4 results for late quaternary sediment core
Sediment recycling and adjustment of deposition during deglacial drowning of a low-accumulation shelf (NW Iberia)
Late Quaternary...Sediment core positions are indicated by black arrows. Depth on y-axis...sediment vibrocores and surface samples of this study....sediments by biogenic production are not displayed....Late-Quaternary stratigraphic interpretation of the profiles A–C in Fig...Late-Quaternary stratigraphic interpretation of the profiles A–C in Fig...late deglaciation (15–10ka BP), early Holocene (10–6ka BP), and late Holocene...Sediment recycling and adjustment of deposition during deglacial drowning...sedimentation...Sediment core columns of the respective Boomer profiles in Fig. 2. Lithology...sediment cores, the distribution of facies types on the NW Iberian margin...Late Quaternary ... Based on a well-established stratigraphic framework and 47 AMS-14C dated sediment cores, the distribution of facies types on the NW Iberian margin is analysed in response to the last deglacial sea-level rise, thus providing a case study on the sedimentary evolution of a high-energy, low-accumulation shelf system.
Sediment delivery and lake dynamics in a Mediterranean mountain watershed: Human-climate interactions during the last millennium (El Tobar Lake record, Iberian Range, Spain)
coring sites....core TOB07-1A-1G (red), the section 2 from thelong core TOB04-1D-1K-2 ...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...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...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...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).
Late Quaternary environmental and landscape dynamics revealed by a pingo sequence on the northern Seward Peninsula, Alaska
sediments. The pingo ice core has partially melted out already and is ...late Quaternary landscape dynamics controlled by mid-Wisconsin and early...late-Quaternary environmental history of the northern Seward Peninsula...Late Quaternary environmental and landscape dynamics revealed by a pingo...sediment. Note different scales for taxa counts....late-Quaternary environmental history of the northern Seward Peninsula...sediments dated to 50–40 ka BP strongly suggest the presence of forest...sediment sequence exposed in an eroding pingo provides insights into the...late Quaternary landscape dynamics controlled by mid-Wisconsin and early ... A terrestrial sediment sequence exposed in an eroding pingo provides insights into the late-Quaternary environmental history of the northern Seward Peninsula, Alaska. We have obtained the first radiocarbon-dated evidence for a mid-Wisconsin thermokarst lake, demonstrating that complex landscape dynamics involving cyclic permafrost aggradation and thermokarst lake formation occurred over stadial–interstadial as well as glacial–interglacial time periods. High values of Picea pollen and the presence of Larix pollen in sediments dated to 50–40 ka BP strongly suggest the presence of forest or woodland early in MIS 3; the trees grew within a vegetation matrix dominated by grass and sedge, and there is indirect evidence of grazing animals. Thus the interstadial ecosystem was different in structure and composition from the Holocene or from the preceding Last Interglacial period. An early Holocene warm period is indicated by renewed thermokarst lake formation and a range of fossil taxa. Multiple extralimital plant taxa suggest mean July temperatures above modern values. The local presence of spruce during the early Holocene warm interval is evident from a radiocarbon-dated spruce macrofossil remain and indicates significant range extension far beyond the modern tree line. The first direct evidence of spruce in Northwest Alaska during the early Holocene has implications for the presence of forest refugia in Central Beringia and previously assumed routes and timing of post-glacial forest expansion in Alaska.
core record (Stroeven et al., 2015, Table 2). The ice recession lines ...core record of Rasmussen et al. (2014). Ages expressed in cal kyr BP....core event stratigraphy (from Rasmussen et al., 2014, Fig. 1), with, indicated...core event stratigraphy (Rasmussen et al., 2014; see also Table 5, Fig...core area of the Fennoscandian Ice Sheet during deglaciation from its ...Late Glacial clay varve chronologies in Sweden and Finland that are used ... To provide a new reconstruction of the deglaciation of the Fennoscandian Ice Sheet, in the form of calendar-year time-slices, which are particularly useful for ice sheet modelling, we have compiled and synthesized published geomorphological data for eskers, ice-marginal formations, lineations, marginal meltwater channels, striae, ice-dammed lakes, and geochronological data from radiocarbon, varve, optically-stimulated luminescence, and cosmogenic nuclide dating. This is summarized as a deglaciation map of the Fennoscandian Ice Sheet with isochrons marking every 1000 years between 22 and 13 cal kyr BP and every hundred years between 11.6 and final ice decay after 9.7 cal kyr BP.