Determination of Scandium, Yttrium and Rare Earth Elements in Rocks by High Resolution Inductively Coupled Plasma-Mass Spectrometry

The high sensitivity, minimal oxide formation and single internal standard capability of high resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS) is demonstrated in the direct determination of Sc, Y and REE in the international reference materials: basalts (BCR-1, BHVO-1, BIR-1, DNC-1), andesite (AGV-1) andultramafics (UB-N, PCC-1 and DTS-1). Time consuming ion exchange separation or preconcentration were found to be unnecessary. Smooth chondrite normalized plots of the REE in PCC-1 and DTS-1 were obtained in the range 0.8-50 ng g-1 (0.01-0.1x chondrite). Method precision was found to be digestion dependent with an average external repeatability of 2-4% for the basalts, AGV-1 and UB-N, and 10% for PCC-1 and DTS-1. The mass peak due to ⁴⁵Sc was completely resolved from ²⁹Si¹⁶O and ²⁸Si¹⁶O¹H spectral interferences using medium resolution, which casts doubt on the accuracy of Sc determinations using quadrupole ICP-MS. Literature values for Y in rock reference materials were found to be approximately 9% high after HR-ICP-MS and XRF analysis.     

Rare Earth Element and Yttrium Variability in South East Queensland Waterways

We present data for the rare earth elements and yttrium (REY) in the National Research Council of Canada natural river water reference material SLRS-4 and 19 natural river waters from small catchments in South-East Queensland, Australia, by a direct ICP-MS method. The 0.22 μm filtered river water samples show a large degree of variability in both the REY concentration, e.g., La varies from 13 to 1157 ppt, and shape of the alluvial-sediment-normalised REY patterns with different samples displaying light, middle or heavy rare earth enrichment. In addition, a spatial study was undertaken along the freshwater section of Beerburrum Creek, which demonstrates that ~75% of the total REYs in this waterway are removed prior to estuarine mixing without evidence of fractionation.     

江西宁都葛藤嘴浅变质岩离子吸附型稀土矿成矿模式

江西宁都葛藤嘴离子吸附型稀土矿床是新近发现的新类型稀土矿床,成矿母岩为一套浅变质岩系。本文对矿区内的浅变质岩岩石类型、稀土元素含量及风化壳中稀土分布特征进行了研究,总结了成矿模式。矿区内岩石类型有变质砂岩、变质凝灰岩、千枚岩及片岩类。稀土元素含量普遍偏高,平均为384×10-6,变质凝灰岩类可达723×10-6,属于LREE型。风化壳钻孔样品中稀土含量增高,稀土配分继承了母岩特征。此类矿床最为特殊的是成矿母岩呈层产出,母岩的岩石类型、厚度及层位是重要的找矿要素。宁都地区浅变质岩类中良好的成矿母岩主要为变质砂岩和变质凝灰岩,两者不仅稀土含量较高,产出厚度较大,风化壳矿体也较为连续。     

天然气溶解过程中组分分馏模型及其应用

天然气不同组分在水中溶解度的差异,导致溶解相与残留游离相天然气组分组成不同,即发生组分的溶解分馏效应。溶解分馏效应在天然气水溶运移、溶解散失等过程中均有发生。揭示天然气组分的溶解分馏规律、建立定量分馏模型,有助于天然气气源对比和成藏过程示踪。以Henry定律为依据,对不同组分溶解特征分析,提出了溶解度分数的概念,并建立了溶解分馏模型。根据该模型和各组分的溶解度分数和天然气溶解量,可计算各组分的溶解分馏量,恢复天然气初始组成特征。计算表明,威远震旦系气藏初期的天然气组成为:CH4为72.70%,C2H6为0.09%,CO2为22.41%,N2为4.07%,干燥系数(C1/C1-5)为99.876%。溶解作用使天然气中CO2含量显著降低,烃类气体含量增加,而天然气干燥系数降低。结果有助于天然气成因判识和气源对比等。     

典型稀土矿区周边土壤中稀土元素含量及赋存形态研究

研究不同类型稀土矿区周边土壤中稀土元素(REE)的含量与形态特征,可为矿区周边污染环境治理提供理论支持与科学建议。本文采用欧盟BCR顺序提取法、电感耦合等离子体质谱测定的方法,对内蒙古白云鄂博稀土尾矿区和江西赣南稀土矿区周边6个土壤样品中15种稀土元素进行了含量及形态分析测定。结果表明:矿区周边土壤中稀土元素总量约为264～15955μg/g,明显高于全国土壤背景值(186μg/g),白云鄂博尾矿区周边土壤富集轻稀土元素,稀土元素主要以残渣态富集,占总含量的64.0%～89.4%,生物有效性较低,对环境影响较小;赣南矿区周边土壤富集重稀土元素,稀土元素的主要存在形式是弱酸提取态和可还原态,占总含量的70%以上,易发生迁移转化及对周边环境造成污染。土壤中稀土元素的形态分布与pH值有显著相关性,随着土壤pH值的降低,稀土元素的弱酸提取态含量不断升高,残渣态含量不断降低。     

榍石LA-ICP-MS U-Pb定年中元素分馏的影响及校正研究

同位素地质年代学是探索地质体时空演化及地球动力学等问题的基础学科,应用最为广泛的当属含铀副矿物的U-Pb定年技术。榍石具有相对较低的U-Pb体系封闭温度,并广泛发育于岩浆岩、各类变质岩、热液成因岩石以及少量沉积岩中,是一种理想的中高温地质事件定年矿物。利用电感耦合等离子体质谱法(ICP-MS)测定榍石U-Pb年龄时,不可避免地要解决高普通铅以及元素分馏效应对测试的影响。本文对榍石LA-ICP-MS实验过程中的元素分馏行为进行研究,采用相同基体的标准样品与未知样品对比,发现了榍石不同颗粒之间元素分馏行为不一致的现象;同时采用不同的元素分馏校正方法,分别应用于锆石、独居石和榍石进行对比研究,认为分馏行为一致的副矿物定年可以采用"指数法"和"均值法"对数据进行校正,但是对于榍石这种分馏行为不一致的副矿物,定年时只有采用"截距法"对数据进行校正才可以获得正确的年龄。进而将此结论应用于秦岭造山带老牛山地区岩浆成因榍石样品,得到的结果与锆石年龄一致,表明"截距法"可以避免分馏行为不一致导致的校正不准确的问题。本研究成果为榍石LA-ICP-MS U-Pb定年方法的完善提供了一种思路。     

我国稀土资源需求结构分析

战略性新兴产业的迅速发展,无论对中国还是对世界经济都具有全局带动和重大引领作用,而稀土当之无愧地成为战略性新兴产业的重要支柱性矿产之一。随着中国稀土产业的不断发展壮大以及政策宏观调控的作用,加之终端消费产业的需求拉动稀土消费,我国的稀土需求一直呈增长态势,而新兴领域的应用的不断开拓,使稀土资源需求结构也发生的很大变化,本文通过分析近年来稀土资源需求变化,为下一步稀土资源管理提出相关政策建议。     

Differential Fractionation of Rare Earth Elements in Oxidized and Reduced Granitic Rocks: Implication for Heavy Rare Earth Enriched Ion Adsorption Mineralization

Ion adsorption rare earth element (REE) deposits in southern China are the exclusive source of heavy REEs (HREEs) in the world, and this HREE‐enriched character of the deposits is inherited from the REE compositions of the underlying granitic rocks. Such HREE‐enriched rocks form from heavy fractionation of reduced granitic magmas. We explore why reduced granitic magmas are enriched in HREEs during the fractionation, based on the REE geochemistry of granitic rocks and abundance of REEs in their constituent minerals in the southwestern Japan arc of Cretaceous to Paleogene age. The compilation of the whole rock geochemistry and REE compositions of the granitic rocks of the Sanin (oxidized), Sanyo (reduced) and Ryoke (reduced) belts in the southwestern Japan arc indicates that: (i) light REEs (LREEs) decease with fractionation of the granitoids in the Sanin belt but this trend is not clear in the granitoids in the Sanyo belt and LREEs rather increase in the Ryoke granitoids; (ii) Eu decreases with fractionation in all the belts; and (iii) HREEs slightly, but steadily decrease in the Sanin belt but enrich significantly in the Sanyo and Ryoke belts with fractionation. Analytical results of REE concentrations by scanning electron microscope with energy dispersive X‐ray spectroscope and laser ablation‐inductively coupled plasma mass spectrometer in the constituent minerals in a granodiorite sample from the Sanin belt show a moderate concentration of REEs in hornblende (577 ppm) in addition to high concentrations in allanite (~20 %), britholite (~30 %), primary titanite (8922 ppm), apatite (4062 ppm), and zircon (1693 ppm). Because primary titanite and allanite are commonly present in the oxidized granitoids but not in the reduced ones, the REE depletion in the fractionated, oxidized granites is attributed to the crystallization of these minerals. In contrast, scarcity of these minerals in the reduced granitoids enriches REEs, in particular HREEs in the fractionated magmas, which finally precipitate REEs in the granites and pegmatites. Both positive, but different correlation ratios between the Nb and Dy concentrations in the granitoids of the Sanin and Sanyo‐Ryoke belts suggest that columbite–pyrochlore‐group and fergusonite‐group minerals are the major HREE host in the oxidized and reduced granites, respectively.     

Geochemistry of Suspended Particulate Matter (SPM) in the Murray-Darling River System: A Conceptual Isotopic/Geochemical Model for the Fractionation of Major, Trace and Rare Earth Elements

A conceptual isotopic/geochemical model is presented to explain the variation of major, trace and rare earth element (REE) geochemistry and Sr isotope systematics in suspended particulate matter (SPM) as a function of particle/colloid size. This conceptual model is an extension of a previous investigation of the origin of SPM in the Murray-Darling River system (MDRS) that utilised Sr isotope systematics to examine aspects of SPM (particle/colloid) origin, structure and mineralogy. The geochemical processes that give rise to the often coherent trends in major, trace and REE geochemistry and Sr isotopic signature as a function of particulate (<1 μm) and colloidal (>1 μm) size in the MDRS have been identified using an enhanced SPM size fractionation technique as a basis to not only obtain a broad range of particle/colloid size ranges, but also to provide sufficient material for subsequent geochemical and isotopic analysis. The conceptual isotopic/geochemical model proposed here contains three major components: (i) the differential weathering of micas and alkali (K-) feldspars to form the majority of the particulate (<1 μm) fractions (high 87Sr/86Sr ratio), which have a geochemical and Sr isotopic signature that closely resembles precursor mineralogies, (ii) the differential weathering of Na, Ca-feldspars (plagioclase) which decompose to form clay minerals in the colloidal (>1 μm) fractions (low 87Sr/86Sr ratio), with a range of geochemical signatures related to the relative proportions of inorganic and organic constituents, and (iii) the presence of natural organic matter as coatings on the particulate (<1 μm) and colloidal (>1 μm) matter and possibly as organo-colloids which exert an increasing influence in particular on bulk colloid geochemistry with decreasing colloid size. This conceptual isotopic/geochemical model also accounts for the distinct variation in major, trace and REE geochemistry and Sr isotopic systematics between the particulate (<1 μm) and colloidal (>1 μm) fractions, the variation being primarily a function of the distinctly different precursor mineralogies of the SPM fractions and geochemical fractionation during the weathering and transport. Additionally, this model explains a systematic fractionation of REE apparent within colloidal (>1 μm) fractions. Statisitcal (hierachical cluster) analysis of two particulate and three colloidal fractions from 23 samples from the MDRS is used as a basis to investigate geochemical and mineralogical associations within the particulate and colloidal size fractions and to provide additional supporting evidence for the conceptual isotopic/geochemical model. This revised version was published online in July 2006 with corrections to the Cover Date.     

中大流域水沙耦合模拟物理概念模型

根据黄河中游、北方干旱地区流域的超渗产流水文特征和冬季积雪的累积及融化机制,提出了中大流域水流模拟模型,结合黄土地区小流域坡面产沙、汇沙和沟蚀产沙、汇沙计算公式,构成了中大流域水沙耦合模拟物理概念模型。该模型较好地处理了北方干旱地区中大流域用下渗曲线计算地面径流中存在的观测资料缺乏、数据处理量太大两大难题;考虑了大流域气候、下垫面因素空间的不均匀性和雨洪径流产沙与融雪径流产沙间的差异。经流域实测资料的模拟检验表明,模型结构较合理,模拟结果较好。     

Sorption Model for Dissolved Aluminium in Freshwaters

A series of aluminium speciation measurements were madein the freshwaters of the Yare and Great Ouse rivers (England). Samples were analysedfor dissolved and particulate Al, suspended particulate matter (SPM), and other alliedchemical species in order to assess the role of sorption processes on the suspended phasesin controlling dissolved Al levels. Partitioning of Al occurs between solid andsolution phases with a distribution coefficient (K_d) which varies over about one anda half orders of magnitude for suspended particle concentrations of comparablemagnitude. A sorption model is proposed for dissolved Al concentrations in thesefreshwaters with most of the data fitting the model defined by a zone with K_dvalues of 0.316 × 10⁶ and 10⁷. However, a few data points lie outside thiszone, suggesting that other processes may also influence dissolved Al distributions.Nevertheless, the model may serve as a starting point for predicting concentrations ofdissolved Al in rivers where SPM levels are moderate to high (>1 mg l^-1 but< 75 mg l^-1), and indeed, this model works reasonably well for the Conway system(Wales). Further, the empirical distribution coefficient, K_d, decreases withincreasing suspended particle concentration, which may be due in part to colloidal phenomena.     

非氢键羟基矿物H同位素平衡分馏议程通式

本文对H同位素平衡分馏系数（αe）与温度（T）、矿物化学组成（M）、羟基振动频率（f）之间的关系作了详细研究，并得出非氢键羟基矿物在450-850℃温度范围内，H同位素平衡分馏方程通式。     

油成甲烷碳同位素分馏的化学动力学及其初步应用

利用金管实验装置,在高压、恒速升温的条件下对塔里木盆地2个油样进行了热解成气实验,结合GC和碳同位素分析,得到了甲烷生成率、甲烷碳同位素与实验温度和升温速率的关系。由此建立并标定了油成甲烷及其碳同位素分馏的化学动力学模型。结果表明：2个油样生成甲烷气时的平均活化能差别不大,但活化能的分布有所差异;¹²C生成的活化能在低值区稍高,而在高值区稍低,从而使生成¹²C的平均活化能稍低于¹³C。正是¹²C、¹³C甲烷生成的活化能分布上的这一微小的差异,导致了甲烷生成时碳同位素的明显分馏。所得模型在塔里木盆地的初步应用显示,英南2气藏天然气主要为晚近期的阶段聚集气,而满东1气藏天然气可能为累积聚集。     

离子吸附型稀土矿储量动态估算方法(RiRee)及其拓展运用

我国南方离子吸附型稀土矿勘查中一般采用传统的地质块段法估算资源储量,存在着探矿工程量大、投入高、效率低的缺点。而稀土资源包含17种不同的稀土元素,不同元素精矿的市场价格差别又很大,现有的基于稀土氧化物总量的工业指标难以快速对接实际矿山生产,造成表外矿实际在产、而表内矿不经济可采甚至可能无法利用的反常现象。本文基于离子吸附型稀土矿床的特点,借鉴土壤化探样品处理的克里格法,建立了离子吸附型稀土矿资源储量估算的三维模型及其相应评价方法,简称RiRee。该模型和方法不但可以对风化壳中的"样品点"进行体积和品位的估算,而且与市场价格直接关联、可根据每天市场价格的动态变化确定边界品位和工业品位,进行实现矿体的实时圈定、资源储量的日常更新与矿山经济效益的动态评价。运用该模型,作者在赣南、滇西、浙江等地不同离子吸附型稀土矿区开展了典型研究和试点示范,取得了初步成效。结果显示,利用克立格法计算的矿体体积与传统手工圈定的块段法相比较,前者计算的结果是合理的,且具有快速、准确、方便的特点。利用自主开发的以克里格法为基础的数字矿山经济评价系统(主要是其中的价格-边界品位敏感性分析模块),动态设置边界品位,灵活圈定不同稀土单元素价格下经济可采的矿体边界,一旦稀土精矿的市场价格发生变化,即可通过软件系统快速修正盈亏平衡点,并随时变更边界品位,动态确定经济可采的矿体的空间范围,为合理布置采矿工程提供科学依据,有助于促进离子吸附型稀土矿产资源(尤其是重稀土)的合理、高效的开发利用。     

Rare earth element and strontium isotope geochemistry in Dujiali Lake,central Qinghai-Tibet Plateau,China: Implications for the origin of hydromagnesite deposits

Rare earth element (REE) and strontium isotope data (⁸⁷Sr/⁸⁶Sr) are presented for hydromagnesite and surface waters that were collected from Dujiali Lake in central Qinghai-Tibet Plateau (QTP), China. The goal of this study is to constrain the solute sources of hydromagnesite deposits in Dujiali Lake. All lake waters from the area exhibit a slight LREE enrichment (average [La/Sm]_PAAS = 1.36), clear Eu anomalies (average [Eu/Eu*]_PAAS = 1.31), and nearly no Ce anomalies. The recharge waters show a flat pattern (average [La/Sm]_PAAS = 1.007), clear Eu anomalies (average [Eu/Eu*] _PAAS = 1.83), and nearly no Ce anomalies (average [Ce/Ce*]_PAAS = 1.016). The REE+Y data of the surface waters indicate the dissolution of ultramafic rock at depth and change in the hydrogeochemical characteristics through fluid-rock interaction. These data also indicate a significant contribution of paleo-groundwater to the formation of hydromagnesite, which most likely acquired REE and Sr signatures from the interaction with ultramafic rocks. The ⁸⁷Sr/⁸⁶Sr data provide additional insight into the geochemical evolution of waters of the Dujiali Lake indicating that the source of Sr in the hydromagnesite does not directly derive from surface water and may have been influenced by both Mg-rich hydrothermal fluids and meteoric water. Additionally, speciation modeling predicts that carbonate complexes are the most abundant dissolved REE species in surface water. This study provides new insights into the origins of hydromagnesite deposits in Dujiali Lake, and contributes to the understanding of hydromagnesite formation in similar modern and ancient environments on Earth.     

Rare earth element sources and modification in the Lower Kittanning coal bed, Pennsylvania: implications for the origin of coal mineral matter and rare earth element exposure in underground mines

In this study, we examine the variations in rare earth elements (REE) from the Lower Kittanning coal bed of eastern Ohio and western Pennsylvania, USA, in an attempt to understand the factors that control mineral matter deposition and modification in coal, and to evaluate possible REE mixed exposure hazards facing underground mine workers. The results of this study suggest that the Lower Kittanning coal mineral matter is derived primarily from a clastic source similar to that of the shale overburden. While highly charged cations like silicon, aluminum, and titanium remained relatively immobile within the coal mineral matter, iron (primarily as pyrite) was added from nonclastic sources, either during deposition of the coal mire vegetation or subsequent to burial. Other mobile cations (e.g., alkali and alkaline earth elements) appear to have been added to and/or leached from the originally deposited clastic mineral matter. Most of the sulfur in the Lower Kittanning coal bed is bound as FeS₂ in the mineral matter, but a majority of samples contain a small excess of S that is most likely organically bound.In general, the total rare earth element content (TREE) in coal ash is greater than that in the shale overburden. If the primary source of mineral matter is the same as that for the overlying shale, then REE must have been enriched in the coal mineral matter subsequent to deposition. The total rare earth element content of Lower Kittanning coals correlates strongly with Si concentration ([TREE]≈0.0024 [Si]), which provides a threshold for evaluating possible mixed exposure health effects. Chondrite-normalized REE patterns reveal a shale-like light rare earth element (LREE) enrichment for the coal, similar to that of the shale overburden, again suggesting a primarily clastic REE source. However, when normalized to the shale overburden, most of the coal ash samples display a small but distinct heavy rare earth element (HREE) enrichment. We surmise that the HREE were added and/or preferentially retained during epigenesis, possibly associated with groundwater flow through the coal unit, but not necessarily in close association with the addition of iron. At least some of the “excess” HREE could be organically bound within the Lower Kittanning coal.     

新型耦合数据驱动模型在降雨径流模拟中的应用研究

为解决传统数据驱动模型的不足,使其能实现降雨径流过程高精度连续模拟,提出新型耦合数据驱动模型——PEK,即:基于偏互信息的输入变量选择、基于新型集成神经网络的出流量预测和基于K最近邻模型的出流量误差预测。PEK模型具有以下特点:(1)提出了基于分离式选择策略和滑窗累积雨量的模型候选输入向量,并与基于偏互信息的输入变量选择方法联合使用,提高了输入信息的充分性和无冗余性,对建立精度高、泛化能力强的高质量模型意义重大;(2)提出了新型集成神经网络——EBPNN及其率定方法。联合使用NSGA-II多目标优化算法和早停止Levenberg-Marquardt算法,通过一次优化过程同时确定全局最优个体网络个数、各个体网络拓扑结构和网络参数。个体网络权重由基于AIC信息准则的权重优选方法确定。EBPNN在模拟精度和网络复杂度间取得了良好折衷,精度高、泛化能力强、率定结果客观;(3)PEK模型能够进行多步外推预报,实现了非实时校正模式下的高精度连续模拟,增长了预见期;(4)PEK模型不需要进行流域状态变量的计算,仅需初始出流量就可进行出流量的连续模拟。在呈村流域应用PEK和CLS两个数据驱动模型进行次洪降雨径流模拟及精度比较。结果表明PEK模型使用简便,模拟精度高于CLS模型,实现了多步外推的高精度连续模拟,增长了数据驱动模型的预见期。     

稀土矿区环境调查SMAIMA方法体系、评价模型及其应用——以赣南离子吸附型稀土矿山为例

本文以赣南典型稀土矿区为重点调查研究对象,以岩(矿)石-风化壳-尾矿-水为系统,采用多学科多方法协同,对离子吸附型稀土(简称iRee)资源开采涉及到的水资源-环境效应进行了系统研究。提出了对采矿过程中的环境效应进行调查、检测、评估的工作方法体系,即:野外调查(S)—实验测试(M)—特征分析(A)—指标体系构建(I)—模型研究(M)—综合评价(A),简称SMAIMA工作法。自2011年以来连续6年分季度系统采集550多件样品,积累了近3万个可靠数据,为iRee矿区及周边水质采样、特征分析、水污染源鉴别提供了依据。通过对iRee矿区及周边地表水中REE及理化指标时空变化特征的综合分析,查明了污染的原因、途径。建立了针对iRee矿区的水环境质量评价指标体系,构建了针对iRee矿区的水环境模糊综合评价模型。在水环境评价的基础上,针对赣南稀土矿区的环境特点,进一步构建了包括自然地理、基础地质、开发占地以及地质环境在内4大类、13小类的二级评价指标体系,首次研建了基于支持向量机(SVM)的iRee矿山环境效应定量评价模型。运用该评价模型,对龙南、安远、寻乌三个不同类型的稀土矿区(以龙南代表重稀土矿区、以安远代表中稀土矿区、以寻乌代表轻稀土矿区)的矿山环境进行了综合评价分级,进而提出了iRee矿山环境保护和治理恢复的对策建议。     

电感耦合等离子体发射光谱法测定稀土铌钽矿中稀土元素和钍量

用等离子体发射光谱法测定了稀土铌钽矿中的稀土元素和钍量。考察了溶样方式和称样量,选择分析线波长,确定了仪器工作条件。对共存元素的干扰量进行试验,稀土元素之间的干扰可忽略不计。精密度试验表明,各稀土元素及钍的相对标准偏差(RSD,n=11)小于10%(除Eu2O3外)。方法用于实际样品的测定,结果与等离子体质谱法及外检结果吻合。     

Rare earth elements of the Altar Desert dune and coastal sands, Northwestern Mexico

Twenty-one surficial sand samples from the Altar Desert coastal and desert dune systems were analysed for rare earth elements (REE) content. This was done to observe the provenance signatures for four strategic dune localities near the Colorado River Delta, the El Pinacate dune fields, and the beaches of the north of the Gulf of California in the state of Sonora, Mexico. Our goals are to show which mechanisms (i.e., aeolian, marine) exert more influence on the composition of the Altar Desert dune sands. This study also shows the usefulness of REE spatial distribution to determine the relative mobility of the sand. Some sand samples from the dune systems in San Luis Río Colorado (SLRC), Golfo de Santa Clara (GSC), and Puerto Peñasco (PP) displayed dissimilar REE concentrations with respect to the rest of the sand samples from the same sites. These differences can be related to short aeolian transport distance in the sands with high REE concentrations and long aeolian transport distance in the sands with low REE concentrations. Besides, high REE concentration in the sands might be due to their closeness to the Colorado River Delta sediments and to recycled sands derived from granitic rocks. In contrast, all the sand samples from the El Pinacate (EP) site have similar REE concentration values, suggesting that the El Pinacate dune sands are influenced by more selective aeolian processes and less diverse heavy mineral content. The Altar Desert dune sands are derived from granitic sources eroded by the Colorado River. Our results also indicate that the Altar Desert dune sands are low in heavy mineral content (with the exception of Fe and Ti bearing minerals) and enriched in carbonates with phosphates (especially at the PP site) yielding poor correlations between REE and major element concentrations. The REE geographical distribution values in the Altar Desert dune sands indicate that light and heavy REE concentration values are related to aeolian transport, maturity of the sands, their low weathering rates, proximity of the source rocks, and the biogenic debris input from beach sands into the dune.