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Continental and marine sediments are composed of a mixture from different sources and are influenced by a variety of environmental factors and transport processes prior to deposition. For analysis and interpretation, these sources and processes are often challenging to disentangle. We show that end‐member modelling of X‐ray fluorescence (XRF) core‐scanning data helps to overcome these challenges by unmixing different environmental signals from high‐resolution sediment geochemical records. We apply this approach to a 100 m long lacustrine succession from Lake Towuti, Indonesia, to separate the regional climate and tectonic history from local ecological and diagenetic processes. The resulting six end‐members (EMs) are interpreted to represent changes in ecological (EM1), climatic (EMs 2–4), tectonic (EM 5) and geomorphic (EM6) processes determining changes in sediment composition. Because end‐member analysis allows for the tracking of transient and overlapping processes, climatic changes can be followed throughout the 100 m‐long succession, suggesting alternating wet and dry periods in Central Sulawesi over long (several 100 000 years) time scales. We show that end‐member analysis on elemental data sets offers a detailed and objective means to disentangle depositional processes in sedimentary successions resulting from varying tectonic and environmental factors involved in sediment formation and deposition. [ABSTRACT FROM AUTHOR]

Abstract The marine organic carbon content in sediments is a useful tool for reconstructing past productivity in the ocean. Bromine has been proposed as a useful proxy for marine organic carbon, since bromine is more concentrated in marine organic matter compared to terrestrial organic matter. Here, we present a high-resolution Quaternary record of marine organic carbon in the hemipelagic sediments of the Japan Sea obtained during Integrated Ocean Drilling Program (IODP) Expedition 346. We measured the bromine content in the sediments using an XRF core scanner (ITRAX). The total organic carbon content, total nitrogen, and stable carbon isotope values were also measured for discrete samples from the same sediments. The total organic carbon/total nitrogen ratio and the stable carbon isotope ratio of the total organic carbon are used to estimate the marine organic carbon content within the total organic carbon. The Br counts and marine organic carbon content show a high correlation, which we used to construct a calibration equation of the marine organic carbon content from the Br counts. Using the calibration equation, we reconstructed the changes in the marine organic carbon content during the Quaternary with a time resolution of ~ 50 years using sediment cores from IODP Site U1424 in the east central Japan Sea. The method to estimate the marine organic carbon content from the Br counts measured by the XRF core scanner proposed in this paper will be a useful tool to reconstruct the organic carbon content with high resolution and high speed.

The introduction and application of high resolution XRF core scanners has made an enormous contribution to palaeoclimate science over the last two decades. These core scanners have become essential analytical tools for the investigation of sedimentary and other natural cumulative records of environmental change. Their widespread adoption by the environmental and geoscience communities has had a significant impact on the ability to systematically record high resolution chemical profiles in marine and lake sediments and soils. The range of applications has broadened beyond sedimentology and palaeoclimatology and now extends into scanning samples of speleothems, corals, mumiyo mounds, rocks, sedimentary nodules, archaeological artefacts, tree sections and melt segregations. Other areas exploiting the capability of XRF core scanners are mineral exploration, geotechnical characterisation, soil remediation studies and carbon capture and storage research. As a consequence of their ability to efficiently determine detailed, non-destructive elemental records in sediments and soils, scientific papers published since the year 2000 now number more than 1000. [ABSTRACT FROM AUTHOR]

Located in NW Switzerland, the Mont Terri rock laboratory is a research facility primarily investigating the Opalinus Clay as potential host rock for deep geological disposal of radioactive waste. In the Mont Terri area, this Jurassic shale formation is characterized by three distinctive lithofacies: a shaly facies, a carbonate-rich sandy facies and a sandy facies. However, the lithological variability at dm- to cm-scale is not yet fully understood and a detailed lithofacies characterization is currently lacking. Within the present study, petrographic descriptions at micro- and macro-scale, geophysical core logging (P-wave velocity and gamma-ray density), geochemical core logging (X-ray fluorescence) and organic matter quantification (Rock-Eval pyrolysis) were combined on a 27.6 m long Opalinus Clay drillcore comprising the three major lithofacies. The high-resolution investigation of the core resulted into a refinement of the three-fold lithofacies classification, and revealed high intra-facies heterogeneity. Five subfacies were defined and linked to distinctive depositional regimes. The studied succession is interpreted as a shallowing-upward trend within a storm-wave-dominated epicontinental sea characterized by relative shallow water depths. [ABSTRACT FROM AUTHOR]

Hydrological changes in East Asia during the last millennium have been addressed by numerous earlier studies, but spatial characteristics and dynamics in precipitation variations during the Little Ice Age (LIA) remain unclear, perhaps especially due to the sparse coverage of high-resolution hydrological records from tropical and sub-tropical regions in East Asia. In this study, a sediment core was obtained from Shuangchi Lake in northern Hainan Island, tropical China, of which geochemical proxies including the ratios of Rb/Sr, Rb/K, Zr/Rb and Si/Ti were analyzed using an X-ray fluorescence (XRF) core scanner. Meanwhile, the grain size distribution of sediments was also determined. The results show that the Rb/Sr and Rb/K ratios decreased significantly during the LIA, whilst the Zr/Rb and Si/Ti ratios increased along with higher median grain size. The changes of these proxies likely suggest that precipitation was enhanced during the LIA in this region, and this was consistent with other hydrological records from tropical southern China. The synthesis of hydrological records from East Asia and the tropical Pacific suggest that the co-existence of a contracted Intertropical Convergence Zone (ITCZ) and strengthened Pacific Walker circulation (PWC) could contribute synchronously to the increased precipitation in the tropical region of southern China during the LIA. [ABSTRACT FROM AUTHOR]

The impact of human activities has been increasing to a degree where humans now outcompete many natural processes. When interpreting environmental and climatic changes recorded in natural archives on historical time scales, it is therefore important to be able to disentangle the relative contribution of natural and anthropogenic processes. Lake Meihua on the Ilan Plain in northeastern Taiwan offers a particularly suitable opportunity to test how human activities known from historical records can be recorded in lacustrine sediment. For this purpose, three cores from Lake Meihua have been studied by a multiproxy approach, providing the first decadal-resolution lacustrine records covering the past 150 years in Taiwan. Profiles of excess 210Pb, 137Cs and 239,240Pu from two short cores (MHL-09-01 and MHL-11-02) allowed a precise chronology to be established. The presence of a yellow, earthy layer with lower levels of organic material coincide with the record of land development associated with the construction of the San-Chin-Gong Temple during AD 1970-1982. Furthermore, in the lower part of the cores, the upwards increasing trend of inc/coh, TOC, TOC/TN, and grain size, coupled with the palynological data (increase of Alnus, Mallotus, Trema and herbs) from the nearby core MHL-5A with radiocarbon chronology, suggest that the area surrounding the lake has been significantly affected by agricultural activities since the arrival of Chinese settlers around ~AD 1874. In sum, this study demonstrates that this suite of lacustrine sediments in northeastern Taiwan has recorded human activities in agreement with historical documents, and that different human activities will leave distinct sedimentological, geochemical, and palynological signatures in the sedimentary archives. Therefore, multiproxy reconstructions are important to capture the complex nature of human-environmental interactions. A better understanding of the weathering and erosion response to human activities can also provide useful information for sustainable land-use management.

The capabilities of X-Ray Fluorescence (XRF) core scanners, to acquire high-resolution geochemical data sets in relatively short time, have made them an increasingly popular geochemical screening tool to study sediment cores for palaeoclimatologic and palaeoceanographic purposes (Peck et al., 2007; Rebolledo et al., 2008). These scanners are able to obtain optical images, X-ray radiographs, and continuous geochemical data with a maximum resolution of 200 µm directly from sediment cores (Croudace et al., 2006). Geochemical results are obtained as peak areas of counts per second that are proportional to element concentrations in the sediment, and thus the assumed semi-quantitative nature of these analyses have hampered the use of this type of instruments to monitor and detect pollution at large; where the availability of a fast screening tool that could substantially cut analytical and time costs will certainly be an advantage. This study explores the sensitivity of a ITRAX core scanner (Cox Analytical Systems) on sedimentary records from estuarine-like environments in NW (Rías Baixas Galicia) and SW Spain (Ría de Huelva). The Galician Rías Baixas sediments are characterized by high contents of organic matter, but in general terms, are not heavily polluted. We have selected one core in the Marín harbour (Ría de Pontevedra) and another in the intertidal area of San Simón Bay (inner Ría de Vigo), close to a ceramic factory, which is relatively highly polluted by lead. By the contrary, the Ría de Huelva is one of the most polluted areas in western Europe because of the high acid mining activity together with the chemical industries located in its margins. We have selected a core in the Padre Santo Channel in the confluence of the Odiel and Tinto rivers. ITRAX sensitivity was obtained by establishing equivalences between peak areas and concentrations obtained by traditional analytical techniques such as ICP-MS, ICP-OES and/or conventional XRF of pressed pellets (Fig. 1). Our results show that the ITRAX was able to detect Hg concentrations lower than 0.6 μg g-1, Cd concentrations around 1 μg g-1, and even REE contents such those of Er around 5 μg g-1. Results show good relationships for most of the trace elements. For the rías Baixas sediments only Pb (in San Simón Bay) and Hg (in the Marín harbour) showed concentrations above sediment quality guidelines that could be associated with adverse effects. For Ría de Huelva sediments it was found a coincidence of the REEs maxima with the As, Cu, Pb and Zn maximum peaks confirming their known acid mining origin. We have also evaluated the suitability of inc/coh, Br/Cl and other element ratios in order to assess the influence of the organic matter variability on the distribution of metals, and to identify salinity and pH changes too. Good correlations were observed between the fraction associated to organic matter and the inc/coh ratio in some of the studied cores. The Cl profile was also useful to show variations in salinity and the marine influence in the sediments. Our study shows the potential of modern XRF core-scanners such as the ITRAX to perform fast high-resolution and relatively inexpensive measurements to screen and identify pollution in three different coastal environments. Pollution levels can be estimated in a few hours from elements’ peak areas avoiding discrete analysis of the whole core. Organic matter-rich levels associated to higher concentration of toxic metals, can be quickly detected by using the inc/coh ratio in sediments dominated by terrestrial organic matter inputs. Variations in salinity and marine influence can also be detected and some ratios such as Y/Ho profile resulted a good proxy for sediments’ origin.

Micro x-ray fluorescence (µXRF) core scanning is capable of measuring the elemental composition of lake sediment at sub-millimetre resolution, but bioturbation and physical mixing may degrade environmental signals at such fine scales. The aim of this research is to determine the maximum possible resolution at which meaningful environmental signals may be reconstructed from lake sediments using this method. Sediment from a coastal lake in the Outer Hebrides, Scotland, has been analysed using calibrated element measurements to reconstruct storminess since AD 200. We find that a Ca/K ratio in lake-core sediments reflects the presence of fine calcium carbonate shell fragments, a constituent of sand in the catchment that is washed and blown into the lake. Variations in this ratio are significantly correlated with instrumental records of precipitation and low pressures, suggesting it is a proxy for storminess. Furthermore, identification of a c. 60-year cycle supports a climatic influence on Ca/K, as this cycle is frequently identified in reconstructions of the North Atlantic Oscillation and North Atlantic sea-surface temperature. Comparison with weather records at different resolutions and spectral analysis indicate that µXRF data from Loch Hosta can be interpreted at sub-decadal resolutions (equivalent to core depth intervals of 3–5 mm in this location). Therefore, we suggest that sub-centimetre sampling using µXRF core scanning could be beneficial in producing environmental reconstructions in many lake settings where sediments are not varved. [ABSTRACT FROM AUTHOR]

A 144-cm-long core was obtained in Lake Petit (2200 m a.s.l., Mediterranean French Alps) in order to reconstruct past interactions between humans, the environment and the climate over the last five millennia using a multidisciplinary approach involving sedimentological, geochemical and botanical analyses. We show a complex pattern of environmental transformation. From 4800 to 4200 cal. BP, podzol-type soils progressively developed under forest cover. This stable situation was interrupted by a major detrital pulse at 4200 cal. BP that we consider as a tipping point in the environmental history. At this point, pedogenetic processes drastically regressed, leading to the development of moderately weathered soils. More frequent detrital inputs are recorded since 3000 cal. BP (ad 1050) as the human impact significantly increased in the catchment area. We conclude that destabilisation of the environment was triggered by climate and exacerbated by human activities to a stage beyond resilience. [ABSTRACT FROM AUTHOR]

Abstract: Bulk chemical fine-grained sediment compositions from southern Victoria Land glacimarine sediments provide significant constraints on the reconstruction of sediment provenance models in the McMurdo Sound during Late Cenozoic time. High-resolution (∼1ka) geochemical data were obtained with a non-destructive AVAATECH XRF Core Scanner (XRF-CS) on the 1285m long ANDRILL McMurdo Ice Shelf Project (MIS) sediment core AND-1B. This data set is complemented by high-precision chemical analyses (XRF and ICP-OES) on discrete samples. Statistical analyses reveal three geochemical facies which are interpreted to represent the following sources for the sediments recovered in the AND-1B core: 1) local McMurdo Volcanic Group (MVG) rocks, 2) Transantarctic Mountain rocks west of Ross Island (W TAM), and 3) Transantarctic Mountain rocks from more southerly areas (S TAM). Data indicate in combination with other sediment facies analyses (McKay et al., 2009) and provenance scenarios (Talarico and Sandroni, 2009) that diamictites at the drill site are largely dominated by local sources (MVG) and are interpreted to indicate cold polar conditions with dry-based ice. MVG is interpreted to indicate cold polar condition with dry-based ice. A mixture of MVG and W TAM is interpreted to represent polar conditions and the S TAM facies is interpreted to represent open-marine conditions. Down-core variations in geochemical facies in the AND-1B core are interpreted to represent five major paleoclimate phases over the past 14Ma. Cold polar conditions with major MVG influence occur below 1045mbsf and above 120mbsf. A section of warmer climate conditions with extensive peaks of S TAM influence characterizes the rest of the core, which is interrupted by a section from 525 to 855mbsf of alternating influences of MVG and W TAM. [Copyright &y& Elsevier]

Abstract: Chinese loess is a unique continental archive of Quaternary climate change, and its elemental components or ratios can provide significant insights into variations in the East Asian palaeomonsoon at tectonic to millennial timescales. However, high-resolution elemental analyses of loess deposits have seldom been reported. To investigate geochemical variations of loess sediments at millennial and centennial timescales, and their potential for recording abrupt climate change, powder and U-channel (long plastic single-boxes used to sub-sample the center of split core sections) samples were collected from the Gulang loess section on the northwestern Chinese Loess Plateau for conventional and scanning X-ray fluorescence (XRF) analyses. Results suggest that although ten elements (Al, Si, K, Ca, Ti, Fe, Zn, Rb, Sr and Zr,) can be detected robustly using scanning XRF method, only five elements (Si, Ca, Fe, Sr and Zr) can be employed confidently to infer the chemical weathering and grain size sorting effects. Comparison of scanning XRF-derived elemental data with magnetic susceptibility, grain size and speleothem records indicates that high-resolution elemental records have great potential for evaluating rapid fluctuations of the East Asia monsoon. [Copyright &y& Elsevier]

High-resolution grain size and major element geochemical measurements were performed on the marine sediments of Core MD05-2895 to help understand the formation of turbidite sequences. Grain-size results show that these turbidite sediments contain more coarse sediment grains than normal marls. The coarse sediment grains are mostly derived from relict sediments on the Sunda Shelf. Relict sediments are composed mainly of quartz, feldspar, tephra and a few titaniferous or ferruginous heavy minerals. Corresponding to the concentration of these minerals, increases in Si/Al, K/Al, Ti/Al and Fe/Al ratios are observed in the turbidite layers. As all the observed turbidite sequences were deposited during the last glacial, the occurrence of these turbidity events is implied to be closely related to instabilities in sea-level-induced sediment supply. We suggest that deposition of sediment particles from a single turbidity current is usually controlled by a counterbalance between gravity and buoyancy, with the interaction of individual grains being of minor importance. [ABSTRACT FROM AUTHOR]

Abstract: Several types of X-ray fluorescence (XRF) core scanners have been developed to fulfill the demands for high-resolution, rapid, chemical analysis of wet sediment cores. However, their application to quantitative analysis has been hampered by the difficulty of evaluating the XRF absorption effect of water in a water film on the sediment surface and interstitial water within the sediments, especially for lighter elements. In this study, we established a non-destructive, rapid, high-resolution, and quantitative chemical analysis method for wet fine-grained sediment samples using an XRF microscanner. Results of our experiments suggest that the degree of XRF absorption by the water film, which develops on the wet sample surface covered with Mylar film, shows a clear positive correlation with the water content of the sediments under the measurement area. A clear positive correlation also exists between the degree of XRF absorption by the interstitial water and the water content of the sediments under the measurement area. We evaluated the XRF absorption by the thin water film using the relationship between the water content and thickness of the thin water film, and the XRF absorption by the interstitial water using its relation with the water content. The water content under the measurement area is estimated from the average transmitted X-ray intensity that is measured on the same measurement area simultaneously with the measurement of XRF intensities. The dry sample equivalent XRF intensities of major elements (Al, Si, K, Ca, Ti, and Fe), which are the XRF intensities of wet samples corrected for the XRF absorption by the thin water film and the interstitial water, show better correlation with the major element concentrations determined by conventional XRF methods. Using this new method, it is possible to measure the average water content and average concentrations of the 6 major elements simultaneously for a square area as small as 0.5×0.5 mm on the wet fine-grained sediment within 6 min, which is nearly ten times faster than the conventional XRF method. [Copyright &y& Elsevier]

• High-resolution XRF-CS data were calibrated to obtain quantitative concentration. • Calibration method increases the correlation coefficient and reduces the data deviation. • WLS regression method reduced significantly the errors of calibrated element concentration. • Low errors allow assessing metal pollution levels according to sediment quality guidelines. • Errors of the calibrated element concentration must be evaluated in future calibration studies. X-ray fluorescence core scanners (XRF-CS) allow rapid, non-destructive, continuous and high-resolution analyses of the elemental composition of sediment cores, providing large sets of semi-quantitative data. These data can be converted to quantitative data through the linear regression approach using a relatively small number of discrete samples analyzed by techniques providing absolute concentrations. However, a precise characterization of the errors associated with the linear function is required to evaluate the quality of the calibrated element concentrations. Here we present a calibration of high-resolution XRF-CS for six metals (Ti, Mn, Fe, Zn, Pb and As) measured in heavily contaminated marine deposits so that absolute concentrations are obtained. In order to determine the best linear function for conversion of XRF data, we have tested three regression methods: the ordinary least-squares (OLS), which does not consider the standard error in any variable (x and y), the weighted ordinary least-squares (WOLS), which considers the weighted standard error of the vertical variable (y), and the weighted least-squares (WLS), which incorporates the standard error in both x and y variables. We demonstrate that the calibration method presented in this study significantly increases the correlation coefficient, higher than r2 = 0.94, and reduces both the data deviation and the errors of the linear function for the three regression methods. Nonetheless, the WLS appears as the best regression method to minimize errors in the calibrated element concentrations. Our results open the door to use calibrated XRF-CS data to evaluate marine sediment pollution according to the levels of the strictest sediment quality guidelines (SQG) with errors lower than 0.4%–2% for Fe, 1%–7% for Zn, 3–14% for Pb and 5%–16% for Mn. They highlight the robustness of the calibration procedure here presented for accurate and precise quantification of element concentrations from XRF-CS semi-quantitative data. [ABSTRACT FROM AUTHOR]

• Continuous testing of XRF core scanner for a loess-paleosol sequence. • A systematic and comprehensive study on the geochemical elements of the profile. • Ca scanning results confirm the special climatic characteristics of MIS15-MIS13. • Tectonic uplift of the Qinling Mountains affected paleoclimatic of surrounding areas. The southern edge of the Chinese Loess Plateau affected by the stepwise uplift of the Qinling Mountains is a transitional climatic area between the different climatic environments and sedimentary characteristics to the north and south sides of the Qinling Mountains. The study of different Quaternary loess deposits in this region is conducive to improving our understanding of the micro-scale climatic effects of tectonic developments. Here, we use a series of experimental methods on a well-preserved loess–paleosol sequence in the South Jingyang Plateau to obtain proxy data, including grain-size, magnetic susceptibility, loss on ignition, and geochemical elemental. Changes in grain-size, magnetic susceptibility and loss on ignition indicate that the East Asian monsoon has undergone significant changes due to the continued global cooling and mid-Pleistocene climate transition during the deposition process of XSD loess, i.e., the intensities of the winter and summer monsoons were simultaneously enhanced. Elemental correlations and factor analysis indicate the sedimentary environment and provenance of the deposits, while elemental enrichment and element ratios, including Si/Ti, Al/Ti, Rb/Sr and Zr/Rb, are consistent with changes in the intensity of pedogenic and of the East Asian monsoon as reflected by climate proxies, illustrating that XRF core scanning analysis technology has great potential in the field of Quaternary environmental changes of loess. Furthermore, the stepwise uplift of the Qinling Mountains, which has blocked the winter and summer monsoons to a certain extent, has had a significant impact on the relative degree of loess accumulation and pedogenic in the northern piedmont, southern piedmont and intermontane basin of the Qinling Mountains and also appears to have promoted settlement by early humans. Hence, the study of paleoclimate in areas of active tectonic movement has the potential to promote our understanding of micro-scale climate change in this region in the future. [ABSTRACT FROM AUTHOR]

The marine organic carbon content in sediments is a useful tool for reconstructing past productivity in the ocean. Bromine has been proposed as a useful proxy for marine organic carbon, since bromine is more concentrated in marine organic matter compared to terrestrial organic matter.Here, we present a high-resolution Quaternary record of marine organic carbon in the hemipelagic sediments of the Japan Sea obtained during Integrated Ocean Drilling Program (IODP) Expedition 346. We measured the bromine content in the sediments using an XRF core scanner (ITRAX). The total organic carbon content, total nitrogen, and stable carbon isotope values were also measured for discrete samples from the same sediments. The total organic carbon/total nitrogen ratio and the stable carbon isotope ratio of the total organic carbon are used to estimate the marine organic carbon content within the total organic carbon.The Br counts and marine organic carbon content show a high correlation, which we used to construct a calibration equation of the marine organic carbon content from the Br counts. Using the calibration equation, we reconstructed the changes in the marine organic carbon content during the Quaternary with a time resolution of ~ 50 years using sediment cores from IODP Site U1424 in the east central Japan Sea. The method to estimate the marine organic carbon content from the Br counts measured by the XRF core scanner proposed in this paper will be a useful tool to reconstruct the organic carbon content with high resolution and high speed. [ABSTRACT FROM AUTHOR]