Mid-ultraviolet and optical photometry of helium stars     

Gopal C. Kilambi  Praveen Nagar  N. Kameswara Rao 《Journal of Astrophysics and Astronomy》1992,13(2):175-194

Mid-ultraviolet and optical photometric analysis of helium stars are presented. A linear relation exists between the effective temperature derived from model atmospheres and (1965-V)₀ index. The effective temperatures derived from (1965-V)₀ index are somewhat higher than that of MK spectral type estimates especially for late B-type helium objects.  相似文献   

Retention of cosmogenic 3He in calcite     

《Quaternary Geochronology》2015

Cosmogenic ³He can be used to date a wide range of mineral phases because it is produced from all target elements and can be readily measured above atmospheric contamination. Calcite is a particularly attractive target mineral due to its natural abundance, large crystal size (>1 mm), and low He closure temperature (<70 °C), which limit non-cosmogenic ³He components (Copeland et al., 2007). However, several recent studies have shown that some calcite may not be retentive to helium, even under surface temperatures (Cros et al., 2014; Copeland et al., 2007). This study thus explores ³He retention and production in natural calcite samples at four different sites. Samples from two high elevation sites appear retentive to ³He over 10 kyr timescales, whereas two additional sites clearly suffer from diffusive loss of ³He. Step-degassing experiments suggest that diffusion in calcite is controlled by multiple diffusion domains, with an apparent activation energy of 25–27 kcal mol⁻¹. Although minor ³He loss is expected from the smallest diffusion domains, the observed kinetics cannot explain the poor retention at all sites. We thus propose that opaque (non-transparent) calcite may be more retentive due to the presence of imperfections in the crystal lattice. We conclude that ³He dating of calcite shows promise in some settings. However, because retention depends on crystallographic variability it must be evaluated on a case-by-case basis until robust criteria for retention can be identified.  相似文献   

土壤样氦气测量在勘查隐伏陷落柱及找深部铀矿中的应用研究     

王建谱 《铀矿地质》1994,10(3):175-180

本文介绍了土壤样氦气测量方法勘查隐伏陷落柱及其找深部铀矿的简要原理和应用效果。通过对５个实例的氦异常特征研究，表明在陷落柱边缘及其中部氦含量变化明显；在隐伏铀矿体的垂直投影部位，地表有较好的氦异常。从而说明：用该法可为煤矿寻找隐伏的陷落柱，可以探测与成矿有关的岩溶塌陷构造，寻找铀矿及各种断裂构造，可以为各种受断裂控制的热液矿床指明远景地段，为勘探设计提供依据。  相似文献   

测定水浸土壤样的水中氦找铀矿方法的研究     

王建谱  冯倡  吴际夫 《铀矿地质》1987,(3)

本文讨论了利用离子泵测氦仪,测定水浸土壤样的水中氦的找铀矿方法。通过十项浸泡条件及测量试验,确定了处理土壤样的水浸技术。在矿床上取样分析的结果表明,在陡倾角地层的条件下,壤中氦异常出现在深部铀矿化范围的水平投影位置上,说明该方法对寻找隐伏铀矿是有效的,可用于地表详测等找矿工作。  相似文献   

Noble gases dissolved in groundwater in a volcanic aquifer: Helium isotopes in the Kumamoto Plain     

Y. Mahara 《Environmental Geology》1995,25(4):215-224

This study Investigates a tracing method using dissolved noble gases to survey the groundwater flow in a large groundwater basin. The tracing method is based on measuring the concentrations of noble gases and the ratio of helium isotopes in groundwater samples. Since it is very difficult to detect trace amounts of noble gases and helium with high accuracy in a 15-ml groundwater sample, dissolved gases were extracted and purified, then a high-resolution mass spectrometer was used for measurement and comparison with standard samples. We used this method with samples from a confined aquifer formed by the deposition of pyroclastic flow in the Kumamoto Plain on the west side of Mt. Aso in central Kyushu, Japan. The groundwater basin under the plain is divided into four small basins, based on the helium concentrations and isotope ratios, with two major groundwater flows. One flow is buried by the Aso pyroclastic flow along the old Kase River; the other is along the Tsuboi River Valley. These two groundwater flows were identified from the different helium isotope-ratios. The helium component from the deep mantle is mixed into the groundwater under the Kumamoto Plain. Finally, data on the concentrations and ratios of³He to⁴He in groundwater samples were used to determine the location of faults in the volcanic aquifer.  相似文献   

Paragenesis of fluids under evaporates in the Volga-Ural Basin     

《Marine and Petroleum Geology》2015

To unravel the mystery of the relationship between evaporates, Ca–Cl brines and accumulations of oil and N₂ in the basins of ancient cratons, their N₂, CH₄ and He concentration ratios, as well as the isotopic composition (δ¹⁵N, δ¹³C and ³He/⁴He) were compared within the Volga-Ural basin. The study allowed subsalt fluids from Volga-Ural Basin to divide into two genetic groups. The first one is found within the basin's platform area. It includes Ca–Cl brines, high-viscosity heavy oil, bitumen and N₂, which has concentrations higher than that of CH₄ and positive values of δ¹⁵N. The second one is tied to the edge of the platform, the Ural Foredeep and Peri-Caspian Depression. In this group, only the oil and gas reservoirs, which have more CH₄ than N₂, and possibly negative values of δ¹⁵N, were discovered. Interaction of gas components in compared fluids indicates great role of degassing in the formation of their composition. It is suggested that the fluids of the first group (N₂ > CH₄) is what remains, and the second group (N₂ < CH₄) is what is disappears from the rocks during their metamorphism and degassing.  相似文献   

基于岩心室应力应变和不确定度分析的致密储层氦孔隙度测量方法          下载免费PDF全文

韩学辉  张浩  毛新军  徐登辉  郭慧英  江佳洋  罗兴平  王振林  刘智桢  李靖  罗振 《地球物理学报》2021,64(1):289-297

致密油气层的物性(孔隙度和渗透率)较差.针对致密储层,目前常用的氦气法孔隙度测量方法存在两个不足:器壁压变性参数G定义不明确;膨胀前压力设置普遍偏小.本次基于氦气法孔隙度测量装置岩心室的应力应变力学分析和不确定度理论分析,开发了一种面向致密储层的氦孔隙度测量方法.本次提出的方法给出了器壁压变性参数G的解析式,并基于G的解析式推导出了新的孔隙度计算公式,将刻度系数减少到1个,简化了刻度过程.其次,基于不确定度理论得到的孔隙度测量不确定度表明:氦气法测量致密储层孔隙度的膨胀前压力大于2 MPa基本可以将孔隙度绝对误差控制在0.5%以内.与高压压汞法孔隙度测量结果对比发现,该方法测量孔隙度的相对偏差在14%以内,远低于常规氦气法测量孔隙度的相对偏差(50%).  相似文献   

哈萨克斯坦卡帕尔-阿拉善4号井氦气（He）含量映震特征   总被引：1，自引：0，他引：1  

崔勇  杨晓芳  陈玲  鲁娜  魏若萍  李新勇 《内陆地震》2008,22(3):243-251

介绍了哈萨克斯坦卡帕尔-阿拉善4号井的水文地球化学环境,分析其17年氦气（He）含量变化映震特征,氦气（He）变化的地震前兆异常表现为：上升（或下降）幅度、速率变化超出正常范围,具有较好的重复性,测值遵循的是,背景值－趋势性上升（或突升）,趋势性下降（或突降）－恢复至背景值的变化过程。将该井氦气（He）观测数据经过滤波、差分处理后,以3倍均方差作为异常识别标准,结果表明：氦气（He）对监测点周围300km范围5级地震、400km范围6级地震的对映率分别为100％、66．7％,是较好的地震前兆手段之一。  相似文献   

利用地下流体氦同位素比值估算大陆壳幔热流比例   总被引：12，自引：2，他引：10  

汪洋 《地球物理学报》2000,43(6):762-770

地下流体中的氦同位素 3He来自地幔的排气作用 ,4He则是铀、钍衰变的产物 .由于铀、钍元素在大陆地壳中富集 ,4He通量与地壳热流呈正相关关系 ;同时 3He通量与地幔热流之间呈正相关 .所以地下流体的氦同位素比值 （3He / 4 He）与大陆壳幔热流比值 （qc/qm）呈反相关关系 .根据欧亚大陆和加拿大地盾的地下流体氦同位素比值数据和相应的壳幔热流比值数据 ,统计出 qc/ qm 与 3He / 4 He之间的回归关系 :qc/ qm =0 81 5- 0 30 0ln（3He / 4 He） ;此处 3He/ 4 He的单位是RA（大气的 3He/ 4 He比值 ） .有了地表热流值和壳幔热流比值即可得到地壳热流和地幔热流 .利用该公式以及热流值估算了中国主要盆地的壳幔热流值 ;根据这些数值得出的热岩石圈厚度和地壳平均生热率结果与地震学研究成果一致 .氦同位素比值是区分大陆热流中地壳热流值和地幔热流值的有用参数 .  相似文献   

聊古一井氦异常与地震的关系   总被引：1，自引：0，他引：1       下载免费PDF全文

魏汝庆 《地震工程学报》1999,21(4):428-429

处理了聊古一井1981 ～1984 年氦的观测资料,发现在两次较近的地震(1981 年宁晋MS5 .8 和1983 年菏泽MS5 .9) 前,氦都有明显的形态相似的异常变化.  相似文献