Measurements of Rare Earth Element and Other Element Mass Fractions in Environmental Reference Materials (NIST SRM 1646a,NIST SRM 1400, IAEA‐395 and IAEA‐450) by INAA,ICP‐AES and ICP‐MS          下载免费PDF全文

Vu Dong Cao  Raymond Sucgang  Thien Quang Tran  Doanh Van Ho  Naoki Shirai  Mitsuru Ebihara 《Geostandards and Geoanalytical Research》2017,41(2):303-315

INAA, ICP‐AES and ICP‐MS were used to elementally characterise four environmental reference materials – NIST SRM 1646a (Estuarine Sediment), NIST SRM 1400 (Bone Ash), IAEA‐395 (Urban Dust) and IAEA‐450 (Algae). An analytical scheme consisting of the three methods was first applied to NIST SRM 1646a to validate the methodology because it has been extensively analysed and has certified values for many elements. With repeated analyses of NIST SRM 1646a, the accuracy and measurement repeatability of the data obtained were evaluated based on two statistical calculations (zeta‐score and Horwitz ratio) and were observed to be good enough for the analytical scheme to be applied to similar sorts of environmental/geochemical samples. Applying the same approach to NIST SRM 1400, IAEA‐395 and IAEA‐450, enabled mass fractions of 29, 38 and 28 elements to be determined, respectively. Among these results, the data for rare earth elements are of particular interest, not only for IAEA‐450 but also for the other three reference samples. The data for Pr, Gd, Dy, Ho, Er and Tm in NIST SRM 1646a are newly reported in this study. By using small test portions (< 100 mg) for NIST SRM 1646a and IAEA‐395, and recommended minimum amounts for NIST SRM 1400 and IAEA‐450, sample homogeneity was evaluated.  相似文献   

High-resolution terrestrial carbon isotope and planktic foraminiferal records of the Upper Cenomanian to the Lower Campanian in the Northwest Pacific     

Reishi Takashima  Hiroshi Nishi  Toshiro Yamanaka  Keiichi Hayashi  Amane Waseda  Akiko Obuse  Takashige Tomosugi  Naoki Deguchi  Sunao Mochizuki 《Earth and Planetary Science Letters》2010,289(3-4):570-582

Making Upper Cretaceous biostratigraphic correlations between the Northwest Pacific and Tethyan–Atlantic sections have been difficult because of rare frequencies of age-diagnostic macro- and microfossils in the sequences in the Northwest Pacific region. In order to correlate these sections precisely, an integrated planktic foraminiferal and bulk wood carbon-isotope stratigraphy from the upper Cenomanian to the lower Campanian succession (the middle–upper part of the Yezo Group) of Hokkaido, northern Japan is established with an average resolution of 50 k.y. The δ¹³C curves from bulk wood of the Yezo Group and from bulk carbonate of English Chalk show remarkably similar patterns of isotopic fluctuation, allowing the correlation of 22 carbon isotopic events between these sections. This high-resolution correlation greatly improves the previous micro- and macrofossil biostratigraphic schemes in the Northwest Pacific region, and reveals that global events, such as the oxygen depletion at the OAE 2 horizon, the constant decrease in pCO₂ during the Late Cretaceous, and the eustatic sea-level falls in the late middle Turonian, Santonian/Campanian Boundary and early Campanian, are recorded in the Upper Cretaceous sequence of the Northwest Pacific.  相似文献   

A high-resolution Holocene record on the Southern Brazilian shelf: Paleoenvironmental implications     

Michel Michaelovitch de Mahiques  Ilana Klein Coaracy Wainer  Leticia Burone  Renata Nagai  Silvia Helena de Mello e Sousa  Rubens Cesar Lopes Figueira  Ilson Carlos Almeida da Silveira  Mrcia Caruso Bícego  Daniel Pavani Vicente Alves   yvind Hammer 《Quaternary International》2009,206(1-2):52

A high-resolution, multi-proxy record has been used to determine the environmental changes during the Holocene on the southern Brazilian shelf. Present oceanographic conditions reveal wind and freshwater input as the determinants of short-term productivity changes in the study area. Magnetic susceptibility and grain-size variations, together with proxies of productivity (organic carbon, carbon accumulation rate, Ba, Sr, and Ca content, Ba/Al, Ba/Ti, and Al/Ti ratios) were analyzed and compared with proxies of redox condition (V/Ti ratio), terrigenous input (Fe/Ca and Ti/Ca ratios), as well as other Element/Ti ratios, to evaluate the paleoceanographic and paleoclimatic changes over the period.The core covers a time interval of about 7650 years, with sedimentation rates varying from 0.025 to 0.250 cm a⁻¹, which represent time intervals of between 8 and 80 a per sample. There is a clear change in the sedimentation rate at about 2800 B.P.All grain-size and elemental results indicate the occurrence of conspicuous changes between 5200 and 5000 cal. B.P., as well as between 3000 and 2800 cal. B.P. A comparison of the results with the palynological information available from the adjacent continental areas suggests that the sedimentary changes in this last interval may be correlated with the onset of modern climatic conditions in South America, and especially, with the onset of the Plata Plume Water, a water mass that carries cold, less saline waters towards the north. However, minor changes are observed at ca. 1500 B.P. and are correlated with an increase in the atmospheric humidity. Furthermore, a time-series analysis undertaken using several proxies indicated the occurrence of Sub-Milankovitch cycles, which may be compared with those reported worldwide.  相似文献   

一种特殊类型硅质岩——浮石状燧石   总被引：7，自引：2，他引：5  

朱嗣昭 Nagai  H 《高校地质学报》1999,5(3):345-350

一种较为少见的特殊硅质岩产于南京及巢湖地区的下二叠统孤峰组地层中。它的显著特征是岩石中存在大量菱形和不规则状孔隙,孔隙周边和孔隙间主要由微晶石英组成。通过对该岩石的成分和结构等特征的研究,认为它是一种交代碳酸盐岩成因的硅质岩,并定名为浮石状燧石。  相似文献   

Depositional environments of well‐sorted detrital limestone from the Minatogawa Formation in the southern part of Okinawa Island,the Ryukyu Archipelago,Japan          下载免费PDF全文

Kazuhiko Fujita  Kayo Aruga  Marc Humblet  Koichi Nagai 《Island Arc》2018,27(3)

Well‐sorted detrital limestone is one of the typical lithofacies of the latest interval of the Pleistocene Ryukyu Group, which is exposed in the Ryukyu Archipelago in southwestern Japan. The depositional environments of the limestone are interpreted to be extremely shallow and to include back‐reef lagoons or moats and subaerial sand dunes. However, detailed micropaleontological analyses have not been performed on this limestone. In this study, the interpretation of the depositional environments and paleo‐water depths was improved by quantitative examination of foraminiferal assemblages for the well‐sorted detrital limestone of the Minatogawa Formation in the southern part of Okinawa Island. Thin sections of limestone collected from the Minatogawa (Horikawa) quarry were subjected to sedimentological and foraminiferal analyses. Comparison with modern foraminiferal distribution within the Ryukyu Archipelago indicates that back‐reef and fore‐reef dwelling foraminifers characterize the fossil assemblages from the well‐sorted detrital limestone (bioclastic grainstone). Three ratios of indicator foraminiferal taxa (ratios of back‐reef to fore‐reef taxa, planktonic foraminifers to Amphistegina lobifera and Amphistegina lessonii, and Calcarina gaudichaudii to other Calcarina species), as well as multivariate analyses suggest that the well‐sorted detrital limestone was deposited in fore‐reef setting shallower than 40 m in water depth. A comparable depth range was reconstructed from the coral assemblage in the associated coral limestone, suggesting that the Minatogawa Formation was deposited in a gently inclined ramp setting with patch reefs and/or fringing reefs. Stratigraphic changes in paleo‐water depth, together with evidence of several unconformities associated with paleosol layers suggest that there were repeated transgressions and regressions, with an amplitude up to several tens of meters, when the Minatogawa Formation was deposited.  相似文献   

Distribution of fossil seawater and its role in Neogene sedimentary rock landslides in Niigata,eastern marginal region of the Japan Sea     

Nariaki Nishiyama  Masahiro Chigira  Koichi Suzuki  Naoki Watanabe 《Island Arc》2020,29(1)

The Neogene marine sedimentary rock area in the eastern marginal region of the Japan Sea is an area with some of the highest landslide densities in Japan. Some of the landslides in this area have been known to involve saline groundwater, which can be the cause of these landslides. In order to demonstrate the relationships between landslides and saline water, topographic, geological, groundwater, and electromagnetic surveys were performed in the eastern marginal region of the Japan Sea. Many landslides and gravitational slope deformations with linear depressions and small scarps were recognized in the study area. The resistivity profile obtained by an electromagnetic survey suggests that there is a wide zonal distribution of saline water with salt concentrations equivalent to seawater at depths of 50–100 m or more and that the groundwater shallower than 50 m has an electrical conductivity of less than 100 mS/m. The shallow resistive groundwater is inferred to be meteoric water that replaced the saline groundwater, which likely weakened the bedrock, resulting in landslides. A ridge of competent tuff overlying mudstone has many linear depressions from gravitational slope deformation and low‐resistivity water to a depth of 600 m, which suggests that the mudstone was weakened by water replacement and deformed under the tuff caprock. The saline groundwater is inferred to be fossil seawater trapped in pores during sediment deposition, which is brought near the ground surface along with rocks by tectonic movement in the hills. Thus, the saline water and its fresh water replacement are among the important basic causes of the landslides. The oil well data obtained in the eastern marginal region of the Japan Sea suggest that such saline water replacement has occurred widely and that replacement is likely one of the predispositions for the frequent landslides there.  相似文献