Alkali contents, Sr isotope and U-Th-Pb data for ocean crust vein minerals from DSDP Holes 27-261, 61-462A, and 72-516F

Cation exchange experiments (ammonium acetate and cation resin) on celadonite-smectite vein minerals from three DSDP holes demonstrate selective removal of common Sr relative to Rb and radiogenic Sr. This technique increases the Rb/Sr ratio by factors of 2.3 to 22 without significantly altering the age of the minerals, allowing easier and more precise dating of such vein minerals. The ages determined by this technique (Site 261 - 121.4+/-1.6 m.y.; Site 462A - 105.1+/-2.8 m.y.; Site 516F - 69.9+/-2.4 m.y.) are 34, 54 and 18 m.y. younger, respectively, than the age of crust formation at the site; in the case of site 462A, the young age is clearly related to off-ridge emplacement of a massive sill/flow complex. At the other sites, either the hydrothermal circulation systems persisted longer than for normal crust (10-15 m.y.), or were reactivated by off-ridge igneous activity. Celadonites show U and Pb contents and Pb isotopic compositions little changed from their basalt precursors, while Th contents are significantly lower. Celadonites thus have unusually high alkali/U,Th ratios and low Th/U ratios. If this celadonite alteration signature is significantly imprinted on oceanic crust as a whole, it will lead to very distinctive Pb isotope signatures for any hot spot magmas which contain a component of aged subducted recycled oceanic crust. Initial Sr isotope ratios of ocean crust vein minerals (smectite, celadonite, zeolite, calcite) are intermediate between primary basalt values and contemporary sea water values and indicate formation under seawaterdominated systems with effective water/rock ratios of 20-200.

Composition of bottom sediments and their exchange with seawater in the Amur and Zolotoy Rog bays, Sea of Japan

Transition of Zn, Cu, Cd, and Pb into solution is studied for experimental suspensions of coastal marine sediments with different degrees of pollution from the Amur Bay (Sea of Japan) over 30-70 days. Concentrations of dissolved metals were measured by a voltammetry method. Transition of Zn and Cd into solution was shown to be linearly dependent on initial pollution of sediments with these metals. Cadmium mobilization is due to gradual degradation of organic matter from sediments. Under degradation processes Zn quickly goes into solution during sedimentation and from silts, while in case of polluted sediments it is slowly mobilized during oxidation of sulfides. Behavior of Cu is complex because of binding of mobilized metal by dissolved organic compounds. Transition of lead into solution is negligible. Calculation of potential transition of metals from sediments into water on the basis of experimental data and its comparison with downward sedimentary flux showed that in the studied area secondary pollution of water by aerobic degradation of sediments is possible only for Cd.

The 2008 DGFI Realization of the ITRS: DTRF2008 (data)

The DTRF2008 is a realization of the International Terrestrial Reference System ITRS. The DTRF2008 consists of station positions and velocities of global distributed observing stations of the space geodetic observation techniques VLBI, SLR, GPS and DORIS. The DTRF2008 was released in May 2010 and includes the observation data of the techniques up to and including 2008. The observation data are processed and submitted by the corresponding international services: IGS (International GNSS Service, http://igscb.jpl.nasa.gov) IVS (International VLBI Service, http://ivscc.gsfc.nasa.gov) ILRS (International Laser Ranging Service, http://ilrs.gsfc.nasa.gov) IDS (International DORIS Service, http://ids-doris.org). The DTRF2008 is an independent ITRS realization, which is computed on the basis of the same input data as the ITRF2008 (IGN, Paris). Both realizations differ with respect to their computation strategies: while the ITRF2008 is based on the combination of solutions, the DTRF2008 is computed by the combination of normal equations. The DTRF2008 comprises the coordinates of 559 GPS-, 106 VLBI-, 122 SLR- and 132 DORIS-stations. The reference epoch is 1.1.2005, 0h UTC. The Earth Orientation Parameters (EOP) - that means the coordinates of the terrestrial and the celestial pole, UT1-UTC and the Length of Day (LOD) - were simultaneously estimated with the station coordinates. The EOP time series cover the period of 1983 to 2008. The station names are the official IERS indications: cdp numbers or 4-character IDs and DOMES numbers (http://itrf.ensg.ign.fr/doc_ITRF/iers_sta_list.txt). The solution is available in different file formats (SINEX and SSC), see below. A detailed description of the solution is given by Seitz M. et al. (2012). The results of a comparison of DTRF2008 and ITRF2008 is given by Seitz M. et al. (2013). More information as well as residual time series of the station positions can be made available by request.