Contributors: Pratima M. Kessarkar, V. Purnachandra Rao, S.M. Ahmad, S.K. Patil, A. Anil Kumar, G. Anil Babu, Sukalyan Chakraborty, R. Soundar Rajan

Date: 2005-09-01

sediment cores used in this study ...sediments compared to unit 1 in both the cores. The unit 2 sediments represent...sediments in core 1 (SK148/2) ...Details of sediment cores used in this study ...sediment at different intervals of cores 1 and 2 ...sediments are predominantly olive black/grey in colour with abundant finer...sediments recovered from two gravity cores of the lower and distal Bengal...concentrations of sediment samples (core 1 and 2) together with the reported...Late Quaternary...Late Quaternary...sediment core SK148/2. OB—olive black, MB—moderate brown. (B) Downcore...sediments are calcareous pelagic sediments, which started depositing ∼...63μm size) of the sediment in core SK148/2. (Aa) and (Ab) show the grain...sediments in core SK148/2 (A), and in AAS37/2 (B). ...keels—K)) in sediment core AAS37/2. OG—olive grey, YB—yellowish brown,...Late Quaternary: Sedimentological and isotopic evidence from the distal...sediments...sediment deposition by turbidity current activity ceased in the distal...core exhibits two distinct units, the lower unit 2 and upper unit 1 sediments...the sediments in core 1 (SK148/2) ... The sediments recovered from two gravity cores of the lower and distal Bengal Fan were investigated for sedimentological properties and Sr–Nd isotopes. Each core exhibits two distinct units, the lower unit 2 and upper unit 1 sediments. The unit 2 sediments are predominantly olive black/grey in colour with abundant finer silt-size fractions, low organic carbon and CaCO3, quartz and mica in the coarse fraction, dominant illite and chlorite in the <2μm fraction and uniform rock-magnetic properties. Biogenic constituents are extremely rare or restricted to the lower part of unit 2. The unit 1 sediments, on the other hand, are moderate brown/yellowish brown in colour with intermittent thin dark-coloured sediment layers. Higher clay, organic carbon, CaCO3, and biogenic constituents in the coarse fraction, and enriched smectite and kaolinite in the <2μm fraction are typical. Magnetic susceptibility values are higher and correlate well with acid-insoluble residue content. Higher Rb, Sr, Sm and Nd concentrations, 87Sr/86Sr ratios and more radiogenic εNd values are characteristic for unit 2 sediments compared to unit 1 in both the cores. The unit 2 sediments represent Pleistocene hemiturbidites, older than 1314CkyrBP with their source from the northern Bay of Bengal (NBOB), derived from the Himalayas and transported by the Ganges–Brahmaputra (G–B) River system. Unit 1 sediments are calcareous pelagic sediments, which started depositing ∼1214CkyrBP, with its clastic sediments derived from the Himalayas and SE Indian/Sri Lankan margins. The change in lithofacies from unit 2 to unit 1 suggests that the sediment deposition by turbidity current activity ceased in the distal Bengal Fan at ∼1214CkyrBP, perhaps because of the rapid rise in sea-level during the melt water pulse 1A and Holocene.

Contributors: R. Klöcker, R. Henrich

Date: 2006-09-20

Late Quaternary high-sedimentation rate core (573 m water depth, Pakistan...Late Quaternary high-sedimentation rate core (573 m water depth, Pakistan...core 137KA is indicated by a star. ...core 137KA indicating organic and carbonate productivity (modified after...transect) and core SO90 137KA off Pakistan. ...sediments, light grey=indistinctly laminated sediments, white=bioturbated...sediment samples showing good to very good preservation (LDX: 2.2 to 1.3...Late Quaternary...Late Quaternary...of core 137KA is indicated by a star. ...core SO90 137KA off Pakistan. ...Late Quaternary pteropod preservation on the Pakistan shelf and continental...sediment core 137KA off Pakistan: (a) present-day situation with shallow...in sediment core 137KA off Pakistan: (a) present-day situation with shallow...sediment samples from the Pakistan shelf and upper continental slope and ... Fifteen surface sediment samples from the Pakistan shelf and upper continental slope and a Late Quaternary high-sedimentation rate core (573 m water depth, Pakistan continental margin) have been analysed to improve the understanding of the factors influencing pteropod preservation. The aragonite compensation depth (ACD) is located at 250–400 m water depth, which corroborates previous observations of a very shallow ACD in the northern Arabian Sea. With the exception of the Hab transect off Karachi, the ACD coincides with the upper boundary of the OMZ located at 250 m water depth. The shell preservation index of the pteropod Limacina inflata (LDX) was applied on six surface sediment samples showing good to very good preservation (LDX: 2.2 to 1.3).

Contributors: Patrick T. Moss, John Tibby, Lynda Petherick, Hamish McGowan, Cameron Barr

Date: 2013-08-05

of the cores. NC is the code for the samples taken from Native Companion...Late Quaternary climate dynamics...sediment core with black representing peat sediments, brown reflecting... the sediment core with black representing peat sediments, brown reflecting...late Quaternary palaeoenvironmental variability available from the subtropics...sediment core with black representing peat sediments and yellow reflecting...Late Quaternary vegetation history of North Stradbroke Island, Queensland...cores. NC is the code for the samples taken from Native Companion Lagoon...Late Quaternary climate dynamics...late Quaternary palaeoenvironmental variability available from the subtropics...late deglacial of Reeves et al. (2013a) have been combined into the LGIT...and late deglacial of Reeves et al. (2013a) have been combined into the...sediments...lithology of the sediment core with black representing peat sediments ... Currently there is a paucity of records of late Quaternary palaeoenvironmental variability available from the subtropics of Australia. The three continuous palaeoecological records presented here, from North Stradbroke Island, subtropical Queensland, assist in bridging this large spatial gap in the current state of knowledge. The dominance of arboreal taxa in the pollen records throughout the past >40,000 years is in contrast with the majority of records from temperate Australia, and indicates a positive moisture balance for North Stradbroke Island. The charcoal records show considerable inter-site variability indicating the importance of local-scale events on individual records, and highlighting the caution that needs to be applied when interpreting a single site as a regional record. The variability in the burning regimes is interpreted as being influenced by both climatic and human factors. Despite this inter-site variability, broad environmental trends are identifiable, with changes in the three records comparable with the OZ-INTIMATE climate synthesis for the last 35,000 years.

Contributors: M.B.L. Mascarenhas-Pereira, B. Nagender Nath, S.D. Iyer, D.V. Borole, G. Parthiban, R. Jijin, V. Khedekar

Date: 2016-04-15

shards (no of shards g−1 of sediment) in BC 14, 20 and 25 with respect t...sediment cores. ...cores. The abundance of glass shards, composition of bulk sediments, and...sediment cores. The data of core BC 8 are provided for comparison. ...sediment cores from the CIB. ...sediment cores collected from water depths >5000m along the transect 76...sediment. The cryptotephra forms the fifth ash horizon and is of ~34ka...cores yielded five volcanic horizons of which four have visual and dispersed...late Quaternary sediments from the Central Indian Basin...bulk sediments). ... CIB sediment cores. ...sub-samples from the three sediment cores. The data of core BC 8 are provided...recovered from three sediment cores from the CIB. ...sediment) in BC 14, 20 and 25 with respect to age (ka) of the cores, with...cores BC 14, BC 20 and BC 25 showing sedimentation rates of 0.27, 0.23...sediments were used to distinguish the volcanic horizons. Of the four ... We have investigated three sediment cores collected from water depths >5000m along the transect 76°30′E in close proximity to a fracture zone in the Central Indian Basin (CIB). The cores yielded five volcanic horizons of which four have visual and dispersed shards. Rhyolitic glass shards of bubble wall, platy, angular and blocky types were retrieved from various stratigraphic horizons in the cores. The abundance of glass shards, composition of bulk sediments, and 230Thexcess ages of the host sediments were used to distinguish the volcanic horizons. Of the four volcanic horizons, three are now newly reported and correspond to ages of ~85, 107–109 and 142–146ka while the fourth horizon is of 70–75ka. By using trace element ratios and Cr and Nb-based normative calculations, cryptotephra has been identified for the first time from the CIB sediment. The cryptotephra forms the fifth ash horizon and is of ~34ka.

Contributors: Gerhardt, Sabine, Groth, H, Rühlemann, Carsten, Henrich, Rüdiger

Date: 2000-01-29

Late Quaternary: Reconstruction of Budget and Currents...Late Quaternary: Reconstruction of Budget and Currents...sediment cores from the Brazilian Continental Slope...late Quaternary sediment cores on the Brazilian Continental Slope: implications...late Quaternary records of aragonite preservation determined for sediment...late Quaternary sediment cores on the Brazilian Continental Slope: implications...cores recovered on the Brazilian Continental Slope (1790-2585 m water ...late Quaternary records of aragonite preservation determined for sediment ... Abstract: We present late Quaternary records of aragonite preservation determined for sediment cores recovered on the Brazilian Continental Slope (1790-2585 m water depth) where North Atlantic Deep Water (NADW) dominates at present. We have used various indirect dissolution proxies (carbonate content, aragonite/calcite contents, and sand percentages) as well as gastropodal abundances and fragmentation of Limacina inflata to determine the state of aragonite preservation. In addition, microscopic investigations of the dissolution susceptibility of three Limacina species yielded the Limacina Dissolution Index which correlates well with most of the other proxies. Excellent preservation of aragonite was found in the Holocene section, whereas aragonite dissolution gradually increases downcore. This general pattern is attributed to an overall increase in aragonite corrosiveness of pore waters. Overprinted on this early diagenetic trend are high-frequency fluctuations of aragonite preservation, which may be related to climatically induced variations of intermediate water masses. Category: geoscientificInformation Source: Supplement to: Gerhardt, Sabine; Groth, H; Rühlemann, Carsten; Henrich, Rüdiger (2000): Aragonite preservation in late Quaternary sediment cores on the Brazilian Continental Slope: implications for intermediate water circulation. International Journal of Earth Sciences, 88(4), 607-618, https://doi.org/10.1007/s005310050291 Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: -8.531667 * LONGITUDE: -34.023333 * DATE/TIME: 1993-03-22T00:00:00 * ELEVATION: -2080.0 m * Recovery: 0.43 m * LOCATION: Brazil Basin * CAMPAIGN: M23/3 * BASIS: Meteor (1986) * DEVICE: MultiCorer EVENT LABEL: * LATITUDE: -8.528333 * LONGITUDE: -34.021667 * DATE/TIME: 1993-03-22T00:00:00 * ELEVATION: -2072.0 m * Recovery: 8.97 m * LOCATION: Brazil Basin * CAMPAIGN: M23/3 * BASIS: Meteor (1986) * DEVICE: Gravity corer (Kiel type) EVENT LABEL: * LATITUDE: -8.573333 * LONGITUDE: -34.345000 * DATE/TIME: 1993-03-22T00:00:00 * ELEVATION: -1790.0 m * Recovery: 0.45 m * LOCATION: Brazil Basin * CAMPAIGN: M23/3 * BASIS: Meteor (1986) * DEVICE: MultiCorer EVENT LABEL: * LATITUDE: -8.735000 * LONGITUDE: -34.135000 * DATE/TIME: 1993-03-23T00:00:00 * ELEVATION: -2585.0 m * Recovery: 0.35 m * LOCATION: Brazil Basin * CAMPAIGN: M23/3 * BASIS: Meteor (1986) * DEVICE: MultiCorer

Contributors: N. Basavaiah, J.L.V. Mahesh Babu, P.B. Gawali, K.Ch.V. Naga Kumar, G. Demudu, Siddharth P. Prizomwala, P.T. Hanamgond, K. Nageswara Rao

Date: 2015-06-12

cores were obtained which included significant peat. The conventional ...layers of the cores as indicated by SIRM/χ values (Fig. 4). For example...inter-deltaic sediments at Kolleru Lake (after Biswas, 1993; Rode et al...sediments. The variation in magnetic mineralogy is related to paleoclimatic...Down-core and Late Quaternary temporal variations in environmental magnetic...sediments at Kolleru Lake (after Biswas, 1993; Rode et al., 2010; Nageswara...during the Late Quaternary period with their mineral magnetic and geochemical...cores, the details of which are given in Table 1, were collected from ...during the Late Carboniferous, resulting in deposition and preservation...cores RG, MW, PN and PP. (b) Age depth model for RG, MW and PN sediment...cores corroborated by mineral magnetic and geochemical proxies indicates...sections of cores RG, MW, PN and PP. (b) Age depth model for RG, MW and...Down-core and Late Quaternary temporal variations in elemental concentrations... of the cores as indicated by SIRM/χ values (Fig. 4). For example, the...cores are characterized by such transition from magnetite to hematite ...sediments representing the inter-deltaic part of the Krishna–Godavari ...Down-core and Late Quaternary temporal variations in environmental magnetic...Late Carboniferous, resulting in deposition and preservation of an ∼8 ...Late Quaternary environmental and sea level changes from Kolleru Lake,...traps of Late Cretaceous–Palaeocene age, Archaean granites and unclassified...Down-core and Late Quaternary temporal variations in elemental concentrations...Late Quaternary period with their mineral magnetic and geochemical imprints...cores as indicated by SIRM/χ values (Fig. 4). For example, the peat sediments...Late Pleistocene. Similarly, the peat layers rich in mangrove pollen indicate...Late Cretaceous–Palaeocene age, Archaean granites and unclassified crystallines...cores as indicated by SIRM/χ (Saturation Isothermal Remanent Magnetization...sediment record compared to climatically modulated riverine supply. The ... The present study employs mineral magnetic, geochemical, and textural parameters to elucidate the climate and sea level change signatures from Kolleru lake sediments representing the inter-deltaic part of the Krishna–Godavari sedimentary basin (KG basin). For this purpose, four cores were obtained which included significant peat. The conventional radiocarbon dating suggested that the peat formation took place during 9 ka–6 ka with an average sedimentation rate of 0.31 cm/y. Thermomagnetic analysis identifies titanomagnetite, magnetite and hematite as the dominant magnetic mineralogy of the KG basin sediments. The variation in magnetic mineralogy is related to paleoclimatic and paleoenvironmental processes; the transitions between (titano)magnetite and hematite coincide with peat layers of the cores as indicated by SIRM/χ (Saturation Isothermal Remanent Magnetization/Magnetic Susceptibility) and S-ratio defined by IRM−0.3T/SIRM values. The various mineral magnetic parameters, χ and S-ratio along with major elemental concentrations of Ti, Al, Fe and Zr show signatures of an arid event before 10 ka, between 9 ka–8 ka periods and during the last 5.5 ka. The overall climate of warm and humid type was inferred from 10 ka to 9 ka, which correlates with Early Holocene Optima and 6 ka to 5.5 ka of Middle Holocene. The presence of evaporite crystals in the lowermost part of the cores corroborated by mineral magnetic and geochemical proxies indicates sub-aerially weathered facies of the arid Late Pleistocene. Similarly, the peat layers rich in mangrove pollen indicate sea level changes between 10 ka and 6 ka. The sub-surface position of the Pleistocene weathered layer and the Holocene peat layer suggests tectonic subsidence of the area, which is situated over the basement graben, known as Gudiwada sub-basin.

Contributors: Olaf Juschus, Maksim Pavlov, Georg Schwamborn, Frank Preusser, Grigory Fedorov, Martin Melles

Date: 2011-11-01

Quaternary lake-level history as derived from sediment cores from the ...sediment cores at the southern shelf and in the deepest part of the lake...sediments on the shelf indicate high lake levels during a warm Mid-Pleistocene...cores Lz1027 and Lz1028 from the southern lake shelf. The oldest sediments...Late Quaternary...sediment cores from the southern lake shelf. There, a cliff-like bench...Late Quaternary...late glacial times the lake level was around 10m lower than today (d).... In late glacial times the lake level was around 10m lower than today ...and position of sediment cores at the southern shelf and in the deepest...relation to wet sediment weight. ...Late Quaternary lake-level changes of Lake El'gygytgyn, NE Siberia...sediment weight. ... to dry sediment weight. ...sediment parallel to the coast and towards the outlet, where the material...from cores Lz1027 and Lz1028 from the southern lake shelf. The oldest sedim...sedimentation occurred. Subsequently, the lake level rose rapidly to the ... Lake El'gygytgyn is situated in a 3.6Ma old impact crater in northeastern Siberia. Presented here is a reconstruction of the Quaternary lake-level history as derived from sediment cores from the southern lake shelf. There, a cliff-like bench 10m below the modern water level has been investigated. Deep-water sediments on the shelf indicate high lake levels during a warm Mid-Pleistocene period. One period with low lake level prior to Marine Oxygen Isotope Stage (MIS) 3 has been identified, followed by a period of high lake level (10m above present). In the course of MIS 2 the lake level dropped to −10m. At the end of MIS 2 the bench was formed and coarse beach sedimentation occurred. Subsequently, the lake level rose rapidly to the Holocene level. Changes in water level are likely linked to climate variability. During relatively temperate periods the lake becomes free of ice in summer. Strong wave actions transport sediment parallel to the coast and towards the outlet, where the material tends to accumulate, resulting in lake level rise. During cold periods the perennial lake ice cover hampers any wave activity and pebble-transport, keeping the outlet open and causing the lake level to drop.

Contributors: Selin Eda TEKIROĞLU, Vedat EDIGER, Semal YEMENICIOĞLU, Selim KAPUR, Erhan AKÇA

Date: 2001-01-01

the cores. ...content (%) of the sediments; unit 1 (+), unit 2 (x), unit 3 (▵) turbidites... silt content (%) of the sediments; unit1 (+), unit2 (x), unit 3 (▵) turbidites...sediments; unit 1 (+), unit 2 (x), unit 3 (▵) turbidites and coccoliths...core, off the south-eastern shelf, indicates the downward increasing precipitation...sediments, some with organic material. The metal concentration is diluted...sedimentation pattern and sedimented material is believed to be the response...core. ...cores. ... taken from each core. ...sediments of Black Sea. ...types of rocks and sediments of Black Sea. ...Late Quaternary deposits of the Black Sea...sediments; unit1 (+), unit2 (x), unit 3 (▵) turbidites and coccoliths ...sediments taken from the south-eastern and western Black Sea have been...sediments form the shore deposits, the deep-sea sediments mainly consist ... Holocene sediments taken from the south-eastern and western Black Sea have been investigated in relation to their geochemical, sedimentological and mineralogical characteristics. Their textures are characterized by their low amount of sand, upward-increasing silt and downward-increasing clay contents. While the terrigenous materials transported from Anatolian volcanic-based sources and European alluvial sediments form the shore deposits, the deep-sea sediments mainly consist of the marine biological production. The highest amount of organic carbon was deposited following the formation of anoxic conditions at the bottom until the beginning of the still continuing carbonate-rich coccolith (Emiliania huxleyi) deposition. The high metal concentrations are associated with fine-grained sediments, some with organic material. The metal concentration is diluted by high organic carbon and carbonate contents within the depositional sequences. While the abundance of illite in the western Black Sea describes the deltaic depositions, the downward decreasing smectite/illite ratio along the core, off the south-eastern shelf, indicates the downward increasing precipitation during the deposition. The variation in the sedimentation pattern and sedimented material is believed to be the response of the biochemical environment in the sea to the changing geological, biological and chemical conditions in and around the Black Sea during the last climatic changes.

Contributors: Wells, Patricia, Wells, Graeme, Cali, Joe, Chivas, Allan R

Date: 1994-02-18

Core...Late Quaternary sediments of core BMR96GC21 in the southeast Indian Ocean ... Abstract: Not Available Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: -23.772167 * LONGITUDE: 108.500667 * ELEVATION: -2100.0 m * Recovery: 1.8 m * LOCATION: Southeast Indian Ocean * DEVICE: Core

Contributors: Wook-Hyun Nahm, Jeong Chan Kim, Phil-Yoon Bong, Ju-Yong Kim, Dong-Yoon Yang, Kang-Min Yu

Date: 2008-01-01

late Pleistocene to Holocene, overlying a Cretaceous-aged basement. From...Late Quaternary stratigraphy of the Yeongsan Estuary, Southwestern Korea...sediments of the paleosol unit is constrained by radiocarbon age of underlying...sediments (unit-2). The timing of pedogenesis is around the Last Glacial...for core MW-1. ...Late Quaternary stratigraphy...sediment core MW-1 from the Yeongsan Estuary consists of five primary ...core MW-1. (a: Planar cross lamination, b: plant fragments). ...Late Quaternary stratigraphy...Photographs of core MW-1. (a: Rootlets with iron encrustations, b: yellowish...core MW-1. ...description of core MW-1. ... coring site (core MW-1). (1: Kyunggi Bay, 2: Cheonsoo Bay, 3: Hampyung...coring site (core MW-1). (1: Kyunggi Bay, 2: Cheonsoo Bay, 3: Hampyung ... The 18.820m long sediment core MW-1 from the Yeongsan Estuary consists of five primary unconsolidated to semi-consolidated units, ranging in age from late Pleistocene to Holocene, overlying a Cretaceous-aged basement. From oldest to youngest, these units include units-1, 2, 3 (fluvial units), unit-4 (paleosol unit), and unit-5 (Holocene estuarine deposits). Units-1, 2, and 3 are interpreted as in-channel or overbank deposits. Plant materials included within the units and the TOC/TN (total organic carbon/total nitrogen) ratios (11–14) are also indicative of terrestrial origin. Unit-2 yields radiocarbon date of 37,700 14C yrBP. Unit-4, the paleosol unit, is estimated to be originally deposited in fluvial setting such as the area of floodplain or backswamp away from the main channel, based on the sporadic distribution of the stagnant freshwater acritarch Pseudoschizaea and algae Spirogyra. The timing of deposition of the original sediments of the paleosol unit is constrained by radiocarbon age of underlying fluvial sediments (unit-2). The timing of pedogenesis is around the Last Glacial Maximum when sea level of the Yellow Sea was lowered, temperature was lowered, rainfall was reduced, and the inland was sparsely vegetated. Estuarine deposits (unit-5) are interpreted to be deposited during the Holocene marine transgression.