迁安紫苏花岗岩的~(40)Ar/~(39)Ar年龄谱

对采自河北省迁安县水厂地区的紫苏花岗岩中的黑云母和紫苏辉石进行了~(40)Ar/~(39)Ar年龄测定,分别给出了18.7亿年和19.6亿年的~(40)Ar保存年龄。这两种矿物的年龄谱的视年龄的梯度变化表明,紫苏花岗岩形成后是缓慢冷却的。3.9亿年左右的一次热事件,造成了放射成因~(40)Ar的丢失。根据热历史和封闭温度的研究,从27亿年(侵入到该区紫花岗岩中的花岗闪长岩的锆石U-Pb年龄)到19.6亿年,紫苏花岗岩岩体的抬升速率为6.5m/Ma,但从19.6亿年到18.7亿年,其抬升速率高达111m/Ma,具有明显的构造抬升作用。     

Radon in soil anomaly observed at Los Azufres geothermal field,Michoacan: a possible precursor of the 1985 Mexico earthquake (Ms = 8.1)

A radon anomaly in a nuclear track detector placed on a fault was detected prior to the destructive (Ms = 8.1) Mexican earthquake of 19 September 1985. The fault is a structural feature of the geothermal field Los Azufres, 260 km NE of the epicentral area. Since no other phenomenon can be found as a possible cause for the radon anomaly, it is proposed that preseismic regional stress perturbations may produce changes in the fluid transport patterns at the fault, suggesting that radon measurements in similar conditions could provide a good precursor in high seismic risk areas.     

Fractal analysis of long-range paleoclimatic data: Oxygen isotope record of pacific core V28-239

R/S analysis of the oxygen isotope curve of Pacific core V28-239 yields a fractal dimension of 1.22. This value is considered to characterize global climatic change over the last 2 million years as expressed by changing O¹⁸ ratios and confirms that climatic variations are characterized by long-term persistence. The fractal dimension of 1.22 compares favorably with the approximate fractal dimension of 1.26 for annual precipitation records for nine major cities in the United States. Although the precipitation and oxygen isotope data are measured in different physical units and recorded at different time scales, fractal analysis allows for a mathematical comparison of the two phenomena. Additionally, since the fractal dimensions of the oxygen isotope and precipitation records are similar, it is implied that such fractal dimensions are characteristic of climate change over the spectral range of 10 to 10⁶ years. Given this temperature curves based on fractal parameters of long-term O¹⁸ data could be constructed which would allow examination of characteristics of temperature variation over tens and hundreds of years. Such studies may allow the establishment of limits on natural temperature variation and document the persistence of temperature trends through time. If these trends and limits can be resolved, long-range climatic prediction is feasible.     

AbnormalSq behaviour

It is well-known that the amplitude and phase of theSq(H) variation show considerable variability from day to day. In this paper we consider one aspect of the phase variability—that associated with AQDs. AQDs (or abnormal quiet days) are defined as magnetically quiet days where the maximum excursion ofH at a mid-latitude station on the poleward side of the focus occurs outside the normal time range 0830–1330 LST. Such days exhibit properties, many of which appear quite distinct from the properties of the normalSq(H) variation. The properties of AQDs, and the proposals that have been made to explain them, are considered in detail. The consequences of these proposals and some problems which need to be addressed in order to obtain a fuller understanding of the dynamics of the ionosphere on AQDs are also discussed.     

我国多雨季和少雨季的一些统计特征

通过对我国31年124季降水距平图的分析发现1.全国性的特多(少)雨季中,在高原东侧(95—105°E间)总有一少(多)雨带出现。2.多(少)雨季之后仍为多(少)雨季的持续性以春一夏最好,秋冬最差。3.一年中出现多雨季的次数与黑潮海温和西太平洋副高强度呈正相关。     

矿山淹井中水位、水量的快速估算和预报

本文用数理统计方法,快速估算和预报矿山淹井中水住、最高水位,矿井水涌量、涌入矿区的总水量和需要排出水量。用简单易行的反推法确定淹井的涌水量,并推导出计算式,以供使用。该方法在某矿淹井中使用,效果良好。     

Niveo-aeolian deposits and denivation forms,with special reference to the great Kobuk Sand Dunes,Northwestern Alaska

The geomorphology, lithology and chronostratigraphy of extensive, late Pleistocene inland and river dune sands, aeolian sand sheets (‘cover sands’) and loess deposits of periglacial origin in northwestern Europe are well known. However, the idea that some of these aeolian sediments result from niveo-aeolian processes is still an open question, as no diagnostic sedimentary features have yet been reported. Moreover, actual niveo-aeolian sediments and related denivation forms, reported from various cold-climate regions, are not suitable analogues. Recent observations in active dune fields in northwestern Alaska indicate that interstratification of wind-driven snow and sand preferentially occurs on slip faces of transverse, barchanoid or parabolic dune ridges. Annual denivation forms develop: e.g. snow ramparts, sinkholes, snow hummocks, snow meltwater fans and tensional cracks. The surface consists of a cracked wet sand layer with a dimpled surface and spongy structure. Although the preservation potential of these features is low in this specific case, similar features may be observed in ancient sediments elsewhere and provide useful palaeoclimatic indicators. The niveo-aeolian concept should therefore not specifically be related to late Pleistocene cover sand deposition in northwestern Europe, as previously assumed.     

Comparison of amplitude decay rates in reflection,refraction, and local earthquake records

Three types of seismic data recorded near Coalinga, California were analyzed to study the behavior of scattered waves: 1) aftershocks of the May 2, 1983 earthquake, recorded on verticalcomponent seismometers deployed by the USGS; 2) regional refraction profiles using large explosive sources recorded on essentially the same arrays above; 3) three common-midpoint (CMP) reflection surveys recorded with vibrator sources over the same area. Records from each data set were bandpassed filtered into 5 Hz wide passbands (over the range of 1–25 Hz), corrected for geometric spreading, and fit with an exponential model of amplitude decay. Decay rates were expressed in terms of inverse codaQ (Q _c ^–1 ).Q _c ^–1 values for earthquake and refraction data are generally comparable and show a slight decrease with increasing frequency. Decay rates for different source types recorded on proximate receivers show similar results, with one notable exception. One set of aftershocks shows an increase ofQ _c ^–1 with frequency.Where the amplitude decay rates of surface and buried sources are similar, the coda decay results are consistent with other studies suggesting the importance of upper crustal scattering in the formation of coda. Differences in the variation ofQ _c ^–1 with frequency can be correlated with differences in geologic structure near the source region, as revealed by CMP-stacked reflection data. A more detailed assessment of effects such as the depth dependence of scattered contributions to the coda and the role of intrinsic attenuation requires precise control of source-receiver field geometry and the study of synthetic seismic data calculated for velocity models developed from CMP reflection data.     

Polar constituents of organic matter rich marls from evaporitic series of the Mulhouse basin

A suite of marl samples from the evaporitic series of the Mulhouse basin (France; Lower Oligocene) was studied for its biomarker content, in particular its polar constituents. Novel series of 3-carboxyalkyl steranes and 15-oxo triaromatic ketones were identified by synthesis. The 3-carboxyalkyl steranes probably originate from highly polar precursors yet unreported in living organisms. Our data suggest that micro-algae could be the major source of these compounds which seem to be indicators of high algal input rather than characteristic of evaporitic environments. The 15-oxo triaromatic ketones could be oxidation products of triaromatic steroid hydrocarbons formed during diagenesis, although their formation during work-up procedure could not be excluded.