Abstract Marine sediment cores are the fundamental data source for information on seabed character, depositional history and environmental change. They provide raw data for a wide range of research including studies of global climate change, palaeoceanography, slope stability, oil exploration, pollution assessment and control, and sea-floor surveys for laying cables, pipelines and siting of sea-floor structures. During the last three decades, a varied suite of new technologies have been developed to analyse cores, often non-destructively, to produce high-quality, closely spaced, co-located downcore measurements, characterizing sediment physical properties, geochemistry and composition in unprecedented detail. Distributions of a variety of palaeoenvironmentally significant proxies can now be logged at decadal and, in some cases, even annual or subannual scales, allowing detailed insights into the history of climate and associated environmental change. These advances have had a profound effect on many aspects of the Earth Sciences, particularly palaeoceanography. In this paper, we review recent advances in analytical and logging technology, and their application to the analysis of sediment cores. Developments in providing access to core data and associated datasets, and data-mining technology, in order to integrate and interpret new and legacy datasets within the wider context of sea-floor studies, are also discussed. Despite the great advances in this field, however, challenges remain, particularly in the development of standard measurement and calibration methodologies and in the development of data analysis methods. New data visualization tools and techniques need to be developed to optimize the interpretation process and maximize scientific value. Amplified collaboration environments and tools are needed in order to capitalize on our analysis and interpretation capability of large, multi-parameter datasets. Sophisticated, yet simple to use, searchable Internet databases, with universal access and secure long-term funding, and data products resulting in user-defined data-mining query and display, so far pioneered in the USA and Australia, provide robust models for efficient and effective core data stewardship.

Abstract A new automated multi-function core scanning instrument, named ITRAX, has been developed that records optical, radiographic and elemental variations from sediment half cores up to 1.8 m long at a resolution as fine as 200 μm. An intense micro-X-ray beam focused through a flat capillary waveguide is used to irradiate samples to enable both X-radiography and X-ray fluorescence (XRF) analysis. Data are acquired incrementally by advancing a split core, via a programmable stepped motor drive, through the flat, rectangular-section X-ray beam. Traditional XRF determination of element composition in sediments provides high-quality data, but it takes a considerable time and normally consumes gram quantities of material that is often only available in limited quantities. The ITRAX core scanner non-destructively collects optical and X-radiographic images, and provides high-resolution elemental profiles that are invaluable for guiding sample selection for further (destructive) detailed sampling. This paper presents a description of the construction, characteristics and capabilities of the ITRAX system. High-resolution ITRAX data obtained from sediment cores are also presented and compared with results from traditional wavelength-dispersive XRF analysis at lower resolution. Finally, some recent technical developments linked to the second-generation ITRAX are presented.

Abstract The upper part (0–20 m) of a long piston core from the SE Balearic Abyssal Plain — spanning the past 50 ka — has been studied using the ITRAX micro-XRF core scanner to obtain downcore elemental profiles. The Ca/Fe ratio was found to be an effective parameter to distinguish between turbidites and pelagites, because turbidites generally have higher Fe contents and lower Ca contents compared with pelagic intervals. Beds that were obscure when visually logged could be identified as turbidites or pelagites on their geochemical characteristics, allowing more complete subdivision of the sequence into genetic units. The ITRAX XRF data also provide useful information on textural grading, bioturbative mixing, identification of geochemically distinctive marker beds, indications of differences in provenance, and confirm or query the presence of early arrivals during turbidite emplacement. A chronostratigraphic framework for the core based on accelerator mass spectrometry (AMS) radiocarbon dating and correlation with oxygen isotope stages of pelagic intervals in other cores (using calcium carbonate stratigraphy) was also established. This shows that turbidite emplacement on this part of the Balearic Abyssal Plain has been modulated strongly by climate and sea-level change, with turbidite emplacement most frequent during the early Holocene when the rate of post-glacial sea-level rise was greatest. Deposition of the coarsest (i.e. sand and silt-based) turbidites at the core site was restricted to the full and Late Glacial (11–25 ka). Turbidite emplacement during Oxygen Isotope Stage 3 was rare. Most of the turbidites at the site are distal, but some coarse-grained-based turbidites are characterized by higher Sr/Ca ratios (possibly indicating a higher aragonite content), higher Ca and lower Fe contents compared to other turbidites, and are interpreted as having a more proximal shelf source. Such turbidites are generally rare, however, and restricted to full Glacial and Younger Dryas time. There is little evidence for large-scale seismogenic turbidites (expected to be seen as randomly timed emplacement, seemingly independent of eustatic control) at the core site, despite proximity to the seismically active Algerian margin 100 km to the south. This suggests that seismogenic turbidites must largely bypass this part of the plain. Although the ITRAX core scanner provides a rapid and non-destructive means of characterizing downcore geochemical distributions in great detail, interpretation of the data requires caution and assessment from an informed standpoint. Analytical artefacts such as those caused by water or organic content, degree of compaction, grain-size and mineral effects, unevenness of the cut core surface and poor discrimination of closely spaced element XRF peaks need identification and elimination.

Abstract The Late Pleistocene-Holocene (0–30 ka BP) allochthonous sedimentation in the Herodotus Basin of the eastern Mediterranean has been controlled, in part, by a combination of regional climatic change and eustatic sea-level fluctuation. A new series of radiocarbon dates, made on planktonic foraminifers and pteropod shells taken from the pelagic and hemipelagic intervals between individual turbidite units, has given bracketing dates for each major turbidity current event that deposited sand and mud on the Herodotus Basin plain. Two partly independent cycles are evident. Climate-induced cycles have lead to an alternation of periods of turbidites sourced from the Nile delta-fan system with those from the North African shelf and Anatolian rise. These correlate with pluvial and inter-pluvial climatic periods recognized in the Nile hinterland. Sea-level cycles have tended to focus turbidite emplacement, from whatever source, at periods of sea-level fall within the latest Wisconsin and sea-level rise from the Wisconsin-Holocene period. In addition to the Herodotus Basin Megaturbidite (HBM) described previously, six other beds with volumes in excess of 25 km 3 and wide lateral extent across the basin can be termed megaturbidites. There is no simple sea-level or climate control on the timing of these events, so we must conclude that triggering and emplacement of megaturbidites is independent and variable.