A tale of shales: the relative roles of production, decomposition, and dilution in the accumulation of organic-rich strata, Middle–Upper Devonian, Appalachian basin

Sageman, Bradley B.; Murphy, Adam E.; Werne, Josef P.; Straeten, Charles A. Ver; Hollander, David J.; Lyons, Timothy W.

doi:10.1016/s0009-2541(02)00397-2

Cited by 587 publications

(307 citation statements)

References 67 publications

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“…As will be further discussed in section 3.4, euxinic systems have an iron biogeochemistry that is unique in some regards. For the sake of the present discussion, however, the estimates in Figure 3 are most appropriate when a stable stratified euxinic water column is absent, consistent with the interpretation of many ancient organicrich strata [e.g., Sageman, 1989;Arthur and Sageman, 1994;Murphy et al, 2000;Sageman et al, 2003;Meyers et al, 2005]. In summary, we can conclude that relatively modest quantities of iron should be sufficient to buffer pore water hydrogen sulfide accumulation in many modern environments, if the kinetics of iron sulfidization are fast enough to keep pace with sulfide production.…”

supporting

confidence: 73%

Production and preservation of organic matter: The significance of iron

Meyers

2007

Paleoceanography

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[1] ''Iron fertilization'' has been previously recognized as a potential mechanism for enhanced organic matter burial in marine sediments. However, the singular view of iron as a control on primary production overlooks its role in sedimentary diagenesis, a factor that must be evaluated when considering organic matter accumulation. This study examines the role of iron as a buffer of pore water sulfide and its implications for marine organic matter burial. Biogeochemical model experiments indicate that dissolved sulfide buildup in surficial marine sediments is highly sensitive to reactive iron concentration. A reduction in reactive iron concentration can initiate dissolved sulfide accumulation, the consequences of which include inhibition of bioturbation/ bioirrigation, a decrease in oxygen exposure time, and enhanced organic matter burial. Alternatively, an increase in reactive iron concentration can serve to decrease organic matter burial. The coupling of iron and phosphorous cycling within marine sediments provides an important positive feedback, and therefore this mechanism is designated the ''sulfide buffer/phosphorous trap hypothesis.'' Given sufficient organic carbon supply, carbonaterich and opal-rich sediments should be especially prone to the development of sulfidic conditions because of a deficiency in terrigenous iron. Widespread chalk and marl deposition during the Cretaceous, in association with the evolutionary expansion of calcareous plankton, may have predisposed many benthic marine environments to the accumulation of toxic hydrogen sulfide and fostered the development of ''oceanic anoxic events.'' Comparison of model results with proxy data from oceanic anoxic event II (middle Cretaceous) suggests a complex role of iron as a control on both organic matter production and preservation.

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supporting

confidence: 73%

Production and preservation of organic matter: The significance of iron

Meyers

2007

Paleoceanography

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“…1). The concentration of Mo is especially remarkable given the high sedimentation rate of the Stoer Group sediments, as other studies suggest that a high sedimentation rate dilutes the authigenic enrichment of trace metals including Mo 3,43 . The Mo/TOC data are much higher than the Proterozoic average of 6.4 p.p.m.…”

Section: Discussionmentioning

confidence: 84%

High Molybdenum availability for evolution in a Mesoproterozoic lacustrine environment

et al. 2015

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Trace metal data for Proterozoic marine euxinic sediments imply that the expansion of nitrogen-fixing cyanobacteria and diversification of eukaryotes were delayed while the availability of bioessential metals such as molybdenum in the ocean was limited. However, there is increasing recognition that the Mesoproterozoic evolution of nitrogen fixation and eukaryotic life may have been promoted in marginal marine and terrestrial environments, including lakes, rather than in the deep ocean. Molybdenum availability is critical to life in lakes, just as it is in the oceans. It is, therefore, important to assess molybdenum availability to the lacustrine environment in the Mesoproterozoic. Here we show that the flux of molybdenum to a Mesoproterozoic lake was 1 to 2 orders of magnitude greater than typical fluxes in the modern and ancient marine environment. Thus, there was no barrier to availability to prevent evolution in the terrestrial environment, in contrast to the nutrient-limited Mesoproterozoic oceans.

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“…Shale organic carbon contents increase to the west through the study area (Sageman et al, 2003). While units such as the Ordovician Utica Shale and the Devonian Marcellus Formation may contain upwards of 3-8% TOC, other shale, siltstone and carbonate units in the region contain substantially less.…”

Section: Geologic Setting Of the Hudson-mohawk Watershedmentioning

confidence: 91%

Linking lithology and land use to sources of dissolved and particulate organic matter in headwaters of a temperate, passive-margin river system

Longworth

Petsch

Raymond

et al. 2007

Geochimica et Cosmochimica Acta

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A number of rivers have been found to transport highly aged organic matter [OM]; however, the sources of this aged material remain a matter of debate. One potential source may be erosion and weathering of headwater lithologies rich in ancient sedimentary OM. In this study, waters, suspended particulates, streambed sediments, rocks and soils from fourteen small headwater watersheds of a mid-size, temperate, passive margin river were sampled and characterized by D 14 C, d 13 C, and POC/TPN ratios to identify sources of particulate and dissolved OM delivered to the river mainstem. These headwater sites encompass a range in lithology (OM-rich shales, OM-lean carbonate/mudstone facies, and OM-free crystalline rocks) and land use types (forested and agricultural), and allow investigation of the influence of agriculture and bedrock types on stream OM characteristics. Streams draining large areas of both agricultural land use and OM-rich lithology contain particulate OM [POM] that is more 14 C-depleted than streams draining forested, shale-free watersheds. However, this is not sufficient to account for the significantly lower D 14 C-POC measured in the river mainstem. Dissolved OM [DOM] D 14 C are in all cases enriched compared to POM from the same stream, but are otherwise highly variable and unrelated to either land use or lithology. POC/TPN ratios were likewise highly variable. POC and DOC d 13 C signatures were similar across all watersheds. Based on isotope mass balance, 14 C-free fossil OM sources contribute 0-12% of total stream POM. Although these results do not unequivocally separate the influences of land use and lithology, watershed coverage by shale and agriculture are both important controls on stream D 14 C-POC. Thus export of aged, particle-associated OM may be a feature of river systems along both passive and active continental margins.

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A tale of shales: the relative roles of production, decomposition, and dilution in the accumulation of organic-rich strata, Middle–Upper Devonian, Appalachian basin

Cited by 587 publications

References 67 publications

Production and preservation of organic matter: The significance of iron

Production and preservation of organic matter: The significance of iron

High Molybdenum availability for evolution in a Mesoproterozoic lacustrine environment

Linking lithology and land use to sources of dissolved and particulate organic matter in headwaters of a temperate, passive-margin river system

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