黑龙江多宝山地区中侏罗世火山岩的发现及其对蒙古-鄂霍茨克洋闭合范围的限定

黑龙江省多宝山地区位于中亚造山带东段、兴安地块东南缘,发育大面积早—中侏罗世侵入岩,但至今未发现同时代的火山岩。在多宝山地区首次发现了同时期的火山岩,并确定为一套英安岩、流纹岩和粗面岩组合。为进一步明确其形成时代及反映的构造意义,对出露的火山岩开展了锆石U-Pb测年和岩石地球化学分析。锆石U-Pb年龄显示,火山岩形成时代为167.1~169.3 Ma,为中侏罗世喷发成岩。火山岩具有富碱（Na2O+K2O=3.70%~7.66%）、富铝（Al2O3=11.42%~19.00%）的特征,属于高钾钙碱性、过铝质（A/CNK=1.08~3.73）岩石。稀土元素呈轻稀土元素富集、重稀土元素亏损的右倾特征,具负Eu异常（δEu=0.53~0.79）。微量元素显示富集Rb、Ba、K、Th、U、Pb,亏损Nb、Ta、Ti、P、Sr。总体显示,该中侏罗世火山岩起源于新生陆壳物质的部分熔融。根据Ta-Yb、Nb-Y构造环境判别图解,该期火山岩形成于挤压背景环境。结合区域构造背景及其演化特征,综合认为,中侏罗世火山岩应是蒙古-鄂霍茨克洋闭合过程导致的陆-陆碰撞作用的产物。闭合导致的陆陆碰撞作用已影响到兴安地块东南缘。     

闽江下游河口区及其邻近海域表层沉积物的地球化学特征

闽江是我国东南沿海地区最大的河流,年径流量位居全国第3位。对采自闽江下游及闽江口邻近海域的沉积物分析表明,沉积物以SiO2含量高、Al2O3等组分的含量较低为特点。样品中碎屑矿物主要是石英、斜长石、正长石、白云母和绿泥石。从SiO2看,闽江沉积物与石英砂岩的成分较接近,不同于浅海沉积物,与黄河、长江、珠江三大河流也有较大差异。地形地貌及水动力条件控制沉积物粒度的分布,粒度又控制沉积物的组分分布。总体表现为,由陆向海,呈SiO2逐渐降低、Al2O3等组分升高的趋势。人类活动对闽侯段及闽江北港到马江段河流沉积物的影响也不容忽视。闽江流域的源区特征、水动力条件和搬运距离以及物理化学条件与生物作用对沉积物的改造,使得沉积物组分间具有良好的相关性。     

多仿生机器人协同编队捕获策略

机器人的协同编队问题是一个综合性的研究课题,主要包括编队策略及路径规划 2 个阶段。针对单一机器人在未知水下环境中执行任务时能源受限等问题,提出一种基于改进蚁群算法的安全域协商捕捉策略,以解决多仿生机器人系统水下环境中对目标的协同编队捕获问题。机器人随机搜索过程中发现目标后, 利用安全域协商策略,实现目标机器人周围捕获点的分配;采用改进的蚁群算法实现编队过程的路径规划和自适应避障。在不同大小的障碍物环境中进行仿真实验,并与经典的路径规划算法进行对比,实验结果表明： 所提出的策略能够使机器人在复杂的水下障碍物环境中完成高效的协作编队捕捉任务,具备有效性。     

RFI Test Observations at a Candidate Ska Site in China

Radio frequency interference (RFI) test observations were carried out at one of the candidate Square Kilometre Array (SKA) sites in Guizhou province, following the “RFI Measurement Protocol for Candidate SKA Sites” (hereafter RFI protocol). All data (raw and calibrated) are preserved in some suitable format, such as that set by the international RFI working group of the Site Evaluation and Selection Committee (SESC). An RFI test in December 2003 was performed according to Mode 1 of the RFI Protocol, in order to identify technical difficulties which might arise during a co-ordinated RFI measurement campaign over a period of 1 year. In this paper we describe the current equipment, observational technique and data presentation. The preliminary results demonstrate that the RFI situation at Dawodang depression in Guizhou province makes it quite a promising location for the proposed SKA. Furthermore, the first session of the RFI monitoring program, which was made in May 2004, showed that a complete RFI measurement including both modes 1 and 2 of the RFI Protocol would take about 2 weeks. The possible ways to minimize some limitations of the current equipment are also discussed, which will enable us to meet the RFI protocol.     

二连盆地赛汉塔拉凹陷腾二段低熟油地球化学特征和油源对比

赛汉塔拉凹陷位于二连盆地腾格尔坳陷西部,是二连盆地低熟油分布区.采用有机地球化学和生物标志物分析方法,对赛汉塔拉凹陷下白垩统腾二段低熟原油和油砂样品进行了地球化学特征和油源对比研究.赛汉塔拉凹陷腾二段低熟油具有饱和烃含量相对较低、非烃和沥青质含量相对较高的族组成特征,正构烷烃分布以前峰型为主,主峰碳为C21或C23,P...     

一种非平稳噪声背景下的线谱相干检测方法

舰艇目标航行时往往向水中辐射大量线状谱结构的声波信号,线谱信号检测对舰艇目标的被动探测至关重要.实际水下环境噪声常表现为时域非平稳噪声,常规离散傅里叶变换类线谱检测方法时域积分时,不可避免会引入非平稳噪声背景中出现的短时强干扰噪声,使积分结果中线谱信噪比大幅降低,线谱检测性能急剧恶化.为解决上述问题,对分段离散傅里叶变...     

青藏高原东缘玛曲沙化高寒草地土壤理化性质北大核心CSCD

沙漠化是青藏高原东缘高寒草地退化的重要指征,土壤理化性质是反映草地沙化过程的重要特征参数。以青藏高原东缘玛曲县为例,分析天然草地和轻度、中度、重度、极重度沙化草地土壤粒度组成、温湿度、有机碳和养分等因子的差异特征,旨在阐明高寒草地沙化过程中土壤理化性质的变化。结果表明:草地土壤黏土和粉沙含量随着沙化的发展显著减小,而沙颗粒含量(细沙和中沙)随着沙化程度的增加而增大;5—8月生长季,重度沙化土壤相比轻度沙化土壤温度明显升高,土壤含水量明显降低;随着沙化程度的增加,土壤有机碳含量显著降低,轻度沙化减少50%以上,中度至极重度沙化草地减少91%—99%;土壤全氮(TN)、碱解氮(AN)、全磷(TP)、有效磷(AP)等含量在轻度以上沙化草地中显著降低,而全钾(TK)变化不明显,速效钾(AK)仅在中度至极重度沙化草地中含量降低。高寒草地沙化进程中,随着植被盖度的不断降低,表层细颗粒物逐渐风蚀、土壤养分流失,粗颗粒物质保留下来,土壤含水量降低,在风的分选作用下不断堆积形成流动性沙丘。     

Crustal structure in and around the region of the 1995 Kobe Earthquake deduced from a wide-angle and refraction seismic exploration

Abstract The 1995 Kobe (Hyogo-ken Nanbu) earthquake (M_JMA 7.2, M_w 6.9) occurred on Jan. 17, 1995, at a depth of 17 km, beneath the areas of southern part of Hyogo prefecture and Awaji Island. To investigate P-wave velocity distribution and seismological characteristics in the aftershock area of this great earthquake, a wide-angle and refraction seismic exploration was carried out by the Research Group for Explosion Seismology (RGES) . The profile including 6 shot points and 205 observations was 135 km in length, extending from Keihoku, Northern Kyoto prefecture, through Kobe, to Seidan on Awaji Island. The charge of each shot was 350–700 kg. The P-wave velocity structure model showed a complicated sedimentary layer which is shallower than 2.5 km, a 2.5 km-thick basement layer whose velocity is 5.5 km/s, overlying the crystalline upper crust, and the boundary between the upper and lower crust.
Almost all aftershock hypocenters were located in the upper crust. However, the structure model suggests that the hypocenters of the main shock and some aftershock clusters were situated deeper than the boundary between the upper and lower crust. We found that the P-velocity in the upper crust beneath the northern part of Awaji Island is 5.64 km/s which is 3% lower than that of the surrounding area. The low-velocity zone coincides with the region where the high stress moment release was observed.     

湖南黄沙坪矽卡岩矿物学特征及地质意义

湘南黄沙坪多金属矿床位于南岭构造带中段北缘,属于矽卡岩型矿床。根据矽卡岩产出状态、矿物共生组合及岩相学特征,从早期到晚期可划分为矽卡岩阶段、退化蚀变阶段、早期硫化物阶段和晚期硫化物阶段。矽卡岩矿物主要为石榴石、辉石、符山石等;金属矿物主要为白钨矿、辉钼矿、磁铁矿、方铅矿、闪锌矿等。电子探针分析结果表明,石榴石为钙铝-钙铁榴石系列,从早期到晚期,石榴石具有由钙铝榴石逐渐向钙铁榴石演化的规律。且钙铁榴石普遍发育震荡环带,而环带结构可持续记录钙铁榴石物理化学条件演化的过程。同时两种石榴石中均含Sn的成分,但钙铁榴石中Sn的含量明显高于钙铝榴石。辉石为透辉石-钙铁辉石系列,而且由内接触带向外接触带,辉石中Fe和Mn的含量有逐渐升高的趋势。矽卡岩矿物学特征及矿物成分的变化表明,成矿流体至少经历了两次氧化还原性质的转变。矽卡岩矿物学特征,对W(Sn) Mo Bi等多金属的矿化具有重要的地质指示意义。     

基于核酸适配体功能化石墨纳米颗粒荧光探针的17β-雌二醇快速检测方法

为构建一种能够简单、快速、特异性检测复杂环境水体中雌激素污染的方法,利用石墨纳米颗粒作为荧光淬灭剂、核酸适配体作为识别元素、1-芘丁酸N-羟基琥珀酰亚胺酯作为异型双功能交联剂,构建了一种新型纳米荧光探针;并探究了构建荧光探针时核酸适配体初始投加量和荧光探针投加量对雌二醇检测的影响及最佳实验条件下检测雌二醇的效果和特异性。实验结果表明：核酸适配体能成功修饰在石墨纳米颗粒表面形成的稳定荧光探针;构建荧光探针时核酸适配体的最佳初始投加量为1.0 μmol/L;检测雌二醇时,荧光探针的最佳投加量为4 μg/mL;最佳实验条件下,相对荧光强度与雌二醇的质量浓度在50~800 ng/mL范围内成正比,最低检测限为34.5 ng/mL,且该荧光探针能实现对雌二醇的简单、快速、特异性检测。