山西省地热资源规律及其地质背景研究

中国大陆蕴藏丰富的地热资源,山西省局部地热异常特征明显。通过收集山西省典型地热区域流体数据,选取典型钻孔分析,探讨并总结山西省地热资源赋存规律和成因机制,为后期地热资源勘探及开发利用提供重要参考依据。通过分析研究结果得出以下几点认识：山西省水热型地热储层水温分布在28～78℃,北部以太古代花岗片麻岩为主,中部以古生代灰岩为主,南部以古生代碳酸盐岩为主;北部热源主要来自花岗岩中放射性元素衰变产生热量,中部和南部热源受地幔上隆及岩浆活动影响;省内深大断裂构成地下热水运移通道,热传导性较好;第四纪和第三纪松散层为省内地热良好的保温盖层,岩性以粘土、砂质粘土及砂层为主。结合前人水文地球化学研究成果,认为山西省地热水pH值呈弱碱性,其中Sr、Li、SiO₂与Cl大体上存在正相关关系,大部分地热水氚含量小于1TU,水源主要为大气降水补给,部分地热田出现δ¹⁸O漂移,氧同位素交换作用显著。     

汶川县绵虒镇板子沟“8·20”大型泥石流堵河特征及危害性预测

汶川地震后,板子沟曾发生过多次大规模泥石流,尤其是2019年“8·20”泥石流对沟口的道路桥梁以及村寨造成了严重的破坏,将主河道向对岸严重挤压,今后仍存在较大堵河的风险。文章在野外调查以及对泥石流基本特征和形成条件综合分析的基础上,分析了堵河特征,计算了不同频率下泥石流的堵河参数,并预测了各频率下溃决洪水对绵虒镇可能产生的影响。计算结果表明,频率为2％、5％和10％的泥石流造成岷江堵塞的可能性较小,假设发生堵河事件,绵虒镇也不会受到溃坝洪水的危害。频率为1％的泥石流很可能造成主河堵塞。体积约57.38×104 m3的泥石流物质可以到达岷江,形成高度约为51.61 m的堰塞坝。在主河洪水的作用下,堰塞坝发生溃坝,溃坝洪水的峰值流量为5 935.49 m3/s,到达绵虒镇后降至2 312.25 m3/s。由于相应的洪水深度（4.00 m）大于防护堤的高度（3.50 m）,因此溃坝洪水很可能会对绵虒镇防护堤附近民房造成破坏。为今后大型泥石流堵河特征的分析,以及溃决洪水对下游城镇可能造成的影响提供了参考。     

Application and discussion of statistical seismology in probabilistic seismic hazard assessment studies

Earthquakes are one of the natural disasters that pose a major threat to human lives and property. Earthquake prediction propels the construction and development of modern seismology;however, current deterministic earthquake prediction is limited by numerous difficulties. Identifying the temporal and spatial statistical characteristics of earthquake occurrences and constructing earthquake risk statistical prediction models have become significant;particularly for evaluating earthquake risks and addressing seismic planning requirements such as the design of cities and lifeline projects based on the obtained insight. Since the 21 st century, the occurrence of a series of strong earthquakes represented by the Wenchuan M8 earthquake in 2008 in certain low-risk prediction areas has caused seismologists to reflect on traditional seismic hazard assessment globally. This article briefly reviews the development of statistical seismology, emphatically analyzes the research results and existing problems of statistical seismology in seismic hazard assessment, and discusses the direction of its development. The analysis shows that the seismic hazard assessment based on modern earthquake catalogues in most regions should be effective. Particularly, the application of seismic hazard assessment based on ETAS(epidemic type aftershock sequence)should be the easiest and most effective method for the compilation of seismic hazard maps in large urban agglomeration areas and low seismic hazard areas with thick sedimentary zones.     

安徽马鞍山市当涂地区地下水水化学特征及演化机制

【研究目的】 了解长江中下游平原地区地下水流系统并深入分析其地下水水化学特征及其演化机制。【研究方法】 综合马鞍山市当涂地区的水文地质条件、水动力场等,基于研究区水化学基本特征,运用多元统计分析、水化学图件、离子比值和反向水文地球化学模拟等方法对该地区浅层地下水水化学演化进行分析。【研究结果】 结果表明：（1）研究区地下水主要为低矿化度偏碱性水,地下水组分中阳离子以Ca²⁺和Mg²⁺为主,阴离子以HCO₃^-和SO₄^2-为主。（2）研究区地下水水化学类型主要可分为7类,其中松散岩类孔隙含水岩组和碎屑岩类孔隙裂隙含水岩组的水化学类型主要为HCO₃^-Ca型、HCO₃^-Ca·Na型、HCO₃·Cl-Ca·Na型以及HCO₃^-Ca·Mg型;基岩类裂隙含水岩组的化学类型主要为HCO₃·SO₄-Ca·Mg型和SO₄·HCO₃^-Ca·Mg型。（3）研究区浅层地下水水样超标率为46%,总体水质较差,超标率较高的组分依次为Mn、高锰酸盐指数（COD_Mn）、硝酸盐（以N计）、Fe、As、氨氮（以N计）等。（4）研究区地下水的化学组分主要受到岩石风化作用的控制;此外,还存在Na-Ca的正向阳离子交替吸附作用。反向水文地球化学模拟结果进一步定量论证了水岩相互作用对本区浅层地下水组分的形成和演化起着主导作用。【结论】 研究区地下水主要为低矿化度偏碱性,主要可分为松散岩类孔隙水、碎屑岩类孔隙裂隙水和基岩类裂隙水。主要离子比例和反向水文地球化学模拟揭示了本区浅层地下水化学组分主要是地下水溶滤方解石、白云石等碳酸盐矿物、石英、长石等硅酸盐矿物,高岭土等黏土矿物以及岩盐、石膏等达到过饱和之后形成的。     

Exhumation History of the Xining Basin Since the Mesozoic and Its Tectonic Significance

The Xining Basin is located in the northeastern Qinghai–Tibetan Plateau, and its continuous Cenozoic strata record the entire uplift and outgrowth history of the Tibetan Plateau during the Cenozoic. The newly obtained apatite fission track data presented here shows that the Xining Basin and two marginal mountain ranges have experienced multiphase rapid cooling since the Jurassic, as follows. In the Middle–Late Jurassic, the rapid exhumation of the former Xining Basin resulted from collision between the Qiangtang Block and the Tarim Block. During the Early–Late Cretaceous, the former Xining Basin underwent a tectonic event due to marginal compression, causing the angular unconformity between the Upper and Lower Cretaceous. In the Late Cretaceous to the Early Cenozoic, collision between the Qiangtang Block and the Lhasa Block may have resulted in the rapid exhumation of the Xining Basin and the Lajishan to the south. In the Early Cenozoic(ca. 50–30 Ma), collision between the Indian and Eurasia plates affected the region that corresponds to the present northeastern Qinghai–Tibetan Plateau. During this period, the central Qilian Block rotated clockwise by approximately 24° to form a wedge-shaped basin(i.e., the Xining Basin) opening to the west. During ca. 17–8 Ma, the entire northeastern Qinghai–Tibetan Plateau underwent dramatic deformation, and the Lajishan uplifted rapidly owing to the northward compression of the Guide Basin from the south. A marked change in subsidence occurred in the Xining Basin during this period, when the basin was tectonically inverted.     

南海北部天然气水合物远景区末次冰期以来底栖有孔虫稳定同位素特征及其影响因素

底栖有孔虫碳同位素负偏移是地质记录中天然气水合物释放的重要证据之一.对南海北部西沙海槽和东沙陆坡等天然气水合物远景区XH-27PC和DS-4PC柱状样分别进行顶空气甲烷含量分析、有机碳含量分析、粒度分析和有孔虫氧碳同位素分析.结合碳酸盐含量及AMS 14C测年,揭示研究区末次冰期以来底栖有孔虫的稳定同位素特征.结果显示:西沙海槽BSR区沉积物中甲烷含量较低;底栖有孔虫碳同位素负偏不明显,与顶空气甲烷含量呈弱正相关(R=0.32),与有机碳含量有强负相关(R=-0.82),说明低通量甲烷不足以引起底栖有孔虫碳同位素显著偏移,在无甲烷或甲烷轻微渗漏的环境中有机碳的厌氧氧化是影响底栖有孔虫碳同位素组成的主要因素.东沙陆坡BSR区沉积物中含有大量的甲烷气体;底栖有孔虫氧同位素记录在末次冰期异常偏重,可能与天然气水合物的分解释放有关;同时可识别出多期碳同位素快速负偏事件,其成因很可能是末次冰期海平面下降导致海底沉积物的温度、压力条件发生变化,从而引发水合物甲烷失稳分解,底栖有孔虫吸收富12C的甲烷源碳致使壳体碳同位素负偏移.     

Sensitivity of carbon budget to historical climate variability and atmospheric CO2 concentration in temperate grassland ecosystems in China

Chinese temperate grasslands play an important role in the terrestrial carbon cycle. Based on the parameterization and validation of Terrestrial Ecosystem Model (TEM, Version 5.0), we analyzed the carbon budgets of Chinese temperate grasslands and their responses to historical atmospheric CO₂ concentration and climate variability during 1951–2007. The results indicated that Chinese temperate grassland acted as a slight carbon sink with annual mean value of 7.3 T?g C, ranging from -80.5 to 79.6 T?g C yr^-1. Our sensitivity experiments further revealed that precipitation variability was the primary factor for decreasing carbon storage. CO₂ fertilization may increase the carbon storage (1.4 %) but cannot offset the proportion caused by climate variability (-15.3 %). Impacts of CO₂ concentration, temperature and precipitation variability on Chinese temperate grassland cannot be simply explained by the sum of the individual effects. Interactions among them increased total carbon storage of 56.6 T?g C which 14.2 T?g C was stored in vegetation and 42.4 T?g C was stored in soil. Besides, different grassland types had different responses to climate change and CO₂ concentration. NPP and R_H of the desert and forest steppes were more sensitive to precipitation variability than temperature variability while the typical steppe responded to temperature variability more sensitively than the desert and forest steppes.     

Investigation on semi-direct and indirect climate effects of fossil fuel black carbon aerosol over China

A Regional Climate Chemistry Modeling System that employed empirical parameterizations of aerosol-cloud microphysics was applied to investigate the spatial distribution, radiative forcing (RF), and climate effects of black carbon (BC) over China. Results showed high levels of BC in Southwest, Central, and East China, with maximum surface concentrations, column burden, and optical depth (AOD) up to 14 μg?m^?3, 8 mg?m^?2, and 0.11, respectively. Black carbon was found to result in a positive RF at the top of the atmosphere (TOA) due to its direct effect while a negative RF due to its indirect effect. The regional-averaged direct and indirect RF of BC in China was about +0.81 and ?0.95 W?m^?2, respectively, leading to a net RF of ?0.15 W?m^?2 at the TOA. The BC indirect RF was larger than its direct RF in South China. Due to BC absorption of solar radiation, cloudiness was decreased by 1.33 %, further resulting in an increase of solar radiation and subsequently a surface warming over most parts of China, which was opposite to BC’s indirect effect. Further, the net effect of BC might cause a decrease of precipitation of ?7.39 % over China. Investigations also suggested large uncertainties and non-linearity in BC’s indirect effect on regional climate. Results suggested that: (a) changes in cloud cover might be more affected by BC’s direct effect, while changes in surface air temperature and precipitation might be influenced by BC’s indirect effect; and (b) BC second indirect effect might have more influence on cloud cover and water content compared to first indirect effect. This study highlighted a substantial role of BC on regional climate changes.     

中国大陆及华北地区地震资料的小波分析

基于地震活动为多尺度多活动这一观点，运用小波变换方法，以不同的小波尺度分析了中国大陆1900～2001年和华北地区1500～2001年M≥5地震的本尼奥夫应变资料，得到了各种层次地震活跃期和平静期，分析结果可信而又符合实际。对历史地震研究和地震危险性预测具有一定的参考价值。     

面向Internet的农业气象产量动态预报

针对信息时代Internet网上用户对产量预报动态查询的需求 ,探讨了面向Inter net的农业气象产量预报的解决方案。试验结果表明 ,由于作物生长发育和产量形成是一个光、温、水、土条件长期、综合作用 ,生物量长期累积的过程 ,因此利用积分回归方法 ,考虑全生育期光、温、水气象因子的综合影响 ,根据已出现的天气实况 ,在假定后期天气条件正常的情况下 ,有可能预测出未来产量的趋势。随着天气实况的逐一出现 ,后期的预报结果可望逐步接近实际值。统计检验和试报结果误差均在允许范围内。