地震监测中的电阻率层析技术

将电阻率层析技术应用于地震监测,由视电阻率值重建出介质的真电阻率图像,取得了较好效果.在宝坻台和昌黎台设立的两个试验点上于1998年4月14日ML5.0和ML4.4唐山两次地震前的6天左右层析图像出现了明显的异常变化:宝坻台的电阻率图像一改通常的在平稳背景上叠加小量随机变化的特点,出现了一种有序性特征的新图样;昌黎台也出现了反差加大、高低阻区集中分布的有序性特征.上述异常图样均在震后消失.层析图像在震前出现的熵值降低可能是这次地震活动的前兆.地层导电结构和孔隙度的变化,是引起电阻率异常的直接原因.研究表明,常规的单一极距的视电阻率测量之所以对真电阻率的变化不敏感且丧失空间分辨能力,是由于该物理量同时具有积分值和位函数这两个固有特征所决定的.在地震监测中,改造现行观测系统,引入层析成像,是发展技术的方向.     

井间层析成像的最大熵方法

本文研究最大熵图像重建用于地球物理学中井间观测问题,着重研究了剑桥算法.对算法中拉格朗日乘子的确定给出了新方法;解决了算法的收敛条件和收敛范围;提出了减少算法计算量和内存量的方法,并编制了实用程序MECT.通过数值模型的研究,最后重建出了某矿区的剖图,与BPT和ART方法的结果进行了比较.证明最大熵图像重建法的优越性在于能有效地抑制噪声,分辨率高,边界影响程度小.若改善观测条件,将提高最大熵成像法的分辨率.     

Identification of different types of harzburgites and their lithofacies zonation in ophiolites : Evidence from the special geological survey of Dingqing ophioliteSCIEI北大核心CSCD

The ophiolite is an ancient oceanic lithosphere remnant emplaced on the continent, and it is the direct carrier to record the ancient ocean basin from formation to demise. Therefore, the study of ophiolite can provide strong evidence for revealing and restoring the tectonic system and evolution history of ancient oceans and continents. The field geological survey and mapping for ophiolite are the basis for the research on the petrogenesis of chromite, peridotite and oceanic crust units. According to the characteristics of mineral composition, structure and mineral chemistry of harzburgites in Dingqing ophiolite, it is divided into massive, inhomogeneous, pyroxene-oriented, spherulitic and mylonitized harzburgite. Five types of harzburgite were discovered for the first time in the Laraka survey area through 1 : 50000 special geological mapping, and there were obvious lithofacies zoning characteristics in the area of five types of harzburgites. The massive harzburgite lithofacies belts are distributed in the middle of the Laraka survey area, and the inhomogeneous harzburgite lithofacies appear symmetrically on both sides. A small amount of pyroxene-oriented harzburgite lithofacies is distributed in the interior or edge of massive harzburgite facies belt in a lenticular shape, and the production of a very small amount of spheroidal harzburgite is related to basic intrusive rocks. The mylonitized harzburgite lithofacies belt is a slender strip outcropping on the southern margin of the peridotite massif. There is a certain spatial correlation between the distribution, type and scale of chromite deposits or mineralization points and the peridotite facies zoning. More than 20 high -chromium -type chromite deposits are distributed in the inhomogeneous harzburgite, but the massive harzburgite lithofacies have few chromite deposits or mineralizations. The A -A' peridotite lithofacies measured profile in the Lallaka survey area and its corresponding mineral chemical profile further confirm the existence of lithofacies zoning. Cr-spinels in different types of harzburgites show different mineral chemical characteristics. The Cr-# of Cr-spinel in massive harzburgite, in inhomogeneous harzburgite, in pyroxene oriented harzburgite and in the spheroidal harzburgite is 65. 59 similar to 69. 37, 49. 99 similar to 57. 86, 75.19 similar to 85.24 and 57.66 similar to 80.04, respectively. The Cr# of Cr-spinel in inhomogeneous -> massive -> pyroxene-oriented harzburgite gradually increases from 49. 99 to 85.24, indicating that these harzburgite have experienced 23% similar to 43% medium -high partially melted. The mineral chemistry data of massive and pyroxene-oriented harzburgite in the mineral chemistry diagram both fall in the fore -arc peridotite environment, and the inhomogeneous harzburgite falls in the overlapping area of deep-sea and fore -arc peridotite. The Fo of olivine in the spherulite harzburgite is 86.43% similar to 87.05%, and the En of orthopyroxene is 84.66% similar to 85.78%, which are bronzite, indicating magmatic origin. The mylonitized harzburgite is the result of tectonic emplacement of the massif. Different types of peridotite and their lithofacies zoning were identified in the Dingqing ophiolite, which provides a new idea for us to deeply study the multi -stage magmatism of the oceanic lithosphere and the genesis of peridotite and chromite.     

元素俘获能谱在深层致密储层评价中的应用:以松科2井为例

松辽盆地沙河子组存在多段气测异常,显示了该地层具有致密气勘探潜力,但研究区深层致密储层非均质性强、厚度薄、互层发育且类型多样。在松科2井常规测井曲线分析基础上,利用元素俘获能谱精细反演矿物组分含量,对地层岩性进行准确识别,并建立了元素交汇图识别出5种类型储层。结合岩石物理实验资料,得到地层的变骨架孔隙度、脆性指数、有机碳含量等储层评价参数,依据气测资料及综合评价指数将储层分为三大类。研究结果表明:沙河子组地层(3 730~4 500 m)孔隙度主要分布在5%~9%,脆性指数主要分布在45%~60%,临近烃源岩TOC含量普遍较高且累计厚度较大,识别出3 798 ~3 831 m、3 950~3 990 m、4 150~4 200 m是具有勘探开发潜力的有利致密气层段。利用元素俘获能谱评价致密气储层结果准确,能为深层致密气储层优选及压裂改造提供参考依据。     

人工冻结法协同竖井淋洗原位修复污染黏性土的可行性试验

针对黏性土淋洗效率低下问题,提出了人工冻结法协同竖井淋洗原位修复污染土壤的方法.通过垂直布设冻结板,水平冻结土体的竖井淋洗模型试验,研究冻结过程中土中温度场、水分场分布及融解期的排水方式,探讨了人工冻结法协同竖井淋洗原位修复污染黏性土的可行性.研究表明:利用人工冻结法,使未冻土侧水分或淋洗液在"冻吸力"作用下向冻结锋面迁移,然后利用塑料排水板完成融化水(淋出液)与土壤分离的方案可行,能够解决抽液过程中抽液井和注液井之间土体容易形成渗流通道出现优先流,导致淋洗效率低下的问题.在分步冻结模式下,未冻土侧水分在"冻吸力"作用下向冻土侧迁移,冻结-吸水量为22.78 L,融化-排水量为24.60 L;经历一次冻融循环后,相同冻结模式下冻结-吸水量达到30.40 L,在负压抽吸模式下排水量达到44.21 L.该研究结果为今后原位修复污染黏性土提供了新的思路.     

流域水文与地貌特征关系研究的回顾与展望

揭示水文过程与地貌过程相互作用的定量关系是水文学家长期追求的目标,也是新国际水文10年PUB计划的重要内容之一。论述了建立这两者定量关系的统计综合途径和具有物理基础途径的思路方法与主要特点,述评一个多世纪以来,尤其是近30年来国外学者在这方面所作的研究,介绍了作者近年来在这方面所做的工作。     

关于构建矿山三维GIS的思考

根据煤矿生产的实际情况，分析了建立煤矿三维GIS的必要性，并针对当前GIS发展的状况，提出了建立矿山三维GIS的思路。     

地震-重力联合反演中的非块状一致性模型

完善地震-重力联合反演的一个重要措施是建立一致性模型.本文按照地震测深的常用办法,采用二维四边形非块状模型,通过网格节点的密度值来刻划连续性或间断性的物性分布.四边形单元内部的密度分布为双线性函数,本文给出了重力异常的严谨解析式.计算中可采用模型分解技术,将四边形化为矩形与直角三角形的组合,简化程序设计.算法的实施有两种途径:独立单元法和整体模型法.在联合反演的数值模拟中,还推出了剪切模量μ模型以及纵波速度V_P,与密度ρ的分布关系.     

吉林南部通化地区古元古代辽吉花岗岩的侵位年代与形成构造背景

辽吉南部古元古代花岗岩极为发育,其中最著名的是具有条痕状构造的正长花岗岩,俗称辽吉花岗岩。因该花岗岩具有条带状、条痕状和似层状构造特征,而被前人认为是由太古宙或元古宙沉积地层经变质变形作用形成,或是交代成因的混合岩。本文通过对分布于吉林南部通化地区辽吉花岗岩的典型代表一钱桌沟岩体的详实野外地质填图及地球化学研究,确定该岩体属岩浆成因的“A”型花岗岩,其岩浆侵位年龄为2160Ma左右。结合目前获得的该区古元古代地层的碎屑锆石年龄,本文认为辽吉花岗岩是辽吉地区古元古代地层沉积的基底岩石,是地层沉积之前地壳拉张作用的结果,属于一种非造山型花岗岩。     

PETROGENETIC AND METALLOGENETIC AGES FOR THE PORPHYRY COPPER DEPOSITS IN THE GANGDISE METALLOGENIC BELT IN SOUTHERN TIBET

In the Gangdise area in the south of Qinghai-Tibet Plateau, a set of calc-alkalinevolcanics-granitic intrusives, which were resulted from subduction of neo-Tethys Ocean at YurlungZangbo oceanic plate beneath Lahsa block in Cretaceous-Palaeogene and subsequentarc-continental collision, were exposed, together with a set of shoshonitic volcanics and hypabyssalporphyries developed in the later stage (Bureau of Geology and Mineral Resources of TibetAutonomous Region, 1993; Li, 2002; Zhao et …