基于航空重、磁数据的南黄海海相地层分布特征识别

基于南黄海海域实测高精度航空重、磁数据,结合航空重、磁场及物性特征,通过平均对数功率谱分析匹配滤波方法技术,对南黄海海相地层界面起伏引起的重、磁异常特征进行分离、提取,采用切线法和外奎尔法计算海相地层界面的深度,经地质和地球物理综合解释,编制了南黄海海相地层底界面、顶界面深度图及海相地层厚度图。在此基础上,初步划分了南黄海海相地层构造单元,探讨了南黄海海相地层的分布特征。苏北—南黄海坳陷区的中部坳陷和南部坳陷均发育在强磁性基底之上,构造变形较弱,海相地层保存完整,埋藏浅,厚度为4~8 km,是南黄海地区具有较大资源潜力的油气勘探区。     

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利用GRACE时变重力场探测2010年中国西南干旱陆地水储量变化

GRACE(Gravity Recovery And Climate Experiment)卫星计划为监测陆地水储量变化提供了有效技术手段.本文采用2003至2010年共计8年的GRACE月重力场模型反演中国西南区域陆地水储量变化,与GLDAS(Global Land Data Assimilation System)全球水文模型进行对比分析,其结果在时空分布上均符合较好,同时在2009年秋至2010年春该区域陆地水储量均呈现明显减少,与该时段云贵川三省的干旱事件相一致;比较分析了2009年秋至2010年春GRACE反演陆地水储量变化与TRMM(Tropical Rainfall Measuring Mission)合成数据计算的月降雨量的时空分布,两组结果均与西南干旱事件对应时段与区域十分吻合;对近8年的陆地水储量变化与月降雨量数据进行相关性分析,其结果表明陆地水储量变化与降雨量强相关,即降雨量是导致陆地水储量变化的主要因素;分析该区域地表温度变化,结果显示2009年9月至2010年3月地表温度均比历史同期高,地表温度的升高加剧了陆地水储量的减少.     

沉积学研究热点与进展:第32届国际沉积学会议综述*

第32届国际沉积学会议(32nd IAS Meeting of Sedimentology)于2016年5月23—25日在摩洛哥马拉喀什召开, 来自43个国家和地区的360余名学者参加了本次会议。综述研究表明, 会议研究热点为陆相沉积环境、浅水沉积与滨岸潮汐、深水沉积与事件沉积、碳酸盐与化学岩沉积、沉积过程与盆地分析、成岩作用与油气储集层等研究领域。会议主要研究进展表现为: 波浪再悬浮作用(wave resuspension)与异重流(hyperpycnal flows)是陆架边缘斜坡快速进积的主要因素;海啸发生周期为14~35, ka, 后积层理(backset-bedding)为海啸沉积识别标志;海底滑坡多由海底地震、天然气水合物泄露等触发, 其块状搬运沉积物(MTD)包括滑塌头部、滑动底面、滑塌主体以及滑塌后期浊流沉积;玄武岩等基岩的风化作用提供硅与富镁碱性水, 有利于菱沸石与白云石的形成;受构造作用影响, 隆起剥蚀区与沉积区可互为转化;物源性质、供给量及搬运或分散过程控制了沉积面貌(源汇系统);构造活动直接控制可容纳空间变化、地貌变化、源区剥蚀速率、沉积物供应速率等。最后, 本文对比了中外沉积学发展差异, 讨论了中国沉积学发展方向。     

The Darfur Dome,western Sudan: the product of a subcontinental mantle plume

Field investigations, K-Ar age determinations and chemical data were used to describe the development of an intraplate volcanic province, the Darfur Dome, Sudan. Magmatism started 36 Ma ago at a small subvolcanic complex (Jebel Kussa) in the center of the dome and was active in the same area between 26 and 23 Ma. Two major volcanic fields (Marra Mountains and Tagabo Hills) developed between 16 and 10 Ma. Volcanism started again at 6.8 Ma with a third volcanic field (Meidob Hills) and at 4.3 Ma in the Marra Mountains and with the reactivation of the center. Activity then continued until the late Quaternary. Having started in the center of the Darfur Dome, volcanism moved in 36 Ma 200 km towards the NNE and 100 km SSW No essential difference in the alkaline magma types (basanitic to phonolitic-trachytic, with different amounts of assimilation of crustal material) in the different fields, was observed. Magmatism is thought to have been produced by a rising mantle plume and volcanism was triggered by stress resolution along the Central African Fault Zone.     

天文教育I: 万有引力与天体物理

分别从物理学和天文学角度引申出天体物理学科, 特别关注万有引力在其中扮演的关键角色. 无论在综合性大学亦或理工科院校, 天文教育均有益于提高学生的科学和人文素养, 而天体物理则是天文学的主要内涵. 介绍了作者讲授``天体物理''课程的相关信息以及个人认识. 最后, 以大气簇射mu子产生、啾质量、宇宙加速膨胀等教学案例结束, 侧面诠释了作者的``天体物理''教育理念.     

Quantitative Evaluation of Water Deposited By Dew on Monuments

Samples of White and Green Carrara marble, and three types oflimestone and brick exposed in the field vertically and horizontally were used to evaluate condensationon monuments during clear sky nights. Experiments in a simulation chamber under controlledconditions led to a general equation for the actual amount of water deposited on a surface by dew.This is determined by: How much and for how long the surface temperature falls below the dew point,the moisture content in the air and the ventilation. On clear nights, the condensation on buildingstructures facing the sky may reach some 0.2 kg m^-2 (or 0.2 mm), whereas condensation on verticalsurfaces is very small. Computation of the seasonal trend of night-time condensationshowed that the maximum amount of water condensed per night occurs in the autumn, with the moreabundant concentration of moisture in the air. The total amount of water condensed per month isfound to be a maximum in the summer-autumn period. Morning condensationfor the thermal inertia of monuments is also relevant, and has been calculated to reach the same order of magnitude as thenocturnal dew. A detailed analysis of the temperature and mixing ratio profiles near a condensingsurface has shown two different situations. In still air, the two profiles follow an exponentiallaw and the thermal and the concentration layers lie within a few tens of millimetres. Inthe presence of turbulence, the thickness of these two layers is dramatically reduced. In still air, infront of a vertical, chilly surface, the deposition rate of air pollutants by thermophoresis and/orStefan flow is increased by 3 or 4 times in comparison with a horizontal surface. In the presence ofturbulence, the thickness of the thermal and concentration layers was dramatically reduced, makingthese two kinds of deposition much faster.     

The flux ejection dynamo effect

Abstract

The mean-field effects of cyclonic convection become increasingly complex when the cyclonic rotation exceeds ½-π. Net helicity is not required, with negative turbulent diffusion, for instance, appearing in mirror symmetric turbulence. This paper points out a new dynamo effect arising in convective cells with strong asymmetry in the rotation of updrafts as against downdrafts. The creation of new magnetic flux arises from the ejection of reserve flux through the open boundary of the dynamo region. It is unlike the familiar α-effect in that individual components of the field may be amplified independently. Several formal examples are provided to illustrate the effect. Occurrence in nature depends upon the existence of fluid rotations of the order of π in the convective updrafts. The flux ejection dynamo may possibly contribute to the generation of field in the convective core of Earth and in the convective zone of the sun and other stars.     

沿岸流非线性不稳定特征数值研究

当不稳定剪切波的波幅达到有限幅值之后,需要用非线性不稳定模型来分析沿岸流不稳定运动特征。本文通过建立并验证沿岸流非线性不稳定数学模型,在讨论该模型参数对沿岸流不稳定影响的基础上,率定实验中的模型参数并利用该数学模型模拟了实验中沿岸流不稳定的发展过程及其特征,主要结论有:（1）底摩擦系数越小,侧混系数越小,不稳定发生的时间越早,不稳定的波动幅值越大;（2）沿岸流非线性不稳定演化可能出现的5个阶段（线性阶段、倍周期阶段、大周期阶段、波群阶段以及不规则阶段）,实验中出现的沿岸流通常处于线性阶段或非线性倍周期阶段,倍周期阶段的涡旋是由线性阶段的涡旋发生追赶、配对直至合并产生的。涡旋配对以碰撞的形式发生,大部分能量转移至追踪波,然后以较慢的涡旋速度沿岸传播。     

中国西北地区北部蚀源区铀含量特征及其地质、成矿意义

中国西北地区北部主要盆地蚀源区包括银额盆地周缘、北山盆地群周缘、三塘湖盆地周缘、准噶尔盆地周缘,主体位于中亚构造域中西部南缘(部)或与之毗邻区。通过对研究区1 416件中性、酸性及碱性岩浆岩样品的年龄和铀含量数据进行分区统计处理,计算其在地史上的铀迁移量和古铀含量,结果显示,研究区岩浆活动主要发生在早石炭世-早三叠世(349~248 Ma),其次在中奥陶世-早泥盆世(470~396 Ma)。这分别与古亚洲洋开始俯冲消减(O2S1)和最终关闭、中亚-蒙古碰撞褶皱带形成(C-T1)的大地构造演化阶段及重大事件相对应。各区富铀岩石主要形成于早石炭世-早三叠世(334~250 Ma),其与晚古生代岩浆活动具有时间上的一致性。在地域上, 两者有从西向东时代变新的趋势。这亦与古亚洲洋关闭、中亚构造域形成西早东晚的演化特征相一致。各蚀源区岩石的铀含量不尽相同,综合对比和评价表明：北山柳园区、准噶尔盆地东北缘阿勒泰-蕴都地区和东南部清河地区岩石铀含量与宗乃山区铀含量相当或更富;准噶尔盆地东北缘卡拉麦里区岩石铀含量偏富;银额盆地南缘雅布赖山、巴彦诺日公及庆格勒地区及其北部的沙拉扎山区,北山盐滩及马鬃山区,三塘湖盆地周缘,以及准噶尔盆地东北缘的阿勒泰西北区和西缘的北部区铀含量中等;其他地区铀含量相对较贫。研究区现今富铀蚀源区的大部地区,在晚三叠世开始隆升,此后进一步发展,为邻近中新生代盆地提供了丰富的沉积物和铀物质,成为相邻中新生代陆相盆地砂岩型、煤岩型及泥岩型铀矿床的主要成矿物质来源;盆内深部烃源岩层富含铀元素,可降低烃源岩的生烃门限温度并增加烃源岩生烃总量,具有重要的地质、成矿意义。