准格尔煤田黑岱沟露天矿煤中稀土及微量元素的分配规律     

刘大锐  高桂梅  池君洲  王永旺  郭昭华 《地质学报》2018,92(11):2368-2375

对准格尔煤田黑岱沟露天矿煤的主量元素、稀土元素和微量元素含量和矿物组成进行了研究。结果表明,黑岱沟露天矿煤中稀土元素平均含量为248.12×10-6,约为中国煤平均值的2.83倍。LREE平均含量为236.66×10-6,HREE平均含量为11.46×10-6,LREE/HREE平均值为20.81,(La/Yb)N平均值为1.59,表明煤中LREE相对HREE富集。煤中部分稀土元素可能富集在勃姆石和黏土矿物中。稀土元素分配曲线δCeS变化区间(0.89～2.21)和δEuS中度亏损(0.46～0.86),验证了沉积环境在煤层形成演化过程中对煤中稀土元素输入的稳定性。黑岱沟煤层中微量元素明显偏高的有Ga、Pb、Se、Sr、Th 和Zr,这些元素的含量高于中国、中国华北晚古生代和美国煤的算术均值,也高于地壳克拉克值。  相似文献   

微波消解-电感耦合等离子体质谱法测定海泡石中的稀土元素   总被引：3，自引：3，他引：0  

张楠  徐铁民  吴良英  魏双  方蓬达  王家松 《岩矿测试》2018,37(6):644-649

海泡石是一种纤维状含水的富镁硅酸盐黏土矿,其中的稀土元素含量在1×10~(-7)～1×10~(-5)之间,目前还没有建立海泡石中稀土元素的国家标准分析方法。测定岩石中的稀土元素主要是采用电感耦合等离子体质谱法(ICP-MS),样品前处理一般采用封闭溶矿和碱熔,但这两种处理方法耗时较长,效率不高。本文通过比较硝酸-氢氟酸-过氧化氢、硝酸-氢氟酸、硝酸-过氧化氢三种样品前处理方法,确定使用硝酸-氢氟酸溶矿,然后进行微波消解同时赶去氢氟酸,避免氢氟酸与稀土元素生成难溶的氟化物,再采用ICP-MS法测定15种稀土元素的含量。由于海泡石中的镁含量较高,为降低基体效应,以~(103)Rh和~(185)Re作内标补偿基体效应和校正灵敏度漂移,各元素测定值的准确性显著提高,回收率为91. 2%～110. 9%,检出限为0. 002～0. 011μg/L,精密度≤2. 79%。本方法与封闭酸溶ICP-MS法的分析结果吻合较好,且用酸量少(7 mL),溶矿效率高(1 h),检出限更低。  相似文献   

基于面向对象分类的稀土开采区遥感信息提取方法研究     

代晶晶  吴亚楠  王登红  令天宇  王俊华 《地球学报》2018,39(1):111-118

离子吸附型稀土矿是我国宝贵的矿产资源,运用遥感影像分类技术提取稀土开采区可以准确地实现对稀土开采状况的监测,但仅利用光谱信息往往难以保证分类精度。本文以江西寻乌稀土矿区为研究区,以IKONOS影像为数据源,应用面向对象分类方法提取了稀土开采区的遥感信息。针对稀土开采区的分布特点,选择基于边缘的分割算法进行影像分割;结合地形信息、光谱信息及几何信息建立规则集,进行特征提取;最后采用隶属度函数法实现面向对象分类,并与传统的光谱角填图分类进行对比分析。研究结果表明,面向对象分类法提取稀土开采区的总体精度为92.49%,Kappa系数为0.857 6,与传统监督分类方法相比有了很大的提高。  相似文献   

Moon-based Earth observation: scientific concept and potential applications   总被引：2，自引：0，他引：2  

Huadong Guo 《International Journal of Digital Earth》2018,11(6):546-557

Although Earth’s surface parameters obtained from satellite data have become more and more precise, it is still difficult to guarantee temporal consistency and spatial continuity for large-scale geoscience phenomena. Developing new Earth observation platforms is a feasible way to improve the consistency and continuity of such data. As the planet’s only natural satellite, the Moon has special advantages as a platform for observing Earth, including long lifetime, whole disk view, tectonic stability and unique perspective. After presenting the observation geometry constructed by using the ephemeris, this paper mainly discusses the characteristics of a lunar platform and the proper Moon-based sensors, as well as the scientific objectives of Moon-based Earth observation. Solid Earth dynamics, the energy budget of Earth, Earth’s environmental elements and the Earth-space environment are four potential applications analysed in this paper.  相似文献   

云南省澜沧地区风化壳型稀土矿化的新发现及找矿前景     

柏杨 《地质与勘探》2021,57(4):762-783

云南省澜沧地区位于滇西南地区,地处西南"三江"造山带南段,主体属班公湖-怒江-昌宁-孟连结合带南段,是云南省重要的铅锌银多金属矿分布区,以往在澜沧地区开展了诸多铅锌银矿调查工作,未对澜沧地区稀土矿化进行详细工作,本次通过矿产地质调查工作发现有花岗岩风化壳型、火山岩风化壳型、灰岩风化壳型三种不同的稀土矿化类型,其中花岗岩风化壳型稀土矿化具有较大的含矿层位面积,估算稀土资源量达大型;灰岩风化壳型矿化为调查区新发现类型稀土矿化,矿化与土壤地球化学异常吻合,稀土总量品位较高,含矿层位具有连续性,已开展概略调查地区估算稀土资源潜力达中型以上,具有较好的稀土矿找矿前景,今后对研究区开展详细的验证工作,特别是对灰岩风化壳型稀土矿化区开展研究,全面探索矿化层位特征、含矿性特征,有望取得新的找矿突破。  相似文献   

云南昆明寒武纪早期浅水相磷块岩的氧化还原环境及成因机制   总被引：1，自引：0，他引：1  

杨兵  金承胜  刘欣  韦一 《地质学报》2021,95(12):3858-3868

磷是重要的营养元素,与古环境和生命演化密切相关.在埃迪卡拉纪—寒武纪之交,伴随着骨骼化动物的辐射,华南甚至全球广泛沉积了大量磷酸盐,这暗示磷是古环境的变化与生命演化之间关系的桥梁.然而,目前,磷块岩的沉积环境和形成机制尚不明确.为探究磷酸盐富集的沉积环境和形成机理,本文研究了华南寒武纪早期梅树村剖面磷块岩的磷酸盐聚集形式、黄铁矿形态学和稀土元素.磷块岩主要是由结晶氟磷酸钙、隐晶质氟磷酸钙和铁氧化物组成.稀土配分模式均为"帽型"配分模式,与沉积物中铁-锰还原带之中的稀土配分模式类似,表明稀土元素遭受了早期成岩的影响.磷块岩中没有草莓状黄铁矿和较低的Ce负异常(Ce/Ce*=0.50～0.82,平均值为0.70),暗示磷块岩沉积于氧化/次氧化的沉积环境.Eu元素未发生异常(Eu/Eu*=0.92～1.08,平均值为0.98),暗示磷块岩可能未受到热液作用的影响.较高的Y/Ho比值(55.3～74.5,平均值为63.6),与海水Y/Ho比值相似,表明磷块岩来源于海水.鉴于华南寒武纪早期广泛的氧化事件、缺氧分层的海水化学结构和上升流活动,本文认为磷块岩的形成源于氧化背景下较高的磷酸盐浓度和深部还原环境中的磷酸盐随上升流活动携带至氧化-次氧化浅水区域.  相似文献   

Geochemical constraints on the distribution of trace elements and volatiles in fluorapatite from the Panasqueira tin-tungsten deposit (Portugal)     

《Chemie der Erde / Geochemistry》2021,81(2):125765

A large, euhedral crystal of fluorapatite (ca. 19.5 × 20.0 mm) from the Panasqueira tin-tungsten deposit (Portugal) was investigated in terms of the distribution of trace elements by using several microanalytical techniques. The studied material represents almost pure fluorapatite with minor amounts of other cations (mainly Sr, Mn, REE and Fe), OH and Cl. Particular interest was given to the distribution of rare earth elements with respect to the crystallographic orientation. A broad range of analytical techniques were used, including optical microscopy coupled with cathodoluminescence imaging, electron probe microanalysis (EPMA), laser ablation – inductively coupled plasma mass spectrometry (LA-ICPMS), Raman microspectroscopy, and simultaneous thermal analysis coupled with mass spectrometry. The investigated crystal consists of the main crystal with a distinct core and rim (Ap_2core and Ap_2rim, respectively), which grew on a previous, euhedral crystal (Ap₁). The fluorapatite demonstrates various types of zoning: regular oscillatory, irregular, and internal sectoring, which is also reflected in trace elements concentrations. The rim Ap_2rim has lower concentrations of Mn, Sr and Fe, and significantly higher concentrations of REE compared to the core Ap_2core and older crystal Ap₁. Furthermore, the rim Ap_2rim is strongly depleted in Th, U and Pb. The entire crystal shows elevated Eu contents, expressed as a strong positive anomaly in chondrite-normalized REE patterns. With regards to the volatiles, F concentrations are constant in Ap₁, Ap_2core and Ap_2rim, whereas Cl is below the EPMA detection limit. The Ap_2rim was the only part of the investigated material containing OH and CO₃, which were observed in the Raman spectra. Furthermore, part of the crystal Ap_2core is extensively altered, likely due to fluid-induced metasomatic processes. LA-ICPMS U-Pb dating yielded highly discordant dates due to common Pb content. A lower intercept age of 297 ± 13 Ma (MSWD = 0.13) indicates the age of the fluorapatite crystallization. The overall analytical data constrain growth and post-growth processes, including crystallization of Ap₁ and Ap_2core, which both have typical hydrothermal Sn-W deposit characteristics, whereas Ap_2rim is related to a carbonate stage of the mineralization in the Panasqueira deposit.  相似文献   

Chemical oceanographic influences on sediment accumulations of a carbonate ramp: Holocene Yucatan Shelf,Mexico     

Eugene C. Rankey  Rodrigo Garza‐Perez  Hassan A. Eltom 《Sedimentology》2021,68(1):324-351

Global controls on the oceanographic influences on the nature of carbonate factories are broadly understood. The details of the influences of changes in temperature and nutrients across individual carbonate shelves are less well constrained, however. This study explores spatial and temporal variations in chemical oceanography along and across the Yucatan Shelf, a modern carbonate ramp, and how these factors relate to variable bottom character, sediment and sediment geochemistry. In‐situ sensors and remote‐sensing data indicate the sporadic presence of cool, upwelled water with low dissolved oxygen and elevated Chlorophyll‐a. This current‐driven, westward flow of upwelled water is most evident in a zone just offshore of the northern peninsular shoreline, but its influence wanes ca 75 km offshore and as the shore turns southward. The impacts of this water mass include a transitional photozoan–heterozoan assemblage with biosiliceous components, relict grains and common thin Holocene sediment accumulations nearshore; further offshore are coralgal reefs and expansive sand plains. Geochemical proxies of bulk sediment, including high δ¹⁸O and elevated HREE/LREE (heavy rare‐earth element/light rare‐earth element) ratios near, and downcurrent of, the upwelling source, are interpreted to represent the signal of nearshore, westward movement of the cool and nutrient‐rich, upwelled water. Collectively, these data emphasize how local processes such as upwelling and longshore transport can variably influence carbonate sediment accumulations and their geochemical signatures, both along and across individual shelves. These data and insights provide an analogue for the influences of spatial variability of water masses in the geological record, and for accurate interpretation of stratigraphic changes of sedimentary and geochemical proxy data in carbonate archives.  相似文献   

内蒙古黄岗梁铁锡矿床中红色萤石的地球化学特征及成因探讨     

陈缘  韩禹  许博  刘金高 《岩石学报》2021,37(12):3869-3879

内蒙古黄岗梁萤石呈现稀有的红色特征,该颜色萤石全球产量稀少,本文利用LA-ICP-MS原位测试技术对其微量元素地球化学特征进行了系统分析,探讨黄岗梁铁锡矿床中红色萤石的成因。微量元素分析结果显示黄岗梁萤石样品中总稀土元素含量较低,并表现出左倾的富集重稀土特征,其中红色和粉色萤石的稀土元素配分曲线显示出Dy-Tm拱顶式凸起的配分模式,表明其结晶作用发生在成矿流体演化的最后阶段;Y/Ho比值104~197,与热液成因萤石一致,且La/Ho比值为0.027~0.126,具强的负异常,表明了黄岗梁萤石为热液成因;Ce/Ce^*比值0.57~0.98,Eu/Eu^*比值0.22~0.63,均表现出负异常,表明形成黄岗梁萤石的热液流体是在相对还原环境下形成且温度高于200℃。综合分析萤石的地球化学特征和其与围岩的接触关系,认为黄岗梁萤石主要分为两阶段结晶,一阶段为与石英同期结晶形成红色、粉色部分,二阶段为在石英形成后结晶形成的由阳起石他色致色的绿色部分,而黄岗梁萤石罕见的红色是由于Y元素较为富集且含量远高于其他稀土元素,从而形成YO₂色心并在萤石中作用而显色。  相似文献   

近20年来长江经济带生态环境变化          下载免费PDF全文

周权平  张澎彬  薛腾飞  姜月华  郭琳  杨冉冉 《中国地质》2021,48(4):1127-1141

长江经济带发展战略实施以来,长江上、中、下游地区经济快速发展,与此同时,生态系统不可避免受到扰动,长江经济带生态环境状况面临压力,亟需开展长江经济带生态环境质量评价。本文选取2001年和2020年MODIS和Landsat遥感影像计算湿度、绿度、干度、热度4个评价指标,通过主成分分析方法计算遥感生态指数RSEI,对长江经济带11省(市)生态环境现状及变化进行定量分析评价。结果表明长江经济带整体生态环境等级为较优,2001—2020年保持总体向好态势。空间分布上,生态环境优等区域主要分布于武夷山、罗霄山、雪峰山、武陵山、巫山、大巴山、大别山、西双版纳等山地丘陵一带,生态环境较差及差等区域主要分布于大中小城镇等人类聚集地、川西横断山区。时空变化上,生态环境等级下降区域主要集中在长三角太湖周边、江汉平原、洞庭湖周边、安徽西北部、湖南南部及四川盆地等人类聚集地周边,生态环境等级上升区域主要集中在四川盆地大部、重庆山区及三峡库区、贵州大部、云南东南部、安徽中部及北部、江苏北部等地区。  相似文献