Authigenic apatite formation and burial in sediments from non-upwelling, continental margin environments
TL;DR: In this paper, the authors present porewater data suggestive of authigenic carbonate fluorapatite (CFA) formation in both these areas, suggesting that CFA is forming at the expense of organic P. This depth increase is mirrored by a decrease in solid-phase organic P at both sites, indicating continued formation of CFA during early diagenesis.
About: This article is published in Geochimica et Cosmochimica Acta.The article was published on 1993-03-01. It has received 550 citations till now. The article focuses on the topics: Authigenic & Diagenesis.
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TL;DR: A sequential extraction method (SEDEX) was developed to separate five sedimentary P reservoirs: loosely sorbed P; ferric iron-bound P; authigenic carbonate fluorapatite + biogenic apatite+ CaCO3-associated P; detrital apatitic P; and organic P.
Abstract: A sequential extraction method (SEDEX) has been developed to separately quantify five sedimentary P reservoirs: loosely sorbed P; ferric iron-bound P; authigenic carbonate fluorapatite + biogenic apatite + CaCO3-associated P; detrital apatite P; and organic P. The SEDEX method successfully separates two of the main categories of authigenic phosphate phases called upon most often as sedimentary sinks for diagenetically mobilized P: ferric oxyhydroxide-associated P and authigenic carbonate fluorapatite (CFAP). It offers a means for separating authigenic CFAP from detrital apatite of igneous or metamorphic origin. The importance of this distinction is that CFAP represents an oceanic sink for reactive P, whereas detrital apatite does not. In addition, a means for reversing secondary adsorption of P onto residual solid surfaces during extraction has been developed.
Extensive standardization of the SEDEX method for application to marine sediments has been performed with analogs for naturally occurring phosphatic phases.
1,016 citations
TL;DR: In this article, it was shown that occurrences of BIF, GIF, Pherozoic ironstones, and exhalites surrounding VMS systems are linked to diverse environmental changes.
Abstract: Iron formations are economically important sedimentary rocks that are most common in Precambrian sedimentary successions. Although many aspects of their origin remain unresolved, it is widely accepted that secular changes in the style of their deposition are linked to environmental and geochemical evolution of Earth. Two types of Precambrian iron formations have been recognized with respect to their depositional setting. Algoma-type iron formations are interlayered with or stratigraphically linked to submarine-emplaced volcanic rocks in greenstone belts and, in some cases, with volcanogenic massive sulfide (VMS) deposits. In contrast, larger Superior-type iron formations are developed in passive-margin sedimentary rock successions and generally lack direct relationships with volcanic rocks. The early distinction made between these two iron-formation types, although mimimized by later studies, remains a valid first approximation. Texturally, iron formations were also divided into two groups. Banded iron formation (BIF) is dominant in Archean to earliest Paleoproterozoic successions, whereas granular iron formation (GIF) is much more common in Paleoproterozoic successions. Secular changes in the style of iron-formation deposition, identified more than 20 years ago, have been linked to diverse environmental changes. Geochronologic studies emphasize the episodic nature of the deposition of giant iron formations, as they are coeval with, and genetically linked to, time periods when large igneous provinces (LIPs) were emplaced. Superior-type iron formation first appeared at ca. 2.6 Ga, when construction of large continents changed the heat flux at the core-mantle boundary. From ca. 2.6 to ca. 2.4 Ga, global mafic magmatism culminated in the deposition of giant Superior-type BIF in South Africa, Australia, Brazil, Russia, and Ukraine. The younger BIFs in this age range were deposited during the early stage of a shift from reducing to oxidizing conditions in the ocean-atmosphere system. Counterintuitively, enhanced magmatism at 2.50 to 2.45 Ga may have triggered atmospheric oxidation. After the rise of atmospheric oxygen during the GOE at ca. 2.4 Ga, GIF became abundant in the rock record, compared to the predominance of BIF prior to the Great Oxidation Event (GOE). Iron formations generally disappeared at ca. 1.85 Ga, reappearing at the end of the Neoproterozoic, again tied to periods of intense magmatic activity and also, in this case, to global glaciations, the so-called Snowball Earth events. By the Phanerozoic, marine iron deposition was restricted to local areas of closed to semiclosed basins, where volcanic and hydrothermal activity was extensive (e.g., back-arc basins), with ironstones additionally being linked to periods of intense magmatic activity and ocean anoxia.
Late Paleoproterozoic iron formations and Paleozoic ironstones were deposited at the redoxcline where biological and nonbiological oxidation occurred. In contrast, older iron formations were deposited in anoxic oceans, where ferrous iron oxidation by anoxygenic photosynthetic bacteria was likely an important process. Endogenic and exogenic factors contributed to produce the conditions necessary for deposition of iron formation. Mantle plume events that led to the formation of LIPs also enhanced spreading rates of midocean ridges and produced higher growth rates of oceanic plateaus, both processes thus having contributed to a higher hydrothermal flux to the ocean. Oceanic and atmospheric redox states determined the fate of this flux. When the hydrothermal flux overwhelmed the oceanic oxidation state, iron was transported and deposited distally from hydrothermal vents. Where the hydrothermal flux was insufficient to overwhelm the oceanic redox state, iron was deposited only proximally, generally as oxides or sulfides. Manganese, in contrast, was more mobile. We conclude that occurrences of BIF, GIF, Phanerozoic ironstones, and exhalites surrounding VMS systems record a complex interplay involving mantle heat, tectonics, and surface redox conditions throughout Earth history, in which mantle heat unidirectionally declined and the surface oxidation state mainly unidirectionally increased, accompanied by superimposed shorter term fluctuations.
758 citations
Cites background from "Authigenic apatite formation and bu..."
...Authigenic carbonate fluorapatite precipitation is the largest burial flux for phosphorous in modern oceans (Ruttenberg and Berner, 1993)....
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TL;DR: In this article, a compilation of marine sedimentary phosphorus burial rates for the last 160 Myr suggests that natural variations have occurred that span one order of magnitude, which suggests that uniform interpretations with respect to the emplacement of major phosphorite deposits should be treated with caution.
694 citations
TL;DR: In this article, the authors studied the role of biogeochemical feedbacks such as desorption (release) of phosphorus bound to clay as salinity increases, lack of planktonic N fixation in most coastal ecosystems, and flux of relatively P-rich, N-poor waters from coastal oceans into estuaries.
Abstract: Nutrient fluxes to coastal areas have risen in recent decades, leading to widespread hypoxia and other ecological damage, particularly from nitrogen (N). Several factors make N more limiting in estuaries and coastal waters than in lakes: desorption (release) of phosphorus (P) bound to clay as salinity increases, lack of planktonic N fixation in most coastal ecosystems, and flux of relatively P-rich, N-poor waters from coastal oceans into estuaries. During eutrophication, biogeochemical feedbacks further increase the supply of N and P, but decrease availability of silica - conditions that can favor the formation and persistence of harmful algal blooms. Given sufficient N inputs, estuaries and coastal marine ecosystems can be driven to P limitation. This switch contributes to greater far-field N pollution; that is, the N moves further and contributes to eutrophication at greater distances. The physical oceanography (extent of stratification, residence time, and so forth) of coastal systems determines their sensitivity to hypoxia, and recent changes in physics have made some ecosystems more sensitive to hypoxia. Coastal hypoxia contributes to ocean acidification, which harms calcifying organisms such as mollusks and some crustaceans. (Less)
659 citations
TL;DR: In this paper, a comprehensive review of the biogeochemical cycling of P within the oceans is given, with particular attention focused on the composition and recycling rates of P in the water column.
609 citations
Cites background from "Authigenic apatite formation and bu..."
...However, recent evidence has found authigenic P formation in coastal, non-upwelling regimes, as well as deep within open ocean Žsediments cores Ruttenberg and Berner, 1993; Reimers et al., 1996; Filippelli and Delaney, 1994, .1996; Slomp et al., 1996 ....
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...A large percentage of the remaining P fraction may have undergone a Asink switchB and been buried only after conversion into Žauthigenic apatite mineral phases Ruttenberg and Berner, 1993; Filippelli and Delaney, 1994, 1996; ....
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References
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Book•
01 Jan 1980
TL;DR: In this article, Berner developed the mathematical theory of early diagenesis, introducing a general diagenetic equation and discussing it in terms of each major diagenetics process, including diffusion, compaction, pore-water flow, burial advection, bioturbation, adsorption, radioactive decay and especially chemical and biochemical reactions.
Abstract: Diagenesis refers to changes taking place in sediments after deposition. In a theoretical treatment of early diagenesis, Robert Berner shows how a rigorous development of the mathematical modeling of diagenetic processes can be useful to the understanding and interpretation of both experimental and field observations. His book is unique in that the models are based on quantitative rate expressions, in contrast to the qualitative descriptions that have dominated the field. In the opening chapters, the author develops the mathematical theory of early diagenesis, introducing a general diagenetic equation and discussing it in terms of each major diagenetic process. Included are the derivations of basic rate equations for diffusion, compaction, pore-water flow, burial advection, bioturbation, adsorption, radioactive decay, and especially chemical and biochemical reactions. Drawing on examples from the recent literature on continental-margin, pelagic, and non-marine sediments, he then illustrates the power of these diagenetic models in the study of such deposits. The book is intended not only for earth scientists studying sediments and sedimentary rocks, but also for researchers in fields such as radioactive waste disposal, petroleum and economic geology, environmental pollution, and sea-floor engineering.
2,849 citations
Book•
01 Jan 1984
TL;DR: Holland et al. as mentioned in this paper reconstruct the chemical evolution of the Earth's atmosphere and oceans using data from a wide spectrum of fields to trace the history of the ocean-atmosphere system.
Abstract: In this first full-scale attempt to reconstruct the chemical evolution of the Earth's atmosphere and oceans, Heinrich Holland assembles data from a wide spectrum of fields to trace the history of the ocean-atmosphere system A pioneer in an increasingly important area of scholarship, he presents a comprehensive treatment of knowledge on this subject, provides an extensive bibliography, and outlines problems and approaches for further research The first four chapters deal with the turbulent first half billion years of Earth history The next four chapters, devoted largely to the Earth from 39 to 06 bybp, demonstrate that changes in the atmosphere and oceans during this period were not dramatic The last chapter of the book deals with the Phanerozoic Eon; although the isotopic composition of sulfur and strontium in seawater varied greatly during this period of Earth history, the chemical composition of seawater did not
1,536 citations