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White, Lisa D; Alexandrovich, Joanne M (1992): Pliocene and Pleistocene abundance of siliceous microfossil assemblages in ODP Leg 127 sites [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.771211, Supplement to: White, LD; Alexandrovich, JM (1992): Pliocene and Pleistocene abundance and preservation of siliceous microfossil assemblages from Sites 794, 795, and 797: implications for circulation and productivity in the Japan Sea. In: Pisciotto, KA; Ingle, JCJr.; von Breymann, MT; Barron, J; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 127/128(1), 341-357, https://doi.org/10.2973/odp.proc.sr.127128-1.140.1992

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Abstract:
A close examination of the siliceous microfossil assemblages from the sediments of ODP Leg 127, Japan Sea Sites 794, 795, and 797, reveals that upper Pliocene and Pleistocene assemblages have been subjected to more dissolution than have lower Pliocene assemblages. This conclusion is based on semiquantitative observations of samples processed for diatoms and radiolarians. Although preservation of opaline microfossils in some upper Pliocene and Pleistocene samples is better than others, in general, the poorly preserved state of these assemblages supports the notion that opal dissolution, in response to lowered productivity, is responsible for the paucity of siliceous microfossils in upper Pliocene and Pleistocene sediments. The lithological transition from diatomaceous oozes to silts and clays corresponds to a change between dominantly well preserved to more poorly preserved siliceous assemblages, and is termed the late Pliocene Japan Sea opal dissolution transition zone (ODTZ). The base of the ODTZ is defined as the uppermost occurrence of high abundances of moderately to well preserved valves of the diatom Coscinodiscus marginatus. The dissolution transition zone is characterized by partially dissolved refractory assemblages of radiolarians, the presence of C. marginatus girdles, C. marginatus fragments, siliceous sponge spicules, and a general decrease in weakly silicified, less solution resistant diatoms upward in the section. The top of the dissolution transition zone marks the level where whole C. marginatus valves and C. marginatus fragments are no longer present in significant numbers.
Dissolution of the late Pliocene and Pleistocene opaline assemblages is attributed mainly to changes in paleoceanographic circulation patterns and decreased nutrient (dissolved silicon) contents of the water column, and possibly dissolution at the sediment/water interface, rather than to post-depositional dissolution or diagenesis. We suggest that the transition from silica-rich to silica-poor conditions in the Japan Sea was due to fluctuations of deep-water exchange with the Pacific through the Tsugaru Strait between 2.9 and 2.3 Ma.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: 41.049560 * Median Longitude: 137.086760 * South-bound Latitude: 38.616000 * West-bound Longitude: 134.536000 * North-bound Latitude: 43.987000 * East-bound Longitude: 138.967000
Date/Time Start: 1989-06-26T00:00:00 * Date/Time End: 1989-08-18T00:00:00
Event(s):
127-794 * Latitude: 40.190000 * Longitude: 138.231000 * Date/Time Start: 1989-06-26T00:00:00 * Date/Time End: 1989-07-11T00:00:00 * Elevation: -2821.3 m * Penetration: 1554 m * Recovery: 422.8 m * Location: Japan Sea * Campaign: Leg127 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 78 cores; 694.4 m cored; 0 m drilled; 60.9% recovery
127-794A * Latitude: 40.190000 * Longitude: 138.231000 * Date/Time Start: 1989-06-26T15:15:00 * Date/Time End: 1989-06-30T12:15:00 * Elevation: -2822.0 m * Penetration: 351.3 m * Recovery: 302.17 m * Location: Japan Sea * Campaign: Leg127 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 37 cores; 351.3 m cored; 0 m drilled; 86 % recovery
127-795 * Latitude: 43.987000 * Longitude: 138.966000 * Date/Time Start: 1989-07-12T00:00:00 * Date/Time End: 1989-07-22T00:00:00 * Elevation: -3310.5 m * Penetration: 1128.1 m * Recovery: 447.2 m * Location: Japan Sea * Campaign: Leg127 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 80 cores; 761.9 m cored; 0 m drilled; 58.7% recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
5 datasets

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Datasets listed in this publication series

  1. White, LD; Alexandrovich, JM (1992): (Table 1) Abundance and preservation of Pliocene and Pleistocene diatoms in ODP Hole 127-794A. https://doi.org/10.1594/PANGAEA.771205
  2. White, LD; Alexandrovich, JM (1992): (Table 2) Abundance and preservation of Pliocene and Pleistocene diatoms in ODP Hole 127-795A. https://doi.org/10.1594/PANGAEA.771206
  3. White, LD; Alexandrovich, JM (1992): (Table 3) Abundance and preservation of Pliocene and Pleistocene diatoms in ODP Hole 127-797B. https://doi.org/10.1594/PANGAEA.771207
  4. White, LD; Alexandrovich, JM (1992): (Table 5) Age control points of ODP Leg 127 sites. https://doi.org/10.1594/PANGAEA.771210
  5. White, LD; Alexandrovich, JM (1992): (Table 4) Location of the late Pliocene opal dissolution transition zone in ODP Leg 127 sites. https://doi.org/10.1594/PANGAEA.771208