X-ray fluorescence (XRF) core scanning provides rapid high-resolution (down to 1 mm) records of chemical composition on split sediment cores. The measurements are non-destructive and require very limited sample preparation. The new Avaatech XRF Core Scanner, operational since 2002, covers the atomic mass range from Al to U. Instrument parameters, especially tube voltage, can be adjusted to provide optimum settings for selected elements or sets thereof. Owing to the nature of the surface of split sediment cores, particularly effects resulting from sample inhomogeneity and surface roughness, results are semiquantitative, yet provide reliable records of the relative variability in elemental composition downcore. Selected case studies from diverse sedimentary settings in the NE Atlantic Ocean illustrate a range of applications of XRF logging data. These include preliminary stratigraphic interpretations (glacial-interglacial cycles), provenance studies of the terrigenous sediment fraction, lithological characterization, early diagenetic processes and distinction between carbonate phases (aragonite v. calcite).

The Avaatech XRF Core Scanner: technical description and applications to NE Atlantic sediments

Sulfur Cycling and Methane Oxidation

XRF core scanners, with their rapid and non-destructive analytical capability, have now been used for two decades in the analysis of marine sediments. Initially they were used to record variations in fundamental parameters such as calcium carbonate stratigraphy and terrigenous sediment delivery, using major element integrals, such as Ca and Fe, to provide detailed insights into oceanographic and climatic processes. In recent years, proxy selection has progressed to routine normalisation and presentation as log-ratios to include 60 elements or ratios to document a wide range of environmental and process changes. We review the development and application of XRF core scanning of marine sediments and discuss the basis of particular proxies, their uses and limitations to assist users in their selection. To date, there has been no systematic overview of elemental proxies and their application in the analysis of marine sediment records.

Twenty Years of XRF Core Scanning Marine Sediments: What Do Geochemical Proxies Tell Us?

Diagenetic Alteration of Magnetic Signals by Anaerobic Oxidation of Methane Related to a Change in Sedimentation Rate

Diagenetic changes of magnetic and geochemical signals by anaerobic methane oxidation in sediments of the Zambezi deep-sea fan (SW Indian Ocean)

Rock magnetic and geochemical data logged by fast, non-destructive X-ray fluorescence and susceptibility half core scanning techniques have been combined to create high-resolution records of redoxomorphic iron mineral diagenesis in suboxic marine sediments. The great potential of this approach and advantage to standard single sample methods is demonstrated on two Late Quaternary sequences from the central Equatorial Atlantic (GeoB 2908–7 and 4317–2). Reducti ve dissolution of ferric minerals, most prominently magnetite (Fe3O4) and hematite (Fe2O43), induced by organic carbon degradation is shown to represent a gradual, mineral- and grain-size selective process. Proportionality of Fe, Ti and magnetite concentrations in the unaltered sections lead us to define proxy parameters for magnetite depletion (Fe/κnd) below and precipitation (κnd/Ti) above the modem and numerous fossil redox boundaries, while iron relocation was detected on basis of the Fe/Ti ratio. By calibrating all three ratios internally, we reconstruct and quantify primary deposition and secondary change of both, magnetite and total Fe profiles. Fine-scaled Corg variations (0.1 to 0.6%) and susceptibility losses (up to 200 · 10−6 SI) show high signal resemblance and appear to be equivalent signatures of cyclic productivity pulses in the study area. Some minor suboxic events are still expressed in the rock magnetic proxy signal, but are not accompanied by residual Corg enrichments.

Integrated Rock Magnetic and Geochemical Quantification of Redoxomorphic Iron Mineral Diagenesis in Late Quaternary Sediments from the Equatorial Atlantic

This is an interdisciplinary and synoptic study of Equatorial Atlantic sediment formation in the Late Quaternary aimed at untangling the interlaced signatures of terrigenous and biogenous deposition and early diagenesis It is based on a stratigraphic network of 16 gravity core records arranged along one meridional and three zonal transects (4°N, 0° and 4°S) crossing the Amazon and Sahara plumes as well as the Equatorial Divergence high productivity region All newly introduced sediment sequences are collectively dated by their coherent CaCO3 content profiles and two available δ18O age models To infer proxy records indicative of individual fluxes and processes, we analyze environmental magnetic parameters describing magnetite concentration, magnetic grain sizes and magnetic mineralogy along with CaCO3, Corg, Fe, Mn, Ba and color data Diagenetically affected layers are identified by a newly introduced Fe/κ index Reach and climatic variability of the major regional sedimentation systems is delimited from lithological patterns and glacial/interglacial accumulation rate averages The most prominent regional trends are the N-S decrease in terrigenous accumulation and the Equatorial Divergence high in glacial Corg accumulation, which decays much faster south- than northwards Glacial enrichments in Corg and proportional depletions in CaCO3, content appear to reflect sedimentary carbonate diagenesis more than lysoclinal oscillations and dominate temporal lithology changes Suboxic iron mineral reduction is low at Ceara Rise and Sierra Leone Rise, but more intense on both flanks of the Mid-Atlantic ridge, where it occurs within organic rich layers deposited during oxygen isotope stages 6, 10 and 12, in particular at the terminations To the equator, these zones reflect a full precessional rhythm with individual diagenesis peaks merging into broader magnetite-depleted zones Rock magnetic and geochemical data show, that the depths of the Fe3+/Fe2+ redox boundary in the Equatorial Atlantic are not indicative of average productivity and were frequently shifted in the past They are now located just above the topmost preserved productivity pulse At 4°N, this organically enriched layer coincides with glacial stage 6, at 0° with glacial stage 2 Subsequent oxic and suboxic degradation of organic material entails stratigraphically coincident carbonate and magnetite losses opening new analytical perspectives

Late Quaternary sedimentation and early diagenesis in the equatorial Atlantic Ocean: Patterns, trends and processes deduced from rock magnetic and geochemical records

Processes and signals of nonsteady-state diagenesis in marine sediment/pore water systems - case histories and future perspectives

A high-resolution study of an active Fe 2+ /Fe 3+ redox horizon has been carried out on sediments of the central equatorial Atlantic. The multidisciplinary approach combining geochemical and rock-magnetic parameters gives evidence of the interrelation of the redox horizon with the last change from glacial to interglacial conditions (T1). Distinct enrichments of redox-sensitive elements (Mn, Fe, V, and U) reveal a characteristic depth-sequence, indicating non-steady-state diagenetic conditions caused by a decrease in productivity and an increase in oxygen content in the bottom water during T1 and a reversal during the Holocene. Thus, the redox boundaries first moved down into the sediment and subsequently upwards. The movement of the redox boundaries led to the development of conspicuous double peaks for Fe and Mn. The reconstruction based on geochemical data is supported by susceptibility and magnetization measurements of the sediments displaying well-defined anomalies in the vicinity of active and paleo redox boundaries. The combination of geochemical and rock-magnetic parameters, like the ferrimagnetic susceptibility, and total Fe concentration ( χ f /Fe) are suitable for characterizing distinct zones of dissolution and precipitation of ferromagnetic mineral phases (e.g. magnetite). Moreover, the small scale movement of the Fe 2+ /Fe 3+ redox-boundary, could be traced in detail by overlaying the peak-shape pattern of V/Al and of χ f / χ tot .

A combined geochemical and rock-magnetic investigation of a redox horizon at the last glacial/interglacial transition

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

J. Funk

Author Tools

Chat about Author

Papers

Integrated Rock Magnetic and Geochemical Quantification of Redoxomorphic Iron Mineral Diagenesis in Late Quaternary Sediments from the Equatorial Atlantic

Late Quaternary sedimentation and early diagenesis in the equatorial Atlantic Ocean: Patterns, trends and processes deduced from rock magnetic and geochemical records

Processes and signals of nonsteady-state diagenesis in marine sediment/pore water systems - case histories and future perspectives

A combined geochemical and rock-magnetic investigation of a redox horizon at the last glacial/interglacial transition