17 research outputs found
In situ Sâisotope compositions of sulfate and sulfide from the 3.2 Ga Moodies Group, South Africa: A record of oxidative sulfur cycling
Sulfate minerals are rare in the Archean rock record and largely restricted to the occurrence of barite (BaSO4). The origin of this barite remains controversially debated. The massâindependent fractionation of sulfur isotopes in these and other Archean sedimentary rocks suggests that photolysis of volcanic aerosols in an oxygenâpoor atmosphere played an important role in their formation. Here, we report on the multiple sulfur isotopic composition of sedimentary anhydrite in the ca. 3.22Â Ga Moodies Group of the Barberton Greenstone Belt, southern Africa. Anhydrite occurs, together with barite and pyrite, in regionally traceable beds that formed in fluvial settings. Variable abundances of barite versus anhydrite reflect changes in sulfate enrichment by evaporitic concentration across orders of magnitude in an arid, nearshore terrestrial environment, periodically replenished by influxes of seawater. The multiple Sâisotope compositions of anhydrite and pyrite are consistent with microbial sulfate reduction. Sâisotope signatures in barite suggest an additional oxidative sulfate source probably derived from continental weathering of sulfide possibly enhanced by microbial sulfur oxidation. Although depositional environments of Moodies sulfate minerals differ strongly from marine barite deposits, their sulfur isotopic composition is similar and most likely reflects a primary isotopic signature. The data indicate that a constant input of small portions of oxidized sulfur from the continents into the ocean may have contributed to the observed longâterm increase in Î33Ssulfate values through the Paleoarchean.Centre National de la Recherche ScientifiqueDeutsche ForschungsgemeinschaftH2020 European Research Counci
Multiple Sulfur Isotope Records of the 3.22 Ga Moodies Group, Barberton Greenstone Belt
Co-auteur Ă©trangerInternational audienceThe Moodies Group, the uppermost unit in the Barberton Greenstone Belt (BGB) in SouthAfrica, is a ~3.7-km-thick coarse clastic succession accumulated on terrestrial-to-shallow marinesettings at around 3.22 Ga. The multiple sulfur isotopic composition of pyrite of Moodies intervalswas newly obtained to examine the influence of these depositional settings on the sulfur isotope record.Conglomerate and sandstone rocks were collected from three synclines north of the Inyoka Fault of thecentral BGB, namely, the Eureka, Dycedale, and Saddleback synclines. The sulfur isotopic compositionof pyrite was analyzed by Secondary Ion Mass Spectrometry (SIMS) for 6 samples from the threesynclines and by Isotope Ratio Mass Spectrometry (IR-MS) for 17 samples from a stratigraphic sectionin the Saddleback Syncline. The present results show a signal of mass-independent fractionation ofsulfur isotopes (S-MIF), although t-tests statistically demonstrated that the Moodies S-MIF signals(mostly 0% < D33S < +0.5%) are significantly small compared to the signal of the older Paleoarchean(3.6â3.2 Ga) records. These peculiar signatures might be related to initial deposition of detrital pyriteof juvenile origin from the surrounding intrusive (tonaliteâtrondhjemiteâgranodiorite; TTG) andfelsic volcanic rocks, and/or to secondary addition of hydrothermal sulfur during late metasomatism.Moreover, fast accumulation (~0.1â1 mm/year) of the Moodies sediments might have led to a reducedaccumulation of sulfur derived from an atmospheric source during their deposition. As a result, thesulfur isotopic composition of the sediments may have become susceptible to the secondary additionof metasomatic sulfur on a mass balance point of view. The sulfur isotopic composition of Moodiespyrite is similar to the composition of sulfides from nearby gold mines. It suggests that, after theMoodies deposition, metasomatic pyrite formation commonly occurred north of the Inyoka Fault inthe central BGB at 3.1â3.0 Ga
Reassessing evidence of MoonâEarth dynamics from tidal bundles at 3.2 Ga (Moodies Group, Barberton Greenstone Belt, South Africa)
Past orbital parameters of the Moon are difficult to reconstruct from geological records because relevant data sets of tidal strata are scarce or incomplete. The sole Archean data point is from the Moodies Group (ca 3.22âGa) of the Barberton Greenstone Belt, South Africa. From the time-series analysis of tidal bundles from a well-exposed subaqueous sand wave of this unit, Eriksson and Simpson (Geology, 28, 831) suggested that the Moonâs anomalistic month at 3.2âGa was closer to 20âdays than the present 27.5âdays. This is in apparent accordance with models of orbital mechanics which place the Archean Moon in a closer orbit with a shorter period, resulting in stronger tidal action. Although this studyâs detailed geological mapping and section measuring of the site confirmed that the sandstone bed in question is likely a migrating dune, the presence of angular mud clasts, channel-margin slumps, laterally aggrading channel fills and bidirectional paleocurrents in overlying and underlying beds suggests that this bedform was likely located in a nearshore channel near lower-intertidal flats and subtidal estuarine bars; it thus carries risk of incomplete preservation. Repeated measurements of foreset thicknesses along the published traverse, measured perpendicular to bedding, failed to show consistent spectral peaks. Larger data sets acquired along traverses measured parallel to bedding along the 20.5âm wide exposure are affected by minor faulting, uneven outcrop weathering, changing illumination, weather, observer bias and show a low reproducibility. The most robust measurements herein confirm the periodicity peak of approximately 14 in the original data of Eriksson and Simpson (Geology, 28, 831). Because laminae may have been eroded, the measurements may represent a lower bound of about 28 lunar days per synodic month. This estimate agrees well with EarthâMoon dynamic models which consider the conservation of angular momentum and place the Archaean Moon in a lower orbit around a faster-spinning Earth
Reassessing evidence of MoonâEarth dynamics from tidal bundles at 3.2 Ga (Moodies Group, Barberton Greenstone Belt, South Africa)
Past orbital parameters of the Moon are difficult to reconstruct from geological records because relevant data sets of tidal strata are scarce or incomplete. The sole Archean data point is from the Moodies Group (ca 3.22âGa) of the Barberton Greenstone Belt, South Africa. From the time-series analysis of tidal bundles from a well-exposed subaqueous sand wave of this unit, Eriksson and Simpson (Geology, 28, 831) suggested that the Moonâs anomalistic month at 3.2âGa was closer to 20âdays than the present 27.5âdays. This is in apparent accordance with models of orbital mechanics which place the Archean Moon in a closer orbit with a shorter period, resulting in stronger tidal action. Although this studyâs detailed geological mapping and section measuring of the site confirmed that the sandstone bed in question is likely a migrating dune, the presence of angular mud clasts, channel-margin slumps, laterally aggrading channel fills and bidirectional paleocurrents in overlying and underlying beds suggests that this bedform was likely located in a nearshore channel near lower-intertidal flats and subtidal estuarine bars; it thus carries risk of incomplete preservation. Repeated measurements of foreset thicknesses along the published traverse, measured perpendicular to bedding, failed to show consistent spectral peaks. Larger data sets acquired along traverses measured parallel to bedding along the 20.5âm wide exposure are affected by minor faulting, uneven outcrop weathering, changing illumination, weather, observer bias and show a low reproducibility. The most robust measurements herein confirm the periodicity peak of approximately 14 in the original data of Eriksson and Simpson (Geology, 28, 831). Because laminae may have been eroded, the measurements may represent a lower bound of about 28 lunar days per synodic month. This estimate agrees well with EarthâMoon dynamic models which consider the conservation of angular momentum and place the Archaean Moon in a lower orbit around a faster-spinning Earth
Global injury morbidity and mortality from 1990 to 2017 : results from the Global Burden of Disease Study 2017
Correction:Background Past research in population health trends has shown that injuries form a substantial burden of population health loss. Regular updates to injury burden assessments are critical. We report Global Burden of Disease (GBD) 2017 Study estimates on morbidity and mortality for all injuries. Methods We reviewed results for injuries from the GBD 2017 study. GBD 2017 measured injury-specific mortality and years of life lost (YLLs) using the Cause of Death Ensemble model. To measure non-fatal injuries, GBD 2017 modelled injury-specific incidence and converted this to prevalence and years lived with disability (YLDs). YLLs and YLDs were summed to calculate disability-adjusted life years (DALYs). Findings In 1990, there were 4 260 493 (4 085 700 to 4 396 138) injury deaths, which increased to 4 484 722 (4 332 010 to 4 585 554) deaths in 2017, while age-standardised mortality decreased from 1079 (1073 to 1086) to 738 (730 to 745) per 100 000. In 1990, there were 354 064 302 (95% uncertainty interval: 338 174 876 to 371 610 802) new cases of injury globally, which increased to 520 710 288 (493 430 247 to 547 988 635) new cases in 2017. During this time, age-standardised incidence decreased non-significantly from 6824 (6534 to 7147) to 6763 (6412 to 7118) per 100 000. Between 1990 and 2017, age-standardised DALYs decreased from 4947 (4655 to 5233) per 100 000 to 3267 (3058 to 3505). Interpretation Injuries are an important cause of health loss globally, though mortality has declined between 1990 and 2017. Future research in injury burden should focus on prevention in high-burden populations, improving data collection and ensuring access to medical care.Peer reviewe
The global burden of adolescent and young adult cancer in 2019 : a systematic analysis for the Global Burden of Disease Study 2019
Background In estimating the global burden of cancer, adolescents and young adults with cancer are often overlooked, despite being a distinct subgroup with unique epidemiology, clinical care needs, and societal impact. Comprehensive estimates of the global cancer burden in adolescents and young adults (aged 15-39 years) are lacking. To address this gap, we analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, with a focus on the outcome of disability-adjusted life-years (DALYs), to inform global cancer control measures in adolescents and young adults. Methods Using the GBD 2019 methodology, international mortality data were collected from vital registration systems, verbal autopsies, and population-based cancer registry inputs modelled with mortality-to-incidence ratios (MIRs). Incidence was computed with mortality estimates and corresponding MIRs. Prevalence estimates were calculated using modelled survival and multiplied by disability weights to obtain years lived with disability (YLDs). Years of life lost (YLLs) were calculated as age-specific cancer deaths multiplied by the standard life expectancy at the age of death. The main outcome was DALYs (the sum of YLLs and YLDs). Estimates were presented globally and by Socio-demographic Index (SDI) quintiles (countries ranked and divided into five equal SDI groups), and all estimates were presented with corresponding 95% uncertainty intervals (UIs). For this analysis, we used the age range of 15-39 years to define adolescents and young adults. Findings There were 1.19 million (95% UI 1.11-1.28) incident cancer cases and 396 000 (370 000-425 000) deaths due to cancer among people aged 15-39 years worldwide in 2019. The highest age-standardised incidence rates occurred in high SDI (59.6 [54.5-65.7] per 100 000 person-years) and high-middle SDI countries (53.2 [48.8-57.9] per 100 000 person-years), while the highest age-standardised mortality rates were in low-middle SDI (14.2 [12.9-15.6] per 100 000 person-years) and middle SDI (13.6 [12.6-14.8] per 100 000 person-years) countries. In 2019, adolescent and young adult cancers contributed 23.5 million (21.9-25.2) DALYs to the global burden of disease, of which 2.7% (1.9-3.6) came from YLDs and 97.3% (96.4-98.1) from YLLs. Cancer was the fourth leading cause of death and tenth leading cause of DALYs in adolescents and young adults globally. Interpretation Adolescent and young adult cancers contributed substantially to the overall adolescent and young adult disease burden globally in 2019. These results provide new insights into the distribution and magnitude of the adolescent and young adult cancer burden around the world. With notable differences observed across SDI settings, these estimates can inform global and country-level cancer control efforts. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd.Peer reviewe
The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019
Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe
Archaische Paleoböden auf Erde und Mars
Paleosols are unique recorders of physical and chemical processes at the
interface between rocks and the atmosphere, hydrosphere and biosphere. Their
capacity to record atmospheric and hydrologic conditions allows them to serve
as information archives on past environments. Archean paleosols are, due to
deformation, metamorphism and limited outcrop, commonly difficult to recognize
and characterize, though the number of findings has increased remarkably over
recent decades. Well-preserved Paleoarchean terrestrial strata are currently
known only from in the Pilbara Block, northwestern Australia and the Barberton
Greenstone Belt (BGB), southern Africa. This study describes the widespread
occurrence of early diagenetic to pedogenic nodules that formed in
unconsolidated sandy sediments in fluvial and coastal settings of the ~3.22 Ga
old Archean Moodies Group, BGB, South Africa. They appear stratiform, in
places rock-forming, in several regionally traceable units composed of
megaquartz pseudomorphs after gypsum, barite and calcite. Nodule growth was
dominated by seasonal fluctuations of the groundwater level under evaporitic
conditions. The nodules likely represent the oldest terrestrial evaporites
known to date. Their formation and composition constrain the local occurrence
of sulfate in the Archean atmo- and hydrosphere and its interaction with the
emerging biosphere, the Archean weathering regime, local climate and vadose-
zone hydrodynamics. The nodules are interbedded with mm-thick heavy mineral
laminations, mainly composed of pyrite. Pyrite grains show rounded detrital
cores corroded by pore fluids related to pedogenic nodule formation and
secondary idiomorphic rims which grew under reducing conditions. The trace
element concentrations (Ni and Co) and ÎŽ34S ratios of the rims are clearly
different from those of the cores. While cores have low Co and Ni
concentrations, rims show up to 5.5 wt.-% of these elements. In-situ sulfur
isotope analyses of pyrite cores show ÎŽ34SVCDT values between +5â° and -5â°
while the rims show ÎŽ34SVCDT values between -20â° and -24.5â°, suggesting a
biogenic fractionation of sulfur. The close spatial association and nearly
contemporaneous formation of pedogenic sulfate and secondary pyrite is
consistent with microbial sulfur processing in the paleosols. This indicates
that Archean soil-forming processes involved not only physical and chemical
but also biological modification of unconsolidated sediment. Microbial life
was already pervasive in terrestrial environments more than 3.2 Ga ago. The
~3.3-3.2 Ga old Sheepbed Member of the Yellowknife Bay Formation in Gale
crater on Mars contains a number of diagenetic features, amongst which nodules
are considered to be of early diagenetic origin. The nodules show solid,
hollow and filled morphologies similar to those of the approximately
contemporaneous paleosols of the lower Moodies Group. They formed pedogenic to
early diagenetic under similar conditions. Moodies nodules are therefore an
excellent Earth analog for the formation of the Sheepbed nodules on Mars. The
S-isotope data, documenting the involvement of biogenic processes in the
formation of the Moodies nodules, strengthens the case for the possibility of
extraterrestrial life on Mars. Although Martian pyrite grains and their
S-isotopic composition cannot be analyzed using the technical instrumentation
of Curiosity, their possible existence and isotopic composition should be of
high scientific interest.Paleoböden sind hervorragend geeignet, um physikalische und chemische Prozesse
an der Schnittstelle zwischen Gestein, Atmo-, Hydro- und BiosphÀre zu
dokumentieren; sie dienen als Informationsspeicher der Vergangenheit.
Archaische Paleoböden sind aufgrund von Deformation, Metamorphose und
limitierter AufschlĂŒsse schwer zu erkennen und zu charakterisieren. Gut
erhaltene palaeoarchaische, terrigene Abfolgen sind derzeit lediglich aus dem
Pilbara Block, Nordwest-Australien, und dem Barberton Greenstone Belt (BGB) im
sĂŒdlichen Afrika bekannt. Diese Arbeit beschreibt kartierbare,
frĂŒhdiagenetische bis pedogene Konkretionen, die sich in Sanden fluviatiler
KĂŒstenebenen der ~3.22 Ga alten Moodies-Gruppe des BGB in SĂŒdafrika bildeten.
Sie treten stratiform, teilweise gesteinsbildend auf und bestehen aus
Megaquarz-Pseudomorphosen nach Gips, Baryt und Kalzit. Verwitterung von
FeldspÀten und tuffigem Material lieferte alkalische Kationen wie Ca2+ und
Ba2+ wÀhrend Karbonat wahrscheinlich durch Silikatverwitterung mafischer
Vulkanite im Kontakt zur CO2-reichen AtmosphÀre entstand. Das
Konkretionswachstum war dominiert von saisonalen Fluktuationen des
Grundwasserspiegels unter evaporitischen Bedingungen. Die Konkretionen
reprÀsentieren die Àltesten bisher bekannten terrestrischen Evaporite. Ihre
Entstehung und Zusammensetzung belegen das lokale Auftreten von Sulfat in der
archaischen Atmo- und HydrosphÀre, ihre Wechselwirkung mit der entstehenden
BiosphÀre, dem Verwitterungsregime, dem lokalen Klima und der Hydrodynamik der
vadosen Zone. Die Konkretionen sind mit mm- dĂŒnnen, ĂŒberwiegend aus Pyrit
bestehenden Schwerminerallaminae wechselgelagert. Diese Pyrite zeigen
gerundete, durch PorenwÀsser korrodierte, detritische Kerne, und idiomorphe
AnwachssÀume, welche unter reduzierenden Bedingungen entstanden. Die
Spurenelement-Gehalte (Ni und Co) und Ύ34S VerhÀltnisse der SÀume
unterscheiden sich deutlich von denen der Kerne. WĂ€hrend die Kerne niedrige
Co- und Ni-Gehalte zeigen, enthalten die SĂ€ume bis zu 5,5 Gew.-% dieser
Elemente. In-situ Schwefelisotopen- Analysen der Kerne zeigt ÎŽ34SVCDT Werte
zwischen +5â° und -5â°, wĂ€hrend die SĂ€ume Werte zwischen -20â° und -24.5â°
aufweisen und damit auf biogene Fraktionierung des Schwefels hindeuten. Die
rÀumliche NÀhe und fast zeitgleiche Entstehung pedogener Sulfate und
sekundÀren Pyrits deutet auf mikrobielle Schwefel-verarbeitung in den
PalÀoböden hin, und zeigt, dass bodenbildende Prozesse im Archaikum nicht nur
physikalische und chemische, sondern auch biogene VerÀnderungen umfassten.
Mikrobielles Leben war in den terrestrischen AblagerungsrÀumen vor 3.2 Ga
bereits fest verankert. Die ~3.3-3.2 Ga alte Sheepbed-Lage der Yellowknife Bay
Formation (Gale Crater, Mars) enthÀlt mehrere diagenetische Ausbildungen,
unter denen die Sheepbed Nodules als frĂŒhdiagenetisch gelten. Die Nodules
haben (Ă€hnlich zu den Konkretionen der Moodies Gruppe) drei morphologisch
unterschiedliche AusprĂ€gungen: massiv, hohl und hohl, aber gefĂŒllt. In beiden
Orten entstanden sie pedogen bis frĂŒhdiagenetisch unter Ă€hnlichen Bedingungen.
Die Moodies-Konkretionen sind deshalb ein exzellentes Erd-Analog fĂŒr die
Sheepbed Nodules auf dem Mars. FrĂŒhdiagenetischer Pyrit, der mit diesen
Nodules, assoziiert sein könnten, ist mit der instrumentellen Ausstattung von
Curiosity nicht belegbar. Seine Isotopie wÀre analog zur Moodies-Gruppe, von
hohem wissenschaftlichen Interesse
In situ S-isotope compositions of sulfate and sulfide from the 3.2 Ga Moodies Group, South Africa: A record of oxidative sulfur cycling
Sulfate minerals are rare in the Archean rock record and largely restricted to the occurrence of barite (BaSO4). The origin of this barite remains controversially debated. The mass-independent fractionation of sulfur isotopes in these and other Archean sedimentary rocks suggests that photolysis of volcanic aerosols in an oxygen-poor atmosphere played an important role in their formation. Here, we report on the multiple sulfur isotopic composition of sedimentary anhydrite in the ca. 3.22Â Ga Moodies Group of the Barberton Greenstone Belt, southern Africa. Anhydrite occurs, together with barite and pyrite, in regionally traceable beds that formed in fluvial settings. Variable abundances of barite versus anhydrite reflect changes in sulfate enrichment by evaporitic concentration across orders of magnitude in an arid, nearshore terrestrial environment, periodically replenished by influxes of seawater. The multiple S-isotope compositions of anhydrite and pyrite are consistent with microbial sulfate reduction. S-isotope signatures in barite suggest an additional oxidative sulfate source probably derived from continental weathering of sulfide possibly enhanced by microbial sulfur oxidation. Although depositional environments of Moodies sulfate minerals differ strongly from marine barite deposits, their sulfur isotopic composition is similar and most likely reflects a primary isotopic signature. The data indicate that a constant input of small portions of oxidized sulfur from the continents into the ocean may have contributed to the observed long-term increase in Î33Ssulfate values through the Paleoarchean
In situ S-isotope compositions of sulfate and sulfide from the 3.2 Ga Moodies Group, South Africa: A record of oxidative sulfur cycling
Sulfate minerals are rare in the Archean rock record and largely restricted to the occurrence of barite (BaSO4). The origin of this barite remains controversially debated. The mass-independent fractionation of sulfur isotopes in these and other Archean sedimentary rocks suggests that photolysis of volcanic aerosols in an oxygen-poor atmosphere played an important role in their formation. Here, we report on the multiple sulfur isotopic composition of sedimentary anhydrite in the ca. 3.22Â Ga Moodies Group of the Barberton Greenstone Belt, southern Africa. Anhydrite occurs, together with barite and pyrite, in regionally traceable beds that formed in fluvial settings. Variable abundances of barite versus anhydrite reflect changes in sulfate enrichment by evaporitic concentration across orders of magnitude in an arid, nearshore terrestrial environment, periodically replenished by influxes of seawater. The multiple S-isotope compositions of anhydrite and pyrite are consistent with microbial sulfate reduction. S-isotope signatures in barite suggest an additional oxidative sulfate source probably derived from continental weathering of sulfide possibly enhanced by microbial sulfur oxidation. Although depositional environments of Moodies sulfate minerals differ strongly from marine barite deposits, their sulfur isotopic composition is similar and most likely reflects a primary isotopic signature. The data indicate that a constant input of small portions of oxidized sulfur from the continents into the ocean may have contributed to the observed long-term increase in Î33Ssulfate values through the Paleoarchean