Evidence of climatic warming in the southern Urals region derived from borehole temperatures and meteorological data

Thirty borehole temperature–depth profiles in the central and southern Urals, Russia were scrutinized for evidence of ground surface temperature histories. We explored two inversion schemes: a simple ramp inversion in which solutions are parameterized in terms of an onset time and magnitude of change and a more sophisticated functional space inverse algorithm in which the functional form of the solution is left unspecified. To enhance and potentially identify latitudinal differences in the ground surface temperature signal, we subdivided the data into three groups based on geographic proximity and simultaneously inverted the borehole temperature–depth logs. The simultaneous inversions highlighted 13 temperature–depth logs that could not both fit a common ground surface temperature history and a priori models within reasonable bounds. Our results confirm that this is an effective way to reduce site-specific noise from an ensemble of boreholes. Each inversion scheme gives comparable results indicating locally variable warming on the order of 1°C starting between 1800 and 1900 AD. Similarly surface air temperature records from 12 nearby meteorological stations exhibit locally variable warming also on the order of 1°C of warming during the 20th century. To explore the degree to which borehole temperatures and surface air temperature (SAT) time series are responding to the same signal, we average the SAT data into the same three groups and used these averages as a forcing function at the Earth's surface to generate synthetic transient temperature profiles. Root mean square (RMS) misfits between these synthetic temperature profiles and averaged temperature–depth profiles are low, suggesting that first-order curvature in borehole temperatures and variations in SAT records are correlated.     

Long-chain alkenones and U37′ variability along a south–north transect in the Western Pacific Ocean

In this paper, we present 50 surface water samples collected during the IMAGES III cruise (June–July 1997) along a transect from New Zealand to the China Sea (42°S–178°E, 21°N–120°E) covering a temperature range from 13.3 to 30.4 °C. A very worthwhile aspect of this study is a coupling of both biomarker (alkenone) and coccolithophorid counting. We show that the U₃₇^k′–temperature relationship is very similar to the Prahl et al. [Geochim. Cosmochim. Acta 52 (1988) 2203] culture calibration and to the global core top calibration of Müller et al. [Geochim. Cosmochim. Acta 62 (1998) 1757]. However, in the warmest surface waters of the Western Pacific ocean (>26.4 °C) where Gephyrocapsa oceanica is likely the most widespread species, the associated U₃₇^k′ has a constant value of 1.0. The consequence is that above this temperature threshold, U₃₇^k′ cannot be used as an accurate paleothermometer.     

Periodicities in the time series of annual minimum temperatures for the United States Gulf Coast region

The minimum winter temperature series for the United States Gulf Coast for 1799–1988 (190 values) was subjected to Maximum Entropy Spectral Analysis. Significant periodicities in the QBO region (T-2–3 years) and atT=3.7, 4.5, 5.5, 6.5, 7.5, 12.9, 15.5 and 22 years were detected. Some of these were present in the first half only (1799–1893) while others in the latter half only (1894–1988), indicating a transient nature. Also, more than 50% of the variance was random. Many of the significant periodicities are seen in other geophysical parameters. Some may be harmonics of the 11-year sunspot cycle and the 22-year Hale magnetic sunspot cycle.     

Deep structure of the Nojima Fault, southwest Japan, estimated from borehole observations of fault-zone trapped waves

To estimate the deep structure of the southern part of the Nojima Fault, southwest Japan without the influence of near-surface structures, we analyzed the Love-wave-type fault-zone trapped waves (LTWs) recorded by a borehole seismometer at 1800 m depth. We examined the polarization, dispersion, and dominant frequency of the wavetrain following the direct S-wave in each seismogram to identify the LTW. We selected eight candidates for typical LTWs from 462 records. Because the duration of the LTW increases with hypocentral distance, we infer that the low velocity fault-zone of the Nojima Fault continues towards the seismogenic depth. In addition, since the duration of the LTW increases nonlinearly with hypocentral distance, we infer that the S-wave velocity of the fault-zone increases with depth. The location of events showing the LTW indicates that the fault-zone dips to the southeast at 75° and continues to a depth of approximately 10 km. We assumed a uniform low-velocity waveguide to estimate the average structure of the fault-zone. We estimated the average width, S-wave velocity, and Q_s of the fault-zone by comparing an analytical solution of the LTW with measured data. The average width, S-wave velocity, and Q_s of the fault-zone are 150 to 290 m, 2.5 to 3.2 km/s, and 40 to 90, respectively. Hence the fault-zone structure with a larger width and smaller velocity reduction than the fault-zone model estimated by previous surface observation is more suitable to represent the average fault-zone structure of the Nojima fault. The present study also indicated that the shallow layers and/or a shallow fault-zone structure drastically changes the characteristics of the LTW recorded at the surface, and therefore cause a discrepancy in the fault-zone model between the borehole observation and surface observation.     

乌鲁木齐台钻孔应变与水位相关性的初步研究

1999年 7月 11日乌鲁木齐台钻孔应变观测井的水位突然变化 ,通过计算该台应变与水位的相关系数和回归系数 ,研究了水位与应变的关系 ,认为利用此关系可以排除水位对观测值的影响     

陕西彬县大佛寺D4钻孔勘察地球化学研究

运用烃类勘察地球化学方法，对鄂尔多斯盆地南部彬县大佛寺井田钻遇中休罗统煤层的耽钻孔，进行了垂向剖面多指标的综合地球化学研究。结果表明：剖面中所有岩样中的烃类物质均为热解烃生成初期演化阶段的煤成烃产物，具明显的同一性；由煤层至地表黄土，所有岩样中的烃类呈明显的、规律性垂直向上运移。这证实地下煤层烃类在近地表具有很好的地球化学信息显示，利用勘察地球化学方法找煤／煤层气是可行的。     

The tectonic regime in Italy inferred from borehole breakout data

In Italy, the horizontal stress directions are well constrained in many regions, but the tectonic regime is not well known because the stress magnitudes are unknown. Our intention is to improve the knowledge of crustal stress in Italy, both at shallow depth and in low seismicity areas. Therefore, we inferred the tectonic regime from the comparison between the depth of breakout occurrence and the physical properties of the rocks in 20 boreholes. The critical value of the maximum horizontal stress, for which the effective tangential stress at the borehole wall overcomes the rock strength to form breakouts, could be computed from rock strength and density. Comparing the theoretical stress distributions for different tectonic regimes with the depth distribution of breakout occurrence, it is possible to infer the tectonic regime that fits best to the breakout depth distribution. We investigated boreholes up to 6 km deep located in different tectonic environments over the Italian peninsula: the Po Plain, the Apenninic chain, the Adriatic foredeep and the Tyrrhenian Quaternary volcanic region. These wells are characterised by breakout data of good quality (A, B and C, according to World Stress Map quality ranking system). The results are in general agreement with the style of faulting derived from earthquake focal mechanisms and other stress indicators. Our results show a predominance of a normal faulting (NF) regime in the inner Apennines and both normal faulting and strike–slip faulting (SS) style in the surrounding regions, possibly also associated with changes in the tectonic regime with depth.     

橄榄岩中尖晶石的O同位素继承性与晶体结构转换

应用增量法计算的矿物对O同位素分馏曲线，得到正尖晶石-矿物对O同位素温度高于尖晶石在地幔中的熔点，而用反尖晶石-矿物对计算的O同位素温度低于尖晶石的熔点，较为合理。因此，地幔橄榄岩中镁铝尖晶石的O同位素组成可能继承了其母体反尖晶石特征，即使反结构尖晶石在发生相变作用变成正结构尖晶石时未发生O同位素再平衡。     

X射线荧光测井的井液效应及其校正

本文从Ｘ射线的性质，以及Ｘ射线与物质作用的机理出发，对井液效应进行了研究，并对其影响过程进行模拟。在理想井液模型上，推导出Ｘ射线活度与钻孔参数的数理关系。在此基础上，进一步研究得到了能适应野外多变情况的井液效应校正公式（ＣＢＷＥ）和方法。