太白金矿流体包裹体中黄铁矿和铁白云石等子矿物的发现及成冈意义

太白金矿含金角砾岩带赋存于秦岭泥盆纪浅变质细碎屑岩系中,地质特征独特。金矿佛主要产于含铁白云石－黄铁矿等胶结物中,这些载金矿物中普遍有大量流体包裹体产出。应用扫描电镜、能谱分析和电子探针技术发现了石英和含铁白云石中的黄铁矿、毒砂和铁白云石等离子矿物,结合流体包裹体成分ＬＲＭ分析资料,对成矿流体特征有了新认识。     

石嘴山水氡低值变化的成因分析

对宁夏石嘴山氡1995－2000年的资料进行了详细研究,对观测环境进行了细致的调查分析,得出该台氡值历6-8月的低值变化主要受降雨影响所致,不是地震前兆异常。     

The characteristics of variation in inhomogeneity of temporal-spatial distribution of short to imminent precursors before strong earthquakes

IntroductionShort-to-imminentprecursorsstillarethemainbasisforearthquakepredictioninthepresenttime.Strongquakes,especiallythosewithnoforeshocks,canbeforecastedtosomeextentbasedonabundantshoat-to-imminentprecursorsandcombiningwiththemid-to-longtermvar...     

华北水氡异常与地震关系的Bayes判别分析

选取华北地区１９９０￣１９９８年８月较完整的水氡观测资料,笔者采用ｘ＾２统计检验法识别前兆异常,利用笔者建立的Ｂａｙｅｓ判别分析方法,对该地区水氡异常与中强震活动性的关系进行了内符检验和外推预测。在风险代价比Ｋｄｎ取４的情况下,内符检验的有震报准率ｃ为０．７１,预报占时率ｂ为０．３３,Ｒ值可达０．３８;外推有震报效率ｃ为０．５,时空占有率０．０５,Ｒ值为０．４５,能够正确预测１９９８年１月１０日张     

地面放射性氡法在寻找层间氧化带型砂岩铀矿中的应用

根据层间氧化带型砂岩铀矿的矿化富集与铀镭平衡变化特征,在西北层间氧化带型砂岩铀矿床运用地面放射性氡法－－＾２１８Ｐｏ测量方法进行了找矿试验,试验表明运用＾２１８Ｐｏ测量结果曲线来圈定层间氧化带中铀矿化富集部位是可行和有效的。     

Evaluating groundwater discharge to tidal rivers based on a Rn-222 time-series approach

The natural flux of groundwater into coastal water bodies has recently been shown to contribute significant quantities of nutrients and trace metals to the coastal ocean. Groundwater discharge and hyporheic exchange to estuaries and rivers, however, is frequently overlooked though it often carries a distinctly different chemical signature than surface waters. Most studies that attempt to quantify this input to rivers use multiple geochemical tracers. However, these studies are often limited in their spatial and temporal extents because of the labor-intensive nature of integrating multiple measurement techniques. We describe here a method of using a single tracer, ²²²Rn, to rapidly characterize groundwater discharge into tidally-influenced rivers and streams. In less than one week of fieldwork, we determined that of six streams that empty into the Indian River Lagoon (IRL), Florida, three (Eau Gallie River, Turkey Creek, and Main Canal) did not receive substantial groundwater inputs, one canal (C-25 Canal) was dominated by groundwater exchange, and the remaining two (Sebastian River system and Crane Creek) fell somewhere in between. For more detailed discharge assessments, we focused on the Sebastian River system, a stratified tidal river estuary, during a relatively dry period (June) and a wet period (July) in 2008. Using time-series ²²²Rn and current velocity measurements we found that groundwater discharge into all three branches of the Sebastian River increased by 1–2 orders of magnitude during the wetter period. The estimated groundwater flow rates were higher than those reported into the adjacent IRL, suggesting that discharge into these rivers can be more important than direct discharge into the IRL. The techniques employed here should work equally well in other river/stream systems that experience significant groundwater discharge. Such assessments would allow area managers to quickly assess the distribution and magnitude of groundwater discharge nature into rivers over large spatial ranges.     

Radon and radium isotopes as tracers of submarine groundwater discharge – Results from the Ubatuba,Brazil SGD assessment intercomparison

We determined groundwater flow rates shortly after the wet season into an embayment near Ubatuba, Brazil as part of an international intercomparison experiment for submarine groundwater discharge (SGD) assessment techniques. Our estimated rates were determined by the combined use of continuous radon measurements and assessment of radium isotope patterns. The spatial distribution of the short-lived radium isotopes (²²³Ra and ²²⁴Ra) provided the means for independent evaluations of radon losses by mixing and atmospheric evasion. We were thus able to construct a well-constrained mass balance for radon that included a groundwater flux term. Our results showed that the groundwater discharge into this embayment from the fractured crystalline rock aquifer is not steady-state but varies with tidal modulation and rain-induced forcing. Tidally modulated and rain-induced flow rates were comparable during this period. The SGD rates estimated from radon ranged from 1 cm/day to 29 cm/day (cm³/cm² day) with a mean and standard deviation of 13 ± 6 cm/day. These estimates were mostly similar to a dye-dilution automatic seepage meter (15 ± 19 cm/day) and were within the broad ranges estimated by manual and continuous heat seepage meters but lower than indicated by an artificial tracer test performed nearshore.     

天津市宁河县土壤氡含量与断裂构造的耦合关系初探

利用MT和EH4大地电磁测深的方法,在对天津市宁河县的断裂构造格局进行了新一轮的探测后,结合前人航磁、重力、电法和地震等资料,重新确定了该地区的断裂构造格架。为了进一步掌握断层的确切位置,笔者利用FD-3017镭A测氡仪对断裂带及其附近位置的土壤氡含量进行了测量,发现在厚大的第四系覆盖地区,土壤氡含量对断裂构造的反应敏感,断裂带正上方氡含量最高。该方法具有实用推广价值。     

Radon daughter disequilibria in the lower marine boundary layer

Radon daughters are produced as free ions, but they become attached to aerosol particles at a rate depending on the particle concentration. In the lower marine boundary layer, most of those which do not become attached plate out on the ocean surface. In this paper a simple model is used to examine the influence of several parameters on radon/radon daughter disequilibria in maritime air. The model is compared with experimental data from Cape Grim.The radon daughter to radon ratio, f, decreases from 0.86 to 0.1 as the particle concentration falls from 1000 to 10 cm^-3. Estimates of radon concentration at sea level, based on daughter measurements may therefore be in error by as much as a factor of 10 unless allowance is made for particle concentration. At 100 cm^-3, the standard deviation of the distribution of measured f values is about 30%, indicating that the particle concentration is not the only factor influencing the loss of radon daughters. The implication is that radon daughters can be used to measure radon concentrations at sea level with an accuracy of about 30%, provided the particle concentration is known.The measurements show that there is a very low proportion of unattached daughers in the air between about 30 and 165 m above sea level. According to the model, this implies that mixing of air up to about 200 m is usually rapid enough to result in plate-out of radon daughters on the ocean on a time scale of less than 100 s.     

油气化探异常预测油气藏埋藏深度探讨

通过对大庆油田丰富的地表油气化探、钻井资料分析研究,结合油藏放射性异常模型,提出了氡异常水平分布及特征值与油气藏深度的关系数学模型及参数计算方法。通过大庆油田杜29井区实际资料验证和平洋来27井区、来36井区试验应用,证实用地表油气化探特征值估算确定油气田埋藏深度的技术方法是可行、实用的。而这种解释结果结合地质解释分析,对指导油气田勘探部署,提高勘探效益都具有实际意义。