Glassy objects from DSDP Hole 5-32 in the northeastern Pacific Ocean

Small glassy spheres, ellipsoids, teardrops, cylinders and dumbbells occur in large numbers in Tertiary deep sea clays cored in the northeastern Pacific by the Deep Sea Drilling Project. These objects morphologically resemble microtektites, but have the composition of an oceanic tholeiite. On the basis of their composition and stratigraphic relationship it is considered that they are of volcanic origin and most likely have been formed in deep water by submarine volcanic processes.

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.

Sediment Trap Data in the northwest Mediterranean Sea from the MedFlux project (2003 - 2005)

MedFlux sampling was carried out at the French JGOFS DYFAMED (DYnamique des Flux Atmospheriques en MEDiterranee) site in the Ligurian Sea (northwestern Mediterranean), 52km off Nice (431200N, 71400E) in 2300m water depth. In 2003, a mooring with sediment trap arrays was deployed 6 March (day of year, DOY 65) and recovered 6 May (DOY 126); this trap deployment will be referred to as Period 1 (P1). The array was redeployed a week later on 14 May (DOY 134) and recovered again on 30 June (DOY 181); this trap deployment will be referred to as Period 2 (P2). Indented-rotating sphere (IRS) valve traps were fitted with TS carousels to determine temporal variability of particulate matter flux. TS traps were fitted with ''dimpled'' spheres. Vertical flux at 200m depth is considered to be equivalent to new or export production, and traps sampled at 238 and 117m during P1 and P2, respectively. We also collected TS material at 711m during P1 and at 1918m during P2. Upon recovery, samples were split using a McLaneTM WSD splitter to allow multiple chemical analyses. Here we report 2003 data on TS particulate mass, and the contributions of organic carbon (OC), opal, lithogenic material and calcium carbonate to mass. In 2005, traps were deployed as described above for 55 d during a single period from 4 March (DOY 63) to 1 May (DOY 121). TS traps were fitted with ''dimpled'' spheres. TS particulate matter was collected from 313 to 924 m.

Occurrence and chemistry of microtektites of ODP Site 121-758

The Toba lake event, the Australasian microtektite event, and the Cretaceous/Paleogene boundary were analyzed on the basis of foraminifers, carbonate content, trace elements, and spherules (microtektites). The Toba ash event, recovered in Hole 758C, may have had minor influences on the foraminiferal populations. The Australasian tektite event has probably some influence on foraminiferal ecology, because the larger specimens become scarce just above the microtektite layer. Microtektites recovered from Hole 758B closely resemble spherules recovered from several Cretaceous/Paleogene boundary localities in North America. The Cretaceous/Paleogene spherules, however, are usually larger and are completely altered to goyazite in the terrestrial environment and to smectite in a marine environment. The Cretaceous/Paleogene boundary of Hole 752B does not show obvious anomalous trace-element concentrations, and iridium concentrations are below our detection limits. The trace-element pattern is dominated by the alternation of chalk with volcanic ash layers above the Cretaceous/Paleogene boundary.

Abundances of dinoflagellate cysts in sediment trap MST-9 (Appendix 1)

To study the ecology of calcareous dinoflagellates we examined the impact of the SW and NE monsoons on cyst formation using sediment trap material, collected at 1032 m water depth, off Somalia from June 1992 to February 1993. The results do not confirm the relationship between cyst production and lower nutrient concentrations, as highest cyst fluxes were recorded during late SW monsoon under the relatively nutrient-rich and less agitated conditions of mature upwelled water. Lowest cyst fluxes were found under strongly stratified, nutrient-depleted surface waters during the inter-monsoon. Although all of the studied species seem to prefer a stratified water column, an elevated concentration of nutrients appears to be necessary to maintain high cyst production. Comparison of the mean cyst flux to the sediment trap with that into the underlying surface sediments reveals a loss of 81-96%, which can be attributed to calcite dissolution. The relatively small spheres of Thoracosphaera heimii are affected more than the cysts of the other species.

Geochemistry of microtektites from Victoria Land Transantarctic Mountains

We extended the petrographic and geochemical dataset for the recently discovered Transantarctic Mountain microtektites in order to check our previous claim that they are related to the Australasian strewn field. Based on color and composition, the 465 microtektites so far identified include two groups of transparent glass spheres less than ca. 800 µm in diameter: the most abundant pale-yellow, or normal, microtektites, and the rare pale-green, or high-Mg, microtektites. The major element composition of normal microtektites determined through electron microprobe analysis is characterized by high contents of silica (SiO2 = 71.5 ± 3.6 (1 sigma) wt%) and alumina (Al2O3 = 15.5 ± 2.2 (1 sigma) wt%), low total alkali element contents (0.50-1.85 wt%), and MgO abundances <6 wt%. The high-Mg microtektites have a distinctly higher MgO content >10 wt%. Transantarctic Mountain microtektites contain rare silica-rich (up to 93 wt% SiO2) glassy inclusions similar to those found in two Australasian microtektites analyzed here for comparison. These inclusions are interpreted as partially digested, lechatelierite-like inclusions typically found in tektites and microtektites. The major and trace element (by laser ablation - inductively coupled plasma - mass spectrometry) abundance pattern of the Transantarctic Mountain microtektites matches the average upper continental crust composition for most elements. Major deviations include a strong to moderate depletion in volatile elements including Pb, Zn, Na, K, Rb, Sr and Cs, as a likely result of severe volatile loss during the high temperature melting and vaporization of crustal target rocks. The normal and high-Mg Transantarctic Mountain microtektites have compositions similar to the most volatile-poor normal and high-Mg Australasian microtektites reported in the literature. Their very low H2O and B contents (by secondary ion mass spectrometry) of 85 ± 58 (1 sigma) ?g/g and 0.53 ± 0.21 ?g/g, respectively, evidence the extreme volatile loss characteristically observed in tektites. The Sr and Nd isotopic compositions of multigrain samples of Transantarctic Mountain microtektites are 87Sr/86Sr ~ 0.71629 and 143Nd/144Nd ~ 0.51209, and fall into the Australasian tektite compositional field. The Nd model age calculated with respect to the chondritic uniform reservoir (CHUR) is TNdCHUR ~ 1.1 Ga, indicating a Meso-Proterozoic crustal source rock, as was derived for Australasian tektites as well. Coupled with the Quaternary age from the literature, the extended dataset presented in this work strengthens our previous conclusion that Transantarctic Mountain microtektites represent a major southward extension of the Australasian tektite/microtektite strewn field. Furthermore, the significant depletion in volatile elements (i.e., Pb, B, Na, K, Zn, Rb, Sr and Cs) of both normal and high-Mg Transantarctic Mountain microtektites relative to the Australasian ones provide us with further confirmation of a possible relationship between high temperature-time regimes in the microtektite-forming process and ejection distance.

Abundance of living coccolithophores in the northern Arabian Sea (Table 2)

The present study was conducted to provide information about living coccolithophores from the northern Arabian Sea as potential proxies in palaeoceanographic studies. In all, 71 plankton samples from 16 stations collected in September 1993 were analysed for their contents of living coccolithophores. Absolute abundances range from less than 400 coccospheres per litre in surface waters to 35 000 spheres per litre at intermediate water depths. From 49 identified taxa, nine species contribute significant cell numbers of more than 2000 coccospheres per litre and comprise more than 10% of the communities in at least one sample. Important species are (in approximate order of cell abundances): Gephyrocapsa oceanica, Florisphaera profunda, Oolithotus antillarum, Calciosolenia murrayi, Umbellosphaera irregularis, Emiliania huxleyi, Umbellosphaera tenuis, Calciopappus rigidus, and Algirosphaera robusta. At most profiles, a vertical succession of coccolithophore species was found. Calciosolenia murrayi and C. rigidus were restricted to surface waters, whereas high numbers of F. profunda and A. robusta occurred at depths below 40 m. The coccolithophore communities reflected the local oceanographic situation and seemed to be more dependent on mixed layer depth and nutrient availability than on temperature and salinity changes. Additionally, synecologic competition with diatoms in part controlled the species composition and generally reduced the abundance of coccolithophores. Synecological and ecological tolerances of species were discussed with the help of cluster analysis.