Granite is an Effective Helium Source Rock: Insights from the Helium Generation and Release Characteristics in Granites from the North Qinling Orogen, China     

ZHANG Wen  LI Yuhong  ZHAO Fenghu  ZHOU Zheng  HAN Wei  ZHOU Junlin  ZHANG Qiao 《《地质学报》英文版》2020,94(1):114-125

Global helium(He) shortage is a challenging problem; however, the types of helium source rock and the mechanisms of He generation and release therein remain still poorly understood. In this study, in order to evaluate the potential of granite as an effective helium source rock, we collected granitic samples from the North Qinling Orogen, Central China, in the south of the helium-rich Weihe Basin. The helium generation and release behaviors in granite were studied through analysis of U and Th concentrations, EMPA images, and He and Ar concentrations and isotopic ratios extracted by crushing and stepwise heating. The results indicate that Ar has a better retention and a lower mobility than He. 3 He/4 He ratios released by crushing and stepwise heating are 0.016–0.056 RA and 0.003–0.572 RA, respectively, where RA is the atmospheric 3 He/4 He of 1.4×10-6, reflecting a crustal and radiogenic source. Helium concentrations extracted by the two ways are 0.13–0.95 ucm3 STP/g and 7.82–115.62 ucm3 STP/g, respectively, suggesting that matrix-sited He accounts for more than 98% of total helium preserved in granite. In addition, the total generated He amounts in granites are calculated based on the measured U and Th concentrations in granitic samples. Dividing the preserved He quantities by the generated He amounts, it turned out that less than 10% of He produced since the formation of the granite is preserved in the rock over geological time, suggesting that more than 90% generated He can be transferred to the Weihe Basin. Temperature and fracture are the two critical factors controlling He release. Based on the relationship between He diffusivity of granites and temperature and the He closure temperatures of a variety of U-and Th-rich minerals(27–250°C), we estimate that He can be partially released out of granite at the depths 400 m and totally released at the depths 7800 m. Fractures provide effective transfer of free He from deep source rocks to shallow reservoirs. Finally, a model on granite as an effective helium source rock is established. We suggest exploring He resources in hydrocarbon basins with granitic basement(or adjacent to granite bodies), high geothermal field, and young active fractures.  相似文献   

利用滨海地下水系统对双频潮汐的响应识别含水层压力传导系数     

代希勤  阳玲  张铭  王同科  赵志学  郝永红 《水文》2021,41(1):66-72

含水层的压力传导系数是地下水溶质运移及扩散的重要参数,通常压力传导系数由抽水试验确定,即通过抽水给地下水系统一个扰动,然后监测地下水水位的响应,进而计算压力传导系数。对滨海地区含水层来说,潮汐波动就是天然的抽(注)水试验。潮汐由不同频率的分潮构成,前两项主频潮汐基本可代表潮汐主要特征。利用地下水水位对潮汐的响应,识别含水层压力传导系数。在推导出地下水对双频潮汐响应的解析解的基础上,提出了潮汐信号衰减法识别压力传导系数,并做了敏感性分析。通过对数值解叠加高斯噪音信号进行参数估算,证明该方法估算压力传导系数具有较高的可靠性和实用性。  相似文献   

溶质类型与矿化度对土壤水分扩散率的影响   总被引：3，自引：0，他引：3  

郭全恩  王益权  马忠明  车宗贤  南丽丽  徐世文  刘延东 《干旱区地理》2011,34(1):86-90

以甘肃省秦安县果园石灰性土壤为研究对象,采用水平土柱入渗法,探讨了不同矿化度下(lg/L、3g/L、5g/L、10g/L)的三种钠盐(Nacl、Na2SO4和Na2CO3)对石灰性土壤水分扩散率的影响.结果表明:在水盐复合迁移体系中盐分与水分迁移具有不同步性,影响不同步性的因子与盐分类型有很大关系.NaCl对水分移动速...  相似文献   

土壤中热量传输计算的研究进展与展望   总被引：11，自引：2，他引：9  

张立杰  江灏  李磊 《冰川冻土》2004,26(5):569-575

土壤中热量传输计算的研究分为土壤热通量计算方法和土壤导温率计算方法两方面的成果. 目前已有土壤热通量的计算方法, 在土壤表层可以得到较好结果, 但在土壤深层的适用性无法确定. 多孔介质模型和考虑水的渗流造成的影响, 是多年冻土区土壤导温率的计算方法的研究方面新的进展. 为研究青藏铁路沿线冻土演化趋势找到合适的土壤热量传输计算方案, 应是今后工作的一个重点.  相似文献   

Hydraulic diffusivity and macrodispersivity calculations embedded in a geographic information system     

F.A.L. Pacheco 《水文科学杂志》2013,58(4):930-944

Abstract

A numerical technique is presented whereby aquifer hydraulic diffusivities (D) and macrodispersivities (α) are calculated by linear equations rewritten from flow and solute transport differential equations. The approach requires a GIS to calculate spatial and temporal hydraulic head (h) and solute concentration gradients. The model is tested in Portugal, in a semi-confined aquifer periodically monitored for h and chloride/sulphate concentrations. Average D (0.46 m²/s) and α (1975 m) compare favourably with literature results. The relationship between α and scale (L) is also investigated. In this context, two aquifer groups could be identified: the first group is heterogeneous at the “macroscopic” scale (solute travelled distances <1 km), but homogeneous at the “megascopic” scale. The overall scale dependency in this case is given by an equation of logarithmic type. The second group is heterogeneous at the macroscopic and megascopic scales, with a scale dependency of linear type.

Citation Pacheco, F.A.L., 2013. Hydraulic diffusivity and macrodispersivity calculations embedded in a geographic information system. Hydrological Sciences Journal, 58 (4), 930–944.  相似文献   

阿拉尔绿洲灌区棉田土壤水分扩散率的测定   总被引：1，自引：0，他引：1  

胡顺军  李修仓  田长彦  宋郁东 《干旱区地理》2009,32(6)

土壤水分扩散率是研究土壤水盐运动的重要参数之一。在室内用非稳定流水平土柱法对塔里木河流域阿拉尔绿洲灌区棉田土壤水分扩散率进行了测定。建立了Boltzmann变换参数、土壤水分扩散率与土壤含水率之间的定量关系。结果表明:土壤水分扩散率与土壤含水率呈单调递增关系。当土壤含水率趋近饱和含水率时,土壤水分扩散率趋近于无穷大。因此,用指数函数或幂函数不能很好地刻画土壤水分扩散系数与土壤的体积含水量之间的定量关系。本文建立的土壤水分扩散率与土壤含水率之间的函数关系较好地反映了土壤水分扩散系数与土壤的体积含水量之间的客观规律。  相似文献   

The sensitivity of ground surface temperature prediction to soil thermal properties Using the Simple Biosphere Model (SiB2)   总被引：1，自引：0，他引：1  

张晓惠  高志球  魏东平 《大气科学进展》2012,29(3):623-634

Using the Simple Biosphere Model (SiB2), soil thermal properties (STP) were examined in a Tibetan prairie during the monsoon period to investigate ground surface temperature prediction. We improved the SiB2 model by incorporating a revised force-restore method (FRM) to take the vertical heterogeneity of soil thermal diffusivity (k) into account. The results indicate that (1) the revised FRM alleviates daytime overestimation and nighttime underestimation in modeled ground surface temperature (T_g), and (2) its role in little rainfall events is significant because the vertical gradient of k increases with increasing surface evaporation. Since the original formula of thermal conductivity (λ) in the SiB2 greatly underestimates soil thermal conductivity, we compared five algorithms of λ involving soil moisture to investigate the cause of overestimation during the day and underestimation at night on the basis of the revised FRM. The results show that (1) the five algorithms significantly improve T_g prediction, especially in daytime, and (2) taking one of these five algorithms as an example, the simulated T_g values in the daytime are closer to the field measurements than those in the nighttime. The differences between modeled T_g and field measurements are mostly within the margin of error of ±2 K during 3 August to 4 September 1998.  相似文献   

Effects of mesoscale eddies in the active mixed layer: test of the parametrisation in eddy resolving simulations     

M. V. Luneva  C. A. Clayson  M. S. Dubovikov 《地球物理与天体物理流体动力学》2015,109(3):281-310

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Detection of a dry-frozen boundary inside Martian regolith     

Fabio Gori  Sandra Corasaniti 《Planetary and Space Science》2008,56(8):1093-1102

The present work investigates the time oscillations of the temperature at several depths of a Martian soil analogue made of two layers of different physical properties. The maximum temperature-time oscillation inside the Martian soil analogue, DT, and its derivative with depth, d(DT)/dz or DDT, can be analysed to understand the presence of a boundary between dry and frozen soil. The maximum temperature-time oscillation, DT, reduces by about one order of magnitude at the boundary between dry and frozen soil if a frozen layer is present. The reduction of DT at the boundary between two dry soils with different porosity is much smaller. DDT decreases by more than one order of magnitude at the boundary between dry and frozen soil if a frozen layer is present. The reduction of DDT at the boundary between two dry soils with different porosity is much smaller.  相似文献   

Thermal fronts and cross-frontal heat flux in the southern Huanghai Sea and the East China Sea   总被引：1，自引：0，他引：1  

PARK Sunghye  CHU Peter C 《海洋学报(英文版)》2008,27(5):1-20

Synoptic features in/around thermal fronts and cross-frontal heat fluxes in the southern Huanghai./Yellow Sea and East China Sea （HES） were examined using the data collected from four airborne expendable bathythermograph surveys with horizontal approxmately 35 km and vertical 1 m（from the surface to 400 m deep） spacings. Since the fronts are strongly affected by HES current system, the synoptic thermal features in/around them represent the interaction of currents with surrounding water masses. These features can not be obtained from climatological data. The identified thermal features are listed as follows ： （ 1 ） multiple boundaries of cold water, asymmetric thermocline intrusion, locally-split front by homogeneous water of approxmately 18 ℃, and mergence of the front by the Taiwan Warm Current in/around summertime southern Cheju - Changjiang/Yangtze front and Tsushima front; （2） springtime frontal eddy-like feature around Tsushima front; （3） year-round cyclonic meandering and summertime temperature-inversion at the bottom of the surface mixed layer in Cheju - Tsushima front; and （4） multistructure of Kuroshio front. In the Kuroshio front the mean variance of vertical temperature gradient is an order of degree smaller than that in other HES fronts. The southern Cheju- Changjiang front and Cheju -Tsushima front are connected with each other in the summer with comparable cross-frontal temperature gradient. However, cross-frontal heat flux and lateral eddy diffusivity are stronger in the southern Cheju - Changjiang front. The cross-frontal heat exchange is the largest in the mixing zone between the modified Huanghai Sea bottom cold water and the Tsushima Warm Current, which is attributable to enhanced thermocline intrusions.  相似文献