九江地震台观测井水氢氧同位素特征及意义

在地震地下流体观测研究中,基于氢氧同位素示踪技术研究地下水补给源及循环过程是常用的技术方法之一。本文给出了九江地震台2号观测井水、大气降水、周边水库水及高山泉水等样品的氢氧同位素测定结果,表明地下水δ~(18)O测值介于-7.59‰～-6.09‰,平均值-6.99‰,δD测值介于-45.22‰～-39.69‰,平均值-42.32‰,变异异数分别为0.09、0.16;大气降水δ~(18)O测值介于-13.00‰～-1.27‰,平均值-4.74‰,δD测值介于-96.13‰～-4.74‰,平均值-46.87‰,变异异数分别为0.40、0.56,与降水相比,地下水氢氧同位素变化更为稳定。大气降水氢氧同位素2017年5～10月表现为明显的降水效应,2018年11～4月表现为明显的温度效应,而地下水氢氧同位素并未表现出明显的降水效应和温度效应。氢氧同位素及过量氘揭示地下水在下渗补给前经历了明显的蒸发分馏作用,并与围岩进行~(18)O交换,δ~(18)O与δD计算得出的补给高程分别约为647、440m。九江台观测井的观测层地下水为大气降水成因的构造裂隙水,属于大气成因型且循环过程为较稳定的裂隙水补给并形成承压自流井。     

Performance of High Speed Railway Subgrade Strengthened by Long-Short Piles—Part I: Experimental Results

Geotechnical and Geological Engineering - The Yinxi Railway is located in the western region of China. As a high speed railway line connecting Yinchuan-Xi'an, it is of great significance for...     

东营凹陷牛38井沙河街组烃源岩生排烃评价

东营凹陷牛38井沙河街组三段烃源岩从沙三下亚段向沙三中-上亚段为一从高水位深湖相向低水位前三角洲相发展的沉积旋回,该沉积环境控制从下向上发育不同类型的有机质。相应地,该段烃源岩品质从下向上变差,其中沙三中亚段上部及沙三中亚段中部烃源岩产烃能力小,沙三下亚段烃源岩整体品质好,局部存在优质烃源岩。其优劣性体现了在该段烃源岩中,Ⅰ型干酪根具有高的生产力,而Ⅲ型、Ⅱ2型干酪根生烃潜力很低,基本为无效有机质。计算结果显示不同数据点的烃源岩单位质量原始生烃潜量可相差3个数量级,体现了烃源岩存在强烈的非均质性。有机碳的非均质性分布为其提供了物质基础,而湖盆的旋回式沉积及湖平面的波动性变化是其内在原因。同时,本文也提供一种计算生排烃量的新方法,结果表明该方法较为有效可行。     

硼酸盐矿物的振动光谱研究：Ⅲ.理论分析

本文利用位置群分析和因子群分析得到硼酸盐矿物的振动模式，并利用正则坐标分析从实测振动频率计算了矿物的力常数，得出：（１）利用位置群分析与因子群分析，可以得到矿物振动光谱所应具有的谱带数目，但理论结果与实测谱图并不完全一致，一般情况下，位置群分析就能得到与实测谱图相近的谱带数目。（２）对于比较简单的配阴离子团，可以利用正则示分析由实测的振动光谱频率计算力常数，从而得到有关化学键的信息，或者由已知的力     

Modeling transient and long-term postseismic deformation: A case study of 1995 M W9.5 Chile earthquake

In this paper, we firstly use finite element method (FEM) with Burgers model to simulate the postseismic viscoe-lastic relaxation taking 1960 Chile earthquake as an example. The postseismic deformation modeled with Burgers model includes co-seismic deformation, transient postseismic deformation and long-term postseismic deformation. So if we apply Burgers model to calculate postseismic deformation of 1960 Chile earthquake, there is no discrep-ancy phenomenon due to different durations of postseismic deformations that happens in Maxwell model.     

The effect of sulfate concentration on (sub)millimeter-scale sulfide δS in hypersaline cyanobacterial mats over the diurnal cycle

Substantial isotopic fractionations are associated with many microbial sulfur metabolisms and measurements of the bulk δ³⁴S isotopic composition of sulfur species (predominantly sulfates and/or sulfides) have been a key component in developing our understanding of both modern and ancient biogeochemical cycling. However, the interpretations of bulk δ³⁴S measurements are often non-unique, making reconstructions of paleoenvironmental conditions or microbial ecology challenging. In particular, the link between the μm-scale microbial activity that generates isotopic signatures and their eventual preservation as a bulk rock value in the geologic record has remained elusive, in large part because of the difficulty of extracting sufficient material at small scales. Here we investigate the potential for small-scale (∼100 μm-1 cm) δ³⁴S variability to provide additional constraints for environmental and/or ecological reconstructions. We have investigated the impact of sulfate concentrations (0.2, 1, and 80 mM SO₄) on the δ³⁴S composition of hydrogen sulfide produced over the diurnal (day/night) cycle in cyanobacterial mats from Guerrero Negro, Baja California Sur, Mexico. Sulfide was captured as silver sulfide on the surface of a 2.5 cm metallic silver disk partially submerged beneath the mat surface. Subsequent analyses were conducted on a Cameca 7f-GEO secondary ion mass spectrometer (SIMS) to record spatial δ³⁴S variability within the mats under different environmental conditions. Isotope measurements were made in a 2-dimensional grid for each incubation, documenting both lateral and vertical isotopic variation within the mats. Typical grids consisted of ∼400-800 individual measurements covering a lateral distance of ∼1 mm and a vertical depth of ∼5-15 mm. There is a large isotopic enrichment (∼10-20‰) in the uppermost mm of sulfide in those mats where [SO₄] was non-limiting (field and lab incubations at 80 mM). This is attributed to rapid recycling of sulfur (elevated sulfate reduction rates and extensive sulfide oxidation) at and above the chemocline. This isotopic gradient is observed in both day and night enrichments and suggests that, despite the close physical association between cyanobacteria and select sulfate-reducing bacteria, photosynthetic forcing has no substantive impact on δ³⁴S in these cyanobacterial mats. Perhaps equally surprising, large, spatially-coherent δ³⁴S oscillations (∼20-30‰ over 1 mm) occurred at depths up to ∼1.5 cm below the mat surface. These gradients must arise in situ from differential microbial metabolic activity and fractionation during sulfide production at depth. Sulfate concentrations were the dominant control on the spatial variability of sulfide δ³⁴S. Decreased sulfate concentrations diminished both vertical and lateral δ³⁴S variability, suggesting that small-scale variations of δ³⁴S can be diagnostic for reconstructing past sulfate concentrations, even when original sulfate δ³⁴S is unknown.     

Long‐term variability in the water budget and its controls in an oak‐dominated temperate forest

Water availability is one of the key environmental factors that control ecosystem functions in temperate forests. Changing climate is likely to alter the ecohydrology and other ecosystem processes, which affect forest structures and functions. We constructed a multi‐year water budget (2004–2010) and quantified environmental controls on an evapotranspiration (ET) in a 70‐year‐old mixed‐oak woodland forest in northwest Ohio, USA. ET was measured using the eddy‐covariance technique along with precipitation (P), soil volumetric water content (VWC), and shallow groundwater table fluctuation. Three biophysical models were constructed and validated to calculate potential ET (PET) for developing predictive monthly ET models. We found that the annual variability in ET was relatively stable and ranged from 578 mm in 2009 to 670 mm in 2010. In contrast, ET/P was more variable and ranged from 0.60 in 2006 to 0.96 in 2010. Mean annual ET/PET_FAO was 0.64, whereas the mean annual PET_FAO/P was 1.15. Annual ET/PET_FAO was relatively stable and ranged from 0.60 in 2005 to 0.72 in 2004. Soil water storage and shallow groundwater recharge during the non‐growing season were essential in supplying ET during the growing season when ET exceeded P. Spring leaf area index (LAI), summer photosynthetically active radiation, and autumn and winter air temperatures (T_a) were the most significant controls of monthly ET. Moreover, LAI regulated ET during the whole growing season and higher temperatures increased ET even during dry periods. Our empirical modelling showed that the interaction of LAI and PET explained >90% of the variability in measured ET. Altogether, we found that increases in T_a and shifts in P distribution are likely to impact forest hydrology by altering shallow groundwater fluctuations, soil water storage, and ET and, consequently, alter the ecosystem functions of temperate forests. Copyright © 2013 John Wiley & Sons, Ltd.     

Influence of temperature and humidity on similar material and its control measures

Similar-material simulation is generally used in mining engineering. The properties of a similar material vary over time in a certain environment. Due to the time-varying characteristics of the material strength, the model and prototype is dissimilar in dynamics and kinematics, which may affect the reliability of simulation results. The present paper conducts block experiments that investigate the time-varying characteristics of the material strength. The paper further investigates methods of reducing the effects of time-varying characteristics of material strength on simulation results and extends the effective monitoring time of the similar-material model in a natural environment and an environment having constant temperature and humidity. The following results are obtained: (1) The strength and moisture content of the similar material have an exponential relationship, which can be divided into three phases. (2) When a similar-material model is laid in a natural environment, sampling and homemade monitoring equipment can be adopted to control the similar-material model’s strength. Meanwhile, homemade monitoring equipment for the relative humidity of the similar material can be used to monitor a critical change in the similar material’s moisture content. (3) An environment having constant temperature and humidity can extend the effective monitoring time of the similar-material model. (4) High humidity can extend the effective monitoring time while high temperature can decrease the effective monitoring time. In an experiment, the temperature and humidity under the environment of constant temperature and humidity and monitoring time of the model should both be set reasonably. Results provide guidelines for setting the model monitoring period and give evidence for the reliability of simulation results.     

陆西凹陷盆地数值模拟及油气评价

在综合分析区域地质、构造和有机地球化学等资料的基础上，应用盆地模拟方法对开鲁盆地陆西凹陷进行了地史、热史、生烃、排烃模拟分析。模拟结果表明，九佛堂组和沙海组是该凹陷的主要生、排烃层系，其主要生烃期为阜新期之后，而排烃主要发生于白垩纪以来，构造运动对盆地热史和生、排烃过程都有明显的抑制作用。综合分析认为，丰富的油气主要分布于生油洼陷附近的构造带和各种砂砾岩储集体中。     

汉江一级阶地抬升以来北亚热带风尘堆积、发育与东亚季风演变的耦合关系——以郧县段汉江上游谷地为例

风成黄土对东亚冬夏季风优势期转换及起迄时间起到良好指示作用,探究风尘黄土堆积、发育特征与东亚季风演变的耦合关系十分必要。本文通过研究汉江一级阶地上覆黄土-古土壤序列的构型、磁化率、烧失量、粒度、元素组成特征,分析汉江一级阶地抬升以来黄土-古土壤序列的成因及成壤特征,探究东亚冬夏季风的演化序列。结果表明：（1）汉江上游地区黄土-古土壤序列的地层构型为表层土（MS）-近代黄土（L₀）-古土壤（S₀）-过渡层（L_t）-马兰黄土（L₁）,磁化率、粒度、烧失量、元素组成等特征指示各地层成壤强度特征为S₀>L₀/L_t>L₁。（2） 成壤强度指示18000 a BP以来,东亚冬夏季风演替特征为末次盛冰期冬季风强烈→全新世早期冬季风减弱→全新世中期夏季风主导→全新世晚期夏季风减弱~,冬季风强盛,其演变滞后于低纬太阳辐射变化2000~3000 a。（3）该风尘堆积物理化性质对6000~5000a BP的气候恶化期有所响应。总而言之,汉江上游一级阶地上覆黄土为风尘堆积物,指示18000a BP以来东亚季风的变迁规律及季风异常事件,能够体现北亚热带对全球气候变化及极端事件的响应。