Chemical Geology: Isotope Geoscience section最新文献_第3页

In situ oxygen isotope analysis of feldspar and quartz by Nd:YAG laser microprobe Nd:YAG激光微探针原位分析长石和石英的氧同位素

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90200-O

Don Elsenheimer, John W. Valley

{"title":"In situ oxygen isotope analysis of feldspar and quartz by Nd:YAG laser microprobe","authors":"Don Elsenheimer, John W. Valley","doi":"10.1016/0009-2541(92)90200-O","DOIUrl":"10.1016/0009-2541(92)90200-O","url":null,"abstract":"<div>In situδ18O analyses have been reproducibly obtained±0.5‰ (1σ) on 400–1200-μm diameter spots of plagioclase using a Nd:YAG laser microprobe system and BrF5. Over 100 analyses if plagioclase megacrysts from a single sample of Marcy Anorthosite were made to determine the optimum analytical conditions. The best results are obtained on 400–800-μm-thick wafers; less accurate and less precise results were obtained on centimeter-thick slabs. Analyses on some individual wafers display very high precision (below±0.2‰, 1σ) that are nearly as good as the precision of conventional analyses. However, such high precision cannot yet be systematically obtained in situ, and it is certain whether it results from especially homogeneous domains within the sample or from differences in operating conditions. Oxygen-leaching and isotope fractionation along the edges of the laser-heated reaction pits may have a minor effect on precision.The combination of sub-millimeter spatial resolution and±0.5‰ precision has not previously been ohbtained on feldspar, and provides the means to investigate fluid-rock interactions in a variety of geologic environments. The plagioclase in this study is the first sample for which oxygen isotope homogeneity has been evaluated in situ. The absence of isotopic zonation restricts theories on the roles of fluids associated with the Marcy Anorthosite Massif, New York, U.S.A. In contrast, replicateδ18O analyses in quartz, K-feldspar and plagioclase grains in granite from the Siljan Ring astrobleme, Sweden, vary by > 1‰, suggesting the existence of intragranular isotopic heterogeneity resulting from interaction with late meteoric fluids.</div>","PeriodicalId":100231,"journal":{"name":"Chemical Geology: Isotope Geoscience section","volume":"101 1","pages":"Pages 21-42"},"PeriodicalIF":0.0,"publicationDate":"1992-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0009-2541(92)90200-O","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79464484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 58

Carbon isotope measurements on diamonds 钻石的碳同位素测量

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90215-Q

B. Harte , M. Otter

引用次数: 27

In situ laser microprobe techniques for stable isotope analysis 稳定同位素原位激光微探针分析技术

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90199-F

Z.D. Sharp

{"title":"In situ laser microprobe techniques for stable isotope analysis","authors":"Z.D. Sharp","doi":"10.1016/0009-2541(92)90199-F","DOIUrl":"10.1016/0009-2541(92)90199-F","url":null,"abstract":"<div>In situ laser extraction techniques have been developed for determining the stable isotope ratios in carbonates, silicates, oxides and sulfides with high spatial resolution. All of these methods use the laser as a heat source to extract the appropriate gas. Carbonate analyses are made by decomposing the carbonate at elevated temperatures to liberate CO2. Oxygen is extracted from silicates by heating the sample surface in a halogen fluoride atmosphere, and sulfur is extracted from sulfides by heating in either an O2 or halogen fluoride atmosphere. The analytical precision for carbonate analyses isσ = ±0.2‰and±0.1‰ forδ18C andδ18O, respectively. Higher scatter in some samples is probably due to sample heterogeneities. In situ silicate analyses have a precision ofσ = ±0.1‰0.6‰ depending upon sample material and heterogeneity. The measured isotopic ratio may be different from the accepted value, but is insensitive to changing operating conditions. Published results for in situ analyses of sulfides have a precision of< ±0.3‰ (1σ). Theδ34S-values obtained with the laser method are less than accepted values, and vary according to the sulfide.A new level of spatial resolution is possible with the in situ laser methods. Oxygen isotope variations of10‰ are found to exist at a scale of< 1mm in greenschist-grade quartz veins. Carbon and oxygen isotopic ratios may be quite heterogeneous in hydrothermal calcites and low-grade marbles. High-grade marbles are isotopically homogeneous. Determinations of isotopic variations at the sub-millimeter scale may be used as an indicator of fluid sources and mechanisms of isotopic exchange.</div>","PeriodicalId":100231,"journal":{"name":"Chemical Geology: Isotope Geoscience section","volume":"101 1","pages":"Pages 3-19"},"PeriodicalIF":0.0,"publicationDate":"1992-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0009-2541(92)90199-F","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81290415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 117

Laser microprobe stable isotope measurements on geological materials: Some experimental considerations (with special reference toδ34S in sulphides) 地质物质的激光微探针稳定同位素测量:一些实验考虑(特别参考硫化物中的δ 34s)

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90202-G

A.E. Fallick, P. McConville, A.J. Boyce, R. Burgess, S.P. Kelley

{"title":"Laser microprobe stable isotope measurements on geological materials: Some experimental considerations (with special reference toδ34S in sulphides)","authors":"A.E. Fallick, P. McConville, A.J. Boyce, R. Burgess, S.P. Kelley","doi":"10.1016/0009-2541(92)90202-G","DOIUrl":"10.1016/0009-2541(92)90202-G","url":null,"abstract":"<div>A laser, especially when focused through a petrographic microscope, can provide a localised heat source for extraction of light elements from solids prior to stable isotope ratio measurements by gas-source mass spectrometry. In certain cases, such as conversion of sulphides to SO2 by combustion in an oxygen atmosphere, it may be necessary to choose operating characteristics which allow the chemistry at the solid target surface to be controlled. Experimental considerations such as wavelength, laser mode and irradiance are discussed and it is shown that several successful system work at very similar irradiances of∼ 109W m−2. It is suggested, for those circumstances where high spatial resolution is required and where deep penetration into the surface cannot be tolerated, that a suitable modus operandi is to use a relatively low power but narrowly focused beam to excavate trenches perpendicular to the direction in which resolution is demanded. This allows a spatial resolution of< 100 μm even for porous pyrite witha poor quality of surface.</div>","PeriodicalId":100231,"journal":{"name":"Chemical Geology: Isotope Geoscience section","volume":"101 1","pages":"Pages 53-61"},"PeriodicalIF":0.0,"publicationDate":"1992-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0009-2541(92)90202-G","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81727086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 54

Oxygen stable isotope measurements on a gravestone exposed to the Hiroshima A-bomb explosion and the “Dosimetry System 1986” 受广岛原子弹爆炸影响的墓碑的氧稳定同位素测量及“剂量测定系统1986”

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90206-K

D. Blamart , W. Ru¨hm , W. Spiegel , K. Kato , G. Korschinek , H. Morinaga , G. Morteani , E. Nolte

{"title":"Oxygen stable isotope measurements on a gravestone exposed to the Hiroshima A-bomb explosion and the “Dosimetry System 1986”","authors":"D. Blamart , W. Ru¨hm , W. Spiegel , K. Kato , G. Korschinek , H. Morinaga , G. Morteani , E. Nolte","doi":"10.1016/0009-2541(92)90206-K","DOIUrl":"10.1016/0009-2541(92)90206-K","url":null,"abstract":"<div>The “Dosimetry System 1986”, DS86, established theoretical neutron spectra and fluences of the atomic-bomb explosions in Hiroshima and Nagasaki correlated with the radiation disease rate of survivors. The actual neutron fluence and spectrum from the Hiroshima explosion can be derived by use of different radioisotopes produced by neutron capture reactions due to different neutron capture cross-sections.In a gravestone 107 m from the hypocentre of the explosion in Hiroshima, the radioisotopes36Cl,41Ca,60Co,152Eu and154Eu were already measured. From this a neutron spectrum can be derived which is much harder than the neutron spectrum used in DS86 provided the gravestone represents a closed system. To check this, petrographic and oxygen stable isotope investigations were performed on the gravestone as well as on a not-irradiated sample coming from the same quarry as the gravestone. The results of the petrographic and geochemical studies both negate the possibility of major isotopic exchange with rainwater.</div>","PeriodicalId":100231,"journal":{"name":"Chemical Geology: Isotope Geoscience section","volume":"101 1","pages":"Pages 93-96"},"PeriodicalIF":0.0,"publicationDate":"1992-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0009-2541(92)90206-K","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87515053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

LASSIE (laser ablation sampler for stable isotope extraction) applied to carbonate minerals 用于碳酸盐矿物稳定同位素提取的激光烧蚀取样器

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90201-F

P.C. Smalley, C.N. Maile, M.L. Coleman, J.E. Rouse

{"title":"LASSIE (laser ablation sampler for stable isotope extraction) applied to carbonate minerals","authors":"P.C. Smalley, C.N. Maile, M.L. Coleman, J.E. Rouse","doi":"10.1016/0009-2541(92)90201-F","DOIUrl":"10.1016/0009-2541(92)90201-F","url":null,"abstract":"<div>LASSIE is an instrument that enables rapid (∼ 30 min) stable isotope analysis of extremely small (∼ 35-μm diameter) areas of carbonates, selected by the operator from a colour TV image of a thin rock slice. This allowspractical routine integration of petrography with isotopic analysis.The main technical problem—isotopic fractionation during laser ablation—has been overcome by generating correction factors based on analyses of standards (for calcite, correction factors are +1.2‰ forδ18O, —0.8‰ forδ13C. Accuracy is determined by the uncertainty (σ) in these correction factors:±0.4‰ forδ18O andδ13C. Reprocducibility of replicate analyses is also∼ ±0.4‰ (σ) forδ18O and ∼±0.2‰ forδ13C.An example in which LASSIE analyses were performed on carbonate-cemented sandstones, demonstrated the ability of LASSIE to resolve the various components of a complex carbonate mixture. The study further demonstrated how conventional bulk analyses can give uninterpretable or, worse, misleading results.</div>","PeriodicalId":100231,"journal":{"name":"Chemical Geology: Isotope Geoscience section","volume":"101 1","pages":"Pages 43-52"},"PeriodicalIF":0.0,"publicationDate":"1992-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0009-2541(92)90201-F","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75148315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 21

Oxygen isotope measurement of magnetites 磁铁矿氧同位素测定

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90214-P

J.W. Valley , C.M. Graham

引用次数: 4

Application of high-sensitivity carbon isotope techniques— a question of blanks 高灵敏度碳同位素技术的应用——一个空白问题

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90205-J

P.D. Yates, I.P. Wright, C.T. Pillinger

引用次数: 13

Oxygen-isotope analysis on the Came´ca® ims-300 come´ca®ims-300的氧同位素分析

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90218-T

J.C. Lorin

引用次数: 11

The Isolab®54 ion microprobe Isolab®54离子微探针

Chemical Geology: Isotope Geoscience section Pub Date : 1992-06-10 DOI: 10.1016/0009-2541(92)90219-U

I. Lyon, G. Turner

引用次数: 2