Late Cenozoic carbonate accumulation rates of ODP Leg 115 samples

The principal paleoceanographic objective of Ocean Drilling Program Leg 115 was to collect a suite of materials that would allow reconstruction of the dynamic features of the late Cenozoic carbonate system in the equatorial Indian Ocean. This goal was achieved with the recovery of sediments from a closely spaced depth transect (1541-4428 m) of five sites (Sites 707 through 711) from on and around the Mascarene Plateau that record the last 50 m.y. of pelagic deposition. More than 2200 measurements of carbonate content are combined here with a highly resolved bio- and magnetostratigraphy to produce the first detailed compilation of bulk, carbonate, and noncarbonate mass accumulation rates (MARs) from the Indian Ocean. These results allow us to recognize three major depositional intervals, each characterized by a distinct depth-dependent pattern of carbonate accumulation: (1) the Paleogene, a time of moderate accumulation rates (0.4-0.7 g/cm**2/1000 yr) and reduced between-site accumulation differences; (2) the early and middle Miocene, a period characterized by greatly reduced carbonate MARs (typically <0.2 g/cm**2/1000 yr) at all sites and a shallow carbonate compensation depth; and (3) the late Miocene to Holocene, a time span marked by the highest bulk and carbonate accumulation rates of the last 50 Ma (1.6-1.8 g/cm**2/1000 yr), and the first appearance of substantial contrasts in carbonate accumulation as a function of the water depth of the drill site. The fundamentally different character of the carbonate system during each of these intervals must represent a regional response to the complex evolution of late Cenozoic oceans and climate.

Calcareous nannofossil stratigraphy, mass accumulation rates and bulk density of sediments from ODP Leg 173 sites

Drilling on the Iberia Abyssal Plain during Ocean Drilling Program Leg 173 allowed us to recover Upper Cretaceous through Paleocene sediments at Sites 1068 and 1069 and only upper Paleocene sediments at Site 1067, which expands considerably the Upper Cretaceous to Paleocene record for this region. Of these three sites, Site 1068 recovered uppermost Cretaceous sediments as well as the most complete Paleocene record, whereas Site 1067 yielded only uppermost Paleocene sediments (Zone CP8). Site 1069 provided a rather complete upper Campanian through Maastrichtian section but a discontinuous Paleocene record. After a detailed calcareous nannofossil biostratigraphy was documented in distribution charts, we calculated mass accumulation rates for Holes 1068A and 1069A. Sediments in Hole 1068A apparently record the final stages of burial of a high basement block by turbidity flows. Accumulation rates through the Upper Cretaceous indicate relatively high rates, 0.95 g/cm**2/k.y., but may be unreliable because of the lack of datum points and/or possible hiatuses. Accumulation rates in the Paleocene section of Hole 1068A fluctuated every few million years from lower (~0.35 g/cm**2/k.y.) to higher rates (~0.85 g/cm**2/k.y.) until the latest Paleocene, when rates increased to an average of ~2.0 g/cm**2/k.y. Mass accumulation rates for the Upper Cretaceous in Hole 1069A indicate a steady rate of ~0.60 g/cm**2/k.y. from 75 to 72 Ma. There may have been one or more hiatuses between 72 and 68 Ma (combined Zone CC24 through Subzone CC25b), as indicated by the very low accumulation rate of 0.15 g/cm**2/k.y. The Paleocene section of Hole 1069A does not show the same continuous record, which may result from fluctuations in the carbonate compensation depth and poor recovery (average = 40%). Zones CP4 and CP5 are missing within a barren interval; this and numerous other barren intervals affect the precision of the nannofossil zonation and calculation of mass accumulation rates. However, in spite of these missing zones, mass accumulation rates do not seem to indicate the presence of hiatuses as the rates for this barren interval average ~1.0 g/cm**2/k.y. This study set out to test the hypothesis that a reliable biostratigraphic record could be constructed from sediments derived from turbidity flows deposited below the carbonate compensation depth. As illustrated here, not only could a reliable biostratigraphic record be determined from these sediments, but sedimentation and mass accumulation rates could also be determined, allowing inferences to be drawn concerning the sedimentary history of this passive margin. The reliability of this record is confirmed by independent verification by the establishment of a magnetostratigraphy for the same cores.

Hydrochemical Atlas of the Arctic Ocean

Introduction: Chemical composition of water determines its physical properties and character of processes proceeding in it: freezing temperature, volume of evaporation, density, color, transparency, filtration capacity, etc. Presence of chemical elements in water solution confers waters special physical properties exerting significant influence on their circulation, creates necessary conditions for development and inhabitance of flora and fauna, and imparts to the ocean waters some chemical features that radically differ them from the land waters (Alekin & Liakhin, 1984). Hydrochemical information helps to determine elements of water circulation, convection depth, makes it easier to distinguish water masses and gives additional knowledge of climatic variability of ocean conditions. Hydrochemical information is a necessary part of biological research. Water chemical composition can be the governing characteristics determining possibility and limits of use of marine objects, both stationary and moving in sea water. Subject of investigation of hydrochemistry is study of dynamics of chemical composition, i.e. processes of its formation and hydrochemical conditions of water bodies (Alekin & Liakhin 1984). The hydrochemical processes in the Arctic Ocean are the least known. Some information on these processes can be obtained in odd publications. A generalizing study of hydrochemical conditions in the Arctic Ocean based on expeditions conducted in the years 1948-1975 has been carried out by Rusanov et al. (1979). The "Atlas of the World Ocean: the Arctic Ocean" contains a special section "Hydrochemistry" (Gorshkov, 1980). Typical vertical profiles, transects and maps for different depths - 0, 100, 300, 500, 1000, 2000, 3000 m are given in this section for the following parameters: dissolved oxygen, phosphate, silicate, pH and alkaline-chlorine coefficient. The maps were constructed using the data of expeditions conducted in the years 1948-1975. The illustrations reflect main features of distribution of the hydrochemical elements for multi-year period and represent a static image of hydrochemical conditions. Distribution of the hydrochemical elements on the ocean surface is given for two seasons - winter and summer, for the other depths are given mean annual fields. Aim of the present Atlas is description of hydrochemical conditions in the Arctic Ocean on the basis of a greater body of hydrochemical information for the years 1948-2000 and using the up-to-date methods of analysis and electronic forms of presentation of hydrochemical information. The most wide-spread characteristics determined in water samples were used as hydrochemical indices. They are: dissolved oxygen, phosphate, silicate, pH, total alkalinity, nitrite and nitrate. An important characteristics of water salt composition - "salinity" has been considered in the Oceanographic Atlas of the Arctic Ocean (1997, 1998). Presentation of the hydrochemical characteristics in this Hydrochemical Atlas is wider if compared with that of the former Atlas (Gorshkov, 1980). Maps of climatic distribution of the hydrochemical elements were constructed for all the standard depths, and seasonal variability of the hydrochemical parameters is given not only for the surface, but also for the underlying standard depths up to 400 m and including. Statistical characteristics of the hydrochemical elements are given for the first time. Detailed accuracy estimates of initial data and map construction are also given in the Atlas. Calculated values of mean-root deviations, maximum and minimum values of the parameters demonstrate limits of their variability for the analyzed period of observations. Therefore, not only investigations of chemical statics are summarized in the Atlas, but also some elements of chemical dynamics are demonstrated. Digital arrays of the hydrochemical elements obtained in nodes of a regular grid are the new form of characteristics presentation in the Atlas. It should be mentioned that the same grid and the same boxes were used in the Atlas, as those that had been used by creation of the US-Russian climatic Oceanographic Atlas. It allows to combine hydrochemical and oceanographic information of these Atlases. The first block of the digital arrays contains climatic characteristics calculated using direct observational data. These climatic characteristics were not calculated in the regions without observations, and the information arrays for these regions have gaps. The other block of climatic information in a gridded form was obtained with the help of objective analysis of observational data. Procedure of the objective analysis allowed us to obtain climatic estimates of the hydrochemical characteristics for the whole water area of the Arctic Ocean including the regions not covered by observations. Data of the objective analysis can be widely used, in particular, in hydrobiological investigations and in modeling of hydrochemical conditions of the Arctic Ocean. Array of initial measurements is a separate block. It includes all the available materials of hydrochemical observations in the form, as they were presented in different sources. While keeping in mind that this array contains some amount of perverted information, the authors of the Atlas assumed it necessary to store this information in its primary form. Methods of data quality control can be developed in future in the process of hydrochemical information accumulation. It can be supposed that attitude can vary in future to the data that were rejected according to the procedure accepted in the Atlas. The hydrochemical Atlas of the Arctic Ocean is the first specialized and electronic generalization of hydrochemical observations in the Arctic Ocean and finishes the program of joint efforts of Russian and US specialists in preparation of a number of atlases for the Arctic. The published Oceanographic Atlas (1997, 1998), Atlas of Arctic Meteorology and Climate (2000), Ice Atlas of the Arctic Ocean prepared for publication and Hydrochemical Atlas of the Arctic Ocean represent a united series of fundamental generalizations of empirical knowledge of Arctic Ocean nature at climatic level. The Hydrochemical Atlas of the Arctic Ocean was elaborated in the result of joint efforts of the SRC of the RF AARI and IARC. Dr. Ye. Nikiforov was scientific supervisor of the Atlas, Dr. R. Colony was manager on behalf of the USA and Dr. L. Timokhov - on behalf of Russia.

(Table 1) Stable oxygen isotopic ratios and yearly snow accumulation of firn and ice cores from Svalbard

We analyse ice cores from Vestfonna ice cap (Nordaustlandet, Svalbard). Oxygen isotopic measurements were made on three firn cores (6.0, 11.0 and 15.5 m deep) from the two highest summits of the glacier located on the SW-NE and NW-SE central ridges. Sub-annual d18O cycles were preserved and could be counted visually in the uppermost parts of the cores, but deeper layers were affected by post-depositional smoothing. A pronounced d18O minimum was found near the bottom of the three cores. We consider candidates for this d18O signal to be a valuable reference horizon since it is also seen elsewhere in Nordaustlandet. We attribute it to isotopically depleted snow precipitation, which NCEP/NCAR reanalysis shows was unusual for Vestfonna, and came from northerly air during the cold winter of 1994/95. Finding the 1994/95 time marker allows establishment of a precise depth/age scale for the three cores. The derived annual accumulation rates indirectly fill a geographical gap in mass balance measurements and thus provide information on spatial and temporal variability of precipitation over the glacier for the period spanned by the cores (1992-2009). Comparing records at the two locations also reveals that the snow net accumulation at the easternmost part of Vestfonna was only half of that in the western part over the last 17 years.

(Table 1) Mass-accumulation rates for the non-authigenic, inorganic, crystalline, eolian component of sediments recovered at DSDP Hole 62-463

Elevated regions in the central parts of ocean basins are excellent for study of accumulation of eolian material. The mass-accumulation rates of this sediment component appear to reflect changes in the influx of volcanic materials through the Early Cretaceous to Recent history of Deep Sea Drilling Project Site 463, on the Mid-Pacific Mountains. Four distinct episodes of eolian accumulation occurred during the Cretaceous: two periods of moderate accumulation, averaging about 0.2 to 0.3 g/cm**2/10**3 yr, 67 to 70.5 m.y. ago and 91 to 108 m.y. ago; a period of low accumulation, approximately 0.03 g/cm**2/10**3 yr, 70.5 to 90 m.y. ago; and a period of high accumulation, about 0.9 g/cm**2/10**3 yr, 109 to 117 m.y. ago (bottom of the hole). Much of the Cenozoic section is missing from Site 463. Upper Miocene to Recent sediments record an upward increase in accumulation rates, from less than 0.01 to about 0.044 g/cm**2/10**3 yr. The late Pliocene-Pleistocene peak may reflect the change to glacial-wind regimes, as well as an increase in volcanic source materials.

Bulk density, ash content, humification, peat accumulation and selected lithogenic data of Store Mosse peat bog

This datafile presents chemical and physical as well as age dating information from the Store Mosse peat bog in southern Sweden. This record dates back to 8900 cal yr BP. The aim of the research was to reconstruct mineral dust deposition over time. As such we have only presented the lithogenic element data (Al, Ga, Rb, Sc, Ti, Y, Zr, Th and the REE) as the sample preparation method was tailored to these. This data is supported by parameters describing the deposit including bulk density, humification, ash content and net peat accumulation rates.

(Table T1) Lithologic and ichnologic description of ODP Hole 174-1073A

When examined in their sedimentologic and stratigraphic context, ichnofabrics and component ichnofossils can help decipher paleoceanography and sea-level histories from marine deposits (Savrda, 1995, http://www.jstor.org/stable/3515095). Thus far, applications of ichnology in paleoceanographic investigations have been restricted to slowly deposited, predominantly biogenic sediments and/or strata deposited in oxygen-deficient, tectonically active basins. Moreover, ichnologic applications in sequence stratigraphic studies largely have been restricted to strata deposited in relatively shallow-water shelf or foreland basin settings. The limits of previous studies provided impetus for detailed postcruise examination of Quaternary deposits recovered at Ocean Drilling Program (ODP) Site 1073 on the New Jersey margin. These deposits provide the opportunity to assess the sedimentary and ichnofabric record of glacio-eustatic cycles in a passive continental slope setting characterized by relatively rapid accumulation of siliciclastic sediments in an area not far removed from the Laurentide ice margin. The primary purpose of this data report is to present basic sedimentologic and ichnologic observations made at the decimeter scale throughout the Quaternary sequence from Site 1073. Data analysis and interpretation in the context of climate and sea-level histories, as inferred from oxygen isotopic, palynologic, and seismic studies, are ongoing and will be presented in subsequent papers prepared for open literature (e.g., Savrda et al., in press).