Maastrichtian calcareous nannofossils of the Indian Ocean and Shatsky Rise

The biotic effects of volcanism have long been the unknown factors in creating biotic stress, and the contribution of the Deccan volcanism to the K-T mass extinction remains largely unknown. Detailed studies of the volcanic-rich sediments of Indian Ocean Ninetyeast Ridge Sites 216 and 217 and Wharton Basin Site 212 reveal that the biotic effects of late Maastrichtian volcanism on planktic foraminifera and calcareous nannofossils are locally as severe as those of the K-T mass extinction. The biotic expressions of these high stress environments are characterized by the Lilliput effect, which includes reduced diversity by eliminating most K-strategy species, and reduction in specimen size (dwarfing), frequently to less than half their normal adult size of both r-strategy and surviving K-strategy species. In planktic foraminifera, the most extreme biotic stress results are nearly monospecific assemblages dominated by the disaster opportunist Guembelitria, similar to the aftermath of the K-T mass extinction. The first stage of improving environmental conditions results in dominance of dwarfed low oxygen tolerant Heterohelix species and the presence of a few small r-strategy species (Hedbergella, Globigerinelloides). Calcareous nannofossil assemblages show similar biotic stress signals with the dominance of Micula decussata, the disaster opportunist, and size reduction in the mean length of subordinate r-strategy species particularly in Arkhangelskiella cymbiformis and Watznaueria barnesiae. These impoverished and dwarfed late Maastrichtian assemblages appear to be the direct consequences of mantle plume volcanism and associated environmental changes, including high nutrient influx leading to eutrophic and mesotrophic waters, low oxygen in the water column and decreased watermass stratification.

Geology, geochemistry, and mineralogy of sediments from the Trans Indian Ocean Geotraverse

The monograph is devoted to the main results of research on the Trans Indian Ocean Geotraverse from the Maskarene Basin to the north-western margin of Australia. These results were obtained by Russian specialists and together with Indian specialists during 15 years of cooperation in investigation of geological structure and mineral resources of the Indian Ocean. The monograph includes materials on information support of marine geological and geophysical studies, composition and structure of information resources on the Indian Ocean, bathymetry and geomorphology, structure and geological nature of the magnetic field, gravity field, plate tectonics, crustal structure and sedimentary cover, seismic stratigraphy, perspectives for detecting oil and gas, solid minerals, sediment composition, composition and properties of clay minerals, stratigraphy and sediment age, chemical composition of sediments, composition of and prospects for solid minerals.

Ages, lithologie descriptions and mineral analyses from different DSDP holes in the Indian Ocean

The present work is based on mineralogical studies of sand and silt layers from a number of Deep Sea Drilling Project sites in the Indian Ocean belonging to different physiographic provinces of different ages. The minerals can be grouped into two major associations: a hornblende-opaque association with varying amounts of pyroxene, garnet, epidote, zircon, etc. and a biotite-chlorite-muscovite assemblage. The dominance of unstable minerals indicates a first generation, though evidence of reworking is reflected in the zircon and tourmaline grains at some sites. A large variety of minerals at some sites indicates a complex source. The mineral composition is nearly homogeneous at different sites for the entire length of the core, indicating that they have been derived from the same source during the deposition of that interval. However, the provenance changed by tectonic activity, the effect of which has been reflected in the mineralogy of some sites. An attempt was made to describe the mineralogic characteristics and their tectonic interpretations in the Pliocene and Miocene periods in the Ganges and Indus fan sites and also in the Wharton and Mozambique basin sites. Similar attempts could not be made for other ages in other physiographic provinces as the numbers of samples were too few. Within the limited scope, some idea about the mineralogical character of different basins and different physiographic provinces can be obtained from the present study. Mineralogical evidence also suggests very long transport of sediments in the deep sea. Regional variation of mineralogy has resulted due to source, sea-floor configuration, selective removal, reworking by different agencies and the processes operating in the ocean. There is no relation between a particular age and a set mineral assemblage for the Cenozoic sediments of the Indian Ocean.

Discarge compilation from The Global River Discharge (RivDIS) Project

The Global River Discharge (RivDIS) data set contains monthly discharge measurements for 1018 stations located throughout the world. The period of record varies widely from station to station, with a mean of 21.5 years. These data were digitized from published UNESCO archives by Charles Voromarty, Balaze Fekete, and B.A. Tucker of the Complex Systems Research Center (CSRC) at the University of New Hampshire. River discharge is typically measured through the use of a rating curve that relates local water level height to discharge. This rating curve is used to estimate discharge from the observed water level. The rating curves are periodically rechecked and recalibrated through on-site measurement of discharge and river stage.

Annotated record of the detailed examination of Mn deposits from the H.M.S. Egeria, H.M.S. Fling Fish and H.M.S. Investigator expeditions in the Indian Ocean and Southern Seas

Captain Wharton, the Hydrographer of the Admiralty sent to the author a series of the deposit-samples collected in the Indian and Antarctic Oceans during the expeditions in 1887 of H.M.S. Flying Fish, H.M.S. Egeria and H.M.S. Investigator. These deposits were submitted to careful microscopical examination and chemical analysis.

Benthic foraminifera in eastern equatorial Indian Ocean surface sediments

Study of Recent abyssal benthic foraminifera from core-top samples in the eastern equatorial Indian Ocean has identified distinctive faunas whose distribution patterns reflect the major hydrographic features of the region. Above 3800 m, Indian Deep Water (IDW) is characterized by a diverse and evenly-distributed biofacies to which Globocassidulina subglobosa, Pyrgo spp., Uvigerina peregrina, and Eggerella bradyi are the major contributors. Nuttalides umbonifera and Epistominella exigua are associated with Indian Bottom Water (IBW) below 3800 m. Within the IBW fauna, N. umbonifera and E. exigua are characteristic of two biofacies with independent distribution patterns. Nuttalides umbonifera systematically increases in abundance with increasing water depth. The E. exigua biofacies reaches its greatest abundance in sediments on the eastern flank of the Ninetyeast Ridge and in the Wharton-Cocos Basin. The hydrographic transition between IDW and IBW coincides with the level of transition from waters supersaturated to waters undersaturated with respect to calcite and with the depth of the lysocline. Carbonate saturation levels, possibly combined with the effects of selective dissolution on the benthic foraminiferal populations, best explain the change in faunas across the IDW/IBW boundary and the bathymetric distribution pattern of N. umbonifera. The distribution of the E. exigua fauna cannot be explained with this model. Epistominella exigua is associated with the colder, more oxygenated IBW of the Wharton-Cocos Basin. The distribution of this biofacies on the eastern flank of the Ninetyeast Ridge agrees well with the calculated bathymetric position of the northward flowing deep boundary current which aerates the eastern basins of the Indian Ocean.