RVSP方法正演模拟及在煤田采空区中的应用

为了提高煤田采空区的地震勘探精度,精准定位采空区边界。在传统VSP地震数据处理成像方法的基础上,通过正演模拟系统地研究了RVSP地震数据处理成像方法,并对采空区填充物及大小分别建立模型进行地震正演模拟数据分析,研究其成像特征。利用正演模拟研究成果,对某水务工程关键地段煤田采空区地震试验数据进行精细处理,并取得了理想的成像效果;形成了一套适合煤田采空区RVSP地震数据处理成像方法,对精准探测煤田采空区具有重要的实际意义。      

面向井周高陡构造的VSP地震干涉成像方法研究

随着我国油气勘探的不断深入,复杂高陡构造区越来越成为当今油气勘探的重点,现有成像方法无法满足井周高陡构造的成像需求。针对井中高陡构造,地震干涉法基于源检互易定理,对不同检波点处VSP资料进行相关/褶积处理,重构虚拟震源数据,得到以某一检波点为虚拟震源,另一检波点处接收到的虚拟SWP地震记录。根据地震干涉原理,将VSP资料的不同波场成分进行分离,并对不同波场成分进行数学运算来生成干涉道集。通过地震干涉法能够使虚拟观测系统更靠近目标区域,提高对高陡界面的成像分辨率,实现面向井周高陡构造的高精度成像。笔者等先是对地震干涉原理进行理论推导,基于扰动理论对VSP干涉道集的波场成分进行分析,验证了不同波场成分在地震干涉中的作用及虚假同相轴产生原因。引入窗函数滤波器,对远离虚拟源和虚拟检波器的记录进行衰减,压制干涉过程中生成的虚假同相轴。最后利用干涉成像条件对处理后的地震资料进行成像,并用盐丘模型进行数值试算,得到其高精度成像结果。     

基于联合约束的压缩感知提高分辨率方法

针对复杂地区油气勘探地震数据分辨率低、成像精度差等问题,笔者提出一种基于联合约束的压缩感知提高分辨率方法。为兼顾纵向分辨率和横向连续性,引入L1范数实现压缩感知最优化求解,快速、稳定地获得地震子波和反射系数;引入全变差约束,解决地震数据传统单道反演存在的同相轴抖动、横向连续性差问题,通过联合约束,提高了地震数据分辨率。经理论模型和实际地震数据处理应用,结果表明该方法拓宽了地震数据频带,频带展宽10 Hz以上,有效提升了数据分辨率和成像精度。     

振幅叠加的井地联合微地震监测技术研究

微地震地面监测主要缺陷在于垂向定位分辨率不足,而井下监测则存在横向定位分辨率较低问题。针对这些问题,通过井中-地面联合监测的方法提高微地震定位可信度,并结合振幅叠加方法对地面噪声进行压制。模拟三维地震数据的反演实验证明该方法的可行性,反演得到的震源位置与模拟震源点位置一致。以山西宁武盆地一次水力压裂监测为例,证明笔者所提出的方法在实际应用中具有可行性。     

利用三维地震勘探技术勘查煤矿采空区

在煤矿生产过程中,随着煤层的被开采挖掘,地下会形成越来越多的采空区,采空区及其上部地层的地球物理性质也随之发生了显著变化,而地震勘探能有效地解决地下物性差异明显的构造。笔者利用三维地震勘探技术对采空区的反射波特征进行了分析,总结地震数据采集工作中影响采空区分辨率的因素,以及采空区资料处理中的关键技术。通过煤矿实际开采验证,证明了三维地震勘探技术对采空区的勘探是可行的、有效的。     

用瞬变电磁数据精细处理技术探测煤矿采空区

为方便煤田采空区瞬变电磁资料的解释,笔者根据瞬变电磁纵向电导微分成像的原理,编制了集层状模型正、反演、微分电导成像、采集数据预处理以及传统的视电阻率等方法于一体的综合瞬变电磁精细处理解释软件,并将这套软件应用于河南省老窑煤矿采空区的解释和推断工作中。结果表明:该软件处理速度快,成像直观,解释精度高。     

波阻抗反演技术在三维地震勘探煤层解释中的应用

通过测井约束波阻抗反演技术,不仅提高地震资料纵向、横向分辨率,也提高了对复杂煤层及煤层宏观结构解释精度.利用该技术可对煤层厚度及结构进行定量解释,较好地完成了勘探中的任务要求.该技术可应用于煤田类似任务要求的勘探工作中.     

基于反褶积算法的地震干涉技术被动源成像

地震干涉技术可以将任意2个检波器接收到的数据合成为在若干检波器之间传播的波,就好像其中的一个检波器作为一个虚拟震源来发挥作用。它可以从混沌无序的地震信号中发现有用信息,从地震噪声中提取有用信号以此推断地震波穿过介质的地质构造。基于反褶积算法,对其理论公式进行了较详细的推导,实现被动源地震干涉成像,证明了反褶积算法的可行性;并将其结果与互相关算法的结果进行对比,分析了2种方法在信噪比和分辨率方面的差异。数值计算表明,反褶积算法的纵向分辨率比互相关算法的高。对其进行的加噪试算表明,震源叠加后的反褶积算法呈现出高信噪比的特点。     

地震层析技术及其应用研究

相对于其它地球物理方法而言，地震反射方法的纵向分辨率较高，横向分辨率较低。为提高地震记录的横向分辨率，解决探测倾角较大的地层和复杂的地质构造及隐伏岩体等问题，在这里进行了地面地震层析技术的试验应用研究。针对非线性地面地震层析技术的基本原理进行了阐述，并就该方法对地震地质模拟记录和实际地震记录的反演结果进行了讨论。     

回线源瞬变电磁法在地质灾害调查中的应用

针对工程与地质灾害调查要求解决精细构造的问题,投入了近年来广泛应用于工程勘测的回线源瞬变电磁探测。分析了瞬变电磁测深的特点,该方法体积效应小,等值作用范围较直流测深和频率测深窄,故横向和纵向分辨率高。通过2个实例的成功应用,说明回线源瞬变电磁在探测构造破碎带、煤田采空区等方面的应用效果。     

Intervening in the environment of the everyday

This paper seeks to explore the radical democratic potential in urban artistic interventions. It does so through bringing Gramsci’s concept of nature together with his ‘cultural writings’ and broader debates around avant-garde artistic practice. Empirically, I focus on the work of City Mine(d), a Brussels-based interventionist collective, and Siraj Izhar, a London-based artist-activist. Within Gramsci’s writings, I argue, socio-natural relationships emerge through sensuous activity or work. Making a somewhat more ambitious claim, I suggest that Gramsci’s concept of nature rests on what geographers have come to understand as the production of nature. Whilst attention has only recently turned to this implicit political ecology, much greater attention has been focussed on Gramsci’s cultural insights. For Gramsci, cultural struggles are an integral part of the effort to shape a new reality. Whilst he emphasises the ‘bottom up’ nature of such struggles, the intervention of enlightened outsiders is often a necessary and frustrating complement. However, by turning attention to the manner in which hegemony relates to the production of nature, and through bringing this into dialogue with radical artistic practice, such implicit elitism might be challenged. City Mine(d) and Izhar, I argue, develop a non-vanguardist politics that sees the contestation of hegemony as a struggle integral to the day-to-day nature of cities.     

Using environmental isotopes in the study of the recharge-discharge mechanisms of the Yarmouk catchment area in Jordan

The recharge sources, the flow mechanisms and discharge areas of the different groundwater bodies underlying the Yarmouk River catchment area in Jordan, have, until now, not been adequately explained, although a wide range of hydrological, hydrogeological, and hydrochemical studies have been done. Along the Jordanian part of the catchment area of the Yarmouk River, groundwater issues from different aquifers with a variety of chemistries and types within the same aquifer and in between the different aquifers. Conventional recharge/discharge mechanisms, water balances and chemical analyses did not adequately explain the chemical variations and the different water types found in the area. Applying environmental isotopic tools combined with their altitude effects due to topographic variations (250–1,300 m a.s.l. within a distance of 20 km), and taking into consideration re-evaporation effects on the isotopic depletion and enrichment of rainwater, has greatly helped in understanding the recharge discharge mechanisms of the different aquifers. Precipitation along the highlands of an average of 600 mm/year is found to be depleted in its isotopic content of O¹⁸ = –7.0 to –7.26 and D = –32.2 to –33.28, whereas that of the Jordan Valley of 350 mm/year is highly enriched in isotopes with O¹⁸ = –4.06 and D = –14.5. The groundwater recharged along the highlands is depleted in isotopes (O¹⁸ = ~ –6, D = ~ –30), groundwater at the intermediate elevations is enriched (O¹⁸ = ~ –5, D = ~ –23) and that of the Jordan Valley aquifers containing meteoric water is highly enriched (O¹⁸ ~ –3.8, D = ~ –18). The deep aquifers in the Jordan Valley foothills are depleted in isotopes (O¹⁸ –18 = –6, D = –30) and resemble those of the highland aquifers. Only through using isotopes as a tool, were the sources of the different groundwater bodies and recharge and discharge mechanisms unambiguously explained. It was found that recharge takes place all over the study area and produces groundwater, which, from the highlands towards the Jordan Valley, shows increasing enrichment in isotopes. The highlands aquifer, with its groundwater depleted in isotopes, becomes confined towards the Jordan Valley; and, due to its confining pressure, leaks water upwards into the overlying aquifers causing their water to become less enriched in isotopes. Water depleted in its isotopic composition also seeps upward to the ground surface at the mountain foothills through faults and fissures.

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Resumen Las fuentes de recarga, los mecanismos de flujo y las áreas de descarga de los diferentes cuerpos de agua subterránea que subyacen el área de la cuenca del Río Yarmouk en Jordania, se han explicado de manera no ambigua únicamente mediante la aplicación de los isótopos como herramienta. A lo largo de la parte Jordana del área de la cuenca del Río Yarmouk el agua subterránea emerge de diferentes acuíferos con una variedad de tipos y composiciones, ya sea que provengan del mismo acuífero o de diferentes acuíferos. Los mecanismos convencionales de recarga/descarga, balances hídricos y variaciones químicas no han podido explicar las variaciones químicas y los diferentes tipos de aguas. La aplicación de herramientas de isótopos ambientales combinadas con los efectos de altitud derivados de variaciones topográficas (250 hasta 1,300 m s.n.m. en una distancia de 20 km) y tomando en consideración los efectos de re-evaporación en el empobrecimiento de isótopos y enriquecimiento del agua de lluvia han ayudado fuertemente en el entendimiento de los mecanismos de recarga/descarga de los diferentes acuíferos. La precipitación en el área varía de 600 mm/año, a lo largo de las tierras altas, a 350 mm/año en el área del Valle Jordán. El flujo de agua subterránea ocurre de las tierras altas hacia el Valle Jordán. El agua subterránea de las tierras altas está empobrecida en isótopos (O¹⁸ =~ –6, D =~ –30), el agua subterránea de elevaciones intermedias está enriquecida (O¹⁸ =~ –5, D =~ –23), y el agua de los acuíferos del Valle Jordan contiene agua meteórica que se encuentra altamente enriquecida (O¹⁸ =~ –3.8, D =~ –18). Los acuíferos profundos que se localizan al pie de las tierras altas del Valle Jordán están empobrecidos en isótopos (O¹⁸ =~ –6, D =~ –30) y son similares a los acuíferos de las tierras altas. Solo al aplicar los isótopos ambientales como herramienta pudo explicarse de manera inequívoca las fuentes de los diferentes cuerpos de agua subterránea y los mecanismos de recarga y descarga.

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Résumé Les zones de recharge, les mécanismes découlement et les zones de décharges des différentes masses deau souterraine sous le bassin versant de la rivière Yarmouk en Jordanie, étaient expliquées de manière ambiguë par les seuls outils isotopiques. Le long de la parti Jordanienne du bassin versant de la rivière Yarmouk leau souterraine provient de différents aquifères et se distinguent par leur type et leur composition chimique, selon que leau provient du même ou des différents aquifères. Les mécanismes conventionnels de recharge et de décharge, bilan hydrologique ne donnaient pas dexplications satisfaisantes concernant les variations chimiques et les différents types deau. En appliquant les isotopes environnementaux combinés aux effets de laltitude sur les variations des teneurs isotopiques (laltitude varie de 250 à 1,300 m sur une distance de 20 km.) et en prenant en considération les effets de ré-évaporation sur lappauvrissement et lenrichissement isotopique des eaux pluviales ont fortement contribués à une meilleure compréhension des mécanismes de recharge des différents aquifères. Les précipitations annuelles sont comprises entre 600 mm dans les zones en altitude et 350 mm dans la vallée de la Jordanie. Les écoulements de leau souterraine sont dirigés des zones en altitude vers la vallée de la Jordanie. Les eaux souterraines des zones en altitude sont isotopiquement appauvries (O¹⁸ = ~ –6, D = ~ –30), les eaux souterraines des zones de moyenne altitude sont enrichies (O¹⁸ = ~ –5, D = ~ –23) et les eaux de la vallée très enrichies (O¹⁸ ~ –3.8, D = ~ –18). Les aquifers profonds dans la vallée de la Jordanie sont appauvris (O¹⁸ –18 = –6, D = –30) et se confondent avec les eaux des zones situées en altitude. En appliquant uniquement les isotopes environnementaux comme des outils de compréhension des phénomènes hydrogéologiques, la source des différentes masses deau souterraines, les mécanismes de la recharge et de la décharge pourraient être expliqués de manière ambiguë.

     

Recent advances in the study of the Mesoproterozoic geochronology in the North China Craton

The Mesoproterozoic successions in the North China Craton (NCC) and the Qinling–Qilian–Kunlun Orogens have been revised using the new and highly reliable age data. Many Proterozoic strata in the Qinling–Qilian–Kunlun Orogens, such as the Qinling, Jinshuikou and Beidahe groups that have been ascribed to be Paleoproterozoic are actually of Mesoproterozoic Era. The most significant advances are recent geochronological studies on the Mesoproterozoic stratigraphy and magmatic events in the NCC. The boundary age between the Dahongyu Formation and the overlying Gaoyuzhuang Formation is well constrained to be ∼1600 Ma, corresponding to the boundary age between Statherian and Calymmian. The boundary between the Tieling Formation and the overlying Xiamaling Formation is best positioned at ∼1400 Ma, which is coeval with the boundary between Calymmian and Ectasian, and is about 400 Myrs older than the conventional value of 1000 Ma originally defined by the All China Commission of Stratigraphy. Hence the Jixianian System, including the Gaoyuzhuang, Yangzhuang, Wumishan, Hongshuizhuang and Tieling formations in ascending order, is comparable with the Calymmian System in the International Stratigraphic Chart. The lower boundary of the Changchengian System, the first system of the Mesoproterozoic in China Regional Stratigraphic Chart, also needs revision from the conventional 1800 Ma to ∼1650 Ma well constrained by the zircon U–Pb ages 1673 ± 10 Ma (LA-MC-ICP-MS) and 1669 ± 20 Ma (SHRIMP) of a granite-porphyry dike that was overlain unconformably by the basal conglomerate of the Changzhougou Formation, the first formation of the Changchengian System. Therefore, the earliest Mesoproterozoic sequence in the NCC represented by the Changchengian and Jixianian Systems in the Yanliao Aulacogen is identical to that of the Vindhyan Supergroup in Central Indian and the Riphean Series in Russia. On the other hand, a series of 1.8–1.6 Ga anorogenic magmatic records were well-preserved around the NCC, which marked the initial rifting of the Columbia Supercontinent in the NCC. The magmatic events can thus be subdivided into three phases with peaks at ca 1.77 Ga, ca 1.70 Ga and ca 1.63 Ga, respectively. In addition to 1.8–1.6 Ga magmatic events, some minor volcanic eruptions at ca 1.56 Ga and 1.44 Ga, and wide-spread bi-modal magmatic intrusions at 1.35–1.32 Ga have been recognized in the northern NCC, marking the continued rifting of the Columbia Supercontinent since ∼1.8 Ga.     

On the wind power potential in the northwest of the Yucatan Peninsula in Mexico

Wind power density, vertical velocity profiles, and other wind characteristics were established using a 51 m meteorological mast located very close to the shoreline on the northwest of the Yucatan peninsula in the Gulf of Mexico. A comparative study of the wind power density was carried out using information obtained between September 2010 and September 2011. The wind speed probability density function was found to be bimodal due to sea-land breezes, a characteristic that becomes less evident as the vertical distance to the ground increases. The distinction between these two wind regimes was used to fit the Weibull-Weibull curve using a linear least-squares criterion in the parameters. In addition, numerical simulations from a mesoscale model are in close agreement with measurements above z = 50 m (z is the vertical distance to the ground). This result suggests that some mesoscale simulations may serve as a preliminary wind energy assessment tool in coastal zones with extended low-lying areas.     

On folding-movements in the zone of the basement

The tectonic style of basement gneiss terrains is discussed and exemplified. The origin of migmatic domes and migmatite naps is explained as the result of secondary forces caused by horizontal flow in the infrastructure. The relationship between structural patterns in different dimensions is discussed.

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Zusammenfassung Der tektonische Stil der Gneisbildungen innerhalb der Sockel wird an Hand von Beispielen dargelegt. Die Entstehung der Migmatit-Kuppeln und -Decken wird als Ergebnis von Sekundärkräften durch horizontales Fließen im Unterbau erklärt. Das Verhältnis zwischen Bautypen verschiedener Größenordnungen wird besprochen.

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Résumé Plusieurs exemples de style des terrains gneissiques des socles sont présentés et discutés. L'origine des dômes et des nappes de migmatites est considérée comme le résultat de forces secondaires ayant comme conséquence des phénomènes d'écoulement dans l'infrastructure. Les rapports entre des types de structure d'ordre de grandeur différente sont discutés.

     

Context of the suboxic layer in the Arabian Sea

The setting of the Arabian Sea is reviewed in order to examine which of the circumstances causing large oxygen depletion in the ocean are responsible for the suboxic layer (concentrations < 0.1 ml 1⁻¹) in the northern thermocline there. The wind field forces circulations that restrict but do not exclude exchange with the south, and a recent box-model interpretation of trichlorofluoromethane measurements indicates a modest throughflow for the layer of about 5 × 10⁶m^{3s −1}.The associated oxygen-flux divergence is roughly consistent with biochemical determinations of local oxygen-consumption rates, both approaches giving values (3–6 pl 1⁻¹ s^τ-1) that are modest in comparison with estimates elsewhere in the world ocean. Despite the high mean-annual surface productivity in the region (nearly 1gCm⁻² day⁻¹), it seems plausible that too little of this particulate matter is consumed at thermocline depths to cause an inflated oxygen demand there. Since the layer is neither an isolated pool, nor a sluggish backwater, nor a conspicuous oxygen sink, the suboxic concentrations must be due (as earlier proposed) to the low concentration in the water entering the layer from the south. That depletion in turn seems due to moderate consumption as the water travels the very long trajectories from its zone of sea-surface renewal (Lats. 40–50°S). Although large seasonal variations are expected in both throughflow volume transport and surface productivity (suggesting comparable changes in consumption rate), the volume of the suboxic layer seems big enough to buffer the oxygen levels there against any very noticeable overall variability.     

Magnetostratigraphy of the Red Beds in the Hengyang Basin

Abstract This paper discusses the Cretaceous-Tertiary magnetic polarity sequence of the the Hengyang Basin on the basis of magnetostratigraphic study. The age of each stratigraphic unit has been determined with the magnetic polarity time scale combined with ³⁹Ar/⁴⁰Ar dating, thus providing evidence for determining the geological ages of different formations. The authors assign the age of the Dongjing Formation of the Hengyang Basin to Early Cretaceous, the Shenhuangshan Formation to Early-Late Cretaceous, the Daijiaping Formation to Late Cretaceous, and the Dongtang and Xialiushi formations to Palaeocene.     

Duration of the first biozone in the Siberian hypostratotype of the Vendian

The first biozone (Anabarites trisulcatus Assemblage Zone) in the Siberian hypostratotype of the Vendian (northwestern slope of the Olenek Uplift) is represented by the Turkut Formation of the Khorbusuonka Group and most of the Syhargalakh Formation of the Kessyusa Group. The lower part of the Kessyusa Group in some of the sections includes stratiform breccia coeval with the middle part of the Syhargalakh Formation. The breccia is shown to be the alteration product of tuff breccia, which is widely distributed in the region and occurs as diatremes. A U-Pb zircon date of 543.9 ± 0.24 Ma for tuff breccia provides the best constraint on the age of the boundary between the Anabarites trisulcatus and Purella antiqua Assemblage Zones. The first appearance of small skeletal fossils Cambrotubulus decurvatus (which define the base of the Anabarites trisulcatus Assemblage Zone) is 1.4 m above the lower boundary of the Turkut Formation. Ichnofabric in the underlying Khatyspyt Formation is globally distributed in the strata 553-551 million years old, always predating the first appearance of small skeletal fossils of the Anabarites trisulcatus Assemblage Zone. The base of the Anabarites trisulcatus Assemblage Zone is therefore younger than 553-551 Ma, whereas the duration of the assemblage zone does not exceed six million years.     

Proper motions of stars in the region of the Great Nebula in Orion

Six Tautenburg astrograph plates have been used to derive proper motions for 12 740 stars in the region of the Great Nebula in Orion. The Oricat catalog of proper motions and B and R photometry has been compiled, incorporating as well data from other published catalogs. The proper motions presented in different catalogs are compared. The Oricat catalog is useful for studies of features of the structure and kinematics of star clusters and groups.