Backman, Jan; Chepstow-Lusty, Alex J (1993): (Table 1) Abundances of Discoaster species in ODP Hole 130-806C. PANGAEA, https://doi.org/10.1594/PANGAEA.781962, Supplement to: Backman, J; Chepstow-Lusty, AJ (1993): Data report: Late Pliocene discoaster abundances from Hole 806C. In: Berger, WH; Kroenke, LW; Mayer, LA; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 130, 755-759, https://doi.org/10.2973/odp.proc.sr.130.057.1993
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Members of the calcareous nannofossil genus Discoaster have been used extensively to subdivide Tertiary deep-sea sediments into biostratigraphic zones or subzones (e.g., Martini, 1971; Bukry, 1973). Haq and Lohmann (1976) mapped biogeographic migrations of this group through time and over latitude. They suggested that expansions and contractions of Discoaster-dominated assemblages across latitudes reflect sea-surface temperature changes. Subsequently, late Pliocene Discoaster species were counted at closely spaced sample intervals from various Atlantic sites (Backman et al., 1986; Backman and Pestiaux, 1987; Chepstow-Lusty et al., 1989, 1991), and Indian Ocean as well as Pacific Ocean sites (Chepstow-Lusty, 1990). In addition to the biostratigraphic information revealing positions and the precision by which the different late Pliocene Discoaster species can be determined, these studies also demonstrated that discoasters strongly fluctuate in abundance as a function of time. These abundance variations occur in equatorial as well as temperate temperature regimes, and show periodicities that reflect orbital frequencies. Chepstow-Lusty et al. (1989, 1991) also suggested that the oscillating abundances partly represent productivity pressure, because discoasters tend to show low abundances under high productivity conditions and vice versa.
In the Pacific Ocean, counts showing late Pliocene Discoaster abundances exist from three sites, namely Ocean Drilling Program (ODP) Site 677 in the eastern equatorial upwelling region, Core V28-179 from the central equatorial region, and Core V32-127 from the mid-latitude Hess Rise. The two Vema cores are condensed and show sedimentation rates below 0.5 cm/1000 yr, thus offering a poorly resolved stratigraphy. Hole 806C from the Ontong Java Plateau provided an opportunity to establish a highly resolved Discoaster record from the western extreme of the equatorial Pacific under an environmental setting that differed from ODP Site 677 by being less influenced by intense upwelling. The Discoaster counting technique is described by Backman and Shackleton (1983).
Latitude: 0.318500 * Longitude: 159.361000
Date/Time Start: 1990-02-23T01:30:00 * Date/Time End: 1990-02-25T19:00:00
Minimum DEPTH, sediment/rock: 37.20 m * Maximum DEPTH, sediment/rock: 56.09 m
130-806C * Latitude: 0.318500 * Longitude: 159.361000 * Date/Time Start: 1990-02-23T01:30:00 * Date/Time End: 1990-02-25T19:00:00 * Elevation: -2520.8 m * Penetration: 776.4 m * Recovery: 523.62 m * Location: North Pacific Ocean * Campaign: Leg130 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 62 cores; 587.6 m cored; 0 m drilled; 89.1 % recovery
Sediment depth is given in mbsf. One (1) counted specimen represents about 0.7 specimens per mm**2.
|#||Name||Short Name||Unit||Principal Investigator||Method||Comment|
|2||Discoaster brouweri||D. brouweri||#/mm2||Backman, Jan|
|3||Discoaster triradiatus||D. triradiatus||#/mm2||Backman, Jan|
|4||Discoaster triradiatus||D. triradiatus||%||Backman, Jan||relative to D. broweri|
|5||Discoaster pentaradiatus||D. pentaradiatus||#/mm2||Backman, Jan|
|6||Discoaster surculus||D. surculus||#/mm2||Backman, Jan|
|7||Discoaster asymmetricus||D. asymmetricus||#/mm2||Backman, Jan|
1068 data points