Investigation of Adequate Calibration Methods for X-Ray Fluorescence Core Scanning Element Count Data: A Case Study of a Marine Sediment Piston Core from the Gulf of Alaska

X-ray fluorescence (XRF) core scanner elemental count data are useful for high-resolution paleoceanographic studies. However, because several factors, such as changes in physical core properties, significantly affect element count intensities, the appropriate calibration of the count data is required. Besides, the existing approaches for calibration were not widely employed and require rigorous testing based on sediment variety. In this study, we analyzed high-resolution element intensity (cps) using a wet muddy marine sediment piston core that was collected from the northeast Gulf of Alaska and tested several approaches with ratio and log-ratio methods, and the reliability was evaluated by comparison with the concentrations that were measured by WD-XRF and an elemental analyzer. The results show that the lighter elements (Ti and K) exhibited a significantly weak relationship between raw counts measured by ITRAX and concentrations that were measured by the WD-XRF, indicating that some factors artificially influence ITRAX intensity data. The Cl intensity that is expressed as the water content in marine sediment increased significantly in the upper 202 cm by 42% and the top 25 cm by 73% as compared to the down-core (below 202 cm), which deviates the X-ray scattering and element-counts. The calibration of raw data through coherent/incoherent X-ray scattering ratio (CIR) and additive- and centered-log ratio reduces the offsets. The calibration by CIR performed best for Sr, Fe, Mn, Ti, Ca, K, and Br (0.56 < R2 < 0.91), and the correlation with concentration significantly increased for Ti and K of 100% and 56%, respectively. Therefore, the study suggests that the correction of raw counts through CIR is an effective approach for wet marine sediment when core physical properties have greater variability.

Benthic foraminifera as indicators for recent sediments transport in the Eastern Mediterranean upper continental slope, offshore Israel

&lt;p&gt;Our study comprises a high-resolution multi-proxy investigation of a ~6 m long piston core DOR280, sampled from the headscarp of a mapped landslide on the upper continental slope (280 m water depth) at the Dor Disturbance area, northern central Israel. The core retrieved the sediment sequence overlaying the sliding plane of the last major landsliding event. Benthic foraminiferal assemblages and taphonomy, alongside particle size distribution, were used to determine the provenance, transport distance, and reoccurrence time of mass transport events in this area. Radiocarbon ages were measured along the core revealed an age of ~600 Cal Yrs. B.P. for the core base, suggesting unexpectedly high average sedimentation rate of ~10 m/kyr, which is highest at the core top meter. Computed Tomography (CT) of DOR280 shows two alternating sedimentary facies: &amp;#160;5 &amp;#8211; 208 cm thick Non-Laminated (NL) and 5 &amp;#8211; 37 cm thick Laminated (L). The L-facies sequences also include 0 &amp;#8211; 4 cm thick High-Density Laminas (HDL). The NL-facies intervals consist of unimodal fine-sediments dominated by clay minerals. Their foraminiferal assemblage is dominated by autochthonous species (e.g. Uvigerina spp.) and low percentage of broken shells. This indicates that the NL-facies represents mostly in-situ hemipelagic deposition. The L-facies intervals also record unimodal size-distribution of fine-sediments dominated by clay minerals, but their foraminiferal assemblages are dominated by allochthonous species (e.g. Ammonia spp.) and high percentage of broken shells, indicating a contribution of transported sediments, originated from mid-shelf habitats. The HDL-facies consist of bimodal sediments comprised of fine silty-clay (~5 &amp;#181;m) and coarse silty components (~40 &amp;#181;m), dominated by quartz and calcite; as well as poorly preserved and broken shells of allochthonous foraminifera species. Thus, the HDL represent significant contribution of mid-shelf-origin sediments and are interpreted as turbidite-like mass transport events.&lt;/p&gt;&lt;p&gt;The temporal distribution of the 27 HDL events is nonrandom, revealing clusters at 59 &amp;#177; 14 (n=9), 134 &amp;#177; 12 (n=8), 453 &amp;#177; 21 (n=4) and 641 &amp;#177; 10 (n=4) years before present. These findings show prevailing cross-shelf and down slope sediments transport in the Dor Disturbance area. The HDL events can be triggered by large remote earthquakes (&gt; 6.5), tsunami, winter storms or by sediment load that coincided with high-stand Nilotic episodes. However, mechanisms controlling the observed recent mass transport in the Dor Disturbance area still need to be studied.&lt;/p&gt;&lt;p&gt;DOR280 is the first piston core studied in high resolution at the upper continental slope of of the Isreali offshore. The use of benthic foraminifera assemblages and their shells taphonomy reveals the transported sediments within the core and enables an assessment regarding their source. The findings reported here identified much higher sediments accumulation rate than previously known and thus have implications to the evaluation and mitigation of marine geo-hazard in the studied area.&lt;/p&gt;

Hazar Gölü Sedimentinde Jeolojik Dönemlere Bağlı Olarak Bazı Elementlerin Konsantrasyonlarının Belirlenmesi

In this study, it was aimed to determine the concentrations of some elements in sediment along depht profile in core collected at the Lake Hazar (Elazıg) and to compared the results according to recent geological periods. For this purpose, the levels of arsenic (As), mercury (Hg), molybdenum (Mo), barium (Ba), uranium (U), tin (Sn), titanium (Ti), lanthanum (La) and beryllium (Be) on every 5 cm of the piston core samples taken as part of a TUBİTAK project (No: 111Y045) from Lake Hazar were detected. The lowest concentrations of Ba, Hg, La, Ti and U were found (111 ppm, 0.01 ppm, 4.4 ppm, 1190 ppm and 0.6 ppm respectively) at 81-83 cm in depth. It was determined that it belonged to 10 000 B.P. and to Holocene Period (10.5 thousand B.P.). The highest concentrations of As, Ba, Hg, Sn, La, Mo, Ti and U were found different depth in the core in Lake Hazar. The highest concentrations of Hg in the core were detected between 4-6 cm that this depth was determined corresponds to present day. The highest levels of As and Ba found that it belonged to Pre-Glacial Period/ Late Pleistocene Period (10.5 thousand B.P.). The highest concentration of other elements (Sn, La, Mo and Ti) determined that it belonged to Last Glacial Maximum Period/Late Pleistocene Period (between 23-16 thousand B.P.). The geological structure of the basin where the lake ecosystem is located, biological and hydrological processes, climatic and anthropogenic factors can be cited as the reasons for these differences.

Caracterización de las asociaciones de cocolitóforos en las cuencas offshore del Pacífico colombiano

This study was conducted on coccolithophores recovered from 39 piston-core samples taken offshore Chocó and Tumaco basins, on the Colombian Pacific. Qualitative and quantitative analyses of the coccoliths showed changes in the relative abundances and the state of preservation in the two basins. The examined sediments were characterized by the coccoliths Gephyrocapsa oceanica, Gephyrocapsamuellerae, Gephyrocapsa <3 μm, Emiliania huxleyi, Calcidiscus leptoporus and Helicosphaera carteri, which presented abundances higher than 2 %. We also identified a minority assemblage (<2%) constituted by Ceratolithus spp., Coccolithus pelagicus, Florisphaera profunda,Helicosphaera princei, Helicosphaera sellii, Helicosphaera wallichii and Pontosphaera spp. together with reworked specimens of Reticulofenestra spp, Sphenolithus spp. and Discoaster spp. The recovery of E. huxleyi as part of the assemblage indicates that the studied sediments are younger than the biozone NN21, covering an age range of Middle Pleistocene (Ionian). The number of coccoliths per gram (cc/g) was calculated, demonstrating an average of 5.7x106 cc/g and 1.2x107 cc/g for Chocó and Tumaco basins, respectively. In order to interpret the causes of this variance, we performed a multivariate redundancy analysis (RDA), showing that the distance to the coastline is the controlling factor of the fluctuations of the relative abundances and distribution of the coccoliths in both basins.

Evidence for surface sediment remobilization by earthquakes in the Nankai forearc region from sedimentary records

Submarine landslides triggered by earthquakes can generate turbidity currents. Recently, several studies have reported that the remobilization of surface sediment triggered by earthquakes can also generate turbidity currents. Such sedimentary processes may be influenced by sediment characteristics, seafloor morphology and seismic motions. Here, we verify surface sediment remobilization using sedimentary records from the Nankai forearc region, SW Japan. We collected multi-core and piston core samples from a small confined basin, mainly composed of silty clay or very fine sand. Radiocaesium measurements of the multi-core show consistently high values in the upper 17 cm and low values below this depth. Rapid sediment deposition after 1950 is assumed, and the most likely cause is the 2004 off the Kii Peninsula earthquake. Based on calculations using bathymetric maps and palaeocurrent data, settlement of the upper 17 cm can be explained by redeposition of the surface (c. 1 cm) slope sediment around the basin. Muddy turbidites are also identified in the piston core. The gap in radiocarbon age observed around 2.0 m bsf (metres below seafloor) implies similar sedimentary processes. Our study represents the first examination of surficial remobilization from sedimentary cores in the Nankai forearc region.

Concentrations and enrichment of metals in sediment cores: geochemistry and correlations with geoaccumulation index

The Mãe d’Água dam was built in 1962 to supply the Federal University of Rio Grande do Sul’s water demanding. Thus, the paper aims to measure Nickel (Ni) and Zinc (Zn) concentrations in many depths of the dam’s bottom, sampling cores of sediments silted in it. The samplings were carried out in June, 2014, and it was sampled four sediment cores in pre-defined points of the dam. The methodology for extraction of sediment cores was ‘Piston Core’. Sediment particles smaller than 63 μm were separated and used for chemical analysis. EPA 3050 acid digestion methodology is used by the U.S. Environment Protection Agency and it was also used in this study. Analyses were carried out in duplicate and two USGS reference materials were used for quality control: SGR-1b and SCO-1. Zn and Ni concentrations were over than local background values and increasing concentrations of the deepest sendiments to the most recent layers as a result of urbanization activities. Geoaccumulation index was able to characterize decreasing of metal concentrations in depth.

Contribuição dos cocolitoforídeos para o aporte de carbonato de cálcio durante o Último Máximo Glacial na Margem Continental Sul Brasileira

O ciclo do carbono durante o período glacial apresenta uma oportunidade única para a investigação de uma condição climática absolutamente distinta da atual. O conhecimento acerca da última glaciação pode ajudar a entender o clima atualmente e as potenciais mudanças ambientais futuras. A sensibilidade dos cocolitoforídeos a mudanças na química da água superficial possui grande relevância para os ciclos biogeoquímicos e como resposta para mudanças no sistema climático. O presente estudo utilizou um testemunho de piston core localizado nas coordenadas 47º 18' 28" W, 29º 24' 19” S, retirado do talude da Bacia de Pelotas a fim de analisar a importância dos cocolitoforídeos no aporte de carbonato de cálcio (CaCO3) para o fundo marinho na região do Cabo de Santa Marta. O testemunho compreende o intervalo entre 18,16 mil anos (ka) e 40,61 ka, incluindo o Último Máximo Glacial (UMG) e o início da deglaciação. Foram quantificados no mínimo 300 cocólitos e 5 campos de visão ao microscópio por amostra para identificação das espécies de cocolitoforídeos. Foram realizadas quatro datações através da técnica do 14C ao longo do testemunho. O conteúdo de CaCO3 nos sedimentos finos foi obtido através de ataque por ácido clorídrico. Os maiores valores de carbonato nos sedimentos ocorrem durante a deglaciação, porém a maior contribuição dos cocolitoforídeos para o aporte de CaCO3 parece ocorrer durante o UMG, quando comparadas as curvas de conteúdo de carbonato e a curva de abundância absoluta das espécies. As espécies que mais contribuíram para o aporte de carbonato foram Emiliania huxleyi, Gephyrocapsa spp. e Florisphaera profunda