检索结果-南通市图书馆

Boron isotopic fractionation in laboratory inorganic carbonate precipitation:Evidence for the incorpora-tion of B(OH)_3 into carbonate

引用

Science china Earth Sciences 2008年第12期51卷 1776-1785页

作者： XIAO YingKai1,2, LI HuaLing1,3, LIU WeiGuo4, WANG XiuFang1 & JIANG ShaoYong5 1 Qinghai institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, china 2 State Key Laboratory of Environmental Geochemistry, institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, china 3 nanjing institute of geology and mineral resources, nanjing 210016, china 4 State Key Laboratory of Loess and Quaternary geology, institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, china 5 State Key Laboratory for mineral Deposits Research, Department of Earth Sciences, nanjing University, nanjing 210093, china Qinghai institute of Salt Lakes Chinese Academy of Sciences Xining China State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang China nanjing institute of geology and mineral resources Nanjing China State Key Laboratory of Loess and Quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China State Key Laboratory for mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing China

A laboratory inorganic carbonate precipitation experiment at high pH of 8.96 to 9.34 was conducted, and the boron isotopic fractionations of the precipitated carbonate were measured. The data show that boron isotopic fractionation factors (αcarb-3) between carbonate and B(OH)3 in seawater range 0.937 and 0.965, with an average value of 0.953. Our results together with those reported by Sanyal and collabo-rators show that the αcarb-3 values between carbonate and B(OH)3 in solution are not constant but are negatively correlated with the pH of seawater. The measured boron isotopic compositions of carbonate precipitation (δ11Bcarb) do not exactly lie on the best-fit theoretical δ 11B4-pH curves and neither do they exactly parallel any theoretical δ 11B4-pH curves. Therefore, it is reasonable to argue that a changeable proportion of B(OH)3 with pH of seawater should also be incorporated into carbonate except for the dominant incorporation of B(OH)4- in carbonate . Hence, in the reconstruction of the paleo-pH of sea-water from boron isotopes in marine biogenic carbonates, the use of theoretical boron isotopic frac-tionation factor (α4-3) between B(OH)4- and B(OH)3 is not suitable. Instead, an empirical equation should be established.

关键词： boron isotopic fractionation biogenic carbonate B(OH)3 incorporation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Lasing on pyroclastic rocks:A case study of 40Ar/39Ar dating on Moshishan Group,eastern Zhejiang Province

Lasing on pyroclastic rocks:A case study of 40Ar/39Ar dating...

引用

中国科学院地质与地球物理研究所2008学术年会

作者： YANG LieKun~(1,2+),WANG Fei~1,SHEN JiaLin~3,CHEN Rong~3 &XING GuangFu~3 1 State Key Laboratory of Lithospheric Evolution,institute of geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,china 2 Graduate University of Chinese Academy of Sciences,Beijing 100049,china 3 nanjing institute of geology and mineral resources,nanjing 210016,china

It is difficult to date pyroclastic rocks,for almost all the dating methods,due to the multiple sources during their ***/Ar incremental heating results on groundmass selected from the samples show that the age spectra are meaningless ***,singe crystal total fusions of CO lasing on the sanidine separates could yield rational Ar/Ar results and distinguish their sources in this *** on three formations of the Moshishan Group,after avoiding the exotic and altered grains by lasing on the single sanidine separate,was reported in this *** lowermost portion of the Chawan Formation gives an age of 113.7±0.3 Ma;the lower part of the Xishantou Formation was formed 116.4±0.4 Ma ago and the bottom of the Gaowu Formation took its shape at 118.4±0.4 *** new ages are much younger than the previous ones,suggesting that these thick volcanic formations had been formed in very short durations.

关键词： pyroclastic rocks CO2 laser sanidine grain 40Ar/39Ar dating the Moshishan Group

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

缅甸还原性次生化翡翠的傅立叶变换红外光谱分析

引用

深圳职业技术学院学报 2003年第3期2卷 30-33页

作者：胡楚雁狄敬茹张丛森深圳职业技术学院设计与艺术学部广东深圳518055 中国地质大学湖北武汉430074 南京矿产地质研究所江苏南京210016

傅立叶变换红外光谱分析表明,原生翡翠与还原性次生化翡翠在3800-3000 cm-1范围内,具有不同的红外吸收图谱标型特征,原生翡翠出现右倾斜的“V”字形吸收曲线,峰谷尖锐,吸收率低;还原性次生化翡翠出现“U”字形吸收曲线,峰谷宽阔,吸收率... 详细信息

傅立叶变换红外光谱分析表明,原生翡翠与还原性次生化翡翠在3800-3000 cm-1范围内,具有不同的红外吸收图谱标型特征,原生翡翠出现右倾斜的“V”字形吸收曲线,峰谷尖锐,吸收率低;还原性次生化翡翠出现“U”字形吸收曲线,峰谷宽阔,吸收率较高。其原因可能与还原性次生化翡翠的微裂隙中穿插充填有绿泥石等含水的粘土类矿物,使其红外光谱在3800-3400 cm-1区段叠加有粘土矿物中水和羟基的吸收峰有关。

关键词：红外光谱还原性次生化翡翠缅甸

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The modes of gold-migration in the gossan-type gold deposit

引用

Chinese Science Bulletin 1999年第S2期44卷 32-33页

作者： HE Jurui and LI Ying nanjing institute of geology and mineral resources, nanjing 210016, china nanjing institute of geology and mineral resources Nanjing 210016 China

MORE than 30 gossan-type gold deposits have beed discovered in the Middle-Lower Yangtze River *** profile of gold-bearing gossan can be divided into four subzones from upper to lower: （i） gold-deficient or gold-leached gossan (Au contents （0.1-0.8）×10-6) transitonal subzone; （ii） secondary goldconcentration subzone (Au（4-20）×10-6); （iii） oxide and sulfide transitional subzone (Au（0.5-1.5）× 10-6); （iV） Primary sulfide ore (Au（0.5-1） × 10-6). Au Concentration in the subzone （ii） is 2-20 times higher than that in subzone （iV）. Obviously migration and secondary concentration of Au hadhappened in the process of oxidation of primary sulfides. Some geologists indicated that there would be four modes of gold-migration and concentration:（1） gravity separation （mechanism）; （2） organic complex or adsorption; （3） colloidal

关键词： gold migration gossan-type gold deposit.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Aoyitake plagiogranite in western Tarim Block, NW china: Age, geochemistry, petrogenesis and its tectonic implications

引用

Science china Earth Sciences 2006年第11期49卷 1121-1134页

作者： ZHANG Chuanlin1,2, YU Haifeng3, YE Haimin2, ZHAO Yu2 & ZHANG Dongsheng4 1. Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, china 2. nanjing institute of geology and mineral resources, nanjing 210016, china 3. Tianjin institute of geology and mineral resources, Tianjin 300170, china 4. The 2nd Regional Geological Investigation Party, Xinjiang Bureau of geology and mineral resources, Changji 831100, china Key Laboratory of Isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China nanjing institute of geology and mineral resources Nanjing China Tianjin institute of geology and mineral resources Tianjin China The 2nd Regional Geological Investigation Party Xinjiang Bureau of Geology and Mineral Resources Changji China

SHRIMPP U-Pb zircon age and geochemical and Nd isotopic data are reported for the Aoyitake plagiogranite in western Tarim Block, NW china. The plagiogranite intruded the Middle Pro- terozoic and Lower Carboniferous with an exposure area of ca. 60 km2 and crystallized at 330.7±4.8 Ma. Rock types mainly include tonalite, trondhjemite and minor amounts of diorite and quartz-diorite. Feldspars in the rocks are dominated by oligoclase-andesine, and minor perthite observed locally. The granites are sodic with Na/K ratios (molar) between 4 and 87. Total REE (50-220 ppm) show a clear positive correlation with SiO2. There is no LRRE/HREE fractionation (LaN/YbN=0.5-1.5), me- dium negative Eu anomalies (δ Eu=0.3-0.6), high Y content and low Sr/Y ratio (~1.0). These granites exhibit relatively juvenile Nd T2DM model ages of 470 to 580 Ma and positive εNd(331 Ma) values of 6.23 to 7.65. The aforementioned characteristics are similar to those of ocean island or ocean ridge plagiogranites. However, the regional geology, especially its scale, precludes that the plagiogranite pluton was derived directly from fractionational crystallization of mantle-derived basaltic magma. We interpreted that the primary magma of the pluton might be tonalitic in composition generated by ca. 50% partial melting of the juvenile basaltic crust. The primary magma experienced intensive frac- tionational crystallization, and intruded into the middle to upper crusts to form the granite pluton. In combination with the previous regional geological data, it is concluded that the plagiogranite pluton was emplaced within the Tarim Block in respond to the Carboniferous continental rifting along the Tianshan orogenic belt.

关键词： western Tarim, Aoyitake plagiogranite, age, geochemistry, tectonic implications.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Vermicular fossils in the Early Cambrian Xidashan Formation in the Quruqtagh region of Xinjiang, china

引用

Progress in Natural Science:Materials International 2006年第5期16卷 559-562页

作者： YANG Ruidong, ZHANG Chuanlin, SONG Guoqi and LUO Xinrong (Postgraduate School of Guizhou University, Guiyang 550025, china nanjing institute of geology and mineral resources, nanjing 210016, china Geological Survey of No. 3 Geological Party, Xinjiang, Kurle 841000, china) Postgraduate School of Guizhou University Guiyang 550025 China nanjing institute of geology and mineral resources Nanjing 210016 China Geological Survey of No. 3 Geological Party Xinjiang Kurle 841000 China

Large amounts of vermicular fossils and a minor amount of sponge animal fossils have been found in the Early Cambrian Xidashan Formation in the region of Quruqtagh, Xinjiang. Vermicular fossils are generally more than 50 mm long and 0. 3-1. 4 mm wide; their wrinkled lamellae are microfine with 3-10 pieces within the length of every each millimeter. The fossils are considered to be Sabellidites cambriensis Sokolov (1965) . The Xidashan Formation is the highest stratum in which Sabellidites occur, as has been so far reported.

关键词： vermicular fossil Early Cambrian Quruqtagh Xinjiang.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Geochronology and Geochemical Characteristics of the Early Mesozoic Tangquan Pluton in Southwestern Fujian and Its Tectonic Implications

引用

Acta Geologica Sinica(English Edition) 2003年第3期77卷 361-371页

作者： MAO Jianren, HU Qing, XU Naizheng, XIE Fanggui and TAO Kuiyuan, nanjing institute of geology and mineral resources, nanjing, Jiangsu 210016 E-mail: mjrmh@*** Hao Ziguo and Zhu Xiling nanjing Inst Geol & mineral resources Nanjing 210016 Jiangsu Peoples R China

The Tangquan granodioritic pluton in Dalian County, southwestern Fujian, china, which extends in a NE direction with an exposed area of about 130 km2, used to be considered a product of Early Cretaceous magmatism. The present study suggests for the first time that the pluton was formed in the Early Jurassic by using multiple methods for isotopic dating, which give zircon U-Pb ages of 186.8 Ma and 179.0 Ma, Rb-Sr isochron age of 162.02±4.5 Ma, and biotite 40Ar/39Ar plateau age of 158.1±0.7 Ma. The cooling rate for the pluton was relatively low (4.76℃/Ma) during the early stage (183-162 Ma) because of the compressional environment. It was emplaced in a higher cooling rate (50℃/Ma) in an extensional environment during the later stage (162-158 Ma). The granodiorites are metaluminous-peraluminous, relatively enriched in Na2O and depleted in K2O, and characteristic of I-type granites of crust-mantle mixed sources. They are moderately enriched in Rb, Th, Hf and LREE, and depleted in Ti, Nb, Ta and Sr, and have geochemical features of cal-alkaline rocks of an island arc or active continental margin. Their (87Sr/86Sr)i ratio varies from 0.70769 to 0.70822, εNd(t) from -9.68 to -10.07 and TDM from 1.52 to 1.55 Ga. They were formed by mixing of mantle-derived mafic magma with the granitic magma resulting from partial melting of crust-derived materials in an upwelling of the asthenospheric mantle in South china during the Early Mesozoic.

关键词： granodiorite Early Jurassic petrogenesis tectonic setting southwestern Fujian china

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Sources of Cretaceous Bimodal Volcanic Rocks in the Coastal Region of Southeastern china -- Constrains of the Sr content and its isotopes

引用

Acta Geologica Sinica(English Edition) 1999年第1期73卷 84-92页

作者： XING Guanfu YANG Zhuliang and TAO Kuiyuan nanjing institute of geology and mineral resources, Chinese Academy of Geological Sciences,534 East Zhongshan Road, nanjing 210016 Chinese Acad Geol Sci Nanjing Inst Geol & Mineral Resources Nanjing 210016 Peoples R China

Cretaceous volcanism in the coastal region of southeastern china was characteristized by occurrenceof bimodal volcanics consisting of basalts and rhyolites, the geneses of which are still controversial. Based on the factthat their isotopic compositions are similar but the Sr content of the former is much higher than that of the latter, thispaper discusses the respective sources of the two end-member rocks, and concludes that basalts were derived fromthe subduction-related enriched upper mantle wedge and their isotopic compositions had not been affected by crustalassimilation, whereas rhyolites were formed by remelting of the old metamorphic basement, but they were mixed upwith the underplating basaltic magmas to various degrees so that their Sr isotopic compositions varied significantlyfrom the sources and tended to be homogeneous to the latter.

关键词： Sr content and its isotopes Cretaceous bimodal volcanics coastal region of southeastern china

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Whole fossil plants of Ephedra and their implications on the morphology,ecology and evolution of Ephedraceae (Gnetales)

引用

Chinese Science Bulletin 2010年第15期55卷 1511-1519页

作者： WANG Xin 1,2 & ZHENG ShaoLin 3 1 nanjing institute of geology and Palaeontology,Chinese Academy of Sciences,nanjing 210008,china 2 Fairy Lake Botanical Garden,Shenzhen 518004,china 3 Shenyang institute of geology and mineral resources,Shenyang 110034,china nanjing institute of geology and Palaeontology Chinese Academy of Sciences Nanjing China Fairy Lake Botanical Garden Shenzhen China Shenyang institute of geology and mineral resources Shenyang China

Although there are many reports of fossil Ephedraceae,whole plant fossil record remains *** to a lack of trust on partially preserved fossil materials,scholars working on molecular clock proposed a recent origin of Ephedra and cast doubt on the earlier origin time of *** better the understanding on this interesting group,here we report whole plants of Ephedra hongtaoi ***.(Ephedraceae,Gnetales) from the Yixian Formation (Early Cretaceous) in western Liaoning,*** whole plants of Ephedra demonstrate clearly the characters of Ephedra,including shrubby growth habit,decussate branching pattern,and terminal ovuliferous unit with micropylar *** whole-plant preservation of the fossils provides more convincing fossil evidence of Early Cretaceous Ephedra,helps to resolve the controversy over the origin time of Ephedra,and sheds light on the whole plant morphology,growth habit,ecology and evolution of Ephedraceae.

关键词：化石植物生态学麻黄形态学进化材料保存早白垩世生长习性

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A sort of iron-manganese nodule developing in drowned platform margin

引用

Chinese Science Bulletin 1999年第S2期44卷 34-35页

作者： JIANG Yuehua, YE Zhizheng and YUE Wenzhe nanjing institute of geology and mineral resources, Chinese Academy of Geological Sciences, nanjing 210016, china nanjing institute of geology and mineral resources Chinese Academy of Geological Sciences Nanjing 210016 China

A sort of purplish red iron-manganese nodules was found in the Middle Ordovician Guniutan-Miaopu period limestone, Anhui Province. About their formational environment, there are two different viewpoints:Yue thought they were deep-water pelagic deposit and Huang et al. believed they were formed inshallow water tide. We think that these nodules were formed in drowned platform margin belonging to atransitional type between shallow-water and deep-water iron-manganese nodules, and different from shoalwater iron-manganese oolites and pelagic iron-manganese nodules in feature and origin. 1 Palaeogeographic setting of iron-manganese nodules

关键词： iron-manganese nodule drowned platform platform margin.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：