Origin of Authigenic Carbonates in Sediment from the Deep Bering Sea

Hein, James R.; O'Neill, James R.; Jones, Marjorie

doi:10.1002/9781444304459.ch3

Cited by 14 publications

(31 citation statements)

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“…Assuming constant thermal gradients and homogeneous isotopic compositions for dolomitic layers, we estimated formation depths from the isotopic temperatures (Table 3). The range is 87 to 658 meters and matches that reported by Hein et al (1979) for authigenic carbonates in sediments of the southern Bering Sea. Using these depths and sedimentation rate curves for each site (see site chapters in this volume), we estimated the age or time of formation of each sample (Fig.…”

Section: Oxygen Isotopes-a Crude Thermometersupporting

confidence: 72%

“…6). Although the single authigenic calcite analyzed (Sample 471-37,CC) falls within the fresh-water limestone field in this diagram, it matches reported isotopic values for organically derived calcites from the southern Bering Sea (Hein et al, 1979). Two nannofossil claystones (calcite) lie well within the range of marine limestone.…”

Section: Isotopessupporting

confidence: 60%

“…Negative δC 13 carbonate values, as low as -25‰, can derive from abundant light-carbon CO 2 (as dissolved bicarbonate) in shallow zones of aerobic microbial oxidation and anaerobic sulfate reduction (Claypool, 1974;Claypool and Kaplan, 1974;Irwin et al, 1977;Curtis, 1978). More positive δC 13 values, up to +18% (Hein et al, 1979), occur below this zone where methane generation by CO 2 reduction in microbial metabolic processes produces residual heavy-carbon bicarbonate in interstitial waters through preferential removal of HC 12 O 3~ (Rosenfeld and Silverman, 1959;Claypool, 1974;Claypool and Kaplan, 1974). Commonly this trend toward δC 13 enrichment reverses at greater burial depths, perhaps because of the imbalance between the rates at which light-carbon CO 2 is added and removed in methane production (Claypool, 1974).…”

Section: Carbon Isotopes-an Index Of Organic Matter Decaymentioning

confidence: 99%

“…The results suggest a wide time range in dolomite formation at any single site. Hein et al (1979) Note: Reactions, depth intervals, and isotopic data compiled from Cooper and Bray (1963), Eisma and Jung (1969), Claypool et al (1973), Claypool (1974, Claypool and Kaplan (1974), Irwin et al (1977), Curtis (1978), Hein et al (1979). a Total dissolved CO2, mainly as bicarbonate, b Methane not present.…”

Section: Oxygen Isotopes-a Crude Thermometermentioning

confidence: 99%

“…Reports of scattered rhombic crystals and detrital grains in deep-sea sediments are common (summary and references in Milliman, 1974). Yet more intriguing are dolomitic cements, layers, and concretionary zones associated with rapidly deposited, organic-rich, finegrained sediments along continental margins and in small ocean basins (e.g., Russell et al, 1967;Murata et al, 1969;Deuser, 1970;Supko et al, 1974;Hein et al, 1979;McKenzie et al, 1980). This lithologic affiliation-dolomite and organic-rich sediments-and the extreme variability of carbon and oxygen isotopic compositions observed in these carbonates directed a number of investigators to postulate formative conditions of shallow burial and low temperature in association with carbon dioxide and methane produced during the microbial breakdown of organic matter (e.g., Spotts and Silverman, 1966;Hathaway and Degens, 1969;Deuser, 1970;Murata et al, 1969;Irwin et al, 1977;Hein et al, 1979;Friedman and Murata, 1979).…”

Section: Introductionmentioning

confidence: 99%

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Isotopic Survey of Diagenetic Carbonates, Deep Sea Drilling Project Leg 63

Kenneth¹,

John²

1981

Initial Reports of the Deep Sea Drilling Project

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Authigenic carbonates, principally calcium-rich dolomites, with extremely variable isotopic compositions were recovered in organic-rich marine sediments during Leg 63 drilling off southern California and Baja California. These carbonates occur as thin layers in fine-grained, diatomaceous sediments and siliceous rocks, mostly deposited during the Neogene. A combination of textural, geochemical, and isotopic evidence indicates these dolomites formed as cements and precipitates in shallow subsurface zones of high alkalinity spawned by abundant CO 2 and methane production during progressive microbial decay of organic matter. Depths and approximate temperatures of formation estimated from oxygen isotopes are 87 to 658 meters and 10°C to 50°C, respectively. Within any sedimentary section, dolomites may form simultaneously at several depths or at different times within the same interval. Highly variable carbon isotopes (-30 to + 16‰) reflect the isotopic reservoir in which the carbonates formed. Oxidation of organic matter through microbial reduction of sulfate at shallow depths favors light-carbon carbonates such as those at Sites 468 and 471; heavy-carbon carbonates at Site 467 most likely formed below this zone where HC 12 O 3~ is preferentially removed by reduction of CO 2 to methane during methanogenesis. An important controlling factor is the sedimentation rate, which dictates both the preservation of organic matter on the sea floor and depth distribution of subsurface zones of organic-matter decay.

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Section: Oxygen Isotopes-a Crude Thermometersupporting

confidence: 72%

Section: Isotopessupporting

confidence: 60%

Section: Carbon Isotopes-an Index Of Organic Matter Decaymentioning

confidence: 99%

Section: Oxygen Isotopes-a Crude Thermometermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Isotopic Survey of Diagenetic Carbonates, Deep Sea Drilling Project Leg 63

Kenneth¹,

John²

1981

Initial Reports of the Deep Sea Drilling Project

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Analysis of longitudinal variations in North Pacific alkalinity to improve predictive algorithms

Fry

Tyrrell

Achterberg

2016

Global Biogeochemical Cycles

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The causes of natural variation in alkalinity in the North Pacific surface ocean need to be investigated to understand the carbon cycle and to improve predictive algorithms. We used GLODAPv2 to test hypotheses on the causes of three longitudinal phenomena in Alk*, a tracer of calcium carbonate cycling. These phenomena are (a) an increase from east to west between 45°N and 55°N, (b) an increase from west to east between 25°N and 40°N, and (c) a minor increase from west to east in the equatorial upwelling region. Between 45°N and 55°N, Alk* is higher on the western than on the eastern side, and this is associated with denser isopycnals with higher Alk* lying at shallower depths. Between 25°N and 40°N, upwelling along the North American continental shelf causes higher Alk* in the east. Along the equator, a strong east-west trend was not observed, even though the upwelling on the eastern side of the basin is more intense, because the water brought to the surface is not high in Alk*. We created two algorithms to predict alkalinity, one for the entire Pacific Ocean north of 30°S and one for the eastern margin. The Pacific Ocean algorithm is more accurate than the commonly used algorithm published by Lee et al. (2006), of similar accuracy to the best previously published algorithm by Sasse et al. (2013), and is less biased with longitude than other algorithms in the subpolar North Pacific. Our eastern margin algorithm is more accurate than previously published algorithms.

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A Climate-Related Oxidizing Event in Deep-Sea Sediment from the Bering Sea

et al. 1982

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Many cores from the deep basins of the Bering Sea have a thin oxidized zone within otherwise reduced sediment. This oxidized zone began to form about 6000 yr ago and represents an interval of about 3200 yr. Mineralogically, the oxidized and reduced sediments are similar, but chemically they differ. Concentrations of Fe and C are lower, and concentrations of Mn, Ba, Co, Mo, and Ni are higher in the oxidized than in the reduced sediment. Mn is enriched about 10-fold in the oxidized zone relative to its concentration in the reduced sediment, Mo about threefold, and Ba, Co, and Ni about twofold. These data suggest that the oxidized zone developed diagenetically as the result of the balance between the flux of organic matter and the available dissolved oxygen in bottom and interstitial waters.We propose that the Bering Sea was substantially ice covered when global glacial conditions prevailed. during the transition to global interglacial conditions, seasonal meltwater from thawing sea ice formed a lens of fresh water that decreased organic productivity. During the winter seasons, however, sea ice reformed and caused downwelling of dense, oxygen-rich waters to recharge bottom waters. The combination of lower organic productivity and more oxygen-rich bottom water allowed oxidized sediment to accumulate. Once full interglacial conditions were established, the volume of sea ice produced was insufficient to affect either productivity or the supply of dissolved oxygen and so bottom conditions again became reducing.Similar events probably occurred during the onset of global glacial conditions, and similar oxidized layers probably formed at these times. Such oxidized zones are highly unstable, however, in a reducing environment and, once buried beyond the influence of bacterial and infaunal activities, are depleted of their available oxygen and converted to reduced sediment.

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Origin of Authigenic Carbonates in Sediment from the Deep Bering Sea

Cited by 14 publications

References 14 publications

Isotopic Survey of Diagenetic Carbonates, Deep Sea Drilling Project Leg 63

Isotopic Survey of Diagenetic Carbonates, Deep Sea Drilling Project Leg 63

Analysis of longitudinal variations in North Pacific alkalinity to improve predictive algorithms

A Climate-Related Oxidizing Event in Deep-Sea Sediment from the Bering Sea

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