Papers by TERUYUKI MARUOKA
Mass Extinction at the Cretaceous–Paleogene (K–Pg) Boundary
Astrobiology, 2019
One of the “Big Five” mass extinctions in the Phanerozoic Eon occurred at the Cretaceous–Paleogen... more One of the “Big Five” mass extinctions in the Phanerozoic Eon occurred at the Cretaceous–Paleogene (K–Pg) boundary (66.0 million years ago). The K–Pg mass extinction was triggered by a meteorite impact that produced a crater at Chicxulub on the Yucatan Peninsula, Mexico. The following environmental perturbations might have been induced by the Chicxulub impact and acted as the killing mechanisms for the K–Pg mass extinction: (1) sunlight shielding, (2) sulfuric and nitric acid rain, (3) CO2-induced global warming, (4) ultraviolet penetration, and (5) toxic effects of ground-level ozone. The details of these perturbation events are summarized in this chapter. Based on evidence in sedimentary rocks, we could confirm whether such perturbation events occurred or not. However, it was difficult to reconstruct quantitatively the magnitudes and durations for such perturbation events because the necessary time-resolved information (yearly to millennium-scale) is lacking.
Journal of the Mass Spectrometry Society of Japan, 2014
Stable isotope studies for paleoenvironmental reconstruction are reviewed. Mass spectrometry has ... more Stable isotope studies for paleoenvironmental reconstruction are reviewed. Mass spectrometry has been an essential technique for these types of studies. e target elements, such as carbon, sulfur, and nitrogen, are converted into gaseous species, CO 2 , SO 2 , and N 2 , respectively. e gaseous products are then introduced into the mass spectrometer and their isotopic compositions are determined. Two types of gas inlet systems dual-inlet and continuous ow has been proposed for isotope analyses. Continuous-ow isotope ratio mass spectrometry CF-IRMS is a more recent development compared to the dual inlet system. e dual inlet system requires high-purity sample gases prepared o ine, whereas the CF-IRMS system introduces sample gases prepared in a continuous ow of helium to the mass spectrometer a er separation by gas chromatography. e continuous ow technique has signi cant advantages over dual inlet in terms of a higher sensitivity and shorter analysis time. e precision of isotope analysis by CF-IRMS is believed to be lower than that of the o-line dual inlet system, but a high-precision, similar to that obtained using o-line methods, has been achieved recently, even for CF-IRMS. e present paper describes research on the Cretaceous Paleogene K Pg mass extinction event as an example of reconstructing paleoenvironments using light stable isotope compositions.
Precambrian Research, 2016
The Trans-North China Orogen (TNCO) represents one of the major Paleoproterozoic collisional orog... more The Trans-North China Orogen (TNCO) represents one of the major Paleoproterozoic collisional orogens across the central part of the North China Craton. Here we investigate the meta-carbonates (marbles and calc-silicate rocks) from the Fuping and Zanhuang Complexes in the TNCO through a combination of detrital zircon U-Pb geochronology, geochemistry and stable isotopes (carbon and oxygen). The U-Pb ages obtained from detrital zircons in both sequences show age populations of 2.50-2.57 Ga, 2.2-2.4 Ga, 2.0-2.1 Ga and 1.85-1.90 Ga. The depositional age for the Wanzi Group in the Fuping Complex is further constrained as 1.95-1.93 Ga and the Central Zanhuang Domain (Zanhuang Complex) as 2.03-1.90 Ga. All samples show nearly flat REE patterns below the concentration level of 1 in the shale-normalized REE distribution diagram. The dolomite-calcite marbles from the Fuping Complex have δ 13 C values ranging from-0.31 ‰ to 3.65 ‰ and δ 18 O values vary from-9.12 ‰ to-2.96 ‰. The calc-silicate rocks from the Fuping Complex show wide variation of δ 13 C (-1.56 ‰ to 3.30 ‰) and δ 18 O (-12.89 ‰ to-5.84 ‰). Dolomite marbles from the Zanhuang Complex show low δ 13 C and δ 18 O values ranging from-3.31 ‰ to-3.69 ‰ and-12.98 ‰ to-13.59 ‰. The dolomite-calcite marbles from the Zanhuang Complex display δ 13 C and δ 18 O compositions of-2.68 ‰ to 1.44 ‰ and-11.77 ‰ to-7.76 ‰, respectively. The correlations between the isotopic results (δ 13 C and δ 18 O) and geochemical compositions (Mn, Sr, Mn/Sr, Mg/Ca, Ca/Sr and Fe/Sr) 3 suggest that the dolomite marbles from the Zanhuang Complex are strongly disturbed and the calc-silicate rocks are moderately affected by the post-depositional processes. The salient lithological, geochemical and isotopic features imply that the protoliths of the meta-carbonates were formed in a proximal and shallow marine environment. The Wanzi Group was deposited in a forearc basin and the Central Zanhuang Domain was formed in a back-arc basin. The geochemical imprints and biospheres of the oceanic basin in the Fuping area were possibly affected by the Lomagundi or Jatulian Event, resulting in the positive excursion of δ 13 C values in the dolomite-calcite marbles. However, the back-arc basin in the Zanhuang area was formed after the 2.1-2.0 Ga rifting event, thus it was generated after the Jatulian Event, thus preserving normal δ 13 C values of marine carbonates.
Journal of Groundwater Hydrology, 2010
Nonlinear Processes in Geophysics, 2015
In order to refine our understanding of how fluid inclusions were trapped in the host minerals, w... more In order to refine our understanding of how fluid inclusions were trapped in the host minerals, we nondestructively observed mercury inclusions (liquid Hg 0) in quartz samples using X-ray computed tomography (CT) technique. The X-ray CT apparatus can observe internal structures of the samples and give cross-sectional images from the transmission of the X-rays through the samples. From the cross-sectional images, we obtained threedimensional spatial distributions of mercury inclusions, and quantitatively analyzed them using fractal and multifractal methods. Although the samples were from different geological settings, the resultant fractal dimensions were 1.70 and 1.71 for the San Benito and Itomuka samples, respectively. The fractal dimensions were also close to those predicted by diffusion-limited aggregation models and percolation theory, which are controlled by the irreversible kinetics. Given the fractal dimension and its implied mechanism, we conclude that the mercury-bearing fluids were not primary fluid inclusions, but migrated into the pre-existing cracks of quartz crystals by diffusion processes.
Scientific reports, Jan 9, 2015
Evaluation of volcanic and hydrothermal fluxes to the surface environments is important to elucid... more Evaluation of volcanic and hydrothermal fluxes to the surface environments is important to elucidate the geochemical cycle of sulphur and the evolution of ocean chemistry. This paper presents S/(3)He ratios of vesicles in mid-ocean ridge (MOR) basalt glass together with the ratios of high-temperature hydrothermal fluids to calculate the sulphur flux of 100 Gmol/y at MOR. The S/(3)He ratios of high-temperature volcanic gases show sulphur flux of 720 Gmol/y at arc volcanoes (ARC) with a contribution from the mantle of 2.9%, which is calculated as 21 Gmol/y. The C/S flux ratio of 12 from the mantle at MOR and ARC is comparable to the C/S ratio in the surface inventory, which suggests that these elements in the surface environments originated from the upper mantle.
Catastrophic events and mass extinctions: impacts and beyond, 2002
Isotopic compositions of sulfur and concentrations of sulfur and carbon have been measured for se... more Isotopic compositions of sulfur and concentrations of sulfur and carbon have been measured for sedimentary rocks across terrestrial Cretaceous-Tertiary (K-T) boundary successions that originated from flood-plain and backswamp environments. Organic carbon contents are relatively constant below the boundary (26 cm for the Dogie Creek section and 9 cm for the Brownie Butte section), but change abruptly at the K-T boundary. At the K-T event, a high input of sulfate to the freshwater wetlands might have resulted from the melt ejecta and/or acid rain. We interpret the low ratio of organic C to nonorganic S at the melt ejecta layer and sulfur isotopic data as consistent with this hypothesis; however, additional analyses across a thicker interval are necessary to rule out alternative hypotheses.
We analyzed noble gases in acid residues extracted from the Canyon Diablo iron meteorite by densi... more We analyzed noble gases in acid residues extracted from the Canyon Diablo iron meteorite by density and colloidal separation. The results do not indicate any significant variation among the samples although spallogenic noble gases were effectively removed by the treatment. The isotopic composi tions of the heavy noble gases are close to those of the terrestrial atmosphere, suggesting that the samples were seriously contaminated by atmospheric noble gases during the treatment. However, the Ne isotopic ratios fall between atmospheric Ne and planetary Ne, suggesting that the primordial component of the noble gases in carbonaceous material in Canyon Diablo is planetary rather than solar.
Geochemical study of arsenic and other trace elements in groundwater and sediments of the Old Brahmaputra River Plain, Bangladesh
Environmental Earth Sciences, 2009
... Faruque Ahmed Æ M. Hawa Bibi Æ Hiroaki Ishiga Æ Takehiko Fukushima Æ Teruyuki Maruoka ... Gro... more ... Faruque Ahmed Æ M. Hawa Bibi Æ Hiroaki Ishiga Æ Takehiko Fukushima Æ Teruyuki Maruoka ... Groundwaters from tube wells are characterized by pH of 6.47.4, dissolved oxygen (DO) of 0.81.8 mg/l, Ca contents of 550 mg/l, and Fe contents of 0.212.9 mg/l. Arsenic ...
We have prepared a new sample of the "floating fraction" of the Allende meteorite and have analyz... more We have prepared a new sample of the "floating fraction" of the Allende meteorite and have analyzed the elemental and isotopic compositions of the noble gases to examine the properties of the separation technique. The "fl oating fraction" is the black fine material, which fl oats on the water during freeze-thaw disaggregation. The floating fraction separated in this study was enriched in noble gases, and its isotopic compositions were very similar to those of chemical residues. We thus confi rmed that the physical separation is an effective method to obtain a noble-gas-rich fraction than the chemical treatment. The only major difference between our fl oating fraction and those previously prepared was that the former had small excesses in 40 Ar and 129Xe which were supposed to be due to the contamination from small amounts of silicate like sodalite. There were some variations in the Xe-Q/Xe-HL ratios among floating fractions, suggesting that Q-and HL-components might be separable by a physical process.
The Journal of Geology, 2008
Continuous sediment core samples and groundwater were collected in the northern part of Sonargaon... more Continuous sediment core samples and groundwater were collected in the northern part of Sonargaon, central Bangladesh, to document the hydrogeological constraints on As-contaminated aquifers. The study area spans the alluvial plain of the Old Brahmaputra River and a Pleistocene terrace, the Madhupur Tract. The Quaternary sequence comprises Plio-Pleistocene sand, Upper Pleistocene mud, and Holocene sand units. Highly As-contaminated groundwater (50-1000 μg/L) is found in the upper aquifer corresponding to the Holocene sand unit that underlies the alluvial plain, and plausibly appears to be closely related to the distribution of lenses of silt to fine sand. As-free (< 1 μg/L) groundwater only occurs within sediments coarser than medium sand. Highly As contaminated groundwater is characterized by low concentrations of Cland SO 4 2and high concentrations of NH 4 + , suggesting that the As is released in association with reduction of waters recharged during rainy season. The restricted occurrence of strongly As-contaminated (>100 μg/L) groundwater is associated with: 1) the intercalation of silt to fine sand lens in the Holocene sandy aquifer, 2) the stagnant condition of the aquifer along the buried valley, 3) the vertical infiltration of groundwater in close proximity to installed tubewells.
The Astrophysical Journal, 2008
We present C, N, O, Si, Al-Mg, K, Ca, and Ti isotopic analyses of seven high-density (ORG1f, $ 2:... more We present C, N, O, Si, Al-Mg, K, Ca, and Ti isotopic analyses of seven high-density (ORG1f, $ 2:02 2:04 g cm À3) graphite grains from Orgueil with 12 C/ 13 C ratios smaller than 20. The presence of 44 Ti in three of these grains indicates an origin in Type II supernovae (SNe). The 13 C excesses in these SNe grains, however, remain enigmatic. The remaining grains have extremely large Ca and Ti isotopic anomalies, some of which are much larger than those predicted for envelopes of asymptotic giant branch (AGB) stars. These anomalies in conjunction with low 12 C/ 13 C ratios can only be explained by pure nucleosynthetic He-shell components of AGB stars. Born-again AGB stars that experience a late He flash are able to explain the low 12 C/ 13 C ratios of some of the grains along with the presence of extreme enrichments in the Ca and Ti isotopes. This study indicates that high-density graphite grains have multiple stellar sources: SNe and born-again AGB stars, in addition to the previously established low-metallicity AGB stars.
Nature Communications, 2011
Early Palaeoproterozoic (2.5-2.0 billion years ago) was a critical phase in Earth's history, char... more Early Palaeoproterozoic (2.5-2.0 billion years ago) was a critical phase in Earth's history, characterized by multiple severe glaciations and a rise in atmospheric o 2 (the Great oxidation Event). Although glaciations occurred at the time of o 2 increase, the relationship between climatic and atmospheric transitions remains poorly understood. Here we report high concentrations of the redox-sensitive element os with high initial 187 os/ 188 os values in a sandstone-siltstone interval that spans the transition from glacial diamictite to overlying carbonate in the Huronian supergroup, Canada. Together with the results of Re, mo and s analyses of the sediments, we suggest that immediately after the second Palaeoproterozoic glaciation, atmospheric o 2 levels became sufficiently high to deliver radiogenic continental os to shallow-marine environments, indicating the synchronicity of an episode of increasing o 2 and deglaciation. This result supports the hypothesis that climatic recovery from the glaciations acted to accelerate the Great oxidation Event.
Abundance and isotopic composition of noble gases in metal and graphite of the Bohumilitz IAB iron meteorite
Meteoritics & Planetary Science, 2001
... Noble gas studies of minerals and inclusions of iron meteorites should be very useful in unde... more ... Noble gas studies of minerals and inclusions of iron meteorites should be very useful in understanding their origin. ... Noble gases in metal and graphite of the Bohumilitz IAB iron meteorite ... the half-life (T1/2) of tritium (1 2.3 year) is much shorter than the exposure age of Bohumilitz ...
Carbon Isotopic Compositions of Shock-produced Diamonds
In order to study the pressure effect on the isotopic fractionation between diamond and graphite,... more In order to study the pressure effect on the isotopic fractionation between diamond and graphite, we analyzed isotopic compositions of diamonds produced by shock experiments.
Geochimica et Cosmochimica Acta, 2006
Geochimica et Cosmochimica Acta, 2004
Carbon isotope data have been obtained for diamonds in diamondites (framesites, polycrystalline d... more Carbon isotope data have been obtained for diamonds in diamondites (framesites, polycrystalline diamond) of unknown origin (presumably from southern Africa), which contain minor amounts of garnet (plus rare clinopyroxene). The carbon isotope abundance ratios show wide inter-and intra-sample ranges. The ␦ 13 C variations of diamonds from diamondites with "peridotitic" or "eclogitic" garnets are indistinguishable from each other, with a range from Ϫ3.2 to Ϫ27.9‰, and a peak around Ϫ18‰, indicating a depletion in 13 C relative to most silicate-bearing single crystal diamonds. This 13 C depletion could have been produced by mass fractionation of C from an isotopically homogeneous mantle source in a CO -H fluid system. Fluids traveling between regions of varying redox conditions in the mantle could have provided the necessary vehicle. The variations of ␦ 13 C can be explained by different degrees of oxidation during the fluid/melt ascent.
Earth and Planetary Science Letters, 2013
The Paleoproterozoic (2.5-2.0 Ga) is one of the most important periods in Earth's history, and wa... more The Paleoproterozoic (2.5-2.0 Ga) is one of the most important periods in Earth's history, and was characterized by a rise in atmospheric oxygen levels and repeated (at least three) severe glaciations (the Huronian glaciations). In this study, we investigate redox conditions in the atmosphere and in shallowmarine environments immediately after the first Huronian glaciation based on the isotopic composition of Os, and the abundance of redox-sensitive elements (Os, Re, and Mo) in sedimentary rocks from the Huronian Supergroup, Canada. We found no significant authigenic enrichment of Os in the sedimentary rocks deposited during the first Huronian deglaciation. The initial isotopic composition of Os in the sediments was close to that of chondrite at the time of deposition (187 Os/ 188 Os = ∼0.11). These results suggest that atmospheric O 2 levels were insufficient to mobilize radiogenic Os through continental weathering (pO 2 < 10 −5-10 −3 present atmospheric level (PAL)). In contrast, we found enrichment of Re in the sedimentary rocks, which suggests the occurrence of oxidative weathering of Re under mildly oxidizing conditions (> 10 −8-10 −5 PAL). Despite the Re enrichment, low abundances of Mo imply possible non-sulfidic conditions in shallow-marine environments at the time of deposition. Together with the results of organic carbon and sulfur analyses, we suggest that atmospheric O 2 remained at relatively low levels of around 10 −8-10 −5 PAL after the first Huronian deglaciation, which contrasts with proposed dramatic increases in O 2 after the second and third Huronian deglaciations. These results imply that the second and third Huronian glaciations may have been global events, associated with climatic jumps from severe glaciations to super-greenhouse conditions and the subsequent blooming of photosynthetic cyanobacteria in the glacial aftermath.
Earth and Planetary Science Letters, 2003
Concentrations of sulfur and carbon, and isotopic compositions of sulfur were determined in sedim... more Concentrations of sulfur and carbon, and isotopic compositions of sulfur were determined in sedimentary rocks from a section across the terrestrial Permian^Triassic (P^Tr) boundary in the northern Karoo Basin, South Africa. High concentrations of sulfide produced by sulfate-reducing bacteria were found in the sedimentary rocks at and just below the perceived P^Tr boundary. The ratios of organic carbon to sulfide of the sedimentary rocks with high concentrations of sulfide are relatively constant and similar to those of marine environments. This means that the enhanced accumulation of sulfide is a result of the enrichment of sulfate in the water. As the sulfide concentrations do not correlate with concentrations of any major elements indicative of weathering intensity, the supply of sulfate was independent of environmental factors, such as temperature and CO 2 concentrations in the atmosphere, which control weathering intensity. Therefore, it is reasonable to consider that the sulfate might have been supplied to the freshwater directly as acid rain by an event such as a bolide impact or a volcanic eruption. The absence of evidence for an impact event in the geological record, though, favors volcanic input as the cause of the acid rain.
Chemical Geology, 2001
Traditional Crucibles for noble gas extraction made of refractory metals are not suitable for met... more Traditional Crucibles for noble gas extraction made of refractory metals are not suitable for metallic samples because these are easily alloyed with liquid metals. To obtain elemental and isotopic compositions of noble gases from metallic samples, new materials, i.e., single crystal MgO and hot-pressed BN have been carefully examined. Low background was achieved using these new crucibles. The MgO crucible is not suitable for materials with high temperature because MgO actively evaporates about 17008C. Inertness to metallic materials and complete degassing from metallic materials were also achieved using the BN crucible. Based on noble gas data obtained using the BN crucible, we determined the cosmic exposure age of the Mundrabilla iron meteorite as 350 " 90 Ma.
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Papers by TERUYUKI MARUOKA