DIRECT Re-Os DATING OF MANGANESE CARBONATE ORES AND IMPLICATIONS FOR THE FORMATION OF THE ORTOKARNASH MANGANESE DEPOSIT, NORTHWEST CHINA

2021 ◽  
Author(s):  
Wen-Jun Li ◽  
Zi-Dong Peng ◽  
Zhi-Guo Dong ◽  
Bang-Lu Zhang ◽  
Bing-Yu Gao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Hanging Wall ◽  
Northwest China ◽  
Global Scale ◽  
Manganese Carbonate ◽  
Complex Interactions ◽  
Mineralization Age ◽  
Depositional Age ◽  
West Kunlun ◽  
Carbonate Deposits

Abstract Sedimentary manganese carbonate deposits, the major economic source of Mn globally, are the product of complex interactions that occur in the marine environment, including both biological Mn(II) oxidation and Mn(IV) reduction. Precise and accurate age constraints for Mn carbonate deposits have been difficult to obtain, hindering the understanding of possible correlations between Mn metallogenic and paleoenvironmental processes at regional to global scale. The involvement of organic matter during Mn carbonate mineralization, however, allows for the Re-Os system, an ideal geochronological tool for determining the depositional or alteration ages of organic-rich rocks, to be applied. Here we present the first Re-Os systematics of Mn carbonate ores from the giant Ortokarnash Mn deposit in the West Kunlun orogenic belt, Xinjiang, China. The use of the Re-Os geochronometer, along with petrographic, whole-rock total organic carbon, and major element analyses, allows for the depositional age and mineralizing processes to be directly constrained. The Mn carbonate ores with relatively homogeneous initial 187Os/188Os values yield a robust mineralization age of 320.3 ± 6.6 Ma (Model 1; Isoplot regression) or 321.8 ± 14.5 Ma (Monte Carlo simulation). This age correlates well with U-Pb ages of the youngest detrital zircon group from the footwall volcanic breccia-bearing limestone and a newly obtained Re-Os age from the hanging-wall marlstones. Enrichment of hydrogenous Re and Os in the Ortokarnash Mn carbonate ores is likely related to the variable redox environments during Mn carbonate mineralization, where Re tends to be preserved in the organic matter that persists following the diagenetic reduction of the Mn(IV) oxyhydroxides in suboxic or anoxic sediment pore water. Conversely, Os was likely absorbed by Mn(IV) oxyhydroxides in oxic seawater during Mn(II) oxidation. Elevated Osinitial(i) for the Mn carbonate ores relative to that of the coeval global seawater value suggests that an increased riverine flux may have been a contributing factor leading to Mn mineralization.

scholarly journals Towards a representation of priming on soil carbon decomposition in the global land biosphere model ORCHIDEE (version 1.9.5.2)

2016 ◽  
Vol 9 (2) ◽  
pp. 841-855 ◽  
Author(s):  
Bertrand Guenet ◽  
Fernando Esteban Moyano ◽  
Philippe Peylin ◽  
Philippe Ciais ◽  
Ivan A Janssens
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Carbon ◽  
Global Scale ◽  
Soil Incubation ◽  
First Order ◽  
Carbon Decomposition ◽  
Litter Manipulation ◽  
Global Land ◽  
Biosphere Model

Abstract. Priming of soil carbon decomposition encompasses different processes through which the decomposition of native (already present) soil organic matter is amplified through the addition of new organic matter, with new inputs typically being more labile than the native soil organic matter. Evidence for priming comes from laboratory and field experiments, but to date there is no estimate of its impact at global scale and under the current anthropogenic perturbation of the carbon cycle. Current soil carbon decomposition models do not include priming mechanisms, thereby introducing uncertainty when extrapolating short-term local observations to ecosystem and regional to global scale. In this study we present a simple conceptual model of decomposition priming, called PRIM, able to reproduce laboratory (incubation) and field (litter manipulation) priming experiments. Parameters for this model were first optimized against data from 20 soil incubation experiments using a Bayesian framework. The optimized parameter values were evaluated against another set of soil incubation data independent from the ones used for calibration and the PRIM model reproduced the soil incubations data better than the original, CENTURY-type soil decomposition model, whose decomposition equations are based only on first-order kinetics. We then compared the PRIM model and the standard first-order decay model incorporated into the global land biosphere model ORCHIDEE (Organising Carbon and Hydrology In Dynamic Ecosystems). A test of both models was performed at ecosystem scale using litter manipulation experiments from five sites. Although both versions were equally able to reproduce observed decay rates of litter, only ORCHIDEE–PRIM could simulate the observed priming (R2  =  0.54) in cases where litter was added or removed. This result suggests that a conceptually simple and numerically tractable representation of priming adapted to global models is able to capture the sign and magnitude of the priming of litter and soil organic matter.

scholarly journals Intrabasinal sediment recycling from detrital strontium isotope stratigraphy

Geology ◽  
2020 ◽  
Vol 48 (10) ◽  
pp. 992-996 ◽  
Author(s):  
Neal C. Auchter ◽  
Brian W. Romans ◽  
Stephen M. Hubbard ◽  
Benjamin G. Daniels ◽  
Howie D. Scher ◽  
...  
Keyword(s):  
Strontium Isotope ◽  
Sediment Storage ◽  
Ancient Source ◽  
Strontium Isotope Stratigraphy ◽  
Source To Sink ◽  
Combined Use ◽  
Magallanes Basin ◽  
Mineralization Age ◽  
Isotope Stratigraphy ◽  
Depositional Age

Abstract Temporary storage of sediment between source and sink can hinder reconstruction of climate and/or tectonic signals from stratigraphy by mixing of sediment tracers with diagnostic geochemical or geochronological signatures. Constraining the occurrence and timing of intrabasinal sediment recycling has been challenging because widely used detrital geo-thermochronology applications do not record shallow burial and subsequent reworking. Here, we apply strontium isotope stratigraphy techniques to recycled marine shell material in slope deposits of the Upper Cretaceous Tres Pasos Formation, Magallanes Basin, Chile. Detrital 87Sr/86Sr ages from 94 samples show that the majority (>85%) of the shells are >1–12 m.y. older than independently constrained depositional ages. We interpret the gap between mineralization age (87Sr/86Sr age) and depositional age of host strata to represent the intrabasinal residence time of sediment storage at the million-year time scale. We also use specimen type to infer relative position of intrabasinal source material along the depositional profile, where oysters represent shallow-water (i.e., proximal) sources and inoceramids represent deeper-water (i.e., distal) sources. The combined use of detrital strontium isotope ages and specimen types from linked depositional segments provides an opportunity to identify and quantify sediment storage and recycling in ancient source-to-sink systems.

Petrography and Geochemistry of the Carboniferous Ortokarnash Manganese Deposit in the Western Kunlun Mountains, Xinjiang Province, China: Implications for the Depositional Environment and the Origin of Mineralization

2020 ◽  
Vol 115 (7) ◽  
pp. 1559-1588
Author(s):  
Bang-Lu Zhang ◽  
Chang-Le Wang ◽  
Leslie J. Robbins ◽  
Lian-Chang Zhang ◽  
Kurt O. Konhauser ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Water Column ◽  
Manganese Carbonate ◽  
Manganese Ore ◽  
Burial Diagenesis ◽  
Kunlun Mountains ◽  
Western Kunlun ◽  
Heavy Rare Earth Elements ◽  
West Kunlun

Abstract The Upper Carboniferous Ortokarnash manganese ore deposit in the West Kunlun orogenic belt of the Xinjiang province in China is hosted in the Kalaatehe Formation. The latter is composed of three members: (1) the 1st Member is a volcanic breccia limestone, (2) the 2nd Member is a sandy limestone, and (3) the 3rd Member is a dark gray to black marlstone containing the manganese carbonate mineralization, which, in turn, is overlain by sandy and micritic limestone. This sequence represents a single transgression-regression cycle, with the manganese deposition occurring during the highstand systems tract. Geochemical features of the rare earth elements (REE+Y) in the Kalaatehe Formation suggest that both the manganese ore and associated rocks were generally deposited under an oxic water column with Post-Archean Australian Shale (PAAS)-normalized REE+Y patterns displaying characteristics of modern seawater (e.g., light REE depletion and negative Ce anomalies). The manganese ore is dominated by fine-grained rhodochrosite (MnCO3), dispersed in Mn-rich silicates (e.g., friedelite and chlorite), and trace quantities of alabandite (MnS) and pyrolusite (MnO2). The replacement of pyrolusite by rhodochrosite suggests that the initial manganese precipitates were Mn(IV)-oxides. Precipitation within an oxic water column is supported by shale-normalized REE+Y patterns from the carbonate ores that are characterized by large positive Ce (>3.0) anomalies, negative Y (~0.7) anomalies, low Y/Ho ratios (~20), and a lack of fractionation between the light and heavy rare earth elements ((Nd/Yb)PAAS ~0.9). The manganese carbonate ores are also 13C-depleted, further suggesting that the Mn(II) carbonates formed as a result of Mn(III/IV)-oxide reduction during burial diagenesis.

Carbon monoxide emissions by phytoplankton: evidence from laboratory experiments

2009 ◽  
Vol 6 (5) ◽  
pp. 369 ◽  
Author(s):  
Valérie Gros ◽  
Ilka Peeken ◽  
Katrin Bluhm ◽  
Eckart Zöllner ◽  
Roland Sarda-Esteve ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Atmospheric Chemistry ◽  
Laboratory Experiments ◽  
Euphotic Zone ◽  
Global Scale ◽  
Emission Rates ◽  
Direct Production ◽  
Diurnal Cycles

Environmental context. Carbon monoxide (CO) is a key component for atmospheric chemistry and its production in the ocean, although minor at the global scale, could play a significant role in the remote marine atmosphere. Up to now, CO production in the ocean was considered to mainly originate from the photo-production of dissolved organic matter (mainly under UV radiation). In this paper, we show evidence for direct production of CO by phytoplankton and we suggest it as a significant mechanism for CO production in the ocean. Abstract. In order to investigate carbon monoxide (CO) emissions by phytoplankton organisms, a series of laboratory experiments was conducted in Kiel (Germany). Nine monocultures, including diatoms, coccolithophorids, chlorophytes and cyanobacteria have been characterised. This was done by following the CO variations from monoculture aliquots exposed to photosynthetically active radiation during one or two complete diurnal cycles. All the studied cultures have shown significant CO production when illuminated. Emission rates have been estimated to range from 1.4 × 10–5 to 8.7 × 10–4 μg of CO μg chlorophyll–1 h–1 depending on the species. When considering the magnitude of the emission rates from the largest CO emitters (cyanobacteria and diatoms), this biotic source could represent up to 20% of the CO produced in oceanic waters. As global models currently mainly consider CO production from the photo-degradation of dissolved organic matter, this study suggests that biotic CO production should also be taken into account. Whether this biological production might also contribute to some degree to the previous observed non-zero CO production below the euphotic zone (dark CO production) cannot be deduced here and needs to be further investigated.

Manganese carbonates as possible biogenic relics in Archean settings

2016 ◽  
Vol 15 (3) ◽  
pp. 219-229 ◽  
Author(s):  
Blanca Rincón-Tomás ◽  
Bahar Khonsari ◽  
Dominik Mühlen ◽  
Christian Wickbold ◽  
Nadine Schäfer ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Oxidation State ◽  
Atmospheric Oxygen ◽  
Anaerobic Respiration ◽  
Manganese Carbonate ◽  
Carbonate Minerals ◽  
Manganese Oxidation ◽  
Anoxygenic Photosynthesis ◽  
Carbonate Deposition ◽  
Carbonate Deposits

AbstractCarbonate minerals such as dolomite, kutnahorite or rhodochrosite are frequently, but not exclusively generated by microbial processes. In recent anoxic sediments, Mn(II)carbonate minerals (e.g. rhodochrosite, kutnahorite) derive mainly from the reduction of Mn(IV) compounds by anaerobic respiration. The formation of huge manganese-rich (carbonate) deposits requires effective manganese redox cycling in an oxygenated atmosphere. However, putative anaerobic pathways such as microbial nitrate-dependent manganese oxidation, anoxygenic photosynthesis and oxidation in ultraviolet light may facilitate manganese cycling even in an early Archean environment, without the availability of oxygen. In addition, manganese carbonates precipitate by microbially induced processes without change of the oxidation state, e.g. by pH shift. Hence, there are several ways how these minerals could have been formed biogenically and deposited in Precambrian sediments. We will summarize microbially induced manganese carbonate deposition in the presence and absence of atmospheric oxygen and we will make some considerations about the biogenic deposition of manganese carbonates in early Archean settings.

scholarly journals Swept under the carpet: the effect of organic matter burial in global biogeochemical ocean models

2013 ◽  
Vol 10 (7) ◽  
pp. 10859-10911 ◽  
Author(s):  
I. Kriest ◽  
A. Oschlies
Keyword(s):  
Organic Matter ◽  
Numerical Models ◽  
Global Scale ◽  
Benthic Fluxes ◽  
Biogeochemical Fluxes ◽  
Biogeochemical Models ◽  
Wide Range ◽  
Potential Impact ◽  
Bathypelagic Zone ◽  
Global Carbon

Abstract. Although of substantial importance for marine tracer distributions and eventually global carbon, oxygen, and nitrogen fluxes, the interaction between sinking and remineralization of organic matter, benthic fluxes and burial is not always represented consistently in global biogeochemical models. We here aim to investigate the relationships between these processes with a suite of global biogeochemical models, each simulated over millennia, and compared against observed distributions of pelagic tracers and benthic and pelagic fluxes. We concentrate on the representation of sediment-water interactions in common numerical models, and investigate their potential impact on simulated global sediment-water fluxes and nutrient and oxygen distributions. We find that model configurations with benthic burial simulate global oxygen well over a wide range of possible sinking flux parameterizations, making the model more robust with regard to uncertainties about the remineralization length scale. On a global scale, burial mostly affects oxygen in the meso- to bathypelagic zone. While all model types show an almost identical fit to observed pelagic particle flux, and the same sensitivity to particle sinking speed, comparison to observational estimates of benthic fluxes reveals a more complex pattern and may be influenced by the data distribution and methodology. Still, evaluating model results against observed pelagic and benthic fluxes of organic matter can complement model assessments based on more traditional tracers such as nutrients or oxygen. Based on a combined metric of dissolved tracers and biogeochemical fluxes, we here identify two model descriptions of burial as suitable candidates for further experiments and eventual model refinements.

scholarly journals Dark Septate Endophytes Isolated From Wild Licorice Roots Grown in the Desert Regions of Northwest China Enhance the Growth of Host Plants Under Water Deficit Stress

2021 ◽  
Vol 12 ◽  
Author(s):  
Chao He ◽  
Wenquan Wang ◽  
Junling Hou ◽  
Xianen Li
Keyword(s):  
Organic Matter ◽  
Drought Stress ◽  
Soil Organic Matter ◽  
Active Ingredient ◽  
Root Biomass ◽  
Host Plants ◽  
Glycyrrhizic Acid ◽  
Northwest China ◽  
Total Biomass ◽  
Osmotic Stress Tolerance

This study aimed to explore dark septate endophytes (DSE) that may improve the cultivation of medicinal plants in arid ecosystems. We isolated and identified eight DSE species (Acremonium nepalense, Acrocalymma vagum, Alternaria chartarum, Alternaria chlamydospora, Alternaria longissima, Darksidea alpha, Paraphoma chrysanthemicola, and Preussia terricola) colonizing the roots of wild licorice (Glycyrrhiza uralensis) in the desert areas of northwest China. Moreover, we investigated the osmotic stress tolerance of the DSE using pure culture, along with the performance of licorice plants inoculated with the DSE under drought stress in a growth chamber, respectively. Here, five species were first reported in desert habitats. The osmotic-stress tolerance of DSE species was highly variable, A. chlamydospora and P. terricola increased the total biomass and root biomass of the host plant. All DSE except A. vagum and P. chrysanthemicola increased the glycyrrhizic acid content; all DSE except A. chartarum increased the glycyrrhizin content under drought stress. DSE × watering regimen improved the glycyrrhizic acid content, soil organic matter, and available nitrogen. Structural equation model analysis showed that DSE × watering regimen positively affected soil organic matter, and total biomass, root length, glycyrrhizic acid, and glycyrrhizin (Shapotou site); and positively affected soil organic matter, available phosphorus, and glycyrrhizin (Minqin site); and positively affected the root length (Anxi site). DSE from the Shapotou site accounted for 8.0, 13.0, and 11.3% of the variations in total biomass, root biomass, and active ingredient content; DSE from the Minqin site accounted for 6.6 and 8.3% of the variations in total biomass and root biomass; DSE from the Anxi site accounted for 4.2 and 10.7% of the variations in total biomass and root biomass. DSE × watering regimen displayed a general synergistic effect on plant growth and active ingredient contents. These findings suggested that the DSE–plant interactions were affected by both DSE species and DSE originating habitats. As A. chlamydospora and P. terricola positively affected the total biomass, root biomass, and active ingredient content of host plants under drought stress, they may have important uses as promoters for the cultivation of licorice in dryland agriculture.

scholarly journals Towards a representation of priming on soil carbon decomposition in the global land biosphere model ORCHIDEE (version 1.9.5.2)

2015 ◽  
Vol 8 (10) ◽  
pp. 9193-9227
Author(s):  
B. Guenet ◽  
F. E. Moyano ◽  
P. Peylin ◽  
P. Ciais ◽  
I. A. Janssens
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Carbon ◽  
Global Scale ◽  
Soil Incubation ◽  
First Order ◽  
Carbon Decomposition ◽  
Litter Manipulation ◽  
Global Land ◽  
Biosphere Model

Abstract. Priming of soil carbon decomposition encompasses different processes through which the decomposition of native (already present) soil organic matter is amplified through the addition of new organic matter, with new inputs typically being more labile than the native soil organic matter. Evidence for priming comes from laboratory and field experiments, but to date there is no estimate of its impact at global scale and under the current anthropogenic perturbation of the carbon cycle. Current soil carbon decomposition models do not include priming mechanisms, thereby introducing uncertainty when extrapolating short-term local observations to ecosystem and regional to global scale. In this study we present a simple conceptual model of decomposition priming, called PRIM, able to reproduce laboratory (incubation) and field (litter manipulation) priming experiments. Parameters for this model were first optimized against data from 20 soil incubation experiments using a Bayesian framework. The optimized parameter values were evaluated against another set of soil incubation data independent from the ones used for calibration and the PRIM model reproduced the soil incubations data better than the original, CENTURY-type soil decomposition model, whose decomposition equations are based only on first order kinetics. We then compared the PRIM model and the standard first order decay model incorporated into the global land biosphere model ORCHIDEE. A test of both models was performed at ecosystem scale using litter manipulation experiments from 5 sites. Although both versions were equally able to reproduce observed decay rates of litter, only ORCHIDEE-PRIM could simulate the observed priming (R2 = 0.54) in cases where litter was added or removed. This result suggests that a conceptually simple and numerically tractable representation of priming adapted to global models is able to capture the sign and magnitude of the priming of litter and soil organic matter.

THE PRE-DEPOSITIONAL AGE OF ORGANIC MATTER IN FLOOD DEPOSITS: INSIGHTS TO THE TIMESCALE OF BIOGEOCHEMICAL PROCESSES

2018 ◽  
Author(s):  
Emily Blackaby ◽  
◽  
William C. Hockaday ◽  
Steven L. Forman ◽  
Gary E. Stinchcomb ◽  
...  
Keyword(s):  
Organic Matter ◽  
Biogeochemical Processes ◽  
Flood Deposits ◽  
Depositional Age

scholarly journals The first global deep-sea stable isotope assessment reveals the unique trophic ecology of Vampire Squid Vampyroteuthis infernalis (Cephalopoda)

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Alexey V. Golikov ◽  
Filipe R. Ceia ◽  
Rushan M. Sabirov ◽  
Jonathan D. Ablett ◽  
Ian G. Gleadall ◽  
...  
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Deep Sea ◽  
Trophic Ecology ◽  
Global Scale ◽  
Phylogenetic Position ◽  
Relict Species ◽  
Global Comparison ◽  
Vampyroteuthis Infernalis ◽  
Isotope Analyses

AbstractVampyroteuthis infernalis Chun, 1903, is a widely distributed deepwater cephalopod with unique morphology and phylogenetic position. We assessed its habitat and trophic ecology on a global scale via stable isotope analyses of a unique collection of beaks from 104 specimens from the Atlantic, Pacific and Indian Oceans. Cephalopods typically are active predators occupying a high trophic level (TL) and exhibit an ontogenetic increase in δ15N and TL. Our results, presenting the first global comparison for a deep-sea invertebrate, demonstrate that V. infernalis has an ontogenetic decrease in δ15N and TL, coupled with niche broadening. Juveniles are mobile zooplanktivores, while larger Vampyroteuthis are slow-swimming opportunistic consumers and ingest particulate organic matter. Vampyroteuthis infernalis occupies the same TL (3.0–4.3) over its global range and has a unique niche in deep-sea ecosystems. These traits have enabled the success and abundance of this relict species inhabiting the largest ecological realm on the planet.

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