壤中氦气测量在401铀矿区的应用效果

赛璐珞球(乒乓球)具有渗透氮气的性质,埋于土壤中可作为氦气的收集器。用质谱法分析滞留于球内的氦气,达到找铀矿和地质研究的目的。积分集聚取样法,既相对提高了样品中氦的浓度,也减少了气象诸因素的影响,可获取好的地质效果。     

HE-602型氦质谱计

HE-602型氦质谱计是核工业部北京铀矿地质研究所,于1978年底研制成功的专用测氦质谱计。该仪器灵敏度高,精确度好,体积小,重量轻,是目前适用于野外氦气测量的主要测量仪器。氦气测量是一种寻找铀矿资源的新技术,是根据氦的放射成因及其特殊的物理化学性质,通过对不同介质(如水、土壤、壤中气、岩石样品等)中氦浓度的测量,寻找断裂构造带,进行区域地质研究和构造填图;圈定铀成矿远景区,探测深部铀矿;勘查地热资源以及预报地震。     

土壤氦气测量方法在金矿勘查和地质构造单元划分中的应用

分析了原生金故控矿构造上方土壤中高氦异常及不同地质构造单元上方氦的分带性；说明了应用氦法勘查原生金矿与划分地质构造单元的依据。并用实例证实了土壤氦气测量方法在这两方面的应用效果。     

土壤释氦测量及其应用的地质效果

氦元素具有惰性和很高的扩散系数,同时,是一种在水中溶解度低,不易被吸附的稳定元素,其基本来源是~(233)U,~(232)Th的放射性衰变产物。因此,近些年来氦被认为是探测深部铀矿体的一种可能的指示元素。氦元素在地下的垂直分布是随深度递增的,而在水平方向上的分布是地质,矿产诸因素的函数。地下氦源通过扩散和液相渗滤来不断向地表迁移。岩石裂隙对扩散有着更重要的意义。由于近地表的土壤疏松,故其中的氦气多与大气中的氦造成平衡,因此壤中氦气测量在     

氦同位素地质研究进展

综述了氦同位素研究在地球物质的循环、地震预报，环境监测、年代学、矿床成因、地质流体及大地构造等方面的进展。近来不断发现具有接近于幔源氦同位素比值的地质注以体、天然气及火成岩等，它们起源于地壳深部及地幔，对应的构造活动（包括地震）可能涉及到幔源深度。异常的氦同位素组成还可用于监测核试验、环境污染等新领域。并概念了我国氦同位素的研究在天然气的起源、火山喷气等方面取得重要进展。     

基于DDS的氦光泵磁力仪射频场智能调频研究

地磁场测量在基础地质研究、矿产资源勘查和军事探测等领域得到广泛应用,作为磁场测量核心之一的氦光泵磁力仪探头,其射频场调频精度是决定其磁测精度的重要影响因素。为实现易调节、高精度、高可靠性的调频信号,本文利用直接数字频率合成器(DDS)与微控制器(MCU)相结合方式,研究了磁力仪探头射频场智能精密调频技术,可灵活、实时、自动、精密地对磁力仪探头射频场进行调频。调频信号加载到氦光泵磁力仪系统的联调试验表明,磁力仪获得了稳定精密的磁共振信号,从而保证了磁力仪实现高精度的磁场测量。     

核技术在油气勘查中的应用研究

通过对在已知油田上方应用钋法 ( 2 1 0 Po)、氦法 ( 4 He)、地面伽马能谱法、热释光法( TLD)等核技术及地面磁法所测得的两条综合剖面的分析研究 ,论述了这些方法在已知油气田中的综合应用效果 ,建立了几种典型油气藏上方的放射性核素异常模式     

氦素定年技术、氦热年代学及其在地质中的应用

本文介绍了氦同位素定年技术和氦热年代学,说明了该方法的理论基础和技术要求,以及其在较小幅度剥露作用研究、古地貌研究和年轻地质体定年等方面的应用情况和前景.      

土样浸泡测氦法

土样浸泡测氦法实质上是一种化探方法。 自然界中的氦由~3He、~4He组成。地球上的氦主要是~4He,它是天然放射性元素衰变过程中产生的α粒子与周围介质的两个电子结合而生成的。氦的形成速度极为缓慢,每克铀每年只能生成1.16×10~(-7)毫克的氦。 氦在地壳中存在形式有三种: 1.束缚氦:存在于矿物品格中或岩石、土壤的封闭裂隙中。 2.自由氦:存在于裂隙或连通的孔隙中。     

金沙江-红河断裂带温泉气体地球化学特征

金沙江-红河断裂带是青藏高原东南缘地热活动强烈、地震活动水平高、各种矿产丰富的深大断裂带。为了探索该断裂带的温泉气体地球化学时空变化特征,2015年3月～2019年7月,经过5次野外考察,采集了54个温泉逸出气体样品,对其化学组分和氦、氖与碳的同位素变化的测试结果表明:(1)金沙江-红河断裂带内温泉气体氦同位素比值(3He/4He)变化范围是0.04～0.62Ra(Ra=空气3He/4He=1.39×10-6),计算获得的幔源氦最大比例达到7.5%,揭示该断裂带内的地质流体主要来自于壳源,幔源氦有从北向南呈现增加的趋势。以CO2为主要组分的温泉,其δ13CCO2值变化范围是-23.6‰～-1.9‰(vs. PDB)。结合区域地质条件分析,这些CO2主要来自三叠系灰岩,所占比例范围是70.1%～89.7%,而幔源CO2的比例最高可以达到4.2%。(2)金沙江-红河断裂带温泉气体的氢气浓度和氦同位素在三处断裂交汇区都出现高峰值,分别是金沙江断裂与巴塘断裂、中甸断裂与红河断裂、红河断裂与小江断裂和奠边府断裂的交汇处。与区域地震活动性的对比分析结果表明,金沙江-红河断裂带内深部流体上涌相对强烈的区域,深部流体对区域地震活动性具有重要的控制作用。     

Groundwater helium surveys in mineral exploration in Australia

The potential for using groundwater helium surveys in exploration has been evaluated by conducting local and regional surveys in several mineralized and background areas in Australia. Dissolved helium contents decrease markedly upwards, particularly in the top 10–15m, due to degassing in attaining dynamic equilibrium with the atmosphere. Gradients of depth profiles are not uniform but because total concentration variations to 50m or more are commonly less than 10, whereas regional variations are 10³–10⁵, samples from the greatest constant depth possible below water-table are adequate for survey purposes. Helium concentrations in excess of the atmosphere equilibrium value of 0.044 μl He/l H₂O were found to be associated with uranium mineralization at Honeymoon (6.9–44.4 μl/l), Manyingee (0.08–1.68 μl/l), Bennett Well (9.9–29.5 μ/l) and the Stuart Shelf—Roxby Downs (910–2495 μl/l), with a carbonatite at Mt. Weld (0.18–13.6 μl/l), and with kimberlites at Wandagee (0.2–3.25 μl/l). No anomaly was associated with the shallow calcrete uranium deposit at Yeelirrie. However, equivalent or higher concentrations were found in groundwaters from unmineralized areas around these deposits, e.g. up to 85 μl/l at Manyingee—Bennett Well, to 215 μl/l at Yeelirrie and to 1525 μl/l, Stuart Shelf—Mt. Gunson. Similarly, helium in waters from stock wells near Mt. Weld appears to indicate the presence of the carbonatite but in a survey of a geologically similar area near Malcolm, equivalent anomalies were not related to carbonatite.Although the uranium (and thorium) mineralization is a significant source, high helium concentrations can arise by accumulation in groundwaters with long residence times and by leakage from deep sources, particularly granitoid basement. The concentration reached is also a function of the porosity and configuration of the aquifer and the permeability of the aquiclude to helium. These factors are more important in determining dissolved helium concentrations than the uranium and thorium contents of the rocks. However, the effects are not readily quantifiable, particularly in exploration areas where geology and hydrology are relatively unknown, hence helium groundwater data can be difficult if not impossible to interpret.     

Helium emanometry under Australian conditions — Preliminary results

Helium has been proposed as a pathfinder in exploration for uranium deposits, hydrocarbons and geothermal energy sources, as an indicator of faults and fissures and as a possible tool for earthquake prediction. The rationale is that during the decay of ²³⁸U to ²⁰⁶ Pb, eight ⁴He atoms are produced via the intermediary of alpha particle emission. Similarly, six ⁴He atoms are produced by the decay of ²³²Th to ²⁰⁸Pb. Some of the common isotopes of the rare earths Ce, Nd and Sm are also alpha emitters, but they are unlikely to give rise to detectable helium anomalies.     

渭河盆地地热水水溶氦气成因与来源研究

渭河盆地地热水中含有丰富的水溶氦气,通过采集分析渭河盆地地热水水溶氦气成分和He同位素研究了氦气的成因与来源。分析结果表明,渭河盆地地热水水溶氦气体积分数普遍超过0.1%,最高达到3.395%。地热水水溶氦气的3He/4He比值介于(3.61±0.29)×10-8～(7.80±0.23)×10-7之间,氦气的R/Ra值小于1.00。天然气的4He/20Ne比值研究一致表明,渭河盆地地热水水溶氦气主要为壳源成因,混有微量的幔源氦。区域地质资料分析表明,富铀花岗岩放射性成因的氦气是渭河盆地地热水水溶氦气的主要来源,大面积出露于秦岭造山带以及隐伏于渭河盆地南缘新生代沉积层下的富铀花岗岩体为渭河盆地地热水水溶氦气的主要气源岩。     

Distribution of helium and hydrogen in sediments and water on the Sakhalin slope

During the geological survey and prospecting, helium and hydrogen are recognized indicators of minerals, deep-seated faults, seismic activity, and ascending deep fluids. Their anomalous concentrations also serve as a marker of metamorphic processes. Helium survey is applied for tracing deep-seated faults and mapping permeable zones. In this work, the first results of gas geochemical survey in marine sediments and water to study the distribution of helium and hydrogen and their relation with the seismic activity of some geological structures in the southwestern Sea of Okhotsk and northern Sea of Japan. Anomalies of these gases (He up to 60 ppm, H up to 120 ppm) were identified in the hydrate-bearing sediments in the fault zones. It was also found that helium concentrations in the water column of the Tatar Strait are higher than in the studied area of the Sea of Okhotsk, possibly, due to the difference in geological structure and seismotectonic activation. Moreover, coal layers could be a significant source of methane in the gashydrate-bearing layers of the Tatar Strait.     

Helium in soil and overburden gas as an exploration pathfinder — an assessment

Orientation surveys were conducted over five deposits to test the potential of determining helium in overburden gas as a pathfinder for uranium mineralization and other deposits containing uranium or thorium. Samples were collected via fixed tubes emplaced at depths of 6 m in backfilled holes drilled for this purpose. Compared to the atmospheric background value of 5.24 ppm v/v He, a variable weak anomaly (maximum 5.45–5.65 ppm He) was found over part of the Angela uranium deposit, N.T., in an arid area where mineralization is mostly at a depth of 60–90 m, at or below the water-table. Helium contents were mostly at background levels over a uranium deposit in the Officer Basin, W.A., where mineralization is at the water-table at 30–35 m, although radon gave a marked anomaly. Neither helium nor radon indicated the Manyingee deposit, W.A., which has uranium mineralization in a confined aquifer at 60–110 m. Similarly, no helium anomalies were found over the uranium- and thorium-rich Mt. Weld carbonatite or mineral sands at Eneabba.There appeared to be no correlation between helium distributions shown by groundwater and overburden-gas sampling at Manyingee or Mt. Weld. At Mt. Weld, groundwaters contained 0.06 to 13.60 μ/l He and overburden gases 5.24–5.47 ppm He, with the higher gas concentrations over country rock, where waters had background helium contents. It is presumed that equilibration between overburden gas and the atmosphere is far more rapid than that between overburden gas and groundwater, so that any helium released from the water is quickly dispersed.Overburden-gas helium concentrations were found to vary according to overburden type, being 5.24–5.32 ppm where sandy and porous and 5.30–5.50 ppm where clay-rich and less permeable. These background variations, which are greater than the total background-anomaly contrasts reported in the literature for shallow soil gases, have not been accounted for in most trial surveys, nor has the possibility of similar variations being due to analytical error. From the data obtained, there is little evidence that helium can be considered an effective pathfinder for blind or concealed deposits using soil gas or overburden gas as sample media. Previous work on the use of soil and soil-gas helium determinations in uranium exploration is reviewed in the light of these findings and the concept and techniques assessed.     

Soil-geochemistry,radiometric and soil gas helium studies in the uranium mineralized zone of Tumallapalle,Cuddapah Basin,Andhra Pradesh

A geochemical soil sampling survey undertaken at Tumallpalle uranium mineralized zone Cuddapah district, has confirmed the presence of uranium anomalies in soils. Bulk soil samples were collected at every 20 m along the traverse from approximately 30 cm below the surface and were assayed for uranium by x-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). The uranium anomalies detected by the insitu radiometric survey show a correlation with the helium highs. The soil gas helium studies have aided in delineating the subsurface extension of the deposit. This study endeavors for an integration of different techniques in a known area which could probably aid in delineating uranium zones for optimal exploitation in the future exploration programmes.     

柴北缘冷湖地区砂岩型铀矿床地质特征及成矿条件分析

冷湖地区砂岩型铀矿是近年柴北缘新发现的具有工业价值的铀矿床,为了进一步研究该地区砂岩型铀成矿岩石学及矿物学特征、铀成矿条件等问题,本文在野外地质调查的基础上,利用偏光显微镜结合电子探针分析手段,对该区内大煤沟组中含矿岩石进行了系统研究。结果表明:研究区中侏罗统大煤沟组含矿岩石类型主要为(粉)砂质泥岩、薄层煤及细粒石英杂砂岩,整体发育一系列后生蚀变。研究区北东侧安南坝山古元古界达肯达坂群及赛什腾山海西期花岗岩为区内砂岩型铀成矿提供了丰富的铀源。砂岩型铀矿中铀主要以独立铀矿物沥青铀矿的形式赋存,其次含有少量分散吸附态铀,沥青铀矿总体呈不规则粒状、星点状、"串珠状、线状"及粉末状赋存于黄铁矿边缘、裂隙部位或黄铁矿与方解石的接触部位,吸附态铀主要赋存于炭屑及煤线内;区内沥青铀矿为柴北缘地区首次揭露并发现的独立铀矿物,总体上填补了柴北缘地区无独立铀矿物出露的空白。铀成矿条件方面,含矿目的层中方解石的发育,显示了铀成矿流体富含CO_2、H_2O等挥发分和矿化剂,其次出露的众多还原性介质(油气、炭屑及黄铁矿等)为区内砂岩型铀成矿提供了氧化还原反应必需的还原剂,最终将U~(6+)还原成U~(4+)以沥青铀矿等形式沉淀成矿。     

Source and movement of helium in the eastern Morongo groundwater Basin: The influence of regional tectonics on crustal and mantle helium fluxes

We assess the role of fracturing and seismicity on fluid-driven mass transport of helium using groundwaters from the eastern Morongo Basin (EMB), California, USA. The EMB, located ∼200 km east of Los Angeles, lies within a tectonically active region known as the Eastern California Shear Zone that exhibits both strike-slip and extensional deformation. Helium concentrations from 27 groundwaters range from 0.97 to 253.7 × 10⁻⁷ cm³ STP g⁻¹H₂O, with corresponding ³He/⁴He ratios falling between 1.0 and 0.26 R_A (where R_A is the ³He/⁴He ratio of air). All groundwaters had helium isotope ratios significantly higher than the crustal production value of ∼0.02 R_A. Dissolved helium concentrations were resolved into components associated with solubility equilibration, air entrainment, in situ production within the aquifer, and extraneous fluxes (both crustal and mantle derived). All samples contained a mantle helium-3 (³He_m) flux in the range of 4.5 to 1351 × 10⁻¹⁴ cm³ STP ³He cm⁻² yr⁻¹ and a crustal flux (J₀) between 0.03 and 300 × 10⁻⁷ cm³ STP ⁴He cm⁻² yr⁻¹. Groundwaters from the eastern part of the basin contained significantly higher ³He_m and deep crustal helium-4 (⁴He_dc) concentrations than other areas, suggesting a localized source for these components. ⁴He_dc and ³He_m are strongly correlated, and are associated with faults in the basin. A shallow thermal anomaly in a >3,000 m deep graben in the eastern basin suggests upflow of fluids through active faults associated with extensional tectonics. Regional tectonics appears to drive large scale crustal fluid transport, whereas episodic hydrofracturing provides an effective mechanism for mantle-crust volatile transport identified by variability in the magnitude of degassing fluxes (³He_m and J₀) across the basin.     

A New Single Vacuum Furnace Design for Cosmogenic 3He Dating

Helium‐3 is a stable cosmogenic isotope that can be used to determine the time interval during which a rock sample has been at or close to the Earth’s surface. As a result of the high production rate of ‘cosmogenic’³He (≈ 130 at g^?1 year^?1) and the low detection limit of modern mass spectrometers, it is possible to date exceptionally young surfaces (≈ 1000 years). The precision and accuracy of cosmogenic ³He measurements depend critically on the passive helium blank (produced by the metalwork of the extraction furnace) which can be significant relative to the sample signals. We have developed and constructed, at the CRPG (Nancy, France), a new high temperature furnace (< 1500 °C) to extract helium in minerals such as apatite, pyroxene and olivine at 1050, 1350 and 1450 °C, respectively. The furnace demonstrated an excellent helium extraction yield (> 99% for olivine and pyroxene for heating times of 20–30 min and temperatures in the range 1050–1450 °C) and low residual helium contributions (the blank, obtained under the same analytical conditions as for sample extraction: 1 × 10^?15 mole ⁴He and < 4 × 10^?21 mole ³He). This is approximately an order of magnitude lower than those reported by other laboratories using conventional furnaces.