Contributors: Patrick De Deckker

Date: 2001-06-01

core and thus helps justify that the bottom portion of the core cannot...core spanning the last 40,000 calibrated years of sedimentation identifies...sedimentation rates adjusted accordingly between dated horizons. Peak ...Late Quaternary cyclic aridity in tropical Australia...core GC-2 used for radiocarbon dating ...sedimentation rate in the core and thus helps justify that the bottom ...Late Quaternary...core spanning the last 40,000 calibrated years of sedimentation identifies...Core GC2 against time in calibrated years BP. The seven aeolian peaks ...Late Quaternary...log of core GC 2. ...core (see Table 2) are represented by vertical bars in the middle diagram...from core GC-2 used for radiocarbon dating ...Quaternary sea level fluctuations, the vast Gulf of Carpentaria, in northern...core GC 2. ... During the numerous Quaternary sea level fluctuations, the vast Gulf of Carpentaria, in northern Australia, was more often a large lacustrine basin than a shallow sea. Recovery of aeolian quartz particles in a core spanning the last 40,000 calibrated years of sedimentation identifies a ~2,600year cyclic pattern of aridity. The most pronounced period peaks around 21,500 calibrated years BP, corresponding to the onstart of the period of lowest global sea level and glacial advance in New Zealand. The following peak of aeolian dust activity in Carpentaria just precedes the termination of the low sea level stand at 19,300 calibrated years BP.

Contributors: M. Cremer, E. Gonthier, J. Duprat, J.-C. Faugères, T. Courp

Date: 2007-02-01

sediment cores across the Sao Tomé system (core location in Fig. 2). ...core) and temporal (average for glacial and interglacial sediments) variability...carbonate-rich sediment are lighter. «Sl» and «sl» stand for the silt ...sedimentation rates ...Quaternary...fraction) in the sediment cores. Data in Table 5. ...sediment records allow addressing the paleoceanographic changes that took...sediment...sedimentation rates. Cores location in Fig. 2. ...sediment cores across the Sao Tomé system (core location in Fig. 2). Lithologic...sediment dynamics that prevailed on this system during the late Quaternary...Carbonate record and sediment structures (X radiograph) in selected sequences...sediment dynamics that prevailed on this system during the late Quaternary...sedimentation. According to the location of the cores at the present day...sediment cores. Data in Table 5. ...sedimentation rate during glacials) the sediment records (chiefly the ...late glacial could be associated to Heinrich events, when NADW production...Spatial (average by core) and temporal (average for glacial and interglacial...Late Quaternary variability of the sedimentary record in the Sao Tome ...cores at the present day interface between NADW and AABW, we infer that...sediment cores located across a deep channel-levee system in the South ... Very few sediment records allow addressing the paleoceanographic changes that took place on orbital and/or sub-Milankovitch time scales in the South–West Atlantic. Here, a set of sediment cores located across a deep channel-levee system in the South Brazilian basin (3700–3900 m depth) is used to infer the sediment dynamics that prevailed on this system during the late Quaternary and to relate this pattern to climate changes. The spatial distribution of deposits (changes in mineralogy, texture, structure, and sedimentation rate according to the morphology) indicates bulk of sediment supplies is distributed on the Sao Tomé system by bottom advective processes. The silty–sandy layers, originate undoubtedly from turbidity currents whereas the fine-grained muds and oozes, that form the major part of the deposits, are controlled by deep geostrophic currents. In addition to variations forced by the orbital cycles, (more turbidites, less carbonates and higher sedimentation rate during glacials) the sediment records (chiefly the CaCO3 record) document outstanding higher frequency regional changes in sedimentation. According to the location of the cores at the present day interface between NADW and AABW, we infer that changes in sedimentation are related to pulses of AABW versus NADW production. These changes, commonly marked by asymmetric carbonate pattern of about 10 kyr, suggest that the relative influence of NADW versus AABW followed, throughout the last 190 kyr, a repetitive sequence of progressive increase and sharp decrease. The rather sharp shut down observed during the late glacial could be associated to Heinrich events, when NADW production stopped, but similar events are also well expressed during MIS 5, MIS 6 and at the end of MIS 7.

Contributors: Marcelo Cancela Lisboa Cohen, Marlon Carlos França, Dilce de Fátima Rossetti, Luiz Carlos Ruiz Pessenda, Paulo César Fonseca Giannini, Flávio L. Lorente, Antônio Álvaro Buso Junior, Darcilea Castro, Kita Macario

Date: 2014-12-01

sediment cores. ...late Quaternary and raised these deposits. The post-glacial sea-level ...sediment accumulation and vegetation change in the study area according...sediment supply. (⋆ core locations). ...late Quaternary and raised these deposits. The post-glacial sea-level ...cores. ...sediment cores and the spatial distribution of main geomorphological features...of studied sediment cores. ...late Holocene led to seaward and downward translation of the shoreline...studied cores. ...sediment supply and relative sea-level fluctuations related to Quaternary...and sediment supply. (⋆ core locations). ...of sediment accumulation and vegetation change in the study area according...late Quaternary at the Doce River mouth, Espírito Santo State, Southeastern... of studied sediment cores and the spatial distribution of main geomorphological...sediment supply and relative sea-level fluctuations related to Quaternary...sedimentation through the variation of accommodation space and base-level ... The sedimentary deposits of the deltaic plain of the Doce and Barra Seca rivers, Southeastern Brazil, were studied by facies analysis, pollen records, δ13C, C/N analysis and AMS 14C-dating. Today, this deltaic plain is dominated by beach ridges and sandy terraces occupied by arboreal and herbaceous vegetation. Between ~47,500 and ~29,400calyrB.P., a deltaic system was developed in response mainly to eustatic sea-level fall. Although the studied stratigraphic succession is compatible with the trend of global sea-level fall, the earlier sea-level suggested by the topographic position of these deltaic deposits was above the one expected during the MIS3 stage. A tectonic uplift likely occurred during the late Quaternary and raised these deposits. The post-glacial sea-level rise caused a marine incursion with invasion of embayments and broad valleys, and it favored the evolution of an estuary with wide tidal mud flats occupied by mangroves between ~7400 and ~5100calyrB.P. The high river sand supply and/or the relative sea-level fall in the late Holocene led to seaward and downward translation of the shoreline during normal/forced regression, producing progradational deposits with shrinkage of mangrove stands and expansion of marshes colonized by herbaceous vegetation. Therefore, the stratigraphic architecture and evolution of the Doce River deltaic plain suggest that fluvial sediment supply and relative sea-level fluctuations related to Quaternary global climatic changes and local tectonism exerted major controls on sedimentation through the variation of accommodation space and base-level changes.

Contributors: Ajit Singh, Debajyoti Paul, Rajiv Sinha, Kristina J. Thomsen, Sanjeev Gupta

Date: 2016-05-01

sediments (~75ka–recent). Major oxide compositions of the core sediments...core sediments. Also shown for comparison are modern sediments from Sutlej...core sediments. Also shown for comparison are modern-river sediments from...Late Quaternary. Aeolian sediments (~150ka) in both the cores are overlain...fraction of GS core sediments. ...in a deep sea sediment core from Arabian sea (Rostek et al., 1993); 6 ...Late Quaternary. Aeolian sediments (~150ka) in both the cores are overlain...core sediments during glacial periods can be explained by increasing sediment...Late Quaternary...core sediments. ...core sediments. Also shown for comparison are modern-river sediments (...drill-sediment cores from a buried channel in the Ghaggar Plains of NW...sediments...sediment contribution from HH. The down-core Sr–Nd isotopic variability...-11 core sediments. Also shown for comparison are modern-river sediments...foraminifera in sediment core from Indian Ocean (Duplessy, 1982); 2 — ... record in a sediment core from Arabian Sea (Van Campo et al., 1982); ...core sediments (n=18) suggest binary mixing of sediments from compositionally...sediments from Ghaggar Plains, NW India: Multi-proxy records of variations...core sediments; (c and d) δ18O and δ13C of carbonate nodules from GS cores ... We report the first geochemical record in two drill-sediment cores from a buried channel in the Ghaggar Plains of NW India, which are used to infer variations in provenance, paleoclimate, and paleovegetation in the locality during the Late Quaternary. Aeolian sediments (~150ka) in both the cores are overlain by fluvial sediments (~75ka–recent). Major oxide compositions of the core sediments (n=35) generally vary between that observed for the modern-day Ghaggar/Sutlej and Yamuna river sand. The isotopic composition (87Sr/86Sr: 0.7365 to 0.7783 and εNd: −14.6 to −19.0) of core sediments (n=18) suggest binary mixing of sediments from compositionally distinct Higher Himalaya (HH) and Lesser Himalaya (LH) endmembers in the catchment, and support involvement of a river system originating in the Himalayan hinterland. Distinctly higher 87Sr/86Sr and lower εNd in the core sediments during glacial periods can be explained by increasing sediment contribution from LH (high 87Sr/86Sr and low εNd) due to an increase in glacial cover over HH. Whereas relatively less glacial cover over HH during interglacial periods resulted in more erosion and sediment contribution from HH. The down-core Sr–Nd isotopic variability clearly reflects climate-controlled sediment erosion in the Himalayan catchment. Temporal variations in δ18O and δ13C of carbonate nodules (n=27) are consistent with that reported from the Ganga interfluves. The δ13C variability (−4.1‰ to 1.2‰) in carbonates is mainly controlled by the extent of silicate (HH) versus carbonate (LH) source weathering due to significant climatic shifts. The δ13C of sediment organic matter (−27.4‰ to −23.2‰, n=24) suggests dominantly C3 plants in the catchment during the last ~75ka. More negative δ13C values in sediments during glacial periods relative to those during interglacial periods can be explained by increasing C4 abundance during interglacial periods characterized with both higher summer rainfall and mean annual temperature.

Contributors: Papay Suparan, Rien A.C Dam, Sander van der Kaars, Theo E Wong

Date: 2001-07-15

palynological analysis of core D6 sediments (hscharacteristic lowland ...Late Quaternary environmental change studies. First, the geologic, morphologic...Mid-Late Holocene, a low-energy fluvial systems and swamps existed in ...Late Pleistocene and Holocene landform development, sedimentation and ...core sediments. All taxa are shown as a percentage of the total pollen...sediment starved floodbasins. (C) The marine erosion cliff in the coastal...Late Quaternary environmental change studies. First, the geologic, morphologic...Late Quaternary...core D6 sediments (hscharacteristic lowland rain-forest tree taxa on Halmaherah...Late Quaternary...sediments (core D6). Core samples were subsampled for texture, organic...sedimentation in humid tropical lowland environments on Halmahera island...Late Pleistocene or Holocene environmental conditions is difficult to ...Late Quaternary tropical lowland environments on Halmahera, Indonesia...confidence) ranges. The sequence of core D6 is discussed in the text. ...Kao River plain sediments (core D6). Core samples were subsampled for ...core D6 is discussed in the text. The locations of cores D6 and D7 are...flooded, sediment starved floodbasins. (C) The marine erosion cliff in...palynological analysis of D6 core sediments. All taxa are shown as a percentage...Late Pleistocene and Holocene landform development, sedimentation and ...sediments and the existence of natural grasslands in the coastal zone. ... Results of a case study of landform development and sedimentation in humid tropical lowland environments on Halmahera island, eastern Indonesia, are presented with the aim to better characterise tropical lowland environments in the context of Late Quaternary environmental change studies. First, the geologic, morphologic and environmental settings of the two areas, the interior Kao River plain and the Kao coastal zone (N. Halmahera), are presented. Subsequently, data concerning Late Pleistocene and Holocene landform development, sedimentation and coastal processes are discussed. Pleistocene landform development involved volcaniclastic sedimentation, base levelling of coastal lowlands, prolonged weathering and crust formation, coastal uplift and eustatic sea level change. A conspicuous ferricrete crust in the subsoil of the coastal plain is tentatively dated with 14C AMS analysis and isotopes of organic matter encapsulated in the soil ferricrete have been determined. Due to interacting sea level change, neotectonic uplift, climatic, hydrologic and vegetational change, unequivocal evidence for anomalous Late Pleistocene or Holocene environmental conditions is difficult to obtain. During the Mid-Late Holocene, a low-energy fluvial systems and swamps existed in the interior Kao River plain; a dense open swamp/swamp forest vegetation contributed to extremely high sedimentation rates in this depositional basin. Palynological analysis of the organic swamp deposits indicates little or no change in sedimentary environmental settings and swamp vegetations, and indications for early human presence in the area. In the coastal area accretion and delta progradation occurred after the Early-Mid Holocene formation of a marine erosion cliff. Tentative evidence for early human presence in the Kao area is derived from charcoal particle frequencies in sediments and the existence of natural grasslands in the coastal zone. As most of the geologic and environmental characteristics of the tropical lowlands in the Kao area are common in eastern Indonesia, the study provides useful information for ongoing research in the region.

Contributors: Simona Giunta, Caterina Morigi, Alessandra Negri, Francois Guichard, Gilles Lericolais

Date: 2007-04-30

analysis of surficial sediment samples ...is shown. (core B2KS24, 46–48 cm).d — Acicular carbonate elements in core...sediments (Jones and Gagnon, 1994, modified). ...Late Quaternary evolution of the Black Sea, specifically to refine its...core MD04 2754 because of its high sedimentation rate. Ecozonal boundary...Late Quaternary...cores collected in the Black Sea. The primary goal was to elucidate the...Late Quaternary...cores studied ...Late Quaternary evolution of the Black Sea, specifically to refine its...rice-grains in core B2 KS02 (866 cm bsl).f — SEM view of aragonite rice-grains...core designations are depths at the core stations. The lithologic units...meters below the core designations are depths at the core stations. The...sediment samples ... In this study, detailed micropaleontological analyses were carried out on 270 samples from eight piston cores collected in the Black Sea. The primary goal was to elucidate the Late Quaternary evolution of the Black Sea, specifically to refine its biostratigraphy and to explore the Holocene paleoenvironmental changes.

Contributors: Zhongyuan Chen, Baoping Song, Zhanghua Wang, Yongli Cai

Date: 2000-01-15

sediment cores, vibrocores, surficial samples and seismic track line. ...sediment distribution. Belt A, delta front fine sand and silt, with trough...the core Cj4. Zone c, the warmest temperature period starting at ca. 7000...sediment sequences reveal a general trend of climate warming from early...late Pleistocene sediments in front of the estuarine depocenter. Gravity...core Cj4. Indicated 14C dates are based from Chen and Wang (1994). ...showing the location of sediment cores, vibrocores, surficial samples ...late Quaternary stratigraphy...Late Quaternary evolution of the sub-aqueous Yangtze Delta, China: sedimentation...sediment belts (A–D) of the Yangtze sub-aqueous delta are defined from...text. ...Sediment distribution of the sub-aqueous Yangtze Delta. Four sediment ...late Quaternary sub-aqueous Yangtze Delta. N, number; S, species; R, rare...S...late Pleistocene period (Ren and Zhen, 1980). ...late Quaternary stratigraphy of the delta consists from bottom upward ...late Quaternary stratigraphy...sediment loading within the depocenter is the major factor in causing ...sediment distribution...lithostratigraphic log of the late Quaternary sub-aqueous Yangtze Delta ... Four sediment belts (A–D) of the Yangtze sub-aqueous delta are defined from the sea-bottom sediment distribution. Belt A, delta front fine sand and silt, with trough cross stratification; Belt B, prodelta silty clay and clayey silt, with abundant burrowing and rich in organic matter; Belt C, prodelta to continental shelf sand–silt–clay, with thin layers of sand and clay interbedded; and Belt D, late Pleistocene relict sands (medium to fine grained), mixed with shell fragments. The late Quaternary stratigraphy of the delta consists from bottom upward of: late Pleistocene terrigenous (fluvial and lacustrine) sand and mud; Holocene transgressive silt, prodelta clay and delta front fine sand and silt. In addition, four pollen-spore zones (a–d) derived from these sediment sequences reveal a general trend of climate warming from early to late Holocene. The Zone c, distributed primarily within the prodelta muds, provides evidence for a temperature maximum starting at ca. 7000 years B.P. (Atlantic period). This indicates that the delta initiation was essentially coeval with the climate optimum in early Holocene. Sub-bottom seismic surveys reveal three (I–III) acoustic facies. Facies I and II are characterized by seaward remobilization of water-saturated Holocene prodelta muds; facies III is composed of highly-contorted late Pleistocene strata and mud diapirs that erupted from deep-seated late Pleistocene sediments in front of the estuarine depocenter. Gravity subsidence due to Holocene sediment loading within the depocenter is the major factor in causing the deformation of underlying unconsolidated strata. Furthermore, the sub-aqueous Yangtze Delta proper is now obviously diverting to southeast owing to the long-term, tectonically induced southward shift of the river mouth, and to the marine currents associated with the Coriolis effect. We thus predict that the large Chongming island in river mouth area will have been coalesced with the northern Yangtze coast in the recent future.

Contributors: S.H. Lee, J.J. Bahk, S.K. Chough, G.G. Back, H.S. Yoo

Date: 2004-05-31

sedimentation caused by an interaction between bottom currents and mass...Location, water depth and length of sediment cores ...core sediments ...late Quaternary. Cross sections cut through the South Korea Plateau and...Late Quaternary sedimentation in the Ulleung Interplain Gap, East Sea ...core sections. For symbols on the right side, see Table 3. Core locations...adjacent areas during the late Quaternary. Cross sections cut through ...sedimentary facies in core sediments ...sediments. Based on vertical distribution of sedimentary facies together...core sediments can be divided into Units I (∼15 ka)....sediment cores (8.6–11.4 m long) together with age data of tephra layers...sediment cores ...cores. For location of cores, see Figs. 1B, 7B, 9D and 10. Solid triangles...Core sediments consist of various deposits of turbidites, muddy contourites... core sections. For symbols on the right side, see Table 3. Core locations... correlation of cores. For location of cores, see Figs. 1B, 7B, 9D and ... The Ulleung Interplain Gap (UIG) is a deep (2300–2700 m) passage which has served as a conduit for deep-water circulation between the Ulleung and Japan basins. A detailed analysis of Chirp (2–7 kHz) subbottom profiles (ca. 6270 line-km) and nine sediment cores (8.6–11.4 m long) together with age data of tephra layers and four AMS 14C from the UIG and the adjacent areas reveals complex sedimentation caused by an interaction between bottom currents and mass flows during the last- and post-glacial periods. From high-resolution subbottom data, rock basement, slide/slump/rock-fall deposits, mass-flow chutes/channels, mass-flow deposits, bottom-current deposits, and a large-scale bottom-current channel system are recognized. Core sediments consist of various deposits of turbidites, muddy contourites, manganiferous contourites, and pelagic/hemipelagic sediments. Based on vertical distribution of sedimentary facies together with a chronostratigraphic framework, core sediments can be divided into Units I (∼15 ka).

Contributors: A Kuijpers, S.R Troelstra, M.A Prins, K Linthout, A Akhmetzhanov, S Bouryak, M.F Bachmann, S Lassen, S Rasmussen, J.B Jensen

Date: 2003-03-30

core is not represented. The core location, where water depth is 620 m...sediment Fe/K ratio. Results of 14C measurements are also shown. Note ...core DS97-7P with whole-core MS, calcium carbonate content, relative abundance...core DS97-4P with grain size (>63 μm) distribution, whole-core MS, XRF...the sediment waves, indicates contour-parallel bottom currents (shown ...sediment transport and mass flow deposition, which is concluded to be ... log of core DS97-7P with whole-core MS, calcium carbonate content, relative...Late Quaternary sedimentary processes and ocean circulation changes at...Pliocene–Quaternary sedimentary sequence. ...late Quaternary depositional processes and bottom current activity on ...late Quaternary depositional processes and bottom current activity on ...sedimentation...core of south flowing LSW between 800 and 1500 m (after Dickson and Brown...sediment core information. The seabed data demonstrate the occurrence ... A study has been made of late Quaternary depositional processes and bottom current activity on the Southeast Greenland margin, using seismic, sub-bottom profiling and deep-tow side-scan sonar data as well as sediment core information. The seabed data demonstrate the occurrence of strong, southerly bottom currents prevailing on the slope and rise. Well-defined longitudinal bedforms indicate maximum mean near-bottom current velocities of up to at least 1.0 m/s at the depth stratum of Labrador Sea water (800–1500 m). Similarly strong currents occur in Denmark Strait overflow water (DSOW) at the base of the slope, whereas more basinward the maximum DSOW flow speed is lower. Iceberg plow marks were found down to about 700 m water depth. Both at the shelf edge and on the lower slope and rise the seafloor morphology is indicative of downslope sediment transport and mass flow deposition, which is concluded to be a typically glacial feature. After generally more sluggish deep-water circulation during the last glacial maximum, DSOW basin ventilation was re-established shortly before 13.3 ka. On the shelf, in front of the retreating Greenland ice margin, permanent or semi-permanent sea ice conditions prevailed until about 12.5 ka. At that time increased Irminger Current activity had resulted in warming, and East Greenland Current (EGC)-controlled iceberg drift increased. No evidence was found for a return to extreme glacial conditions or a ceasing of DSOW flow during the Younger Dryas. Abundant coarse IRD collected at greater water depth from shallow sub-seabed strata has a provenance mainly in the northern part of East Greenland (68–73°N), which demonstrates the existence of a pre-Holocene EGC system initially extending to beyond the shelf edge.

Contributors: Patricia Wells

Date: 1994-01-01

Late Quaternary sediments of core BMR96GC21 in the southeast Indian Ocean ... 398 occurrences