测定震源深度的意义的初步讨论

在地震目录中，震源深度是地震学最基本的参数之一，然而它也是一个最不易测准的参数，ＰＤＥ报告中的震源深度以及ＵＳＧＳ和Ｈａｒｖａｒｄ大学的ＣＭＴ反演的矩心深度和利用宽频带波形的深度震相资料获得的震源深度各不相同，其含义也不同，而宽频带波形模拟得到又是一种破裂“核心”的深度。本文对不同测量手段的震源深度的不同物理意义做了初步的探讨。     

旋回年代学及其应用意义--华北地台中寒武世碳酸盐岩鲕滩高频旋回的年代学研究

华北地台中寒武世鲕滩碳酸盐岩沉积序列中发育大量分属4～7级的高频层序,依据旋回平均厚度的频率分布、不同级别旋回叠加样式和比率、沉积发育样式和跨越整个地台的可对比等特征认为,它们受控于地球轨道参数变动,是典型的米兰柯维奇旋回,其中Ⅳ、Ⅵ级分别对应于长、短偏心率旋回,时限分别为0.4Ma和0.1Ma.应用轨道旋回规则的周期间隔给出了中寒武世各级层序、地层阶和相应界面的年龄值.     

扬子地台西缘宁蒗泸沽湖地区志留系沉积旋回及锶、碳、氧同位素特征

本系统研究了扬子地台西缘宁蒗泸沽湖地区志留系沉积旋回及海相碳酸盐岩的锶、碳、氧同位素特征，并对同位素曲线演化规律与海平面变化和区域地壳运动的关系进行了探讨。研究结果表明，本区志留系除底部有少量细碎屑岩沉积外，主要为浅海潮坪相碳酸盐岩沉积，其锶、碳、氧同位素值变化范围分别是0．7093～0．7196、-1．28‰～2．74‰和-1．302‰～-10．721‰；平均值分别是0．7114、0．984‰和-7．810‰。由于受区域地壳隆升运动的影响，同位素组成和同位素演化规律与海平面变化的关系并不明显。     

华北陆台侏罗－白垩纪岩石地层基本特征

本文以鄂尔多斯地层分区和燕辽—阴山地层分区为例，论述了华北陆台侏罗－白垩纪稳定和复杂两种地质条件下岩石地层单位的岩石组合面貌，叠覆关系和区域变化，提出盆地世代划分依据，认为区域构造的演化发展是制约不同世代盆地空间分布格局的主要因素。概述了华北陆台侏罗－白垩纪各类岩石地层发育和空间展布格架以及不同成盆期含煤状况和生物群组合     

Triangular Configuration Tension Leg Platform behaviour under random sea wave loads

This study investigates the dynamic response of a Triangular Configuration Tension Leg Platform (TLP) under random sea wave loads. The random wave has been generated synthetically using the Monte-Carlo simulation with the Peirson–Moskowitz (P–M) spectrum. Diffraction effects and second-order wave forces have not been considered. The evaluation of hydrodynamic forces is carried out using the modified Morison equation with water particle kinematics evaluated using Airy's linear wave theory. Wave forces are taken to be acting in the surge degree-of-freedom. The effect of coupling of various structural degrees-of-freedom (surge, sway, heave, roll, pitch and yaw) on the dynamic response of the TLP under random wave loads is studied. Parametric studies for random waves with different H_s and T_z under the presence of current have also been carried out. For the orientation of the TLP, surge, heave and pitch degrees-of-freedom responses are influenced significantly. The surge power spectral density function (PSDF) indicates that the mean square response is affected by the amplification at the natural frequency of the surge degree-of-freedom and also at the peak frequency of the wave loading. The PSDF of the heave response shows higher peak values near the surge frequency and near the peak frequency of the wave loading. Surge response, therefore, influences heave response to the maximum. Variable submergence seems to be a major source of nonlinearity and significantly enhances the responses in surge, heave and pitch degrees-of-freedom. In the presence of current, the response behaviour of the TLP is altered significantly introducing a non-zero mean response in all degrees-of-freedom.     

Late Devonian and Triassic basalts from the southern continental margin of the East European Platform,tracers of a single heterogeneous lithospheric mantle source

In Late Devonian and Early-to-Late Triassic times, the southern continental margin of the Eastern European Platform was the site of a basaltic volcanism in the Donbas and Fore-Caucasus areas respectively. Both volcanic piles rest unconformably upon Paleoproterozoic and Late Paleozoic units respectively, and emplaced during continental rifting periods some 600 km away from expected locations of active oceanic subduction zones. This paper reports a comparative geochemical study of the basaltic rocks, and views them as the best tracers of the involved mantle below the Eastern European Platform. The Late Devonian alkaline basic rocks differ from the calc-alkaline Triassic basic rocks by their higher alkali-silica ratio, their higher TiO₂, K₂O, P₂O₅ and FeO contents, their higher trace element contents, a higher degree of fractionation between the most and the least incompatible elements and the absence of Ta-Nb negative anomalies. These general features, clearly distinct from those of partial melting and fractional crystallization, are due to mantle source effects. With similar Nd and Sr isotopic signatures indicating mantle-crust mixing, both suites would originate from the melting of a same but heterogeneous continental mantle lithosphere (refertilized depleted mantle). Accordingly the Nd model ages, the youngest major event associated with mantle metasomatism occurred during Early Neoproterozoic times (∼650Ma).     

Space-time analysis of the relative local secular variations of the geomagnetic field (1966–2005) along the Zgorzelec-Wiżajny profile

The Zgorzelec-Wiżajny profile cuts through the main European geotectonic units of the Palaeozoic Western and Central European Platform and the East European Craton, including the connecting Trans-European Suture Zone. The paper summarises 40 years of research on geomagnetic secular variations along the Zgorzelec-Wiżajny profile since 1966. It discusses methods of processing measurement records and presenting their results. The latter are presented against the background of the local geology and the crustal deep magnetic structure data. The hitherto method of variation analysis was modified to address a new trend in the geomagnetic secular variations that has emerged in the East European Craton during the last five years (2001–2005).     

金伯利岩中铬的相态及找矿地球化学信息--以华北地台为例

对华北地台金伯利岩地球化学找矿信息提取表明:铬是判别岩体含矿与否的重要指示元素。铬的相态分属尖晶石、镁铝榴石和镁钛铁矿三类矿物族。研究得出,各矿物指示含矿的化学成分标型为:铬尖晶石Cr2O3>53%,Al2O3<11%,MgO<12%,Cr#值大于0 7。镁铝榴石Cr2O3>5%,Al2O3<19%,Cr#值大于0 2。镁钛铁矿Cr2O3>1%,MgO>11%。由于铬尖晶石相对稳定,其化学组成为提取金伯利岩找矿信息的首选对象。     

华北地台石炭系—二叠系界线的腕足动物标志

依据现代地层学理论,年代地层界线应具有全球一致性或近一致性。根据华北地台石炭纪、二叠纪地层特点,笔者主张在华北地台以Pseudoschwagerina(s.s)带(确切地说是最早出现该带特征化石层位)底作为二叠纪的开始。本文通过对华北地台若干典型地点界线附近的腕足动物化石进行系统研究,认为腕足动物面貌在界线附近有清晰的变化,与界线标志(竹蜓)属有一定的对应关系,以此作为界线的辅助标志具有区域性的普遍意义。     

重视和加强我省金刚石矿普查和找矿

我省开展金刚石普查和找矿的重点地区是大理海东-马关八寨新生代基性-超基性火山角烁岩筒分布地区。其次是腾冲新近纪及第四纪火山群分布地区及腾冲-瑞丽沿瑞丽江两岸冲积层、冲积阶地沉积分布区;第三是姚安及镇源新生代火山岩-次火山喷发侵入及煌斑岩分布区。