Spacial and temporal variations of water characteristics in the Japan Sea bottom layer

Gamo, Toshitaka; Nozaki, Yoshiyuki; Sakai, Hitoshi; Nakai, Toshisuke; Tsubota, Hiroyuki

doi:10.1357/002224086788401620

Cited by 138 publications

(85 citation statements)

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“…The present seawater, particularly the bottom water of the Japan Sea, is well oxygenated probably due to an annual and massive sink of the cold water generated at the surface in the northern part of Japan Sea during winter (Gamo et al, 1986). The oxic bottom water has also been suggested by the positive Ce-anomaly of the surface sediments at Site 799 as shown in Figure 17.…”

Section: Paleoenvironmental Implications Of Diagenetic Carbonatesmentioning

confidence: 90%

Diagenetic Dolomite, Calcite, Rhodochrosite, Magnesite, and Lansfordite from Site 799, Japan Sea-Implications for Depositional Environments and the Diagenesis of Organic-Rich Sediments

Matsumoto¹

1992

Proceedings of the Ocean Drilling Program

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Abundant and various diagenetic carbonates were recovered from a 1084-m-thick, Quaternary to lower Miocene section at ODP Site 799 in the Japan Sea. Petrographic, XRD, SEM, EDS-chemical, and isotopic analyses revealed wide variations in occurrence and textural relations and complex mineralogy and chemistry. Diagenetic carbonates include calcite, calcium-rich rhodochrosite, iron-and manganese-rich magnesite, iron-and manganese-rich dolomite and ankerite, and iron-and manganeserich lansfordite (hydrous Mg-carbonate).Rhodochrosite commonly occurs as small, solid nodules and semi-indurated, thin layers in bioturbated, mottled sediments of Units I and II (late Miocene to Quaternary). Lansfordite occurs as unindurated nodules and layers in Unit II (late Miocene and Pliocene), whereas magnesite forms indurated beds a few centimeters thick in slightly bioturbated-to-faintly laminated sediments of Unit III (middle and late Miocene). Some rhodochrosite nodules have dark-colored, pyritic cores, and some pyrite-rhodochrosite nodules are overgrown by and included within magnesite beds. Dolomite and ankerite tend to form thick beds (>IO cm) in bedded to laminated sediments of Units III, IV, and V (early to late Miocene). Calcite occurs sporadically throughout the Site 799 sediments. The δ 18 θ values of carbonates and the interstitial waters, and the measured geothermal gradient indicate that almost all of the Site 799 carbonates are not in isotopic equilibrium with the ambient waters, but were precipitated in the past when the sediments were at shallower depths. Depths of precipitation obtained from the δ 18 θ of carbonates span from 310 to 510 mbsf for magnesite and from 60 to 580 mbsf for dolomite-ankerite. Rhodochrosite and calcite are estimated to have formed within sediments at depths shallower than 80 mbsf.Diagenetic history in the Site 799 sediments have been determined primarily by the environment of deposition; in particular, by the oxidation-reduction state of the bottom waters and the alkalinity level of the interstitial waters. Under the well-oxygenated bottom-water conditions in the late Miocene and Pliocene, manganese initially accumulated on the seafloor as hydrogenous oxides and subsequently was mobilized and reprecipitated as rhodochrosite within the shallow sulfate-reduction, sub-oxic zone. Precipitation of lansfordite occurred in the near-surface sediments with abundant organic carbon and an extremely high alkalinity during the latest Miocene and Pliocene. The lansfordite was transformed to magnesite upon burial in the depth interval 310 to 510 mbsf. Dolomite first precipitated at shallow depths in Mn-poor, anoxic, moderately biocalcareous sediments of early to late Miocene. With increasing temperature and depth, the dolomite recrystallized and reequilibrated with ambient waters at depths below about 400 mbsf.

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Section: Paleoenvironmental Implications Of Diagenetic Carbonatesmentioning

confidence: 90%

Diagenetic Dolomite, Calcite, Rhodochrosite, Magnesite, and Lansfordite from Site 799, Japan Sea-Implications for Depositional Environments and the Diagenesis of Organic-Rich Sediments

Matsumoto¹

1992

Proceedings of the Ocean Drilling Program

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“…The uniformities of water temperature and salinity are characteristic of the deep water in the Sea of Japan (Gamo et al, 1986). …”

Section: Water Mass Structurementioning

confidence: 99%

“…The Sea of Japan is connected to the western Pacific and the Sea of Okhotsk by shallow channels (Tsushima, Tsugaru, Souya and Mamiya channels; maximum depths are less than 150 m). The deep water of the Sea of Japan has interesting properties such as the presence of a homogeneous water mass and a high dissolved oxygen content (Gamo et al, 1986). However, relatively little chemical research has been done on the Sea of Japan.…”

Section: Introductionmentioning

confidence: 99%

Anomalous distribution of dissolved organic carbon in the Sea of Japan.

et al. 2001

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Dissolved organic carbon (DOC) in the Sea of Japan was determined by the high temperature catalytic oxidation (HTCO) method. The chemical parameters related to DOC, i.e., the three-dimensional excitation-emission matrix spectrum, nutrients, chlorophyll a, dissolved oxygen and monosaccharides concentration were also determined. The vertical distribution of DOC in the northernmost sampling site (CM10; 44.1°N, 138.6°E) was not like that those in other sampling sites. An anomalously high DOC concentration was observed for the middle layer (250 to 1000 m) at CM10, which was two or three times higher than the concentration for the same layer at other sampling sites. Moreover, dissolved oxygen, nutrients and fluorescence intensity of marine humic-like substances were also unusual for the middle layer of CM10, compared to the same layer at other sampling sites. The amounts of Chl. a and monosaccharides between the surface and 100 m depth at CM10 were larger than those of other sampling sites. In the middle layer, the water mass structure of CM10 differed from that of other sampling sites. These results suggested that the cause of the DOC distribution anomaly at CM10 could be considered as due to the inflow of quite different water mass with incomplete oxidation of organic matter.

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“…In the present-day Japan Sea, potential temperature and salinity are more or less uniform at approximately 0°C and 34.1 o/ oo below the surface water layer (200-300 m thick), and the water is well oxygenated (O 2 >210 µmol/kg) at all depths (Ohwada and Tanioka, 1971;Gamo et al, 1986). This is due to the formation of Japan Sea Proper Water (JSPW), which originates in the northern part of the Japan Sea during the winter (Hidaka, 1966).…”

Section: Introductionmentioning

confidence: 99%

Correlation of Dark and Light Layers, and the Origin of Their Cyclicity in the Quaternary Sediments from the Japan Sea

Tada¹,

Koizumi²,

Cramp³

et al. 1992

Proceedings of the Ocean Drilling Program

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Nearly continuous cores of Quaternary fine-grained sediments with distinct dark-light colored cycles were recovered from Sites 794, 795, and 797 in the basinal parts of the Japan Sea during Leg 127. A comparison of gray value (darkness) profiles supplemented by visual inspection of core photographs between sites indicated that most of the dark and light layers were correlatable between sites, and that two of the dark layers lie close to adjacent marker ash layers. These observations indicate that deposition of dark and light layers resulted from basin-wide synchronous events.In order to understand the origin of these dark-light cycles, petrographical, mineralogical, compositional, and paleontological studies were carried out on closely spaced samples from the upper Quaternary sediments recovered from Site 797. Age model was constructed based on comparison between variation in diatom abundance and the standard oxygen isotope curve of Imbrie et al. (1984), the latter was interpolated between the five age controlled levels established at Site 797. The two curves show similar patterns which enabled us to "tune" the sediment ages to the oxygen isotope stages. We have to use variation in diatom abundance as a substitute for oxygen isotope curve since oxygen isotopic data are not available at the studied sites.Bottom water oxygenation conditions were estimated based on two criteria: (1) the degree of lamina preservation and (2) the ratio of C org to S tot . The surface water productivity was deduced from the C org and biogenic silica content.Results suggest that the bottom water oxygenation level and the surface water productivity varied significantly in response to the glacial-interglacial cycles. Glacio-eustatic sea-level changes and subsequent changes in water circulation in the Japan Sea appear to have been responsible for these variations and consequent changes in sediment composition throughout the Quaternary.

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Spacial and temporal variations of water characteristics in the Japan Sea bottom layer

Cited by 138 publications

References 0 publications

Diagenetic Dolomite, Calcite, Rhodochrosite, Magnesite, and Lansfordite from Site 799, Japan Sea-Implications for Depositional Environments and the Diagenesis of Organic-Rich Sediments

Diagenetic Dolomite, Calcite, Rhodochrosite, Magnesite, and Lansfordite from Site 799, Japan Sea-Implications for Depositional Environments and the Diagenesis of Organic-Rich Sediments

Anomalous distribution of dissolved organic carbon in the Sea of Japan.

Correlation of Dark and Light Layers, and the Origin of Their Cyclicity in the Quaternary Sediments from the Japan Sea

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