Behaviours of REE and Other Trace Elements During Pedological Weathering-Evidence from Chemical Leaching of Loess and Palaeosol from the Luochuan Section in Central China

The chemical leaching method is used for a systematic analysis of distribution characteristics of acid-soluble and acid-insoluble REE and other trace elements from the Luochuan loess deposits. The study shows that the acid-insoluble phase in loess and palaeosol is a stable component of old aeolian dusts and is characteristic of the provenance; the acid-soluble phase is the unstable component in the weathering pedogenic process and reflects rock-forming features after accumulation of aeolian dusts. The acid-insoluble REE and acid-soluble Sr and Pb can be used as geochemical indicators respectively to trace the provenance characteristics and the weathering pedogenic process.     

Rare earth and other trace element mobility during mylonitization: a comparison of the Brevard and Hope Valley shear zones in the Appalachian Mountains, USA

In progressing from a granitoid mylonite to an ultramylonite in the Brevard shear zone in North Carolina, Ca and LOI (H₂O) increase, Si, Mg, K, Na, Ba, Sr, Ta, Cs and Th decrease, while changes in Al, Ti, Fe, P, Sc, Rb, REE, Hf, Cr and U are relatively small. A volume loss of 44% is calculated for the Brevard ultramylonite relative to an Al–Ti–Fe isocon. The increase in Ca and LOI is related to a large increase in retrograde epidote and muscovite in the ultramylonite, the decreases in K, Na, Si, Ba and Sr reflect the destruction of feldspars, and the decrease in Mg is related to the destruction of biotite during mylonitization. In an amphibolite facies fault zone separating grey and pink granitic gneisses in the Hope Valley shear zone in New England, compositional similarity suggests the ultramylonite is composed chiefly of the pink gneisses. Utilizing an Al–Ti–Fe isocon for the pink gneisses, Sc, Cr, Hf, Ta, U, Th and M-HREE are relatively unchanged, Si, LOI, K, Mg, Rb, Cs and Ba are enriched, and Ca, Na, P, Sr and LREE are lost during deformation. In contrast to the Brevard mylonite, the Hope Valley mylonite appears to have increased in volume by about 70%, chiefly in response to an introduction of quartz. Chondrite-normalized REE patterns of granitoids from both shear zones are LREE-enriched and have prominent negative Eu anomalies. Although REE increase in abundance in the Brevard ultramylonites (reflecting the volume loss), the shape of the REE pattern remains unchanged. In contrast, REE and especially LREE decrease in abundance with increasing deformation of the Hope Valley gneisses. Mass balance calculations indicate that ≥95% of the REE in the Brevard rocks reside in titanite. In contrast, in the Hope Valley rocks only 15–40% of the REE can be accounted for collectively by titanite, apatite and zircon. Possible sites for the remaining REE are allanite, fluorite or grain boundaries. Loss of LREE from the pink gneisses during deformation may have resulted from decreases in allanite and perhaps apatite or by leaching ofy REE from grain boundaries by fluids moving through the shear zone. Among the element ratios most resistant to change during mylonitization in the Brevard shear zone are La/Yb, Eu/Eu*, Sm/Nd, La/Sc, Th/Sc, Th/Yb, Cr/Th, Th/U and Hf/Ta, whereas the most stable ratios in the Hope Valley shear zone are K/Rb, Rb/Cs, Th/U, Eu/Eu*, Th/Sc, Th/Yb, Sm/Nd, Th/Ta, Hf/Ta and Hf/Yb. However, until more trace element data are available from other shear zones, these ratios should not be used alone to identify protoliths of deformed rocks.     

浙江杭嘉湖平原区环境地球化学研究

根据杭嘉湖平原区区域地球化学调查结果,对本区开展了区域和城市(杭州市)环境质量评价的环境地球化学研究。研究结果表明,杭嘉湖平原区区域环境质量和杭州市区环境质量良好,各环境质量区较好的反映各区内工业生产水平、人口密集程度、历史长短。通过对杭州市不同环境质量区内蔬菜的分析研究证明,杭州市区污染区内有害元素尚未对人体健康产生影响,但为防止今后出现超标现象,应当高度重视,加强土壤环境保护。     

山东牟平邓格庄金矿的地球化学特征及成因

邓格庄大型石英脉型金矿，分布于燕山期昆嵛山花岗岩体内金牛山断裂带次级断裂中。成矿年龄１１８×１０６ａ，它比容矿岩体冷凝至３５０℃时还晚１２×１０６ａ。成矿深度小于１ｋｍ（约０．７５ｋｍ），而容矿岩体的定位深度大于１３ｋｍ，它们的定位深度差大于１２ｋｍ。成矿流体来自地壳深部，通过水－岩反应又从容矿岩体中萃取一部分金。故此金矿不是传统意义的岩浆期后热液矿床     

云南腾冲热泉金的有机地球化学研究——Ⅰ生物标志物浅析

本文主要通过对比分析研究热泉软泥中的金含量与有机质及含硫化合物的相关性。并测定泉水及软泥中含金量和软泥中有机碳含量，以及对抽提物中的饱和烃和芳烃族组分进行色谱—质谱分析，最后得出的结论：有机质的沉积环境为还原—强还原，有机质属于腐泥－腐殖型，接近和达到了成熟阶段。软泥中金含量与有机质的性质无明显相关关系，与有机碳含量也无明显相关关系，而与其成熟度相关密切。样品分析证实软泥中含硫化合物与金含量呈正相关性。对比分析了水及软泥中金含量，认为两者之间也无明显相关关系     

胶东昆嵛山花岗岩的特征、成因及其与金矿的关系

昆嵛山花岗岩是牟平—乳山金矿成矿带的围岩，在其成因和定位时代上长期存在争议。本文对岩体地质和地球化学特征进行了系统研究，并就岩体成因及其与金矿的关系进行了讨论。作者认为，昆嵛山花岗岩是在中生代由岩浆缓慢冷凝结晶形成的大型复式岩基，并非交代成因。它由垛崮顶片麻状花岗闪长岩（１４７Ｍａ）、八门邹家斑状花岗闪长岩（１３５Ｍａ）、瓦善—水道弱片麻状二长花岗岩及五爪山片麻状含榴二长花岗岩（１２０Ｍａ）组成，成分具贫铝富碱的特点。岩浆来源于中下地壳中酸性变质火山岩系部分熔融形成的岩浆，其形成温度为６５０—７５０℃。岩体经历了韧性和脆性变形作用，不同方向的片麻状构造是岩浆结晶期韧性变形作用的结果。脆性变形形成的断裂和破碎带是本区主要的导矿和容矿构造。花岗岩定位、韧和脆性变形作用与金矿成矿作用有十分密切的关系     

Geochemistry of the Rare Earth Elements in Natural Terrestrial Waters：A Review of What Is Currently Knows

The range of observed chemical compositions of natural terrestrial waters varies greatly especially when compared to the essentially constant global composition of the oceans.The concentrations of the REEs in natural terrestrial waters also exhibit more variation than what was reported in seawater,In terrestrial waters ,pH values span the range from acid up to alkaline,In addition,terrestrial waters can range from very dilute waters through to highly concentrated brines.The REE concentrations and their behavior in natural terrestrial waters reflect these compositional ranges,Chemical weathering of rocks represents the source of the REEs to natural terrestrial waters and ,consequently,the REE signature of rocks can impart their REE signature to associated waters,In addition,Because of the typical low solubilities of the REEs both surface and solution complexation can be important in fractionating REEs in aqueous solution.Both of these processes are important in all natural terrestrial waters,however,their relative importance varies as a function of the overall solution composition,In alkaline waters,for example,Solution complexation of the REEs with carbonate ions appears to control their aqueous distributions whereas in acid waters,the REE signature of the labile fraction of the REEs is readily leached from the rocks.In circumneutral pH waters,both processes appear to be important and their relative significance has not yet been determined.     

Sediment—Hosted Gold Deposits in China_geochemistry and Prospecting

Sediment-hosted gold deposits are the major type of gold resources in china,Concen trated mostly in the two“Triangle Regios“,they are generally hosted in fine-clastic turbidite,hydrothermal chet and marl ranging from cambrian to Triassic in age,structurally controlled by domes,anticlines and second-ordered faults.They are similar to the Carlin-type gold deposits in mineral assemblage and geochemical marks,with an element association closely comparable to those of modern springs and submarine hydrothermal sediments.Organic matter may have played an important role in mineralization .The ore solution may be hydrothermally altered meteoric water developed i areas of local geothermal anomaly.     

蚀变带元素地球化学成矿预测法──以金龙山微细浸染型金矿为例

金矿化作用伴围岩蚀变，且多受断裂控制，反映在地球化学上出现某些元素的异常。在已发现一害矿化体并掌握一般控制矿特征的地区，利用已有工程在蚀变带内连续捡块采样，分析有关批示元素，总结有关的地球化学指标，建立地球化学预测模式，对已知矿体及外围异常进行了地球化学评价。     

瑶沟等地区勘查金矿的放射性和非放射性气体地球化学方法的研究

本文介绍了瑶沟等地区勘查金矿的放射性和非放射性气体地球化学方法的研究成果：基本查明了应用本方法勘查金矿的主要条件是金矿中伴生有足够的Ｕ，Ｈｇ和碳酸盐矿物；研制成了壤中气（Ｒｎ－ＣＯ２）联测技术，提高了测量质量和探测深部矿体的能力；利用壤中气（Ｒｎ－ＣＯ２）异常进行了成矿预测，并已获得成功。