22 results for late quaternary sediment core
Late Quaternary micropalaeontological record of a semi-enclosed marine basin, North Evoikos, central Aegean Sea
Contributors: Hara Drinia, Assimina Antonarakou, George Anastasakis
cores are reported in Table 1 and depicted in Fig. 2.Table 1Details of...sediment cores. ...plotted for each core (Fig. 4a–f).Table 3Eigenvalues.Value%SimilarityCumulativeEigenval...coring locations in the North Evoikos Gulf. ...fossil sediments is based on 6 gravity cores (EYB: 1, 10, 6, 5, 7, 8) ...cores ...sediment cores: location, depth and lengthCoresLatitudeLongitudeWater ... by CA, of core EYB10, together with the distribution of the Biofacies...cores and correlation. ...sediment cores: location, depth and length ... by CA, of core EYB1, together with the distribution of the Biofacies....the cores are reported in Table 1 and depicted in Fig. 2.Table 1Details...sediments is based on 6 gravity cores (EYB: 1, 10, 6, 5, 7, 8) ranging... sediment cores. ...of the sediment cores: location, depth and lengthCoresLatitudeLongitudeWater...Details of the sediment cores: location, depth and length ...core (Fig. 4a–f).Table 3Eigenvalues.Value%SimilarityCumulativeEigenval...cores retrieved from different physiographic settings of the Gulf were...Late Quaternary micropalaeontological record of a semi-enclosed marine ... North Evoikos Gulf constitutes a deep (450 m) semi-enclosed basin in east-central Greece connected to the Aegean Sea via a 42-m sill to the north and a 40-m wide, 8-m deep channel to the south. Six gravity cores retrieved from different physiographic settings of the Gulf were analyzed for their benthic foraminiferal content, in order to reconstruct the local and regional palaeoenvironmental changes.
Invited review - Lacustrine carbonates of Iberian Karst Lakes: Sources, processes and depositional environments
Contributors: Blas Valero-Garcés, Mario Morellón, Ana Moreno, Juan Pablo Corella, Celia Martín-Puertas, Fernando Barreiro, Ana Pérez, Santiago Giralt, María Pilar Mata-Campo
Late Quaternary. The lakes, relatively small (1ha to 118ha) and relatively...Late Quaternary...Late Quaternary. The lakes, relatively small (1ha to 118ha) and relatively...sediment cores. ...location of the sediment core. ...sediment core. ...map and location of the sediment cores. ... location of the sediment cores. ...Late Quaternary... and location of the sediment core. ...sediments. In this review we summarize the main processes controlling ...Quaternary lake sediments. In this review we summarize the main processes ... Carbonates are the main components of Iberian Quaternary lake sediments. In this review we summarize the main processes controlling carbonate deposition in extant Iberian lakes located in Mesozoic and Tertiary carbonate-dominated regions and formed through karstic activity during the Late Quaternary. The lakes, relatively small (1ha to 118ha) and relatively shallow (Zmax=11 to 40m) provide examples of the large variability of sedimentary facies, depositional environments, and carbonate sources. Hydrology is dominated by groundwater inflow except those directly connected to the fluvial drainage. Nine lakes have been selected for this review and the main facies in palustrine, littoral and profundal environments described and interpreted.
Research paper - Conduits, timing and processes of sediment delivery across a high-relief continental margin: Continental shelf to basin in Late Quaternary, Gulf of Papua
Contributors: Erlangga Septama, Samuel J. Bentley, André W. Droxler
...sand example from core MV-23. ...formed during the bulk sediment sample immersion into liquid nitrogen....late Quaternary lithofacies and stratigraphic framework to better understand...sediment delivery across a high-relief continental margin: Continental...sediment budget. For the map clarity, cores are referred to by number ...sediment sample immersion into liquid nitrogen. This artifact can be used...sediment delivery from terrestrial and shelf settings to deep marginal...core x-radiographs and thin sections....sediment-core stratigraphy and physical properties, accelerometer mass...sediment deposition across the Gulf of Papua, from shelf margin to the...compartment used to calculate sediment budget. For the map clarity, cores...cruise in 2004. ...Late Quaternary, Gulf of Papua...sediment–water interface was not recovered in piston cores. ...sediment budget in deep-sea Gulf of Papua. ...Sediment delivery...late Quaternary lithofacies and stratigraphic framework to better understand...sediment discharge >> 220 million metric tons (Mt) per year, comparable ... The Gulf of Papua (GoP), between Australia and Papua New Guinea, is the receiving basin for multiple substantial rivers draining southern Papua New Guinea with collective sediment discharge >> 220 million metric tons (Mt) per year, comparable to a continental-scale river, but draining a combined catchment area of only ∼160,000 km2. This study of the deepest marginal basins in the Gulf of Papua was undertaken to build a regional late Quaternary lithofacies and stratigraphic framework to better understand processes, timing, and conduits of sediment delivery from terrestrial and shelf settings to deep marginal basins, using the GoP as a natural laboratory. Methods include observations of sediment-core stratigraphy and physical properties, accelerometer mass spectrometry (AMS) C-14 dates, core x-radiographs and thin sections.
Foraminiferal records of bottom-water oxygenation and surface-water productivity in the southern Japan Sea during 160–15ka: Associations with insolation changes
Contributors: Kazuko Usami, Takeshi Ohi, Shiro Hasegawa, Ken Ikehara
sediment lightness (L*; gray bars indicate dark layers), sediment-fabric...foraminifera, respectively) for core MD01-2407. ...Late Quaternary...core MD01-2407. ...below sea floor; L*, sediment lightness values (also see Fig. 2); dashed...Late Quaternary...sediment fabrics, respectively), and sampling horizons (P and B indicate...in the far right column. ...sediment core IMAGES MD01-2407 (water depth, 932m) from the southern Japan...floor (mbsf), layer number, sediment lightness (L*; gray bars indicate...sediment fabrics, respectively. ...sediments underestimates surface productivity during depositional conditions...core were classified into six types on the basis of benthic foraminiferal...correlations between sediment fabrics and benthic foraminiferal assemblages i...core MD01-2407. cmbsf, cm below sea floor; L*, sediment lightness values ... Analyses of the benthic and planktonic foraminiferal record were conducted to understand temporal variations in sea-floor oxygenation and surface productivity during periods of dark-layer deposition between 160 and 15ka, based on data from sediment core IMAGES MD01-2407 (water depth, 932m) from the southern Japan Sea. The dark layers in the core were classified into six types on the basis of benthic foraminiferal assemblages, which reflect the nature and amount of organic material on the sea floor, as well as the degree of oxygenation of bottom waters. Three of the dark layer types were deposited in conditions strongly associated with increased surface productivity, which correlates with positive or negative peaks of summer insolation in the Northern Hemisphere. During periods of insolation maxima, summertime surface productivity was enhanced because of the inflow of nutrient-rich surface waters associated with high precipitation in eastern Asia, caused by intensification of the East Asian summer monsoon. In contrast, relatively sustained organic matter fluxes to the sea floor occurred during insolation minima, possibly affected by active vertical mixing. When the East Asian summer and winter monsoons were both intensified in a given period well oxygenated bottom-water environments combined with high surface productivity may have resulted in dark-layer deposition, because of a combination of strong wintertime water convection and increased summertime surface productivity. It is likely that the organic carbon content of sediments underestimates surface productivity during depositional conditions favoring the sedimentary decomposition of organic matter.
Late Quaternary evolution of Lago Castor (Chile, 45.6°S): Timing of the deglaciation in northern Patagonia and evolution of the southern westerlies during the last 17 kyr
Contributors: Maarten Van Daele, Sébastien Bertrand, Inka Meyer, Jasper Moernaut, Willem Vandoorne, Giuseppe Siani, Niels Tanghe, Zakaria Ghazoui, Mario Pino, Roberto Urrutia
sediment core CAST01. The ages were calibrated with CLAM 2.2 (Blaauw, ...sediment core penetrating all lacustrine seismic units, was retrieved....sediment core. This dry period likely resulted from the increased orographic...sediments in the mound. This is not visible in the core density (Fig. ...coring compaction of the sediments as a result of gravity coring (Lebel...the profile. (b) sediment core units, lithology (see Fig. 5 for legend...late Quaternary climate evolution remain unresolved. The timing of maximum...sediment core CAST01. (b) interpretation of the same composite profile...Sediment drift...late Quaternary climate evolution remain unresolved. The timing of maximum...sediment drifts resulting from strong bottom current during periods of...penetration of composite sediment core CAST01. (b) interpretation of the...sediment core CAST01 (white circle) was retrieved, and an elongated southwestern...penetration of the sediment core CAST01, as well as the depth of the (...Late Quaternary evolution of Lago Castor (Chile, 45.6°S): Timing of the...sedimentation was more directly influenced by the southern westerlies,...which the sediment core CAST01 (white circle) was retrieved, and an elongated ... Even though Patagonia is ideally located to study climate of the southern mid-latitudes, many questions on the late Quaternary climate evolution remain unresolved. The timing of maximum glacier extent is still uncertain in vast areas, and the postglacial evolution of the Southern Westerly Wind Belt (SWWB) remains highly debated. Here, we study the sedimentary infill of a glacigenic lake (Lago Castor; 45.6°S, 71.8°W) located at the leeside of the Andes in Chilean Patagonia to i) reconstruct the deglacial evolution of the eastern flank of the Patagonian Ice Sheet (PIS), and ii) discuss postglacial changes in wind strength at a critical location where westerly wind records are critically lacking. A dense grid of high-resolution reflection-seismic data was used to reconstruct the large-scale infill history of the lake, and a radiocarbon dated sediment core penetrating all lacustrine seismic units, was retrieved. Results indicate that the deglaciation of the lake basin and its catchment occurred no later than ∼28 cal kyr BP (i.e. an early LGM), but possibly even already after MIS 4. Afterwards, the Lago Castor area was covered by a large proglacial lake that drained – possibly through an outburst flood – when the PIS outlet glaciers retreated to a critical location. Subsequently, very dry conditions caused the lake to desiccate, as evidenced by an unconformity visible on the seismic profiles and in the sediment core. This dry period likely resulted from the increased orographic effect of the PIS-covered Andes, accompanied by weaker westerlies. From ∼20 kyr BP onwards, the combination of a shrinking PIS and a southward shift of the SWWB resulted in increased precipitation, which caused the lake level to rise. After ∼17 cal kyr BP, lake sedimentation was more directly influenced by the southern westerlies, with the formation of sediment drifts resulting from strong bottom current during periods of intense westerly winds. Our results suggest a progressive increase in wind strength at 46°S from 11.2 to 4.5 cal kyr BP, which supports the hypothesis that the SWWB broadened during the early and middle Holocene.
Detrital cave sediments record Late Quaternary hydrologic and climatic variability in northwestern Florida, USA
Contributors: Tyler S. Winkler, Peter J. van Hengstum, Meghan C. Horgan, Jeffrey P. Donnelly, Joseph H. Reibenspies
sediment, and finally into (iii) fine-grained organic matter (gyttja) ...cores that reached (did not reach) bedrock. Note: ‘Sediment bypass’ down...Quaternary-scale hydrographic variability in the Apalachicola River drainage...) circles denote cores that reached (did not reach) bedrock. Note: ‘Sediment... Exley) denoting core locations, along with idealized cave cross section...coring locations and sediment recovery from Hole in the Wall Cave and ...Lithologic variability (core logs and photographs), bulk organic matter (w...cores. ...sediment in Florida's (USA) submerged cave systems may preserve records...sediment cores from two phreatic cave systems in northwestern Florida ...and sediment recovery from Hole in the Wall Cave and Twin Cave (N/R=not...results on core samples from Hole in the Wall Cave and Twin Cave. ...sediment column before compression occurred during coring (not recovered...sediments were also deposited in one of the caves during the Bølling/Allerød...core logs and photographs), bulk organic matter (wt. %), coarse sediment...sediments record Late Quaternary hydrologic and climatic variability in...sediment contains abundant invertebrate fossils, and likely documents ...Sedimentation in these caves is dominated by three primary sedimentary ... Detrital sediment in Florida's (USA) submerged cave systems may preserve records of regional climate and hydrologic variability. However, the basic sedimentology, mineralogy, stratigraphic variability, and emplacement history of the successions in Florida's submerged caves remains poorly understood. Here we present stratigraphic, mineralogical, and elemental data on sediment cores from two phreatic cave systems in northwestern Florida (USA), on the Dougherty Karst Plain: Hole in the Wall Cave (HITW) and Twin Cave. Water flowing through these caves is subsurface flow in the Apalachicola River drainage basin, and the caves are located just downstream from Jackson Blue (1st magnitude spring, >2.8m3s−1 discharge). Sedimentation in these caves is dominated by three primary sedimentary styles: (i) ferromanganese deposits dominate the basal recovered stratigraphy, which pass upsection into (ii) poorly sorted carbonate sediment, and finally into (iii) fine-grained organic matter (gyttja) deposits. Resolving the emplacement history of the lower stratigraphic units was hampered by a lack of suitable material for radiocarbon dating, but the upper organic-rich deposits have a punctuated depositional history beginning in the earliest Holocene. For example, gyttja primarily accumulated in HITW and Twin Caves from ~5500 to 3500calyr. BP, which coincides with regional evidence for water-table rise of the Upper Floridian Aquifer associated with relative sea-level rise in the Gulf of Mexico, and evidence for invigorated drainage through the Apalachicola River drainage basin. Gyttja sediments were also deposited in one of the caves during the Bølling/Allerød climate oscillation. Biologically, these results indicate that some Floridian aquatic cave (stygobitic) ecosystems presently receive minimal organic matter supply in comparison to prehistoric intervals. The pre-Holocene poorly sorted carbonate sediment contains abundant invertebrate fossils, and likely documents a period of enhanced limestone dissolution and cave formation (speleogenesis) during lower paleo water levels. Further work is still required to (a) determine whether precipitation of the ferromanganese deposits is inorganically or biologically mediated, (b) temporally constrain the emplacement history of the primary sedimentary styles, and (c) determine the full geographic extent of these sedimentary signals. However, these preliminary observations suggest that sedimentation in the inland underwater caves of northwestern Florida is related to Quaternary-scale hydrographic variability in the Apalachicola River drainage basin in response to broader ocean and atmospheric forcing.
Late Quaternary vegetation and lake system dynamics in north-eastern Siberia: Implications for seasonal climate variability
Contributors: B.K. Biskaborn, D.A. Subetto, L.A. Savelieva, P.S. Vakhrameeva, A. Hansche, U. Herzschuh, J. Klemm, L. Heinecke, L.A. Pestryakova, H. Meyer
Late Quaternary vegetation and lake system dynamics in north-eastern Siberia...sediment core PG2023. ...content in sediment core PG2023. ...sediment cores PG2023 and PG2022 are marked in the lake. Catchment is ...the age–depth model of core PG2023 to core PG2022. (For interpretation...sediment composition in the sediment core PG2023. Mineral contents were... modelled age to the sediment surface (∼0 BP) from 210Pb dating. Loss-on-ignition...late Holocene indicating a shortening of the seasonal ice cover that continues...core PG2023 to core PG2022. (For interpretation of the references to colour...mineralogical sediment composition in the sediment core PG2023. Mineral...sediment surface (∼0 BP) from 210Pb dating. Loss-on-ignition (green line...sediment geochemistry, and diatom and pollen data from lake-sediment cores... the sediment cores PG2023 and PG2022 are marked in the lake. Catchment ... Although the climate development over the Holocene in the Northern Hemisphere is well known, palaeolimnological climate reconstructions reveal spatiotemporal variability in northern Eurasia. Here we present a multi-proxy study from north-eastern Siberia combining sediment geochemistry, and diatom and pollen data from lake-sediment cores covering the last 38,000 cal. years. Our results show major changes in pyrite content and fragilarioid diatom species distributions, indicating prolonged seasonal lake-ice cover between ∼13,500 and ∼8900 cal. years BP and possibly during the 8200 cal. years BP cold event. A pollen-based climate reconstruction generated a mean July temperature of 17.8 °C during the Holocene Thermal Maximum (HTM) between ∼8900 and ∼4500 cal. years BP. Naviculoid diatoms appear in the late Holocene indicating a shortening of the seasonal ice cover that continues today. Our results reveal a strong correlation between the applied terrestrial and aquatic indicators and natural seasonal climate dynamics in the Holocene. Planktonic diatoms show a strong response to changes in the lake ecosystem due to recent climate warming in the Anthropocene.
Sediment delivery and lake dynamics in a Mediterranean mountain watershed: Human-climate interactions during the last millennium (El Tobar Lake record, Iberian Range, Spain)
Contributors: Fernando Barreiro-Lostres, Erik Brown, Ana Moreno, Mario Morellón, Mark Abbott, Aubrey Hillman, Santiago Giralt, Blas Valero-Garcés
correlation of short core TOB07-1A-1G (red), the section 2 from thelong...the nearby Lake La Parra (sediment delivery, Barreiro-Lostres et al., ...right: units, core image, sediment stratigraphy, facies with sedimentary...sediment delivery, Barreiro-Lostres et al., 2014) and Lake La Cruz (pollen...Late Quaternary...sediment delivery to the lake (PC1) and sediment organic content (PC2)...sediment core multi-proxy analyses and reconstructions of past land uses...comparison of the sediment. Sedimentary events (inlight brown) can be ...Late Quaternary...core image, sediment stratigraphy, facies with sedimentary evolution organized...sediment delivery event, showing strong resilience of the lacustrine system...sediment delivery periods. During the last millennium, the lake depositional...Sediment delivery and lake dynamics in a Mediterranean mountain watershed...coring sites. ...late 18th, mid 19th and early 20th centuries as a result of large land...sediment. Sedimentary events (inlight brown) can be easily traced along...sediment delivery have been identified in the 8m long sediment sequence...brown-shaded) and changes in sediment delivery to the lake (PC1) and sediment...Sediment delivery ... Land degradation and soil erosion are key environmental problems in Mediterranean mountains characterized by a long history of human occupation and a strong variability of hydrological regimes. To assess recent trends and evaluate climatic and anthropogenic impacts in these highly human modified watersheds we apply an historical approach combining lake sediment core multi-proxy analyses and reconstructions of past land uses to El Tobar Lake watershed, located in the Iberian Range (Central Spain). Four main periods of increased sediment delivery have been identified in the 8m long sediment sequence by their depositional and geochemical signatures. They took place around 16th, late 18th, mid 19th and early 20th centuries as a result of large land uses changes such as forest clearing, farming and grazing during periods of increasing population. In this highly human-modified watershed, positive synergies between human impact and humid periods led to increased sediment delivery periods. During the last millennium, the lake depositional and geochemical cycles recovered quickly after each sediment delivery event, showing strong resilience of the lacustrine system to watershed disturbance. Recent changes are characterized by large hydrological affections since 1967 with the construction of a canal from a nearby reservoir and a decreased in anthropic pressure in the watershed as rural areas were abandoned. The increased fresh water influx to the lake has caused large biological changes, leading to stronger meromictic conditions and higher organic matter accumulation while terrigenous inputs have decreased. Degradation processes in Iberian Range watersheds are strongly controlled by anthropic activities (land use changes, soil erosion) but modulated by climate-related hydrological changes (water availability, flood and runoff frequency).
A multidisciplinary approach for reconstructing the stratigraphic framework of the last 40ka in a bathyal area of the eastern Tyrrhenian Sea
Contributors: Simona Morabito, Paola Petrosino, Alfonsa Milia, Mario Sprovieri, Stella Tamburrino
Late Quaternary...sediments of CET1 core and average composition of the reference pyroclastic...studied sediments of CET1 core. ...sediments of the studied interval of CET1 core. ...features of the tephra layer embedded in the sediments of the studied ... in the studied sediments of CET1 core and average composition of the ...core. ...cored succession....through a cubic spline function in a core from the Salerno Gulf by Lirer...Late Quaternary...sediments of CET1 core. ...carbon isotope data in CET1 core. ... A detailed integrated stratigraphic framework for the last 40ka in the eastern Tyrrhenian Sea (central Mediterranean) was obtained through quantitative analyses of planktonic foraminifera assemblages, tephrostratigraphical studies and δ18O measurements on the basinal CET1 cored succession.
Palynological record of tropical rain forest vegetation and sea level fluctuations since 140ka from sediment core, south-eastern Arabian Sea
Contributors: Anjum Farooqui, J.N. Pattan, G. Parthiban, Jyoti Srivastava, Ranjana
core, south-eastern Arabian Sea. ...sediment core from the south-eastern Arabian Sea covers a time span of...SK-129 CR-05 core, south-eastern Arabian Sea. ...core indicates high productivity that suggests upwelling induced by seasonal...sediment core, south-eastern Arabian Sea...sediment accumulation corresponding to Marine Isotopic Stages. ...Late Quaternary...Late Quaternary...CR-05 core, south-eastern Arabian Sea. ...sediment core SK-129/CR-05. ...sedimentation corresponding to high percentage of terrestrial rain forest...magnitude and rate of sediment accumulation corresponding to Marine Isotopic...core in the south-eastern Arabian Sea and its proximity to the west coast...core is Western Ghats of India. High percentage of planktic foraminifera...the sediment core SK-129/CR-05. ... Palyno-chronological study of a 552cm deep sediment core from the south-eastern Arabian Sea covers a time span of ~140ka. The age estimate is based on oxygen isotopic data of planktic foraminifera. Six zones were identified on the basis of palynology covering partially MIS-6 and MIS-5 to MIS-1 (Marine Isotopic Stages). The interglacial period (MIS-5) shows high rate of sedimentation corresponding to high percentage of terrestrial rain forest pollen. The palynological study reveals highstand and intense rain forest vegetation during MIS 5a which corresponds to the similar earlier records of estuarine ecosystem on land in Kerala. The relative sea level rise and fall since ~140ka have been inferred through quantitative estimate of marine versus terrestrial palynomorphs. The terrigenous non-pollen forms comprised abundant Neogene extinct nanoplanktons (Discoaster spp.) until MIS-3 which was transported from the Varkala Formation (highlands of the Kerala coast). The pollen assemblage is comparable to the present day flora in Kerala except Ongokea gore which is now present in South Africa and therefore, the provenance of pollen recorded in the studied core is Western Ghats of India. High percentage of planktic foraminifera and dinoflagellate cysts throughout the core indicates high productivity that suggests upwelling induced by seasonal reversals in the monsoon winds even during the glacial periods. Botryococcus remains and poaceous leaf cuticles dominated by the Pooideae group in the marine realm also point towards active winter monsoon. Considerable fragmentation of rain forest took place post 74ka and during the LGM as the sea retreated to its maximum which resulted into the vast exposure of land favoring the expanse of grassland with pockets of rain forest “plant refugia” on land. Neogene rain forest flora recorded earlier from the Varkala Formation and the present record of its existence since MIS-6 in the region provide an understanding that the monsoon circulation over southern India was similar since the Middle Miocene Climate Optimum and the flora in the South-Western Ghats is a fossil ecosystem and a relic of the Tertiary period.