搜索结果: 16-30 共查到“知识库 同位素地球化学”相关记录552条 . 查询时间(3.953 秒)
本文对关中浐河流域河水-土壤-植物的硝酸盐和氮同位素组成进行调查，并与前期对浐河河水氮同位素的结果对比。研究表明：从浐河上游至下游，土壤NO3−-N含量表现出：农耕区（43.5 mg ∙ kg−1）>森林区（3.25 mg ∙ kg−1）>城市区（0.63 mg ∙&...
四川盆地及邻区中上寒武统洗象池群碳同位素特征与芙蓉统底界标志
四川盆地 同位素
2018/12/25
四川盆地中上寒武统洗象池群为一套以台地相为主的白云岩，过去一直未能找到有效的方法来确定上寒武统的底界标志，导致对该层位的天然气勘探工作较为滞后。以岩屑碳氧同位素剖面的建立为依托，发现洗象池群中部存在着碳同位素正漂移事件且这一现象可全球比对，可作为识别芙蓉统（相当于上寒武统）的重要标志。进而结合电性曲线特征，确定了芙蓉统底界的划分标志，初步找到了解决芙蓉统划分难题的方案。研究结果表明：①洗象池群沉积...
Tellurium isotope compositions in acid leach fractions of carbonaceous chondrites
tellurium isotopes acid leaching N-TIMS carbonaceous chondrites isotope anomaly
2017/4/10
We present the tellurium (Te) isotope compositions of the acid leachates and residues from three carbonaceous chondrites,
namely, Allende, Murchison, and Tagish Lake. Most of the Te isotope compositi...
Relationship between CAIs and chondrules: A case study of a compound chondrule from the Allende (CV3) meteorite
chondrule calcium-aluminium rich inclusion CV chondrite oxygen isotopes silicon isotopes
2017/4/10
We report the mineralogy, petrology, major, minor and trace element geochemistry, O and Si isotopes of a complex
compound chondrule from the Allende meteorite. The chondrule contains zones of refract...
Evidence for the solar wind in lunar magmas: A study of slowly cooled samples of the Apollo 12 olivine basalt suite
hydrogen isotopes melt inclusions mare basalts SIMS lunar olivine
2017/4/10
While it is now recognized that the Moon has indigenous water and volatiles, their total abundances are unclear, with
current literature estimates ranging from nearly absent to Earth-like levels. Sim...
朝鲜平南盆地埃迪卡拉系-下寒武统地层碳同位素特征
朝鲜半岛 中朝古陆(华北古陆) 埃迪卡拉系 下寒武统 碳同位素 负漂移
2016/11/18
中朝古陆（华北古陆）平南盆地位于朝鲜半岛中部，广泛发育新元古界-古生界地层。根据化石记录，一般认为燕滩群（自下而上包括飞狼洞组和棱里组）主体属于埃迪卡拉系，黄州（超）群坪山组和中和组主体属于下寒武统。然而，该套地层记录的新元古界-古生界界线处在什么位置，燕滩群是否记录冰期事件（如，Gaskiers冰期），尚有争议。本文对这些地层开展了碳、氧同位素分析。结果表明，飞浪洞组δ13C值从底部+2‰开始，...
晴隆锑矿床是华南中生代低温成矿域右江盆地Au-Sb-As-Hg矿集区内的大型锑矿床，成矿时代约150Ma。本文以该矿床矿石矿物辉锑矿中的流体包裹体为测试对象，研究了成矿流体的He和Ar同位素地球化学。研究表明，成矿流体的3He/4He为0.13~0.46Ra（Ra为空气的3He/4He值，1.4×10-6），40Ar/36Ar为305~327，He、Ar同位素组成具有一定程度的正相关；成矿流体由两...
朝鲜半岛北部显生宙花岗岩成因研究及地质意义
朝鲜半岛北部 显生宙花岗岩 锆石U-Pb Hf-O同位素
2016/11/18
朝鲜半岛北部图们江褶皱带和冠帽地块发育大面积的花岗岩，长期被认为形成于晚古生代二叠纪-早中生代三叠纪。采用锆石原位微区U-Pb测年技术（SIMS U-Pb），对6个代表性岩体的16个样品进行了侵位年龄测定，结合早期发表的年代学数据，确定朝鲜北部花岗岩主要形成于中生代的侏罗纪（199~173Ma），少部分为晚二叠世（265~263Ma）和早三叠世（248~240Ma）。岩石学及地球化学特征表明，朝鲜...
对板石沟表壳岩中的斜长角闪岩和角闪片岩进行了锆石U-Pb年代学、地球化学以及Hf同位素分析，以探讨华北克拉通东北部新太古代晚期的构造环境和地壳演化。板石沟表壳岩主要岩石类型包括斜长角闪岩、斜长片麻岩、角闪片岩和磁铁石英岩，LA-ICP-MS锆石U-Pb测年显示斜长角闪岩（BA-1）岩浆锆石形成于2548±11Ma，绿帘角闪片岩（BA-6）岩浆锆石形成于2548±23Ma，代表了表壳岩的形成时代，在...
胶东是中国最重要的金矿集中区，破碎带蚀变岩型金矿床是区内最主要的金矿床类型，该类型金矿床已探明金资源量占全区的90%以上，其巨量金的来源是引人瞩目的关键科学问题。招平断裂带是该区内规模最大的断裂-成矿带，位于招平金矿带中段的大尹格庄金矿床是该金矿带最具代表性的破碎带蚀变岩型金矿床之一，已探明金金属量约283t。大尹格庄金矿床严格受沿胶东群与玲珑花岗岩接触带发育的NNE向招平断裂带控制，矿体赋存在招...
Controlling factors in stalagmite oxygen isotopic composition and the paleoprecipitation record for the last 1,100 years in Northeast Japan
ortheast Japan stalagmite d18O growth rate precipitation famine records
2017/4/10
Stable oxygen isotopic analysis was performed on the UT-A stalagmite with annual microbanding from the Uchimagido
Cave in Iwate Prefecture on the Pacific side of Northeast Japan. High-resolution anal...
Carbon isotope ratios of organic matter in Bering Sea settling particles: Extremely high remineralization of organic carbon derived from diatoms
diatoms coccolithophores carbon isotope organic carbon remineralization rain ratio
2017/4/10
The carbon isotope ratios of organic carbon in settling particles collected in the highly-diatom-productive Bering Sea
were determined. Wet decomposition was employed to oxidize relatively fresh orga...
Origin of unusual fractionation of Pb isotope ratios with calcium in thalliumspiked multiple collector-inductively coupled plasma mass spectrometry
Pb isotope, fractionation, MC-ICPMS
2017/4/10
We report the origin of significant fractionation of Pb isotope ratios in Ca-doped 0.08 mol L–1 HNO3 solutions. We
applied Tl-spiked standard bracketing mass fractionation correction using solution-b...
Determination of relative Faraday cup efficiency factor using exponential law mass fractionation model for multiple collector thermal ionization mass spectrometry
Faraday cup efficiency TIMS Sr isotope exponential
2017/4/10
A new method for determining the relative Faraday cup efficiency (RFCE) for nine Faraday cups has been developed
using 86Sr, 87Sr, and 88Sr isotope signals, and the exponential mass fractionation law...
Presolar silicate grains: Abundances, isotopic and elemental compositions, and the effects of secondary processing
presolar grains silicates nucleosynthesis isotopes AGB stars
2017/4/10
Close to a thousand presolar silicate grains have been identified since their initial discovery in interplanetary dust
particles (IDPs) just over ten years ago. Studies have shown that silicates are ...