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Every year, tens of thousands of tons of cosmic dust accumulate at the Earth's surface, representing a continuation of the accretion process that started 4.57 billion years ago. The unique geochemical properties of these materials, compared to the Earth's surface, render them excellent tracers of Solar System, atmospheric, oceanographic, and geolog...
A reconstruction of seawater 187Os/188Os ratios during the late Eocene (∼36–34 Ma), based upon bulk sediment analyses from the sub-Antarctic Southern Atlantic Ocean (Ocean Drilling Program (ODP) Site 1090), Eastern Equatorial Pacific Ocean (ODP Sites 1218 and 1219) and the uplifted (land-based) Tethyan section (Massignano, Italy), confirms that the...
The few previously reported values of 187Os/188Os ratios from non-marine K–Pg boundary sections are distinctly higher than the range of 187Os/188Os ratios measured in chondrites and the range of ratios predicted by models of physical mixing between chondrites and upper crust. Here, Re–Os data from the West Bijou continental K–Pg boundary site, loca...
About a quarter of all meteorites falling on Earth today originate from the breakup of the L-chondrite parent body ∼470 Ma∼470 Ma ago, the largest documented breakup in the asteroid belt in the past ∼3 Ga∼3 Ga. A window into the flux of meteorites to Earth shortly after this event comes from the recovery of about 100 fossil L chondrites (1–21 cm in...
The Re-Os and major element geochemistry of an expanded gray shale
sequence from the Central Basin in Spitsbergen, Svalbard Archipelago
(Norway) over the Paleocene Eocene Thermal Maximum (PETM) is presented.
The data suggest that a significant volcanic episode, as indicated
primarily by a large drop in 187Os/188Os, occurred
just prior to or coincid...
The geochemical nature of the impactites from International Continental
Scientific Drilling Project—El'gygytgyn lake drill core 1C is
compared with that of impact melt rock fragments collected near the
western rim of the structure and literature data. Concentrations of
major and trace elements, with special focus on siderophile metals Cr,
Co, Ni, a...
[1] An impact-induced osmium (Os) isotope excursion provides a unique means of assessing the completeness of marine Cretaceous-Paleogene (K-Pg) boundary sections, and surmounting challenges associated with constraining the time scale of the Earth system recovery from this extreme perturbation. A model of the recovery of seawater187Os/188Os followin...
Osmium, an ultra-trace element in seawater, is subject to strong authigenic enrichment in reducing marine sediments, and to a lesser degree of enrichment in oxic marine deposits. Temporal variations in sedimentary 187 Os/ 188 Os ratio preserve a rich archive from several types of deposi-tional environments that reflect changes on the Earth's surfac...
A simple, rapid method for the determination of Re and Os concentrations and isotope compositions using isotope dilution multi-collector inductively coupled plasma-mass spectrometry (ID-MC-ICP-MS) combined with Carius tube digestion and sparging introduction of Os was developed. For Os measurement, four channeltron ion counters to detect different...
Formation and emplacement constraints for a continuous section of
impactites and traces of the impacting projectile from trace-element
data (platinum-group elements and Os-isotopes) in drill core samples
from El’gygytgyn crater.
The Early Cretaceous Greater Ontong Java Event in the Pacific Ocean may have covered ca. 1% of the Earth's surface with volcanism. It has puzzled scientists trying to explain its origin by several mechanisms possible on Earth, leading others to propose an extraterrestrial trigger to explain this event. A large oceanic extraterrestrial impact causin...
Osmium isotope composition (187Os/188Os) and concentrations of Os, Ir and Pt are reported for an early Pleistocene section from the ODP Site 849 in the eastern equatorial Pacific. Using the data obtained in this study, the contributions from detrital and extraterrestrial particulate matter to Os concentration and 187Os/188Os of sediment are estimat...
The Letters by Archibald et al. , Keller et al. , and Courtillot and Fluteau question our conclusion that the Cretaceous-Paleogene mass extinction was caused by the asteroid impact at Chicxulub. All three Letters stress that Deccan flood basalt volcanism played a major role in the extinction. Keller
Oceanic anoxic events (OAE's) represent global marine deposition of organic carbon-rich sediments attributed by many workers to the emplacement of Large Igneous Provinces [e.g., 1-3]. In particular, the 121-125 Ma eruption of Ontong Java Plateau (OJP) has been linked to OAE1a due to their temporal coincidence [4,5]. Two end-member models, plume vs....
The Cretaceous-Paleogene boundary ~65.5 million years ago marks one of the three largest mass extinctions in the past 500
million years. The extinction event coincided with a large asteroid impact at Chicxulub, Mexico, and occurred within the time
of Deccan flood basalt volcanism in India. Here, we synthesize records of the global stratigraphy acro...
The hypothesis that an extraterrestrial (ET) impact as a triggering mechanism for the abrupt Bølling-Allerød/Younger Dryas climatic transition, the North American megafaunal extinction and the demise of the Clovis culture still remains controversial. Reports of elevated iridium concentrations (> several ng/g) measured in magnetic grains and bulk se...
Although numerous studies have reported variations in the marine 187Os/188Os record associated with recent glacial cycles, little to no work has been done to investigate high frequency variability in the marine Os isotope record beyond the last 200 kyr. A recent high resolution bulk sediment Os record from ODP Site 849 in the Eastern Equatorial Pac...
Physical and chemical weathering responses to changes in temperature at the Earth's surface are strongly debated, yet are critical to understanding the long-term effects of global climate change. One manner of studying such relationships is to use geochemical proxies of weathering (such as osmium isotopes) to examine periods of climate change in th...
High concentrations of iridium have been reported in terrestrial sediments dated at 12.9 ka and are interpreted to support an extraterrestrial impact event as the cause of the observed extinction in the Rancholabrean fauna, changes in the Paleoindian cultures, and the onset of the Younger Dryas cooling [Firestone RB, et al. (2007) Proc Natl Acad Sc...
A composite late Maastrichtian (65.5 to 68.5 Ma) marine osmium (Os) isotope record, based on samples from the Southern Ocean (ODP Site 690), the Tropical Pacific Ocean (DSDP Site 577), the South Atlantic (DSDP Site 525) and the paleo-Tethys Ocean demonstrates that subaerially exposed pelagic carbonates can record seawater Os isotope variations with...
The large-volume eruption and the short-period of emplacement shown by the geochronological, geological, and geophysical studies of the Ontong Java Plateau (OJP) require some explanation beyond what is already known from plate tectonic processes. Plume impact, bolide impact, and their variants have been proposed to account for the origin of these f...
Results from several studies indicate that the eruption of large igneous provinces (LIPs), both continental flood basalts and oceanic plateaus, is associated with shifts toward lower 187Os/188Os ratios in the marine Os isotope record. These isotope excursions are significant because they serve as chemostratigraphic markers of volcanism in the marin...
Variations in the marine Os isotope record have been reconstructed based on more than 150 analyses of sediments from 4 locations: the South Atlantic (DSDP 525); the Southern Ocean (ODP 690C); the Equatorial Pacific (DSDP 577) and the Tethys (Bottaccione Section in Gubbio, Italy). All records show 187Os/188Os values close to 0.6 throughout most of m...
The known temporal relationship between the benthic foraminiferal delta 18O record and the marine Os isotope record is used to reinterpret the absolute chronology and paleoceanographic context of an episode of organic carbon burial on the West African margin Ocean Drilling Program (ODP) Site 959. Although organic-rich sediments require significant...
Decreases in the seawater 187Os/188Os ratio caused by the impact of a chondritic meteorite are indicative of projectile size, if the soluble fraction of osmium carried by the impacting body is known. Resulting diameter estimates of the Late Eocene and Cretaceous/Paleogene projectiles are within 50% of independent estimates derived from iridium data...
The Dufek layered mafic intrusion in the Pensacola Mts. and Basement Sill in the Dry Valleys of southern McMurdo Sound are part of the Ferrar large igneous province (FLIP), emplaced in a Paleozoic mobile belt developed adjacent to the East Antarctic Craton during the Mid Jurassic. Zircon, baddeleyite and rutile U-Pb dating shows that emplacement oc...
Paired analyses of Os isotope composition and concentration of bulk sediment and leachable Os in a metalliferous pelagic clay sequence from the North Pacific, ODP Site 886C, are used to reconstruct the marine Os isotope record and the particulate meteoritic Os flux between 65.5 and 78 Ma. Measured 187Os/188Os of bulk sediments ranges from approxima...
Analyses of Os concentrations and ^{187}Os/^{188}Os ratios performed on bulk sediment samples from ODP 690C in the Weddell Sea yield the highest resolution marine Os isotope record available for the Maastrichtian. Comparison of this record to coeval data from Shatsky Rise (DSDP 577) and Walvis Ridge (DSDP 525) suggests three insights on the use of...
Organic-rich sediments of Eocene to Oligocene age, deposited under anoxic to moderately reducing conditions from the Ocean Drilling Program (ODP) Site 959 on the continental margin of the Cote d'Ivoire- Ghana were investigated in order to empirically test the fidelity of organic-rich marine sediments as recorders of past seawater Os isotope variati...
New osmium (Os) isotope and platinum group element (PGE) concentration data are used in conjunction with published 3He and Th isotope data to determine the relative proportions of lithogenic, extraterrestrial and hydrogenous iridium (Ir) in a Pacific pelagic carbonate sequence from the Ocean Drilling Program (ODP) Site 806 on the Ontong Java Platea...
High resolution records (ca. 100 kyr) of Os isotope composition (187Os / 188Os) in bulk sediments from two tropical Pacific sites (ODP Sites 1218 and 1219) capture the complete Late Eocene 187Os / 188Os excursion and confirm that the Late Eocene 187Os / 188Os minimum, earlier reported by Ravizza and Peucker-Ehrenbrink [Earth Planet. Sci. Lett. 210...
The Basement Sill in the Dry Valleys of southern McMurdo Sound is part of a sill complex interconnected by dikes, emplaced in a Paleozoic mobile belt developed adjacent to the East Antarctic craton. This complex of sills is linked both geochemically and spatially to intrusive, hypabyssal and volcanic rocks of the Ferrar Magmatic Province (FMP), a M...
The marine Osmium isotope record has great potential as a tool for chemostratigraphic correlation, and as a proxy for tracking changes in inputs to seawater. In order to evaluate the utility of this record for correlation, 45 analyses have been performed on sediment samples from the Eocene-Oligocene (E-O) section of the equatorial Pacific (Leg 199,...
In this review emphasis is placed on isotopic records of ocean chemistry. In general terms, a conscious decision was made to emphasize those records that document long-term changes in the chemical and physical properties of the global ocean over the course of the Cenozoic. For example, while reconstructions of burial fluxes of barium or phosphorus...
The elemental concentration pattern for the platinum group elements (PGEs), and their periodic table neighbors Au and Re in modern seawater, is highly fractionated relative to their proportions in the upper continental crust, mantle or meteorites. This may be due to a combination of factors, including chemical weathering and estuarine fractionation...
Continental flood basalt (CFB) volcanism is hypothesized to have played a causative role in global climate change and mass
extinctions. Uncertainties associated with radiometric dating preclude a clear chronological assessment of the environmental
consequences of CFB volcanism. Our results document a 25% decline in the marine 187Os/188Os record tha...
Osmium (Os) isotope analyses of bulk sediments from the South Atlantic, Equatorial Pacific, and the Italian Apennines yield a well-dated and coherent pattern of 187Os/188Os variation from the late Eocene to the early Oligocene. The resulting composite record demonstrates the global character of two prominent features of the low-resolution LL44-GPC3...
Osmium and other platinum-group elements (PGEs) have been measured in sediments accumulating directly under the Rainbow hydrothermal plume at 36°N on the Mid-Atlantic Ridge. 187Os/188Os and PGE concentrations in the sediments of four cores taken 2-25 km from the active vent site reveal evidence of both radiogenic Os scavenged from seawater and, imp...
Concern has recently emerged over the release of platinum from automobile catalysts and increasing environmental concentrations. The history of platinum deposition is followed through the natural incorporation of pollutants into the sediment record of the Upper Mystic Lake. Platinum was determined by ICP-MS in dated sediments. Platinum concentratio...
Osmium (Os) isotope analyses of bulk sediments from the South Atlantic (DSDP 522), Equatorial Pacific (DSDP 574C), and the Italian Apennines yield a coherent pattern of 187Os/188Os variation across the Eocene-Oligocene transition. This record has potentially important implications for our understanding of (1) the causative factors responsible for t...
Several recent studies have highlighted the potential of using authigenic Re enrichments in marine sediments, in conjunction with other trace metals, to constrain paleo-redox conditions. Specifically Re is strongly enriched in sediments deposited under reducing conditions. Interpreting the sedimentary records of authigenic Re enrichment is complica...
Data on the volume-age relationship of gray and black shales in North and Central America (Cook and Bally, 1975; Berry and Wilkinson, 1994) are used to define their mean age (190 Myr) and, by extrapolation, their total global mass on the continents at 4.1 x 1020 kg. New data on the area-age relationship of Tertiary-Cambrian sedimentary bedrock in t...
Umbers from 8 of 11 localities studied yield 187Os/188Os ratios that range from 0.51 to 0.57. We interpret this range as reflecting the Os isotopic composition of mid-Cretaceous seawater. 187Os/188Os measured in samples from the remaining three localities fall above and below this range and are believed to result from post-depositional redistributi...
In the latest Paleocene an abrupt shift to more negative delta13C values has been documented at numerous marine and terrestrial sites [Bralower et al., 1997; Cramer et al., 1999; Kaiho et al., 1996; Kennett and Stott, 1991; Koch et al., 1992; Stott et al., 1996; Thomas and Shackleton, 1996; Zachos et al., 1993]. This carbon isotope event (CIE) is c...
Sr isotopic variations in vent fluids from six high-temperature hydrothermal vents from between 9°46′N and 9°54′N on the East Pacific Rise are reported. The Mg/Sr-87Sr/86Sr systematics of one vent, Biovent, require the presence of a fluid component that has experienced significant Mg depletion (≈50%), but has undergone very little Sr exchange with...
The 65 Ma Chicxulub impact is known to have triggered large submarine
slope failures near the crater in the Gulf of Mexico and Caribbean. Here
we show that the impact also precipitated massive submarine failure of
the continental margin around the western North Atlantic. We have
identified mass-flow deposits containing impact ejecta of
Cretaceous-P...
Over the past decade the marine osmium isotope record has been developed into a new tracer in palaeoceanographic research. Several analytical developments, particularly in the past few years, have significantly increased our ability to study the behaviour of osmium in the surficial environment. The ¹⁸⁷Os/¹⁸⁸Os and osmium concentration of seawater,...
We present osmium isotopic compositions and Os, Re and platinum-group element (PGE) contents in the lower oceanic crust gabbros from ODP Site 735B on the Southwest Indian Ridge. The average gabbros are very depleted in PGEs, e.g. the Os concentrations are very low and range from 0.5 to 38 ppt. One troctolite sample is an exception, containing, e.g....
We reevaluate the effects of sampling artifacts on estimates of the flux of cosmic dust to Earth by modeling the population of extraterrestrial particles as a function of surface–area and time–interval sampled. Results from a Monte Carlo simulation for nonvolatile tracers such as Os and Ir indicate that samples corresponding to ≥2.5 m2a adequately...
We present a method for the rapid determination of Os isotopic compositions and platinum group element (PGE) concentrations using ICP-MS on the same sample split. The method makes use of transfer of volatile OsO4 by an Ar gas stream into the torch of a magnetic sector ICP-MS for analysis. A variety of partial or complete sample dissolution methods...
Anthropogenic activity has increased recent sediment concentrations of Pt and Pd in Boston Harbor by approximately 5 times background concentrations. Surface sediments and downcore profiles were investigated to evaluate Pt and Pd accumulation and behavior in urban coastal sediments. There is no clear correlation between temporal changes in Pt and P...
The major element, rare earth element, and platinum-group element
chemistry of the Margi umbers have been investigated in order to
evaluate these sediments as recorders of past variations in the Os
isotopic composition of seawater. Because of the compositional
similarity of the Margi umbers to metalliferous sediments and
hydrothermal-plume particle...
Os concentrations (6.6 to 9.8 pg/l) and isotopic compositions (mean 187Os/188Os = 1.067±0.011; 2σ error) were measured by a new method in seawater samples collected from the eastern Pacific Ocean. In contrast to recent work in the Indian Ocean, measured Os concentrations display a 30% depletion coincident with both the core of the oxygen minimum zo...
Particulate samples (>0.45 μm) from a neutrally buoyant hydrothermal plume at 9°45′N on the northern East Pacific Rise were collected using large volume in situ filtration and analyzed for Fe, Al, Mn, Ni, and fourteen rare earth elements (REE). The Sm/Fe ratio (a proxy for overall REE/Fe) and Nd/Er (light/heavy REE fractionation) increased moderate...
Analyses of Re, Os, and Ir concentrations, as well as Os-isotopic compositions, are reported for a suite of sediments from Ocean Drilling Program Site 959. These samples vary in age from late Neogene to Late Cretaceous, and represent a range in depositional oxidation-reduction conditions from suboxic in the Neogene to anoxic in the Late Cretaceous....
Seawater 187 Os/ 188 Os ratios for the Middle Miocene were reconstructed by measuring the 187 Os/ 188 Os ratios of metalliferous carbonates from the Pacific (DSDP 598) and Atlantic (DSDP 521) oceans. Atlantic and Pacific 187 Os/ 188 Os measurements are nearly indistinguishable and are consistent with previously published Os isotope records from Pac...
Knowledge of the composition of the lower continental crust is important for understanding the formation and evolution of the crust as a whole, and the petrogenesis of continental basalts. Here we present rhenium - osmium isotope data for two well characterized suites of lower-crustal xenoliths from North Queensland, Australia, which have average m...
We have modified methods currently used to determine Os isotope ratios with NiS fire assay preconcentration to allow measurement of PGE concentrations and Os isotope ratios on the same sample powder. Samples are spiked with an isotopically enriched solution of Pt, Pd, Ir and Os prior to fusion. After filtration of the insoluble residue resulting fr...
High concentrations of osmium (Os) and silver (Ag) and low 187Os/186Os ratios in Boston sewage make these elements sensitive tracers of the influence of sewage on marine sediments in Massachusetts and Cape Cod bays. Pristine marine sediments have Ag concentrations more than 200 times lower than sewage sludge, Os concentrations 10–40 times lower, an...
The isotopic composition of osmium (Os) in continental surface waters and shallow ground waters has been determined by analyzing fresh-water Fe-Mn nodules and bog ores. The isotopic composition of the continental runoff from the Precambrian Baltic shield is much more radiogenic (187Os/186Os = 31.2 65.4) than the runoff from the Phanerozoic sediment...
Os isotopic analyses of a suite of samples from the TAG hydrothermal area, 26°N on the Mid-Atlantic Ridge, reveal evidence of release of ocean crust-derived Os to seawater and removal of seawater-derived Os to the seafloor. ratios of sulfide samples from the active TAG mound vary between 8.7 and 1.3. The highest ratios are indistinguishable from th...
In an attempt to confirm the proposed dependency of bio-Ba fluxes to the seafloor on dissolved Ba concentrations in seawater additional data on organic carbon and bio-Ba fluxes in the deep sea have been compiled. These data confirm Dymond et al.'s findings that settling particles have significantly higher Corg/bio-Ba in the western Atlantic compare...
We report new187Os/186Os data and Re and Os concentrations in metalliferous sediments from the Pacific to construct a composite Os isotope seawater evolution curve over the past 80 m.y. Analyses of four samples of upper Cretaceous age yield187Os/186Os values of between 3 and 6.5 and187Re/186Os values below 55. Mass balance calculations indicate tha...
Compiles modern Corg/bio-Ba data from Equat- to -N. Atlantic and Equat.- to N. Pacific sites. Demonstrates that the ratio is not a function of dissolved Ba. Instead argues that High ratio values reflect input from terrigenous Corg or resuspended shelf sediment. This is so because Barite formation is believed to develop in microenvironments around d...
The osmium concentration and isotopic composition of metalliferous sediments from the East Pacific Rise (EPR) and Bauer Basin have been determined. 187 Os / 186 Os ratios range from 7.9 to 8.6, with EPR samples between 8.4 and 8.6, and Bauer Basin samples between 7.9 and 8.2. The osmium isotopic composition of EPR samples is indistinguishable from...
The Os concentration and isotopic composition of metalliferous carbonates deposited on the East Pacific Rise over the past 28 Ma are reported with complimentary Sr isotope data. Variations in the Os isotopic composition of these samples are interpreted as a record of past changes in the Os isotopic composition of seawater. These results are consist...
Rhenium (Re) is one of a suite of elements (including uranium and molybdenum) that display conservative behavior in seawater and are enriched in anoxic sediments. The decay of187Re to187Os provides a geochronometer in ancient sedimentary rocks and gives rise to Os-isotopic variations in nature. In order to better characterize its sources to seawate...
The variation of sea water 187Os/186Os during the Cenozoic has been determined by analyzing the hydrogenous Os released by acidic hydrogen peroxide leaching of layers in an abyssal North Pacific pelagic clay core. Overall, sea water 187Os/186Os has increased from 3.2 at 58 Ma to the present-day value of ∼ 8.6. This pattern is similar to the well-kn...
The osmium (Os) concentration and187Os/186Os ratio of several recent, marine, organic-rich sediment samples from three widely separated sites have been measured. Os concentrations range from 0.095 to 0.212 ppb and187Os/186Os ratios range from 8.2 to 8.9. The calculated fraction of hydrogenous Os exceeds 78% in all samples. Thus, the187Os/186Os rati...
The Os isotopic composition of recent sediments from the Black Sea are reported with the concentrations of Re, Os, and major and minor elements. Osmium concentrations range from 0.23 to 0.69 ppb and Re concentrations range from 21 to 85 ppb. Concentrations of both elements are large relative to average crustal material and are positively correlated...
The decay of 187Re to 187Os provides a tool for determining depositional ages of black shales. Re and Os concentrations and Os isotopic compositions of whole rock samples of the Bakken Shale, a Mississippian/Devonian boundary black shale, yield a whole rock isochron with an age of 354 ± 49 Ma. This age is in agreement with the accepted age of the B...
Researchers at Yale has approached the problem of the osmium isotopic composition of marine deposits formed in contact with both oxidized and reduced bottom waters. The measured (187) Os/(186) Os ratios of modern bulk sediment can be explained using mixing equations involving continental detrital, volcaniclastic, cosmogenic and hydrogeneous compone...