Prediction method of sand-movement direction in water by geochemical elements

The analysis of sand samples by x-ray fluorescent spectroscopy (XRF) gives the ratio of the geochemical elements to construct the sand samples. The x-ray analysis therefore shows the geochemical characteristics of sand in the sampled area. In this study, sand is sampled on coasts and rivers of the Noto Peninsula to determine the geochemical elements and to show the geological characteristics that occur, especially iron and calcium. The experiments show the effect of rivers and Kotogahama beach on iron and calcium, respectively. Applying the method of ratio matching to the measured data of the geochemical elements, the direction of movement of sand on the coast is determined by considering the correlation matrix and the ratio of geochemical elements between sand samples at two locations. The predominant longshore direction movement of sand offshore in the study area is from south to north. Sand in rivers is not directly transported to adjacent beaches; however, offshore sand is transported to beaches. The estimated direction of movement of sand longshore near coastal structures agrees with observations. The proposed method to predict the direction of movement of sand gives the correct one in comparison with the observed data in rivers.     

Petrogeochemical characteristics of the kimberlites from the Middle Markha region with application to the problem of the geochemical heterogeneity of kimberlites

A comparative geochemical investigation of kimberlites from the Middle Markha region and traditional diamond-bearing areas of Yakutia supported the division of kimberlites into two geochemical types. One of them includes kimberlites from the traditional diamond-bearing areas of Yakutia, and the other is represented by the kimberlites of the Middle Markha region and the rocks of the Zolotitsa field and V. Grib pipe of the Arkhangelsk province. The obtained representative parameters of the two kimberlite types indicate a sharp geochemical contrast between them, and the individual features of correlation relationships between the elements in the rocks of the two types suggest that these differences are related to fundamental genetic factors, which concern primarily the group of highly charged incompatible trace and radioactive elements. The presence of geochemically contrasting rocks within a rather uniform petrochemical association and the geochemically specialized occurrences of kimberlites and related rocks are consequences of repeated metasomatic transformations of mantle rocks under the influence of deep-derived fluids or volatiles released during the recycling of subneous source and subsequent derivation of geochemically specialized types of deep magmas showing signatures of individual mantle sources.     

Guidelines for sampling bedload transport with minimum uncertainty

The stability of river channels and their suitability as habitat for aqueous organisms is strongly controlled by the rate of bedload transport. Quantification of bedload transport rates in rivers is difficult, not only because of the temporal variation in transport, but also because of the cross‐channel variation in transport. The objectives of this study were: (i) to determine the effect of cross‐channel variation in bedload transport on the uncertainty of width‐integrated transport rates; and to use this knowledge (ii) to improve guidelines for bedload sampling. This was done through a thorough statistical evaluation of stochastic and systematic uncertainties involved in bed‐load transport measurements. Based on this evaluation, new guidelines are presented for determination of the number of samples and sampling positions across the channel that are required for bedload measurements in several types of sand‐bed rivers and gravel‐bed rivers. The guidelines relate to bedload measurements made with pressure‐difference (Helley‐Smith type) samplers that require numerous bedload samples of short duration at several positions across the channel. The results show that generally more sampling positions across the channel are required in gravel‐bed rivers than in sand‐bed rivers. For gravel‐bed rivers with unknown cross‐channel distribution of transport, at least 10 sampling positions are recommended, whereas for most sand‐bed rivers five positions suffice. In addition, at least 12 short‐duration samples are required at each position to obtain bedload estimates with uncertainties below 20%. If the same level of uncertainty is desired in the case of high spatial and temporal variation in transport rates, the number of short‐duration samples needed per sampling position increases to 40.     

上海市近岸海域表层沉积物类型与元素丰度相关关系特征

通过上海市近岸海域多目标区域地球化学调查,共采集947件表层沉积物样品,分析测试了52种化学元素以及pH值和有机碳等指标。总结了该区域表层沉积物及深层沉积物类型和分布特征,沉积物类型主要为细砂、粉砂质砂、砂质粉砂、粉砂、粘土质粉砂,其中粘土质粉砂分布最为广泛。元素含量与砂含量呈正相关的元素主要为SiO2、Sr、Na2O等。其它指标大都与粘土含量呈正相关关系。     

Geochemical records of the sediments and their significance in Dongping Lake Area,the lower reach of Yellow River,North China

Dongping Lake area, located in the lower reaches of Yellow River, is an ideal place to study the changes of modern river and lake sedimentary environment. The sediment samples of Dawen River, Yellow River, and Dongping Lake were collected, and the major elements, trace elements and organic matter geochemical composition of the samples were analyzed. Cluster analysis, characteristic element ratio method and graphic method were used to explore the geochemical characteristics of sediments and their environmental implication. The results show that the contents of SiO_2, Na_2O, TiO_2 and Zr in sediments of Dawen River and Yellow River are relatively high, and the contents of iron and manganese oxides, organic matter, CaO, P_2O_5 and Sr in lake sediments are relatively high. That reveals the differences of sedimentary environments between the rivers and the lake. The contents of Sr and Zr in Dawen River are affected by the rapid migration of clastic materials in the upstream carbonate source area during the flood season; the δCe,ΣREE and REE's ratios in the sediments of the Yellow River reflect the influence of the Loess source; and the distribution of elements changes along the flow direction during the flood season. The characteristics of p H, element composition and LREE HREE fractionation of the lake sediments indicate that the sediment source is complex, and the lake environment is affected by the flood season. The study shows that the geochemical content and its variation characteristics of sediments effectively reveal the sedimentary environment, material composition and characteristics of flood season of rivers and the lake in the study area.     

浙中丘陵盆地区1∶5万土地质量地球化学调查方法研究

摘要：以1∶5万土地质量地球化学调查成果服务于土地精准管理为目标,在浙中丘陵盆地选择金华市汤溪镇地块细碎的典型区域,开展了两种采样密度的对比研究：(1)按1∶5万土地质量地球化学调查的采样密度上限采样,平均采样密度164件/km2,采用克里金插值法进行图斑赋值(下文简称插值);(2)以土地精准管理为目标,以地块为单元采样,平均采样密度1795件/km2,用实测值对图斑赋值(下文简称实测)。以图斑为评价单元,对比上述两种方法间元素含量、土壤环境及养分指标分级、土壤质量综合分级的差异。研究表明：(1)与土壤质量评价密切相关的15项指标中,有9项指标插值与实测值元素含量的相对双差合格率达到90%,4项指标接近90%,仅2项指标合格率低于80%;(2)插值与实测值的土壤环境单指标分级与环境指标综合分级结果极为接近,养分指标分级差异略大;(3)实测值与插值土壤质量综合分级一级、二级图斑数所占比例相差118%,图斑面积相差74%,约40%的图斑土壤质量综合等级发生变化。研究区内环境指标变异性较小,插值与实测值的评价分级结果基本一致;养分指标N、P、K的空间变异较强,是导致插值与实测值土壤质量综合分级差异的主要原因。以上结果表明,浙中丘陵盆地区1∶5万土地质量地球化学调查成果对土地利用规划、科学平衡施肥等具有重要价值,但其成果精度尚难满足土地精准管理的需要。     

热田勘查中新的地球化学指标

两年来,我们利用土壤汞量测量在国内许多已知热田上进行了大量试验研究,无论高温还是中低温热田均有汞异常存在,表明汞量测量是热田勘查中一种有前景的地球化学方法。     

荒漠戈壁区超低密度地球化学调查与评价——以东天山为例

中国的干旱荒漠戈壁区,约占国土面积的1/4.自然特点是极其干旱,沙漠和戈壁广布,土壤呈碱性.大部分面积尚未进行区域化探扫面工作,即使进行工作的地区,由于风成沙和土壤碱性的影响,结果并不理想,难以了解整个地区资源潜力.超低密度地球化学方法经过近10年发展,已经显示它不受地表覆盖物影响,能够快速有效地圈定战略靶区.因此,超低密度地球化学方法被用于东天山1.5×105km2的调查试点研究,发现弱胶结层是干旱荒漠区超低密度调查的有效采样介质,并且深部含矿信息主要赋存在细粒级部分和氧化地球化学障中,使用细粒级部分与提取氧化物膜中的金属元素相互补充可以有效地识别含矿信息.使用超低密度地球化学方法可以达到迅速、有效圈定有利于大型矿床或矿集区战略靶区的目的.通过1.5×105km2地球化学调查,制作了30余种元素地球化学图,填补了东天山部分地区地球化学空白.新发现远景Cu、Au、U和W异常10余处,并发现东天山存在3条Cu异常带东天山北带、中带和南带,其中土屋铜矿和黄山铜镍矿都位于中带,新发现的维权铜矿位于南带,北带还有待于进一步证实.相信这些异常的发现,对今后整个东天山矿产勘查的战略部署具有重要意义.     

应用地层倾角测井资料研究古河流特征

鄂尔多斯盆地绥德-榆林地区石炭、二叠系砂岩体大多为点砂坝,通过本区仅有的3口井倾角测井资料的研究,提供了古河流特征参数。这些数据表明石盒子和山西期的河流类型为辫状河-曲流河;太原期为低弯度曲流河。砂体宽度300-900m,平均496m.经镇川堡气田试采验证,这种认识与客观实际相符。另外,本区地层倾角测井所得垂直于倾向的走向方向才是河流的古流向,为测井数据合理解释古流向提供了理论依据。     

内蒙干旱荒漠区域化探工作方法初步研究

内蒙和我国其它干旱荒漠区一样,由于:(1)风成沙干扰,使通常所选用的采样介质(土壤、水系沉积物)元素含量遭到稀释、歪曲,乃至样品间几乎没有差异；(2)缺乏一套针对干旱环境特点和该区地貌组合的特殊工作方法,致使区域性化探工作长期处于不利局面。     

巴彦淖尔市临河区狼山镇和新华镇一带富硒土壤地球化学特征及影响因素北大核心CSCD

内蒙古自治区巴彦淖尔市临河区狼山镇和新华镇一带发现大面积硒高含量区。为研究该地区富硒土壤的地球化学特征及土壤硒含量的控制因素,采集6250件表层土壤样品,并设计5条土壤垂直剖面进行化学元素测试分析。结果表明,研究区耕地土壤硒含量介于(0.06~0.77)×10^(-6)之间,平均含量为0.32×10^(-6),硒的背景值为0.32×10^(-6),是巴彦淖尔市表层土壤背景值(0.20×10^(-6))和中国土壤背景值(0.20×10^(-6))的1.6倍,且研究区耕地土壤中达到富Se水平(0.4×10^(-6)以上)的样品数为1072个,占全部采样点位的17.2%,表明研究区耕地土壤中硒含量相对较高。研究区土壤中硒和营养元素及重金属元素存在正相关关系,与土壤pH存在一定的负相关关系;硒在土壤垂直方向上分布总体上表现出表聚性特征,随剖面深度增加,硒含量逐渐降低。表层土壤中硒含量主要受土壤有机质含量影响,土壤垂直方向上硒含量主要受有机质与粘土矿物影响。     

Seasonal changes of direction of sand movements on Kotogahama Coast

 X-ray fluorescent spectroscope-analysis and the method of ratio matching can determine mean directions of sand movement and geochemical classifications of sand grains. The result can also evaluate the physical condition of seabeds in a study area (erosion or accretion). This method is applied to a sedimentation problem in the fishing port of Tsurugiji in Japan and the result is in agreement with the comparison of the change of sea bottom topography measured in different years. The seasonal changes of sand movement on this coast and sedimentation in the port are also investigated. Received: 8 October 1998 · Accepted: 15 February 1999     

Geochemical studies on urban soil from two sampling depths in Tampere Central Region,Finland

Preliminary geochemical mapping was carried out within urban areas in Tampere Central Region, Finland, to gain a better understanding of element concentrations in urban soil and to provide information on baselines in soil within urban centres for soil contamination assessment purposes. The soil samples were taken from central city parks, day-care centres and school yards, and residential areas. Various sampling depths have generally been used in urban geochemical surveys. The aim of this study was to compare the results from two commonly used sample types taken from the same sites in urban soil: single samples of minerogenic topsoil from the 0–25 cm layer and composite samples of minerogenic topsoil from a depth of 0–2 cm. The concentrations of most of the studied trace elements showed a significant correlation between samples from 0 to 2 and 0 to 25 cm, but element concentrations differed between the two studied sample depths. For most of the studied elements, the median concentrations were higher in the 0–25 cm samples, but anomalous concentrations were more often found in the 0–2 cm samples. Some elements had elevated concentrations when compared with the Finnish guideline values for soil contamination assessment. This study did not conclusively establish whether a sampling depth of 0–2 or 0–25 cm should be recommended for similar studies in the future. Selection of the sampling depth in geochemical studies greatly depends on the aim of the project. In order to determine the upper limits of geochemical baseline variation, the deeper sampling depth appears to be more feasible. However, for the preliminary health risk assessment of areas with sensitive land uses, e.g. children’s playgrounds, samples from 0–2 cm depth are considered informative. Such samples may also be used to indicate local sources of dusting creating site-specific hotspots of potentially harmful elements in urban topsoil.     

GIS assisted inverse geochemical modeling for plausible phase transfers in aquifers

A geographical information system (GIS) assisted approach that couples a groundwater flow model and an inverse geochemical model is presented to quantify the phase mole transfers between two points on the flow path within a groundwater system. It is used to investigate the plausible phase transfers in the unconfined aquifer of Mehsana district of Gujarat State, India. X-ray diffraction analysis of soil samples is carried out for mineral characterization. The groundwater flow field is simulated using MODFLOW and flow paths used for inverse geochemical modeling are traced using PMPATH, a particle tracking algorithm. The plausible phase mole transfers in the flow path are quantified using PHREEQC geochemical code. The different scenarios generated by inverse modeling routine are used as input to the geochemical model and simulation runs are taken as forward models. The obtained results are compared to the target solution chemistry by using the square of the Pearson product moment correlation coefficient. Results reveal that the groundwater is undersaturated with anhydrite, carbon dioxide (gas), fluorite, gypsum, halite, jarosite-K, and siderite. It is oversaturated with aragonite, calcite, dolomite, ferrihydrite, goethite, and hematite. Results further reveal that calcite is precipitating, while dolomite, gypsum, carbon dioxide, and fluorite are dissolving together with ion exchange in the flow path.     

1:50 000山东毕郭幅地球化学数据集

该数据集依托中国地质调查局“山东莱州-招远地区金矿整装勘查区矿产调查与找矿预测”项目,在充分收集地质、物探、化探、遥感及矿产等资料基础上,开展毕郭幅矿产地质调查。项目共采集1 875件水系沉积物样品,采样粒级为-10～+80目,平均采样密度4.5个/km²。采用电感耦合等离子质谱法（ICP-MS）、原子荧光光谱法（AFS）、粉末发射光谱法（ES）和石墨炉原子吸收光谱法（GF-AAS）分析了16种元素,最终形成1：50 000山东毕郭幅地球化学数据集,数据集包含有1 875件样品×16种元素的原始分析数据表格一个,图集一套（含有1张矿产地质图、一张采样点位图和16张元素地球化学图）。区内共新发现单元素地球化学异常149处,综合异常10处,结合地质、矿产、物探、化探、遥感等信息并圈出金矿找矿靶区5处。     

Representativity of wide-spaced lower-layer overbank sediment geochemical sampling

To develop a technique of implementing global ultra-low density geochemical sampling and as a contribution to the International Geochemical Mapping Program (IGCP Project No. 259), an orientation study in the use of deep (lower-layer) overbank sediments was conducted in Jiangxi Province of Southeast China in 1989–1990. Ninety-four samples were collected at depths of 50 to 120 cm from overbank terraces at an average density of 1 site per 1800 km². The total area of sampled catchment basins is approximately equivalent to 18% of Jiangxi Province. Most of the samples were collected at outflow sites of catchment basins with areas of 100 to 800 km². The samples were analyzed for 39 elements.The representativity of wide-spaced lower-layer overbank sediment sampling is discussed from various perspectives; the following features have been observed: (1) Widespaced lower-layer overbank sediment data and the data from China's national geochemical mapping (RGNR) project show similar geochemical patterns for W, Sn, Pb, Cu and Zn. (2) The results of wide-spaced lower-layer overbank sediment sampling demonstrate that catchment basins with areas of 100 to 800 km² are suitable sample site locations for the global geochemical reference network. (3) Wide-spaced lower-layer overbank sediment sampling is a fast and cost-effective way to identify geochemical provinces and has strategic significance in mineral exploration. (4) There is a significant correlation between the W content of wide-spaced lower-layer overbank sediment samples and the presence of W mineralizations within the catchment basins. (5) The distributions of Ni, Cr and V in wide-spaced lower-layer overbank sediment samples distinctly reveals the boundary between the Yangtze sedimentary platform and the South China Caledonian fold system in Jiangxi Province. (6) Distributions of Rb and Be coincide with the Yanshan granites, which are closely related to the major ore-forming episodes in Jiangxi Province.     

川西连龙含锡花岗岩的时代与形成构造环境

通过岩石地球化学和Rb Sr同位素研究 ,发现川西连龙花岗岩是富含Sn、Ag多种成矿元素的高K钙碱性岩体 ,地球化学上显示出A型花岗岩特点。 4个全岩样品给出的Rb Sr等时线年龄为 87± 1Ma,相关系数R =0 .9988,Isr=0 .70 95。结合构造环境分析 ,查明该岩体是燕山运动晚期 ,在弧陆碰撞造山之后陆内伸展阶段 ,主要由地壳富泥质岩石部分熔融形成。     

The Coso volcanic field reexamined: Implications for obsidian sourcing and hydration dating research

Obsidian from the Coso locality, Inyo County, California, has long been regarded by archaeologists as a single “source.” However, studies by the U.S. Geological Survey have provided evidence of geochemical variability among flows within the volcanic field. to determine whether these geochemical distinctions could be applied productively to archaeological research, nondestructive x-ray fluorescence analyses were conducted on samples recently collected from 15 obsidian-bearing loci. the results of this research show that geochemically distinct varieties of artifact-quality obsidian can be recognized within the Coso volcanic field, and subsequent nondestructive x-ray fluorescence analyses of artifacts from two nearby archaeological sites document that different geochemical varieties of obsidian were used prehistorically to manufacture tools. Implications of these results for studies of prehistoric exchange and obsidian hydration dating are discussed.     

地球化学普查样品实验室分析异常点抽检改进方法

在地球化学样品多元素分析过程中,为了实现地球化学异常点抽查和整批测试质量监控的双重目的,本文提出了一种基于地球化学异常统计的多区间分元素组异常点抽样方法。该方法主要包括:(1)按照正态分布或对数正态分布假设,对各元素,将该元素的测量值集,划分为离群低值区间、累积频率分布区间(有多个区间)和离群高值区间,统计每个样品中各元素测量值所属区间;(2)将测量元素分为几个元素组,统计各元素组中每个样品的总异常元素数、高异常元素数和低异常元素数;(3)对Au元素组,设置各个区间的抽检比例,随机抽取异常点抽检样品;对其他元素组,按照"总异常元素数"为第一顺序、"高异常元素数"为第二顺序和"低异常元素数"为第三顺序,按降序排序所有样品,顺序抽取异常点抽检样品;(4)必要时进行分析批补充抽检样品。该方法兼顾了地球化学异常和实验室测试"异常"的抽查;同时考虑非异常点抽查和分析批平衡抽检,有效解决了有限抽样数量和抽样代表性不足两者之间的矛盾;并开发了EXCEL应用程序,应用于实验室地球化学样品分析异常点抽检取得了满意效果。