Climatic  Vs Anthropogenic Control on the Holocene Hydrology of a Playa-Lake System in the Western Mediterranean

2021 ◽  
Author(s):  
Antonio Garcia-Alix ◽  
Gonzalo Jiménez-Moreno ◽  
Fernando Gázquez ◽  
Ricardo Monedero-Contreras ◽  
Alejandro López-Avilés ◽  
...  
Keyword(s):  
Western Mediterranean ◽  
The Holocene ◽  
Lake System ◽  
Playa Lake

Middle Holocene environmental reconstruction and climatic inferences through multi-proxy records from Seymareh lake sediments (Zagros Mts., Iran)

2021 ◽  
Author(s):  
Michele Delchiaro ◽  
Giulia Iacobucci ◽  
Francesco Troiani ◽  
Marta Della Seta ◽  
Paolo Ballato ◽  
...  
Keyword(s):  
Sedimentation Rate ◽  
Water Discharge ◽  
Sediment Supply ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
The Holocene ◽  
Middle Holocene ◽  
Lake System ◽  
Proxy Records ◽  
The Impact

<p>The Seymareh landslide is the largest rock slope failure (44 Gm<sup>3</sup>) ever recorded on the exposed Earth surface. It detached ∼10 ka BP from the northeastern flank of the Kabir-Kuh anticline (Zagros Mts., Iran) originating the natural dam responsible for the formation of a three-lake system (Seymareh, Jaidar, and Balmak lakes, with an area of 259, 46, and 5 km<sup>2</sup>, respectively). The lake system persisted for ∼3000 yr during the Holocene before its emptying phase due to overflow. A sedimentation rate of 21 mm yr<sup>−1</sup> was estimated for the Seymareh lacustrine deposits, which increased during the early stage of lake emptying because of enhanced sediment yield from the lake tributaries. </p><p>To reconstruct the climatic and environmental impact on the lake infilling, we reviewed the geomorphology of the basins and combined the results with multi-proxy records from a 30 m thick lacustrine sequence in Seymareh Lake. Major analyses comprise grain size analysis, carbon and oxygen stable isotopes of carbonate-bearing sediments, and X-ray diffraction analysis of clay minerals.</p><p>Lake overflowing is largely accepted as the main response to variations in water discharge and sediment supply since the alternation from dry to wet phases enhances sediment mobilization along hillslopes decreasing the accommodation space in the downstream sedimentary basins. In this regard, during the early-middle Holocene, the Seymareh area, as well as the entire Middle East, was affected by short-term climate changes at the millennial-scale, as testified by both paleoecological and archaeological evidence. Indeed, several records from Iranian lakes (i.e., Mirabad, Zeribar, Urmia) well documented the temperature and the moisture conditions of the western Zagros Mountains during the Holocene. During the early Holocene, the precipitation remained low up to 6 ka BP, reaching the driest condition around 8-8.2 ka BP. The impact of this abrupt climate change is evident across West Asia, where the first large villages with domesticated cereals and sheeps disappeared, converting to small hamlets and starting habitat-tracking. As regards the Seymareh area, a more irregular distribution of rainfalls and their increasing seasonality may support rhexistasy conditions, during which the scarce vegetation cover enhances both the hillslope erosion and sedimentation rate in the basins, most likely contributing to the overflow of Seymareh Lake. </p>

Centennial to millennial-scale variability of Holocene climate and environmental dynamics in the western Mediterranean (Lake Sidi Ali, Middle Atlas, Morocco)

2021 ◽  
Author(s):  
Johannes Schmidt ◽  
Cathleen Kertscher ◽  
Markus Reichert ◽  
Helen Ballasus ◽  
Birgit Schneider ◽  
...  
Keyword(s):  
North Atlantic ◽  
Climate Changes ◽  
Western Mediterranean ◽  
Future Climate ◽  
Holocene Climate ◽  
The Holocene ◽  
The North ◽  
Middle Atlas ◽  
Environmental Responses

<p>The Western Mediterranean region including the North African desert margin is considered one of the most sensitive areas to future climate changes. In order to refine long-term scenarios for hydrological and environmental responses to future climate changes in this region, it is important to improve our knowledge about past environmental responses to climatic variability at centennial to millennial timescales. During the last two decades, the recovery and compilation of Holocene records from the subtropical North Atlantic and the Mediterranean Sea have improved our knowledge about millennial-scale variability of the Western Mediterranean palaeoclimate. The variabilities appear to affect regional precipitation patterns and environmental systems in the Western Mediterranean, but the timescales, magnitudes and forcing mechanisms remain poorly known. To compare the changes in Holocene climate variability and geomorphological processes across temporal scales, we analysed a 19.63-m long sediment record from Lake Sidi Ali (33°03’ N, 5°00’ W, 2080 m a.s.l.) in the sub-humid Middle Atlas that spans the last 12,000 years (23 pollen-based radiocarbon dates accompanied with <sup>210</sup>Pb results). We use calibrated XRF core scanning records with an annual to sub-decadal resolution to disentangle the complex interplay between climate changes and environmental dynamics during the Holocene. Data exploration techniques and time series analysis (Redfit, Wavelet) revealed long-term changes in lake behaviour. Three main proxy groups were identified (temperature proxies: 2ky, 1ky and 0.7ky cycles; sediment dynamic proxies: 3.5ky, 1.5ky cycles; hydrological proxies: 1.5ky, 1.2ky, 0.17ky cycles). For example, redox sensitive elements Fe and Mn show 1ky cycles and higher values in the Early Holocene and 1.5ky cycles and lower values in the Mid- to Late Holocene. All groups show specific periodicities throughout the Holocene, demonstrating their particular climatic and geomorphological dependencies. Furthermore, we discuss these periodicities relating to global and hemispheric drivers, such as the North Atlantic Oscillation (NAO), El-Niño Southern Oscillation (ENSO), Innertropical Convergence Zone variability (ITCZ) and North Atlantic cold relapses (Bond events).</p>

scholarly journals Saharan dust deposited in Lake Bastani, Corsica: The northernmost dust record of the termination of the Holocene African Humid Period?

2020 ◽  
Author(s):  
Maxime Leblanc ◽  
Charlotte Skonieczny ◽  
Pierre Sabatier ◽  
Christophe Colin ◽  
Serge Miska ◽  
...  
Keyword(s):  
Biogenic Silica ◽  
Hydrological Cycle ◽  
Clay Fraction ◽  
High Elevation ◽  
Western Mediterranean ◽  
Saharan Dust ◽  
Sahara Desert ◽  
Vegetation Feedback ◽  
The Holocene ◽  
Hydrological Changes

<p>Throughout the Quaternary, variations of the insolation received over Africa have governed the monsoon dynamics in this region, generating a recurrence of intense rainfall periods. These African Humid Periods (AHP) are characterized by a major transformation of the Saharan hydrological cycle, favouring the development of vast fluvial systems and tropical humid ecosystems in the currently hyper-arid Sahara Desert. In the current context of global warming, the mechanisms as well as the environmental responses associated with these periods of rapid changes between two extreme climatic contexts remain crucial to understand. Many studies have investigated the mechanisms associated with the last AHP that occurred in the early Holocene (9 to 5ka), and more particularly its initiation and termination. Despite all these efforts, these climatic transitions remain highly debated (e.g. influence of high latitudes versus regional forcing, vegetation feedback). Here, we propose to improve our understanding of the Holocene AHP by studying Saharan dust deposited in Lake Bastani (Corsica, western Mediterranean) during the last 12ka. Indeed, as dust emissions are function of the aridity of their sources, among other parameters such as wind intensity, Saharan dust fluxes recorded over and out of Africa may represent an indirect way to reconstruct Sahara past hydrological changes. Bastani Lake is a high elevation system with a very restricted watershed and has been described as a natural Saharan dust trap during the last 3ka (Sabatier et al., accepted). In this study, we present a Holocene multi-proxy characterization of the fine-grained sediments recorded in Bastani lake. We develop a multiproxies approach based on mineralogy and major elements composition of the clay fraction as well as microscopic observations and quantification of the biogenic silica, which complicates Saharan dust supply estimation in this system. This effort to decipher the Bastani lake sediments composition will allow us to qualify and quantify the Saharan dust signal from the bulk sediment record (watershed erosion/alteration, biogenic silica productivity) in order to discuss, to our knowledge, the northernmost aeolian response of the Sahara desert hydrological changes of the termination of this key climatic transition.</p><p> </p><p>Reference: Sabatier et al., Past African dust inputs in Western Mediterranean area controlled by the complex interaction between ITCZ, NAO and TSI, <em>Climate of the Past</em>, accepted.</p><p>Keywords: Saharan dust, Saharan hydrological cycle, Paleoclimatology, Holocene, clay mineralogy, geochemistry, biogenic silica.</p>

scholarly journals Impact of relative sea level and rapid climate changes on the architecture and lithofacies of the Holocene Rhone subaqueous delta (Western Mediterranean Sea)

2014 ◽  
Vol 305 ◽  
pp. 35-53 ◽  
Author(s):  
Anne-Sophie Fanget ◽  
Serge Berné ◽  
Gwénaël Jouet ◽  
Maria-Angela Bassetti ◽  
Bernard Dennielou ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sea Level ◽  
Climate Changes ◽  
Western Mediterranean ◽  
Relative Sea Level ◽  
The Holocene ◽  
Western Mediterranean Sea

scholarly journals New speleothem data from Molinos and Ejulve caves reveal Holocene hydrological variability in northeast Iberia

2017 ◽  
Vol 88 (2) ◽  
pp. 223-233 ◽  
Author(s):  
Ana Moreno ◽  
Carlos Pérez-Mejías ◽  
Miguel Bartolomé ◽  
Carlos Sancho ◽  
Isabel Cacho ◽  
...  
Keyword(s):  
Water Availability ◽  
Marked Change ◽  
Western Mediterranean ◽  
Early Holocene ◽  
Spring Precipitation ◽  
The Holocene ◽  
Middle Holocene ◽  
Hydrological Variability ◽  
Iberian Range ◽  
Climatic Signal

AbstractNew speleothem records from northeastern Iberian caves provide data to explore the climatic patterns during the Holocene. We present δ13C and Mg/Ca from three speleothems from two different caves located in the Iberian Range allowing replication of the climatic signal for several millennia. Through the integration of those stalagmites covering since the Holocene onset to 2 ka, the early Holocene (11.7–8.5 ka) appears as the wettest interval. A marked change towards aridity is observed during the middle Holocene (8.5–4.8 ka) and an increase of humidity afterwards (4.8–2 ka). This three-part pattern, contrasting with other Iberian sequences, seems to be associated with the different role that seasonality has played in the response of different proxies (or records) to changes in water availability. Interpreting our speleothem records as changes in winter-spring precipitation along the Holocene allows reconciling previous data on hydrological variability from the western Mediterranean borderlands.

Evidence for Holocene sea level and climate change from Almenara marsh (western Mediterranean)

2017 ◽  
Vol 88 (2) ◽  
pp. 206-222 ◽  
Author(s):  
Ana M. Blázquez ◽  
Ana Rodríguez-Pérez ◽  
Trinidad Torres ◽  
José E. Ortiz
Keyword(s):  
Aquatic Macrophytes ◽  
Western Mediterranean ◽  
The Holocene ◽  
Amino Acid Racemization ◽  
Biomarker Analysis ◽  
Oligohaline Marsh ◽  
Alluvial Material ◽  
Peat Formation ◽  
The Relationship ◽  
Paleontological Study

AbstractIn the Almenara marsh (western Mediterranean), four cores were analyzed to establish the relationship between the marsh record of the Almenara marshlands and the environmental factors responsible for its evolution during the Holocene. One hundred and eighty-six samples were collected for sedimentologic and paleontological study: 63 for biomarker analysis; 5 for amino acid racemization (AAR) dating; and 5 for 14C dating. Litho and biofacies analyses identified distinct paleoenvironments, with the presence of a marsh environment alternating with inputs of alluvial material and marine sediments. Biomarkers indicated the constant presence of terrestrial (herbaceous) plants, together with a variable development of aquatic macrophytes. During the Holocene transgression, the Almenara marsh was occupied by oligohaline marsh facies with an oscillating water level and peat formation, which was established at the bottom of the record at 7570 cal yr BP and persisted until 3100±780 yr (AAR). Maximum surface flooding occurred at 5480 cal yr BP, registered 450m from the current coastline. At least three peat beds (dated with 14C dating and AAR) correlated with Bond (episode 5900 cal yr BP) and Wanner (episodes 4800–4500 and 3300–3500 cal yr BP) cycles and thus correspond to a regional model that affected the Northern Hemisphere.

scholarly journals The Holocene Cedrus pollen record from Sierra Nevada (S Spain), a proxy for climate change in N Africa

2020 ◽  
Author(s):  
Gonzalo Jiménez-Moreno ◽  
R. Scott Anderson ◽  
María J. Ramos-Román ◽  
Jon Camuera ◽  
Jose Manuel Mesa-Fernández ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Climatic Variability ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Northern Africa ◽  
Pollen Record ◽  
North African ◽  
The Holocene ◽  
Middle And Late Holocene ◽  
Millennial Scale

<p>In this study, we synthesized pollen data from seven sites from the Sierra Nevada in southern Spain to investigate the response of forests in the western Mediterranean area to centennial- and millennial-scale climate changes and to human impact during the Holocene. In particular, here we focused in <em>Cedrus</em> pollen abundances, which most-likely originated from Northern Africa and were carried to Sierra Nevada by wind. Although <em>Cedrus</em> abundances are generally lower than 1% in the studied pollen samples, a comparison with North African pollen records shows similar trends at long- and short-term time-scales. Therefore, this record could be used as a proxy for changes in this forest species in North Africa. A Middle and Late Holocene <em>Cedrus</em> pollen increasing trend has been observed in the Sierra Nevada synthetic record, which seems to be the result of decreasing summer insolation. This would have produced overall cooler annual temperatures in Northern Africa (Atlas and Rif Mountains), benefiting the growth of this cool-adapted montane tree species, and lower summer evaporation, increasing available moisture during the summer, which is critical for this water-demanding species. Millennial- and centennial-scale variability also characterize the Sierra Nevada <em>Cedrus</em> synthetic record. <em>Cedrus</em> abundance oscillations could have been produced by well-known millennial-scale climatic variability that controlled cedar abundance in montane areas of N Africa.  </p>

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