Geochemical analyses of chert nodules and beds from deep-sea sediments (Table 1)

Concentrations of Fe, Mg, Ca, Sr, Mn, Zn, and other heavy metals were analyzed by atomic absorption spectrometry in 27 chert samples from the Pacific deep sea, 17 chert samples from land, and 4 associated sediments from the Pacific Ocean. Among the elements, Fe and Mg concentrations are highly correlatable as are the relationships between Ca and Sr, or between Ca and CO2. The correlation between Fe and Mg is particularly high for Pacific deep-sea flints and cherts, and for cherts of deep-sea origin from outcrops on land. Enrichments in heavy metals were recognized in some deep-sea cherts; volcanogenic cherts are enriched in Fe, a chert nodule containing basaltic fragments is enriched in Zn and Cr, and biogenically enclosed carbonates in flint nodules are enriched in Mn. The correlation of Fe and Mg and their constant ratio [Mg(%)/Fe(%)] of around 0.33 might be characteristic features in the pelagic clays contained in deep-sea flints and cherts, and the concentrations of heavy metals in them would be controlled by the concentrations of Fe-Mg correlated clays. Although the mineralogical nature of the Fe-Mg clay in deep-sea cherts was not clarified by dissolution experiments on opaline minerals in chert, the high concentrations of Fe-montmorillonite and fine-grained olivine or other ferromagnesian silicate minerals in the clay may result in the high correlations between Fe and Mg.

Clay minerals and their assemblages at DSDP Leg 63 Holes

This paper discusses the distribution of clay minerals and identification of their assemblages in relation to sedimentary facies encountered during DSDP Leg 63 drilling off southern California and Baja California. We also consider how these assemblages are determined by source areas and changes in general paleogeographic environments during different periods of sedimentation.

Radiocarbon ages and clay minerals in sediment cores obtained during a 2009 Jan Mayen cruise to the Norwegian Sea

The origin of two acoustic sediment units has been studied based on lithological facies, chronology and benthic stable isotope values as well as on foraminifera and clay mineral assemblages in six marine sediment cores from Kveithola, a small trough west of Spitsbergenbanken on the western Barents Sea margin. We have identified four time slices with characteristic sedimentary environments. Before c. 14.2 cal. ka, rhythmically laminated muds indicate extensive sea ice cover in the area. From c. 13.9 to 14.2 cal. ka, muds rich in ice-rafted debris were deposited during the disintegration of grounded ice on Spitsbergenbanken. From c. 10.3 to 13.1 cal. ka, sediments with heterogeneous lithologies suggest a shifting influence of suspension settling and iceberg rafting, probably derived from a decaying Barents Sea Ice Sheet in the inner-fjord and land areas to the north of Kveithola. Holocene deposition was episodic and characterized by the deposition of calcareous sands and shell debris, indicative of strong bottom currents. We speculate that a marked erosional boundary at c. 8.2 cal. ka may have been caused by the Storegga tsunami. Whilst deposition was sparse during the Holocene, Kveithola acted as a sediment trap during the preceding deglaciation. Investigation of the deglacial sediments provides unprecedented details on the dynamics and timing of glacial retreat from Spitsbergenbanken.

Concentration and composition of aerosols over the North Atlantic in August 1995

Data on composition of aerosols are considered. Investigations include electron microscopy, grain size, mineralogical and chemical analyses. Samples of aerosols were collected Cruise 37 of R/V Akademik Mstislav Keldysh along a transatlantic section along 40°-50°N. Variability of concentrations and composition of aerosols with distance from continents is shown: concentrations of aerosols decrease by factor of ten and more. Significant portion of mineral components in aerosols collected over the continent is replaced by organic matter due to mechanical differentiation during transportation. Such anthropogenic components as soot, ash, and combustion spheres were detected in all samples. North African dust was found in one sample in the western part of the section.