共查询到19条相似文献，搜索用时 296 毫秒
1.
在研究区域地质背景基础上,分析了金红铅锌矿区赋矿地层及控矿断裂构造岩的稀土元素组成特征.按其特征和配分模式得知：赋矿白云岩属于LREE富集-HREE平坦型,轻重稀土分馏程度都较高,Eu异常差异明显,Ce异常差异较大,（La/Yb）N、（La/Sm）N和（Gd/Yb）N值具有一定的差异;断裂构造岩属于LREE富集-HREE平坦型,轻重稀土分馏程度都较高,Eu异常差异微弱,Ce异常差异明显,（La/Yb）N、（La/Sm）N和（Gd/Yb）N值比较相似.以上特征可作为成矿预测的微观标志. 相似文献
2.
摘要：运用岩石地球化学方法,对广东惠东地区离子吸附型稀土矿床的地球化学特征进行研究。结果显示,风化壳中元素含量及配分特点总体上取决于母岩,但稀土元素在继承母岩稀土元素的基础上含量进一步富集,且各风化层中元素含量变化与风化作用之间具有一定相关性。WIG指数相较于CIA指数能更有效地描述风化壳风化强度,风化壳中稀土元素迁出富集与WIG指数及元素迁移系数具有一定规律性,轻稀土元素多在全风化层上部富集,而重稀土元素在全风化层下部及半风化层明显迁入富集,Ce、Eu均具明显负异常。 相似文献
3.
冀北地区蓟县系铁岭组顶部普遍发育一套古风化壳,该层位轻稀土元素和Rb均出现显著的富集现象。为了进一步探讨风化过程中元素的迁移规律以及古环境特征,文章对该套古风化壳开展了详细的地球化学研究。结果表明,古风化壳中轻稀土元素、Rb和Ti等含量自下而上表现为“先升高,后降低”的分布规律,且随着风化层中黏土物质的增加而升高,在中上部黏土岩中达到富集的峰值,推测与黏土矿物的吸附作用相关;古风化壳δCe正异常、δEu明显的负异常等特征指示轻稀土元素主要富集于中上部的氧化环境,且氧化作用越强越富集;化学蚀变指数CIA介于53.54~79.50,风化淋滤指数BA变化范围为0.39~1.08,共同指示了风化壳形成于温暖湿润的气候环境。综合稀土元素、微量元素和La/Yb-∑REE图解显示,风化壳稀土元素和微量元素主要来源于下伏铁岭组碳酸盐岩以及火山岩浆活动。 相似文献
4.
东北黑土的形成长期备受学者们的关注,然而人类活动不同程度影响着表层黑土的自然特征。地下黑土能较为真实地反映客观属性,但其研究仍然匮乏,由此本文选择松嫩平原黑土区阿荣旗钻孔内的地下黑土为研究对象,进行稀土元素地球化学测试,采用地质统计学分析地下黑土层ΣREE、HREE、LREE的分布特征,结合Ce异常、Eu异常、(La/Yb)N、(La/Sm)N、(Gd/Yb)N、Al2O3/TiO2图解、Ceanom讨论了黑土的物源特征与环境记录。结果显示,阿荣旗地下黑土ΣREE含量较高,平均值为141.45×10-6。球粒陨石标准化曲线表现为向右倾斜,轻稀土富集,δEu微弱负异常,δCe明显负异常。(La/Yb)N平均值7.58,(La/Sm)N平均值为1.14,(Gd/Yb)N平均值为3.54,表明地下黑土重、轻稀土元素分异程度大,轻稀土元素相比重稀土元素分馏... 相似文献
5.
碳酸盐岩风化形成的红土保存着喀斯特发展演化历史证据,同时也是喀斯特地区土壤研究的重要对象。文章选取云
南石林地区的两处典型碳酸盐岩剖面为研究对象,对主量元素,微量元素及稀土元素在风化层的迁移特征及分布规律进行
研究,为探究风化层的成因提供依据。结果显示：（1） 以Ti为参比元素的剖面迁移特征表明,两剖面的主量元素在成土过
程中有相似的迁移规律,多数表现为淋失;微量元素略有差异,富集淋失程度不一。（2） UCC 标准化蜘蛛图显示,相对于
基岩,风化层中的Ca和Sr均出现亏损;与UCC相比,Fe、Ti等元素轻微富集,Mg、Ca、Na、K、P等元素显示了强烈的亏
损特征。（3） 基岩与风化层的REE分布模式相似,但风化层的稀土相对富集,轻稀土元素间的分异较大而重稀土元素间的
分异较小,且SJC剖面的轻、重稀土元素比值大于QST剖面;稀土元素球粒陨石标准化后,SJC剖面的Eu为负异常,剖面
上部和下部出现Ce负异常;QST剖面Ce负异常,Eu明显负异常。（4） 元素含量变化和元素对Al-Ti、Al-Fe及Zr-Hf相关性
说明剖面上覆红土是下伏基岩风化的结果。研究结果显示,两个剖面的元素地球化学特征与基岩存在很好的继承性,风化
层是基岩原位风化的产物。 相似文献
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滇西临沧花岗岩中段岩性主体为黑云母二长花岗岩,是离子吸附型稀土矿的天然成矿母岩。研究区湿热的气候使得在地势相对平缓的中山地区形成巨厚的花岗岩风化带,依据风化程度由地表至基岩依次分为腐殖土层、亚黏土层、全风化层、半风化层、弱风化层和新鲜基岩。全风化层是本区离子吸附型稀土矿的主要赋矿层位,该层位元素地球化学特征显示,经过风化后稀土元素发生了富集和分馏,稀土矿化是以轻稀土为主。轻稀土又以La和Ce这两种元素为主。依据本区不同地貌类型建立了倾缓的山脊、平缓的山顶和低缓的山丘3种离子吸附型稀土矿成矿模式。 相似文献
8.
四川沐川地区上二叠统宣威组底部稀土富集层地球化学特征及其成因 总被引：1，自引：0，他引：1
扬子陆块西南缘滇、黔地区上二叠统宣威组(P3x)底部存在的稀土富集层已经有很多报导.采集四川沐川地区ZK15-3钻孔宣威组底部的16件黏土岩及玄武岩样品进行地球化学测试分析,通过矿物学和地球化学特征的研究探讨了稀土富集层的成因.测试结果表明,样品ΣREE为263.87～12 820.56×10-6,ΣLREE/ΣHREE 为4.31～43.31;w(TiO2)为 1.65％～14.6％,LaN/YbN 比值介于7.73～130.26,属于轻稀土富集.δEu值介于0.26～0.92,Eu负异常明显,δCe值介于0.87～1.25,Ce丰度无明显异常.稀土富集层自下而上ΣREE先增长后降低,依层序变化曲线总体呈"中隆形",岩性上稀土元素显著富集于铁质、铝质黏土岩中.综合稀土富集层的地质特征、稀土分配模式、对峨眉山玄武岩钛元素高含量背景的继承性、主微量元素建立的物源性质图解判别结果以及Ce/La和Sm/Nd比值的DF判别结果等,认为稀土富集层下亚段铁质黏土岩的形成以高钛玄武岩风化淋滤作用为主,上亚段铝质黏土岩、深灰色黏土岩等为玄武岩风化剥蚀后搬运再沉积并混有上地壳中酸性火成岩提供的部分物源的产物.该项研究可为川南地区稀土矿的找矿工作提供重要线索,对构架整个西南峨眉山玄武岩地区黏土岩型稀土矿的成矿理论具有重要意义. 相似文献
9.
稀土元素由于其独特的化学特征被广泛应用于环境地球化学分析过程研究。以淮南采煤沉陷区表层沉积物中稀土元素(REEs)为研究对象,采集研究区潘一、顾桥、谢桥沉陷区的表层沉积物样品共12个,采用ICP-MS对样品的稀土元素含量进行测试分析,探讨了表层沉积物中稀土元素的含量分布特征、控制因素及其物质来源。结果表明:研究区表层沉积物中稀土元素含量为54.63~130.45 μg/g,平均102.60 μg/g;LREE/HREE比值为11.89~20.55,平均14.29,轻稀土呈现明显富集现象;相关性分析结果显示,REEs趋向于黏土组分中富集;研究区养殖和捕捞活动导致表层沉积物中稀土元素含量的降低;球粒陨石标准化结果表明,研究区稀土元素呈现不同程度的La和Gd正异常,其中,Gd正异常主要是受到燃煤的影响,而La正异常主要与燃煤和化肥有关。结合Pearson相关性、球粒陨石标准化和(La/Yb)N-(La/Sm)N-(Gd/Yb)N三元图判别,认为研究区水体表层沉积物中稀土元素与人类活动(燃煤和化肥)有关,研究认识为污染物的源头控制和煤矿区环境的生态治理提供参考依据。 相似文献
10.
云南建水普雄铌稀土矿床是近年来发现的一处大型铌稀土多金属矿床,产于霞石正长岩和碱性正长岩组成的长岭岗碱性岩体的风化壳中,累计探明铌资源量超过5.7×10~7 kg,总稀土资源量超过47×10~7kg。目前,对该矿床的研究主要集中在矿物学特征和找矿勘查技术上,在矿床地球化学研究方面,仅限于部分成矿元素(如铌和稀土等)的基本分析上。本次工作在深入的野外观测基础上,对具有代表性的12号勘探线64号钻孔进行了系统取样(24件)和高精度微量、稀土元素含量分析。结果显示,微量元素与上地壳元素平均含量相比,全部样品Li、Ga、Nb、Sb、Cs、Pb、Th和U等有不同程度富集;稀土元素相对球粒陨石也均有不同程度富集,但稀土总量变化范围较大,总体上表现为全风化层样品(∑REE介于1046×10~(-6)～9154×10~(-6))高于粘土层(630×10~(-6))和半风化层样品(163×10~(-6)～1369×10~(-6)),表明成岩作用和风化过程导致了这些元素的不同程度富集。此外,全部样品的轻稀土总量和重稀土总量比值较大,轻稀土元素和重稀土元素间分异明显,∑LREE/∑HREE=20～58,(La/Yb)N=25～143,轻稀土元素内部分异((La/Sm)N=11～26)较重稀土元素内部分异明显((Gd/Yb)N=1～6),表明稀土元素发生了不同程度分异和富集。全部样品Eu负异常明显(δEu=0.5～0.7),Ce异常显著,正、负异常均有(δCe=0.1～3.8),表明成岩作用和风化过程没有导致Eu异常改变,但对Ce异常产生了显著影响。综上,普雄铌稀土矿床富集多种三稀(稀有、稀土和稀散)元素,成岩作用和风化过程共同导致了三稀元素不同程度分异和富集。 相似文献
11.
Veronique Kamgang Kabeyene Beyala Estelle Ndome Effoudou Priso Georges Emmanuel Ekodeck 《Chemie der Erde / Geochemistry》2009,69(1):61-13
An in situ weathering profile overlying chlorite schists in the Mbalmayo-Bengbis formations (South Cameroon) was chosen for the study of the behaviour of REE and the evaluation of geochemical mass balance. After physical and mineralogical studies, the chlorite schists and the undisturbed weathered materials were chemically analyzed for major elements (X-ray fluorescence and titrimetry) and REE (ICP-MS). The behaviour of the REE in the Mbalmayo weathering system was established in comparison with the REE of the reference parent rock. Mass balance calculations were applied to both major elements and REE. The mineralogy of the materials was determined with the aid of a Philips 1720, diffractometer. The chlorite schists of the Mbalmayo sector show low REE contents (Σ=153.44 ppm). These rocks are relatively rich in LREE (about 125 times the chondritic value) and relatively poor in HREE (about 20 times the chondritic value). The REE diagram normalized to chondrites shows a slightly split graph ((La/Yb)N=6.18) with marked enrichment in LREE (LREE/HREE=9.50) in relation to HREE. Moreover, these spectra do not present any Ce anomaly, but a slightly positive Eu anomaly. The imperfectly evolved profile, whose materials are genetically linked, shows an atypical behaviour of REE. In effect, the LREE are more mobile than the HREE during weathering ((La/Yb)NASC<1) with weak Ce anomalies. This has been rarely reported in lateritic profiles characterized by higher HREE mobility than LREE during weathering processes with high Ce anomalies. This is either due to the difference in the stability of REE-bearing minerals, or to the weak acidic to basic pH conditions (6.70<pH<7.80), or even due to the average evolution of the weathering materials. The pathway of the REE along the profile is as follows: (1) leaching in the saprolites and summit of the profile, except for Ce, which precipitates very weakly in the nodular materials and the coarse saprolite materials, (2) at the base of the profile, solutions come in contact with chlorite schist formations, at this level, the pH increases (pH=7.79), HREE and a part of LREE partially void of Ce precipitate and (3) the other part of LREE precipitates further up in the profile. The geochemical mass balance calculations reveal that these elements are leached in the same phases as the relatively high Si, Al, K and Fe2+ contents. 相似文献
12.
塔里木盆地塔北隆起奥陶系-侏罗系泥岩稀土元素地球化学特征 总被引：12，自引：0，他引：12
分析了塔里木盆地塔北隆起奥陶系、三叠系和侏罗系泥岩的稀土元素丰度。不同时代泥岩都表现出轻稀土富集、重稀土含量均一和具有Eu负异常特征;但它们∑LREE/∑HREE、LaN/YbN、(La/Yb)UCC、Eu/Eu和Ce/Ce等参数则显示这些泥岩形成时的物源和环境有差别。奥陶纪时,研究区处于相对稳定的沉积环境,物源为成熟度高的大陆上地壳;二叠纪到三叠纪构造-火山活动强烈,部分沉积物来自火山岩的风化;侏罗纪塔北隆起区则进入稳定构造沉降阶段。这一差别对认识塔里木盆地及周边造山带形成演化研究有指示意义。 相似文献
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珠江三角洲中部钻孔PRD20和PRD17晚第四纪以来的沉积记录较为完整,尤其是晚更新世海侵记录良好。以其为研究对象,对两孔的有孔虫微体动物群记录和沉积特征进行了分析和对比,并结合前人研究成果,重建珠江三角洲晚更新世以来的古环境演变,并着重分析了晚更新世海侵事件。约44500 cal a BP以前,研究区为河流环境,发育河道砂砾沉积。约44500—21300 cal a BP,发生晚更新世海侵,形成溺谷型河口湾,两孔沉积物中有孔虫的垂直分布记录了水体条件发生的多次变化,可辨识出2次海侵海退次级旋回;其中PRD20孔中有孔虫以滨岸广盐型占绝对优势,PRD17孔中以滨岸广盐型为主、海相—半咸水型有孔虫占有一定比例,表明研究区位于溺谷湾中径流与潮流共同作用的区域,且PRD20孔受径流影响更大。约21300 cal a BP后,受末次冰盛期海退影响,研究区暴露于地表遭受风化剥蚀,风化产物在PRD20孔表现为1层褐红色砂砾,在PRD17孔表现为1层花斑黏土。约8000 cal a BP,海平面回升导致河水滞留形成沼泽环境,PRD20孔发育1层泥炭层。约8000—5500 cal a BP,PRD20孔发育受径流影响较大的河口湾湾头沉积,仅在全新世海侵最盛时含有少量有孔虫记录。约5500 cal a BP后,研究区发育三角洲平原沉积。受构造抬升影响,PRD17孔地势较高,于约4700 cal a BP才开始重新接受沉积,零星出现潮水搬运而来的有孔虫。 相似文献
14.
重庆城口高燕锰矿属于大型碳酸盐锰矿床。文章在系统野外地质调查及样品采集基础上,结合前人研究工作,采用等离子质谱仪(ICP-MS)分析了高燕矿区师家沟、板相沟及750平硐样品的稀土元素含量。分析结果显示,其稀土元素总量范围49.79×10~(-6)~281.24×10~(-6),平均含量125.92×10~(-6);轻重稀土比值范围1.79~3.58,显示轻稀土元素富集,且轻稀土元素之间的分馏程度高于重稀土元素;w(La)/w(Ce)=0.36~0.93,δEu=1.13~2.96,呈现弱正铕异常;δCe=2.09~5.84,有强的正铈异常。认为含锰碳酸盐岩形成于强还原的碱性环境沉积过程中,且有热水参与,成岩成矿的温度小于250℃,锰富集阶段处于滨岸的高能环境中。CeS10在本区具有示矿作用。 相似文献
15.
渝东南地区的下志留统石牛栏组作为重要的油气储集层,研究其古环境变化、物质来源及物源区构造背景具有重要意义。本文采用稀土元素总量w(ΣREE)、REE配分模式、以及w(ΣLREE)/w(ΣHREE)、w(La)_N/w(Yb)_N、w(Ce)_N/w(Yb)_N、w(La)_N/w(Sm)_N、w(Gd)_N/w(Yb)_N、δEu、δCe、Ce_(anom)等特征值研究方法,对渝东南下志留统石牛栏组典型剖面的稀土元素特征及古海洋环境和物源进行深入研究。结果表明:石牛栏组灰岩稀土元素总量略低于大陆地壳平均值,轻稀土较为富集,重稀土亏损,铕明显负异常,铈负异常较微弱。w(ΣREE)证实了石牛栏组的沉积水体由浅缓慢变深再急剧变浅的变化过程。Eu负异常、Ce负异常和C_(eanom)值均揭示石牛栏组沉积时期海水具有弱还原性。REE的分异程度反映了石牛栏组从沉积早期到沉积晚期,沉积速率总体降低。稀土元素的比值特征及w(ΣREE)—w(La)/w(Yb)图解表明其物源源自雪峰山隆起,源岩主要为沉积岩。 相似文献
16.
REE geochemistry of the recent playa sediments from the Thar Desert, India: An implication to playa sediment provenance 总被引：3，自引：0，他引：3
The playas (saline lakes) situated in the Thar Desert, north-west India, provide prominent examples of alkaline brine and varying assemblages of detrital and evaporite mineralogy. The eastern margin of the desert is relatively semi-arid, whereas the central to western region is arid to hyper-arid in nature. Rare earth elements (REEs) systematics in the sediments of nine different playas of the Thar Desert were studied to understand the provenance of the sediments and the intensity of chemical weathering in the region. Based on the REE patterns, fractionation of light REE (LREE) (La/Sm)N and heavy REE (HREE) (Gd/Yb)N, and Eu anomaly (Eu/Eu*), the upper continental crust normalised playa sediments are divided into two different groups. The eastern margin playa sediments show homogeneous REE contents, relatively positive Eu anomaly and depleted HREE values, whereas the western arid core playa sediments have highly variable REE contents, relatively negative Eu anomaly and similarly fractioned LREE and HREE patterns. The dissimilarity in the degree of HREE fractionations both in the eastern and western playa sediments is attributed to the differential distribution of minerals, depending upon their resistance to chemical weathering. It is believed that the relatively higher abundance of REE bearing heavy minerals and the presence of higher amounts of evaporites influence the large variation of REE distribution and enriched HREE in the western playa sediments. Apart from the relatively higher abundance of heavy minerals, the presence of rock fragments of variable petrographic character and roundness mirror the lower rock–water interaction in the arid western region. The presence of well-rounded metamorphic rock fragments and minerals, sourced from the eastern margin Aravalli mountains, indicates that the playas of the entire desert get the detrital and dissolved material mainly from the Aravalli mountains. Additionally, the western playas receive sediments from their surrounding Proterozoic and Mesozoic formations. This interpretation is supported by the presence of angular rock fragments of basalt, rhyolite and limestone in the western playas. 相似文献
17.
Rare earth element studies of surficial sediments from the southwestern Carlsberg Ridge,Indian Ocean
The rare earth element (REE) contents of sixteen surficial calcareous sediments from the southwestern Carlsberg Ridge, Indian
Ocean, have been determined. The total REE vary from 35 ppm to 126 ppm and are inversely related to the calcium carbonate
content. REEs show a strong positive correlation with Al + Fe + K + Mg + Na (r
2= 0.98) and Mn + Fe + Cu + Ni (r
2= 0.86) suggesting that the REE is associated with a combined phase of clays (mainly illite) and Mn-Fe oxyhydroxides. The
aeolian input into these sediments is suggested from the weak positive Eu/Eu* anomaly. Shale-normalized (NASC) pattern along
with La(n)/Yb(n) ratio suggest enrichment of heavy REE (HREE) relative to the light REE (LREE) with a negative Ce/Ce* anomaly implying retention
of a bottom water REE pattern.
An erratum to this article is available at . 相似文献
18.
萤石经常以脉石矿物存在于各类金属矿床中,但以矿石矿物与金属矿物共存较为少见。布拖小洞子铅锌矿体和萤石矿体是赋存在震旦系灯影组不同部位的典型矿床,受四开-交际河断裂的次级断层带控制,是该区较为特殊,研究程度较低的一类矿床。其中萤石矿床产于与黑色燧石条带白云岩相关的断裂构造,矿石矿物以萤石为主。本文通过对震旦系灯影组下部萤石矿床开展稀土元素地球化学研究,结果表明轻稀土元素富集,重稀土元素略亏损,LREE/HREE介于0.96~1.61,(La/Yb)_N为1.19~3.23,稀土元素配分图表现出略微右倾的特征,具Eu正异常和Ce负异常特征。Tb/Ca-Tb/La、Y/Ho-La/Ho及La/Yb-∑REE等图解表明小洞子萤石矿床主要为同一体系不同阶段的热液产物,破碎带充填交代型矿床成因,其成矿物质来源与灯影组地层和峨眉山玄武岩热液有关。 相似文献
19.
Rare earth elements (REE) of dissolved and suspended loads in the Xijiang River, South China 总被引：4，自引：0，他引：4
The Xijiang River is the main channel of the Zhujiang (Pearl River), the second largest river in China in terms of water discharge, and flows through one of the largest carbonate provinces in the world. The rare earth element (REE) concentrations of the dissolved load and the suspended particulate matter (SPM) load were measured in the Xijiang River system during the high-flow season. The low dissolved REE concentration in the Xijiang River is attributed to the interaction of high pH and low DOC concentration. The PAAS-normalized REE patterns for the dissolved load show some common features: negative Ce anomaly, progressively heavy REE (HREE) enrichment relative to light REE (LREE). Similar to the world’s major rivers the absolute concentration of the dissolved REE in the Xijiang River are mainly pH controlled. The degree of REE partitioning between the dissolved load and SPM load is also strongly pH dependent. The negative Ce anomaly is progressively developed with increasing pH, being consistent with the oxidation of Ce (III) to Ce (IV) in the alkaline river waters, and the lack of Ce anomalies in several DOC-rich waters is presumably due to both Ce (III) and Ce (IV) being strongly bound by organic matter. The PAAS-normalized REE patterns for the dissolved load and the SPM load in rivers draining the carbonate rock area exhibit middle REE (MREE) enrichment and a distinct maximum at Eu, indicating the preferential dissolution of phosphatic minerals during weathering of host lithologies. Compared to the Xijiang River waters, the MREE enrichment with a maximum at Eu disappeared and light REE were more depleted in the South China Sea (SCS) waters, suggesting that the REE sourced from the Xijiang River must be further fractionated and modified on entering the SCS. The river fluxes of individual dissolved REE introduced by the Xijiang River into the SCS vary from 0.04 to 4.36 × 104 mol a−1. 相似文献