests were subjected to a much drier climate, when selection for deciduousness led to the present-days Deciduous Complex scenario.

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