scholarly journals Lower Wenlock black shales in the northern Holy Cross Mountains, Poland: sedimentary and geochemical controls on the Ireviken Event in a deep marine setting

2016 ◽  
Vol 154 (2) ◽  
pp. 247-264 ◽  
Author(s):  
JUSTYNA SMOLAREK ◽  
WIESŁAW TRELA ◽  
DAVID P. G. BOND ◽  
LESZEK MARYNOWSKI
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Water Column ◽  
Black Shale ◽  
Bottom Water ◽  
Black Shales ◽  
Redox Conditions ◽  
Pyrite Framboids ◽  
Redox History ◽  
Deposition Conditions

AbstractThe stratigraphic variability and geochemistry of Llandovery/Wenlock (L/W) Series boundary sediments in Poland reveals that hemipelagic sedimentation under an anoxic/euxinic water column was interrupted by low-density bottom currents or detached diluted turbid layers that resulted in intermittent seafloor oxygenation. Total organic carbon values and inorganic proxies throughout the Wilków 1 borehole section suggest variable redox conditions. U/Mo ratios > 1 throughout much of the Aeronian and Telychian stages, together with an absence of pyrite framboids, suggest oxygenated conditions prevailed. However, elevated total organic carbon near the Aeronian/Telychian boundary, together with increased U/Th and V/(V + Ni) ratios and populations of small pyrite framboids are consistent with the development of dysoxic/anoxic conditions at that time. U/Th, V/Cr and V/(V + Ni) ratios, as well as Uauthig and Mo concentrations, suggest that during the Ireviken black shale deposition, bottom-water conditions deteriorated from oxic during Telychian time to mostly suboxic/anoxic immediately prior to the L/W boundary, before a brief reoxygenation at the end of the Ireviken black shale sedimentation in the Sheinwoodian Stage. Rapid fluctuations in U/Mo during the Ireviken Event are characteristic of fluctuating redox conditions that culminated in an anoxic/euxinic seafloor in Sheinwoodian time. Following Ireviken black shale deposition, conditions once again became oxygen deficient with the development of a euxinic zone in the water column. The Aeronian to Sheinwoodian deep-water redox history was unstable, and rapid fluctuations of the chemocline across the L/W Series boundary probably contributed to the Ireviken Event extinctions, which affected mainly pelagic and hemipelagic fauna.

scholarly journals Black shale deposition during Toarcian super-greenhouse driven by sea level

2013 ◽  
Vol 9 (6) ◽  
pp. 2703-2712 ◽  
Author(s):  
M. Hermoso ◽  
F. Minoletti ◽  
P. Pellenard
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Sea Level ◽  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Black Shale ◽  
Black Shales ◽  
Positive Trend ◽  
Sea Level Changes ◽  
Organic Carbon Burial

Abstract. One of the most elusive aspects of the Toarcian oceanic anoxic event (T-OAE) is the paradox between carbon isotopes that indicate intense global primary productivity and organic carbon burial at a global scale, and the delayed expression of anoxia in Europe. During the earliest Toarcian, no black shales were deposited in the European epicontinental seaways, and most organic carbon enrichment of the sediments postdated the end of the overarching positive trend in the carbon isotopes that characterises the T-OAE. In the present study, we have attempted to establish a sequence stratigraphic framework for Early Toarcian deposits recovered from a core drilled in the Paris Basin using a combination of mineralogical (quartz and clay relative abundance) and geochemical (Si, Zr, Ti and Al) measurements. Combined with the evolution in redox sensitive elements (Fe, V and Mo), the data suggest that expression of anoxia was hampered in European epicontinental seas during most of the T-OAE (defined by the positive carbon isotope trend) due to insufficient water depth that prevented stratification of the water column. Only the first stratigraphic occurrence of black shales in Europe corresponds to the "global" event. This interval is characterised by >10% Total Organic Carbon (TOC) content that contains relatively low concentration of molybdenum compared to subsequent black shale horizons. Additionally, this first black shale occurrence is coeval with the record of the major negative Carbon Isotope Excursion (CIE), likely corresponding to a period of transient greenhouse intensification likely due to massive injection of carbon into the atmosphere–ocean system. As a response to enhanced weathering and riverine run-off, increased fresh water supply to the basin may have promoted the development of full anoxic conditions through haline stratification of the water column. In contrast, post T-OAE black shales during the serpentinum and bifrons Zones were restricted to epicontinental seas (higher Mo to TOC ratios) during a period of relative high sea level, and carbon isotopes returning to pre-T-OAE values. Comparing palaeoredox proxies with the inferred sequence stratigraphy for Sancerre suggests that episodes of short-term organic carbon enrichment were primarily driven by third-order sea level changes. These black shales exhibit remarkably well-expressed higher-frequency cyclicities in the oxygen availability in the water column whose nature has still to be determined through cyclostratigraphic analysis.

scholarly journals Black shale deposition during Toarcian super-greenhouse driven by sea level

2013 ◽  
Vol 9 (4) ◽  
pp. 4365-4384 ◽  
Author(s):  
M. Hermoso ◽  
F. Minoletti ◽  
P. Pellenard
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Sea Level ◽  
Sequence Stratigraphy ◽  
Carbon Isotopes ◽  
Black Shale ◽  
Black Shales ◽  
Positive Trend ◽  
Sea Level Changes ◽  
Organic Carbon Burial

Abstract. One of the most elusive aspects of the Toarcian Oceanic Anoxic Event (T-OAE) is the paradox between carbon isotopes that indicate intense global primary productivity and organic carbon burial at a global scale, and the delayed expression of anoxia in Europe. During the earliest Toarcian, no black shales were deposited in the European epicontinental seaways, and most organic carbon enrichment of the sediments postdated the T-OAE (defined by the overarching positive trend in the carbon isotopes). In the present studied, we have attempted to establish a sequence stratigraphy framework for Early Toarcian deposits recovered from a core drilled in the Paris Basin using a combination of mineralogical (quartz and clay relative abundance) and geochemical (Si, Zr, Ti and Al) measurements. Combined with the evolution in redox sensitive elements (Fe, V and Mo), the data suggest that expression of anoxia was hampered in European epicontinental seas during most of the T-OAE due to insufficient water depth that prevented stratification of the water column. Only the first stratigraphic occurrence of black shales in Europe corresponds to the "global" event. This interval is characterised by > 10% Total Organic Carbon (TOC) content that contains relatively low concentration of molybdenum compared to subsequent black shale horizons. Additionally, this first black shale occurrence is coeval with the record of the major negative Carbon Isotope Excursion (CIE), likely corresponding to a period of transient greenhouse intensification likely due to massive injection of carbon into the Atmosphere–Ocean system. As a response to enhanced weathering and riverine run-off, increased fresh water supply to the basin may have promoted the development of full anoxic conditions through haline stratification of the water column. In contrast, post T-OAE black shales were restricted to epicontinental seas (higher Mo to TOC ratios) during a period of relative high sea level, and carbon isotopes returning to pre-T-OAE values. Comparing palaeoredox proxies with the inferred sequence stratigraphy for Sancerre suggests that episodes of short-term organic carbon enrichment were primarily driven by third-order sea level changes. These black shales exhibit remarkably well-expressed higher-frequency cyclicities in the concentration of redox-sensitive elements such as iron or vanadium whose nature has still to be determined through cyclostratigraphic analysis.

Accumulation Conditions and Gas Content Characteristics of the Lower Silurian in Northwestern Hunan, China

2013 ◽  
Vol 868 ◽  
pp. 192-195
Author(s):  
Tuo Lin ◽  
Jin Chuan Zhang ◽  
Bo Li ◽  
Wei He ◽  
Xuan Tang
Keyword(s):  
Black Shale ◽  
Sedimentary Environment ◽  
Sedimentary Facies ◽  
Black Shales ◽  
Gas Content ◽  
Burial Depth ◽  
Reservoir Properties ◽  
Isothermal Adsorption ◽  
Lower Silurian ◽  
Deposition Conditions

The Lower Silurian marine shale is widely distributed in Northwestern Hunan and features in a large thickness of dark shale showed at outcrops. However, the accumulation conditions and gas content is unknown. The sedimentary facies, thickness and distribution, organic matter types and content, maturity, reservoir properties and gas content of the Lower Silurian black shale in Northwestern Hunan were investigated by field observation, sampling and experimental analysis. The results show that the black shales sedimentary environment is deep water continental shelf, with featured in abundant fossil. The burial depth of the Lower Silurian black shale is 0-3000 m, and its thickness is 10-40m while the average TOC is 1.0% and average Ro is 2.9%. For the disadvantaged sedimentary facies and shallow depth, the maximum gas content of the Lower Silurian black shale from well site desorption test is 0.59m3/t only, but the result of isothermal adsorption simulate test show that the Lower Silurian black shale have a good adsorption capacity, and can generate a large number of shale gas in Northwestern Hunan where better deposition conditions and suitable depth exist in.

scholarly journals Dynamic climate-driven controls on the deposition of the Kimmeridge Clay Formation in the Cleveland Basin, Yorkshire, UK

2019 ◽  
Author(s):  
Elizabeth Atar ◽  
Christian März ◽  
Andrew Aplin ◽  
Olaf Dellwig ◽  
Liam Herringshaw ◽  
...  
Keyword(s):  
Organic Matter ◽  
Trace Metals ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Distal Part ◽  
Hadley Cell ◽  
Redox Conditions ◽  
Climate Modelling ◽  
Lower Variability ◽  
Clay Formation

Abstract. The Kimmeridge Clay Formation (KCF) is a laterally extensive, total organic carbon-rich succession deposited throughout Northwest Europe during the Kimmeridgian–Tithonian (Late Jurassic). Here we present a petrographic and geochemical dataset for a 40 metre-thick section of a well-preserved drill core recovering thermally-immature deposits of the KCF in the Cleveland Basin (Yorkshire, UK), covering an interval of approximately 800 kyr. The new data are discussed in the context of depositional processes, sediment source and supply, transport and dispersal mechanisms, water column redox conditions, and basin restriction. Armstrong et al. (2016) recently postulated that an expanded Hadley Cell, with an intensified but alternating hydrological cycle, heavily influenced sedimentation and total organic carbon (TOC) enrichment, through promoting the primary productivity and organic matter burial, in the UK sectors of the Boreal Seaway. Consistent with such climate boundary conditions, petrographic observations, total organic carbon and carbonate contents, and major and trace element data presented here indicate that the KCF of the Cleveland Basin was deposited in the distal part of the Laurasian Seaway. Depositional conditions alternated between three states that produced a distinct cyclicity in the lithological and geochemical records: lower variability mudstone intervals (LVMIs) which comprise of clay-rich mudstone, TOC-rich sedimentation, and carbonate-rich sedimentation. The lower variability mudstone intervals dominate the studied interval but are punctuated by three ~ 2–4 m thick intervals of alternating TOC-rich and carbonate-rich sedimentation (here termed higher variability mudstone intervals, HVMIs). During the lower variability mudstone intervals, conditions were quiescent with oxic to sub-oxic bottom water conditions. During the higher variability mudstone intervals, highly dynamic conditions resulted in repeated switching of the redox system in a way similar to the modern deep basins of the Baltic Sea. During carbonate-rich sedimentation, oxic conditions prevailed, most likely due to elevated depositional energies at the seafloor by current/wave action. During TOC-rich sedimentation, anoxic-euxinic conditions led to an enrichment of redox sensitive/sulphide forming trace metals at the seafloor and a preservation of organic matter, and an active Mn-Fe particulate shuttle delivered redox sensitive/sulphide forming trace metals to the seafloor. In addition, based on TOC–S–Fe relationships, organic matter sulphurisation appears to have increased organic material preservation in about half of the analysed samples throughout the core, while the remaining samples were either dominated by excess Fe input into the system or experienced pyrite oxidation and sulphur loss during oxygenation events. New Hg/TOC data do not provide evidence of increased volcanism during this time, consistent with previous work. Set in the context of recent climate modelling, our study provides a comprehensive example of the dynamic climate-driven depositional and redox conditions that can control TOC and metal accumulations in the distal part of a shallow epicontinental sea, and is therefore key to understanding the formation of similar deposits throughout Earth's history.

Late Jurassic – earliest Cretaceous prolonged shelf dysoxic–anoxic event and its possible causes

2020 ◽  
Vol 157 (10) ◽  
pp. 1622-1642
Author(s):  
MA Rogov ◽  
EV Shchepetova ◽  
VA Zakharov
Keyword(s):  
Organic Carbon ◽  
Black Shale ◽  
High Latitude ◽  
Late Jurassic ◽  
Black Shales ◽  
Time Interval ◽  
Oceanic Circulation ◽  
Anoxic Event ◽  
Anoxic Events

AbstractThe Late Jurassic – earliest Cretaceous time interval was characterized by a widespread distribution of dysoxiс–anoxiс environments in temperate- and high-latitude epicontinental seas, which could be defined as a shelf dysoxic–anoxic event (SDAE). In contrast to black shales related to oceanic anoxic events, deposits generated by the SDAE were especially common in shelf sites in the Northern Hemisphere. The onset and termination of the SDAE was strongly diachronous across different regions. The SDAE was not associated with significant disturbances of the carbon cycle. Deposition of organic-carbon-rich sediment and the existence of dysoxic–anoxic conditions during the SDAE lasted up to c. 20 Ma, but this event did not cause any remarkable biotic extinction. Temperate- and high-latitude black shale occurrences across the Jurassic–Cretaceous boundary have been reviewed. Two patterns of black shale deposition during the SDAE are recognized: (1) Subboreal type, with numerous thin black shale beds, bounded by sediments with very low total organic carbon (TOC) values; and (2) Boreal type, distinguished by predominantly thick black shale successions showing high TOC values and prolonged anoxic–dysoxic conditions. These types appear to be unrelated to differences in accommodation space, and can be clearly recognized irrespective of the thickness of shale-bearing units. Black shales in high-latitude areas in the Southern Hemisphere strongly resemble Boreal types of black shale by their mode of occurrence. The causes of this SDAE are linked to long-term warming and changes in oceanic circulation. Additionally, the long-term disturbance of planktonic communities may have triggered overall increased productivity in anoxia-prone environments.

Correlation of chemostratigraphy, total organic carbon, sequence stratigraphy, and bioturbation in the Woodford Shale of south-central Oklahoma

2018 ◽  
Vol 6 (1) ◽  
pp. SC43-SC54
Author(s):  
Sabrina M. Coleman ◽  
Douglas W. Jordan
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Sequence Stratigraphy ◽  
Algal Blooms ◽  
Bottom Water ◽  
Woodford Shale ◽  
X Ray ◽  
South Central ◽  
Technological Advances ◽  
Water Conditions

Technological advances in handheld X-ray fluorescence (HHXRF) have been instrumental in demonstrating the utility of chemostratigraphic data to create higher order sequence stratigraphic interpretations. This study seeks to identify the correlation between chemostratigraphy, total organic carbon, sequence stratigraphy, and bioturbation in the Woodford Shale of south-central Oklahoma using HHXRF and X-ray diffraction technologies. The use of multiproxy correlations allows for higher confidence identifying lateral changes in the Woodford Shale. Elemental data collected through HHXRF can be used as proxies to better understand the depositional environment of a formation. Titanium, Zr, K, and Al are all proxies for transgression and regression. Silica is associated with so many different elements that Si alone does not provide useful information; however, the ratio of Si/Al coupled with detrital proxies can give information on the presence of possible algal blooms, continentally derived sediment, or hiatal surfaces. Furthermore, relationships between other elements can give further understanding to bottom-water conditions at the time of deposition. This study examines the relationships between Mo, V, Ni, and P along with other elements and laboratory-collected data to further understand the bottom-water conditions during deposition of the organic-rich muds that make up the Woodford Shale in south-central Oklahoma. To some extent, it is then possible to correlate these higher-resolution understandings to open-hole well logs to increase our understanding, where the core is unavailable.

scholarly journals Dynamics of nutrients, total organic carbon, prokaryotes and viruses in onboard incubations of cold-water corals

2011 ◽  
Vol 8 (9) ◽  
pp. 2609-2620 ◽  
Author(s):  
C. Maier ◽  
A. de Kluijver ◽  
M. Agis ◽  
C. P. D. Brussaard ◽  
F. C. van Duyl ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Bottom Water ◽  
Cold Water ◽  
Inorganic Nitrogen ◽  
Inorganic Phosphorus ◽  
Lophelia Pertusa ◽  
Turnover Rates ◽  
Clear Trend ◽  
Incubation Experiments

Abstract. The potential influence of the cold-water corals (CWCs) Lophelia pertusa and Madrepora oculata on the dynamics of inorganic nutrient and total organic carbon (TOC) concentrations and the abundances of prokaryotes and viruses in bottom water was assessed in onboard incubation experiments. Ammonium, nitrite, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and TOC concentrations and N:P ratios were typically higher in incubation water with corals than in controls, whereas nitrate concentrations did not reveal a clear trend. Mucus release (normalized to coral surface) was estimated by the net increase rate of TOC concentrations and averaged 23 ± 6 mg C m−2 h−1 for L. pertusa and 21 ± 8 mg C m−2 h−1 for M. oculata. Prokaryotic and viral abundance and turnover rates were typically stimulated in incubation water with corals. This estimated prokaryotic stimulation averaged 6.0 ± 3.0 × 109 cells m−2 h−1 for L. pertusa and 8.4 ± 2.9 × 109 cells m−2 h−1 for M. oculata, whereas the estimated viral stimulation averaged 15.6 ± 12.7 × 109 particles m−2 h−1 for L. pertusa and 4.3 ± 0.4 × 109 particles m−2 h−1 M. oculata. Our data suggest that prokaryotes and viruses are released from corals and that nutrient and mucus release enhanced prokaryotic and viral production. The result of this stimulation could be a fuelling of bottom water in CWC reefs with nutrients and organic matter and consequently an enhancement of microbe-mediated processes.

scholarly journals Ordovician Jeleniów Claystone Formation of the Holy Cross Mountains, Poland – Reconstruction of redox conditions using pyrite framboid study

2014 ◽  
Vol 3 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Justyna Smolarek ◽  
Leszek Marynowski ◽  
Wiesław Trela
Keyword(s):  
Standard Deviation ◽  
Water Column ◽  
Redox Conditions ◽  
Diameter Distribution ◽  
Mean Values ◽  
Anoxic Conditions ◽  
Pyrite Framboids ◽  
Holy Cross Mountains ◽  
Two Samples ◽  
Insight Into

Abstract The aim of this research is to reconstruct palaeoredox conditions during sedimentation of the Jeleniów Claystone Formation deposits, using framboid pyrite diameter measurements. Analysis of pyrite framboids diameter distribution is an effective method in the palaeoenvironmental interpretation which allow for a more detailed insight into the redox conditions, and thus the distinction between euxinic, dysoxic and anoxic conditions. Most of the samples is characterized by framboid indicators typical for anoxic/euxinic conditions in the water column, with average (mean) values ranging from 5.29 to 6.02 μm and quite low standard deviation (SD) values ranging from 1.49 to 3.0. The remaining samples have shown slightly higher values of framboid diameter typical for upper dysoxic conditions, with average values (6.37 to 7.20 μm) and low standard deviation (SD) values (1.88 to 2.88). From the depth of 75.5 m till the shallowest part of the Jeleniów Claystone Formation, two samples have been examined and no framboids has been detected. Because secondary weathering should be excluded, the lack of framboids possibly indicates oxic conditions in the water column. Oxic conditions continue within the Wólka Formation based on the lack of framboids in the ZB 51.6 sample

Description and ecology of a new Middle Ordovician (Llanvirn) odontopleurid trilobite from the Builth Inlier of Mid-Wales, with a review of the genus Meadowtownella

2011 ◽  
Vol 149 (3) ◽  
pp. 397-411 ◽  
Author(s):  
TIM M. CONWAY ◽  
JOSEPH P. BOTTING
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Water Column ◽  
Environmental Preferences ◽  
Middle Ordovician ◽  
Framboidal Pyrite ◽  
Bottom Waters ◽  
New Diagnosis ◽  
Stratigraphic Range

AbstractA new odontopleurid trilobite, Meadowtownella serrata, is described from a new Llanvirnian (Darriwilian; Didymograptus murchisoni Biozone) locality in the Builth Inlier, Mid-Wales. This unusually spinose species displays a remarkable array of pygidial spines and extends the stratigraphic range of the genus back into the Abereiddian. Benthic faunas are rare in the predominantly ‘anoxic’ D. murchisoni Biozone of the Welsh Basin, and these beds are an unusual habitat for odontopleurids. Environmental analyses (framboidal pyrite and associated total organic carbon) in this study, together with the distribution of benthic faunas (described and figured) in the section, indicate a likely oxic water column and episodically oxic bottom waters. A new diagnosis for Meadowtownella is presented with a review of the genus, as a clarification of previous work. The greater spinosity of earlier members of the lineage may reflect either changing environmental preferences, or the derivation of Meadowtownella from an original more spinose lineage.

scholarly journals Dynamics of nutrients, total organic carbon, prokaryotes and viruses in onboard incubations of cold-water corals

2011 ◽  
Vol 8 (2) ◽  
pp. 3829-3861 ◽  
Author(s):  
C. Maier ◽  
A. de Kluijver ◽  
M. Agis ◽  
C. P. D. Brussaard ◽  
F. C. van Duyl ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Bottom Water ◽  
Cold Water ◽  
Inorganic Nitrogen ◽  
Inorganic Phosphorus ◽  
Lophelia Pertusa ◽  
Turnover Rates ◽  
Clear Trend ◽  
Incubation Experiments

Abstract. The potential influence of the cold-water corals (CWCs) Lophelia pertusa and Madrepora oculata on the dynamics of inorganic nutrient and total organic carbon (TOC) concentrations and the abundances of prokaryotes and viruses in bottom water was assessed in onboard incubation experiments. Ammonium, nitrite, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and TOC concentrations and N:P ratios were typically higher in incubation water with corals than in controls, whereas nitrate concentrations did not reveal a clear trend. Mucus release (normalized to coral surface) was estimated by the net increase rate of TOC concentrations and averaged 23 ± 6 mg C m−2 h−1 for L. pertusa and 21 ± 8 mg C m−2 h−1 for M. oculata. Prokaryotic and viral abundance and turnover rates were typically stimulated in incubation water with corals. This prokaryotic stimulation averaged 6.0 ± 3.0 × 109 cells m−2 h−1 for L. pertusa and 8.4 ± 2.9 ×109 cells m−2 h−1 for M. oculata, whereas the viral stimulation averaged 15.6 ± 12.7 × 109 particles m−2 h−1 for L. pertusa and 4.3 ± 0.4 × 109 particles m−2 h−1 M. oculata. Our data suggest that prokaryotes and viruses are released from corals and that nutrient and mucus release enhanced prokaryotic and viral production. The result of this stimulation could be a fuelling of bottom water in CWC reefs with nutrients and organic matter and consequently an enhancement of microbe-mediated processes.

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