北京泥石流暴雨基本特征

本文分析了北京地区泥石流暴雨的时空分布特征,并指出,泥石流暴雨主要是盛夏经向环流背景下的华北暴雨过程;局地大气有明显潜在不稳定,降水强度达60mm/h以上;泥石流暴雨落区是位于地面中尺度能量锋区、能量锋锋生和强水汽辐合的重叠区域.     

微气象观测数据采集系统

微气象观测数据采集系统是微气象自动观测网的子系统。该子系统包括塔站、辐射站的数据采集以及塔站向中心站的数据传输。本文介绍了这两部分的硬件组成及软件编制,并从原理上描述了研制温度传感器时采用的“准噪声测量消噪法”这一特殊技术。     

中国大陆科学钻探井区深部构造地震波反射特征

中国大陆科学钻探（CCSD）井位于苏鲁超高压变质带南部的东海县境内。井区地震勘探是钻探综合研究项目之一,该项目采用世界先进的数字地震仪和三分量数字检波器,对line 1线剖面进行了测量。依据地震勘探成果和CCSD岩心资料,通过对该地震剖面深部构造反射特征的详细分析,发现该区深部反射构造具有明显的三单元层结构。第一单元层,约在11 km内,出现6个强反射带,产状基本一致,倾向SE,倾角28°。岩心资料和VSP勘探资料证实前4个反射带主要是榴辉岩带和韧性剪切带的反射,榴辉岩带与片麻岩成不规则层状相间分布。第二单元层,约在11~30 km,有4个比较清楚的反射带,反射弱,连续性差,带内分布有不规则的弱反射。其产状也基本一致,倾角很小,比较平缓,由浅到深,倾向逐渐变为NW,它与第一单元层为角度不整合接触关系。第三单元层,约在30 km以下深度,其顶部出现了比较强的反射带,连续性较好,产状较平缓,倾向NW;而在顶部反射带以下,则反射均匀,没有不规则反射带。据上述反射特征,结合该区地质背景,推测第一单元层为中朝与扬子板块俯冲带的折返地壳层,第二单元层为扬子克拉通层,主要为变质岩层,第三单元层为上地幔层,其顶部的反射为莫霍面的反射。     

内蒙古双尖子山银多金属矿床侏罗纪成矿的年代学证据及其找矿意义

双尖子山银多金属矿床是近年来在大兴安岭南段发现的一超大型规模矿床,其银资源量为2.6×10~4t,锌3.3Mt,铅1.1Mt,但矿床的成矿时代目前还未得到精确的厘定,这制约了对矿床成因、区域成矿规律及找矿方向的认识。本文在详细的矿床地质特征调查基础上,识别出了与双尖子山银多金属矿床成矿有关的斑状花岗岩。该岩体内部发育浸染状方铅矿和矿化的隐爆角砾岩,岩体外接触带硅化、绿泥石化及银铅锌矿化强烈,这指示双尖子山矿床的银铅锌矿化和蚀变作用与斑状花岗岩的侵入作用密切相关。鉴于此,作者对斑状花岗岩的锆石进行了LA-MC-ICP-MS U-Pb定年,获得该岩体16颗锆石的~(206)Pb/~(238)U加权平均年龄为159.3±2.3Ma,该年龄可近似代表双尖子山矿床的成矿年龄。上述结果表明,双尖子山银多金属矿床为与晚侏罗世斑状花岗岩有关的热液脉型矿床。尽管精确的成矿年龄数据已揭示大兴安岭南段存在侏罗纪成矿事件,但大多数的观点认为早白垩世(~135Ma)是大兴安岭南段内生金属矿床成矿作用的峰期,因此忽视了侏罗纪成矿事件的重要性。鉴于双尖子山矿床银、铅和锌的资源量均已达超大型矿床规模,作者认为,大兴安岭南段侏罗纪成矿作用的强度可能并不亚于早白垩世,应在今后的找矿勘察中得到足够的重视。     

Landslide Hazard and Risk Assessment on the Northern Slope of Mt. Changbai, China

Landslide hazard and risk assessment on the northern slope of Mt. Changbai, a well-known tourist attraction near the North Korean-Chinese border, are assessed. This study is divided into two parts, namely, landslide hazard zonation and risk assessment. The 1992 Anbalagan and Singh method of landslide hazard zonation （LHZ） was modified and used in this area. In this way, an Associative Analysis Method was used in representative areas to get a measure for controlling factors （slope gradient, relative relief, vegetation, geology, discontinuity development, weak layer thickness and ground water）. For the membership degree of factor to slope failure, the middle range of limited values was used to calculate LHZ. Based on an estimation of the potential damage from slope failure, a reasonable risk assessment map was obtained using the relationship of potential damage and probable hazard to aid future planning and prediction and to avert loss of life.     

40Ar(40Ar＊＋40ArE)、39Ar释气特征与过剩氩的甄别及年代学意义

对具有不同地质历史背景的3类⁴⁰Ar/³⁹Ar法样品中的⁴⁰Ar和³⁹Ar释出特征进行对比,研究结果表明,⁴⁰Ar/³⁹Ar法样品中的⁴⁰Ar、³⁹Ar释气曲线主要表现为以下3种形式:完全重合型、过剩氩型和不规则型。当⁴⁰Ar与³⁹Ar释气曲线呈完全重合型时,⁴⁰Ar/³⁹Ar法全熔年龄代表了岩体的形成年龄;当⁴⁰Ar、³⁹Ar释气曲线是过剩氩型时,⁴⁰Ar/³⁹Ar法全熔年龄则大于岩体的形成年龄;当⁴⁰Ar与³⁹Ar释气曲线呈不规则型时,表明样品中的放射成固氩(⁴⁰Ar^*)发生了丢失,其全熔年龄一般较岩体的形成年龄小。对于⁴⁰Ar、³⁹Ar释气曲线呈过剩氩型的样品,⁴⁰Ar/³⁹Ar法年龄谱通常呈马鞍形,且马鞍形年龄谱的底部年龄一般都具有地质意义,代表了岩体的形成年龄。对于⁴⁰Ar、³⁹Ar释气曲线呈不规则型的样品,对其年龄谱的解释应持谨慎态度。     

Preliminary site classification of free-field strong motion stations based on Wenchuan earthquake records

During the great Wenchuan earthquake, about 460 permanent free-field stations in National Strong Motion Observation Network System (NSMONS) of China captured the main shock acceleration records. These records can be applied to site effect analyses, and then the site classification of those permanent stations can be carried out firstly, which will served as the fundamental information for further research. In this paper, the site of near-fault stations is classified by horizontal-to-vertical spectral ratio (...     

Thermodynamic analysis of ore-forming conditions and sulfur isotopic systematics of Dachang ore field

On the basis of ore-forming periods and stages of the Dachang ore field, the pH and conditions and the S isotopic systematics during ore formation have been thcrmodynamically treated in this paper. Calculations show a progressively decreased pH, an increased oxidation regime and an intensified activity of sulfur from the early to the late stage. Owing to the unreliability of inferring the S source from δ³⁴S_min, has been calculated using the Ohmoto’s model. Results indicate that the δ³⁴ _min frequency distribution is more concentrated than that of δ³⁴S_min and the peak value shifts to negative region by 2.5%. The sulfur in the whole ore field seems to be of multiple source, i.e., different deposits have their own S sources. But the S isotopic composition pertaining to each stage is nearly constant, suggesting that the ore-forming system be open to sulfur and the supply of sulfur be sufficient. The conclusions deduced from calculations are supported by many lines of geological evidence.     

红外光谱用于粘土矿物羟基取向的测定

粘土矿物羟基取向的问题，为许多学者所关注。本文利用羟基对红外光的敏感性，据吸收强度与入射光电矢量和振动电偶极矩的关系以及片状粘土矿物定向羟基的分布特征建立羟基相对于（００１）面取向的电矩圆锥模型，由此模型推导建立了一套测定羟基取向的方法。此方法的理论依据是量子化学，但又避开了复杂的量子化学计算过程。测定方法既简单又经济，具有较广泛的应用范围，已成功地测定了部分粘土矿物羟基取向。     

汶川Ms 8.0级地震强震记录所揭示的地震断层特征分析

基于2008年5月12日汶川Ms8.0级地震的强震台站记录,对比发震断层两侧的峰值加速度与地表破裂带上同震位移的分布特点,探讨了地震动强度分布特征与地表破裂位移分布之间的相关关系。分析近断层典型台站的强震动记录时程特征,获得了强地震动记录中所包含的断层破裂过程和破裂习性信息,从强震观测记录的角度进一步证实了汶川地震主震的多次破裂特征。结果表明,汶川地震主震至少包含了4次地震破裂事件,最主要的前两次破裂事件分别对应映秀—北川断裂段和北川—南坝断裂段的破裂过程,后两次破裂事件释放的能量相对较小,应该是第二次破裂过程触发局部次级破裂所引起的。此外,垂直于断层的峰值加速度剖面揭示的发震断层的高倾角逆冲特性,与地震地质调查和小震精定位等确定的相应结果是一致的。