潍坊市城区第四系地层研究

通过整理近年来地震地质工作中积累的大量钻孔资料,对比分析潍坊市城区第四纪各沉积层的组成特征、形成时代、成因类型等性质,将城区沉积层划分为23个主层及众多亚层。在此基础上,编制潍坊市城区第四系厚度等值线图、第四纪不同地层单位沉积厚度等值线图及相关的地层埋深剖面图、模型图等,从而较系统地摸清本区第四系各土层的空间分布规律及其结构变化特征,并对潍坊市城区第四系沉积的主要控制因素进行初步分析和探讨。     

杭州湾海域50年一遇波浪数值模拟研究

杭州湾外围海域岛礁众多,波浪传播机制复杂。为了了解该海域的波浪分布特征,采用MIKE 21 SW模块建立了杭州湾海域波浪数值模型,利用实测波浪资料对模型进行了验证,结果表明该模型适用于模拟杭州湾海域的波浪传播。利用1970—2002年嵊山海洋站实测极值波浪资料推算50年一遇波浪要素,将其作为模型边界条件,对杭州湾海域50年一遇的设计波浪进行了模拟,并对该海域的波浪传播特征进行了分析。结果表明,杭州湾内波高较之外海明显减小,外围众多岛礁起到了很好的遮挡保护作用。     

Tectonics of an extinct ridge-transform intersection,Drake Passage (Antarctica)

New swath bathymetric, multichannel seismic and magnetic data reveal the complexity of the intersection between the extinct West Scotia Ridge (WSR) and the Shackleton Fracture Zone (SFZ), a first-order NW-SE trending high-relief ridge cutting across the Drake Passage. The SFZ is composed of shallow, ridge segments and depressions, largely parallel to the fracture zone with an `en echelon' pattern in plan view. These features are bounded by tectonic lineaments, interpreted as faults. The axial valley of the spreading center intersects the fracture zone in a complex area of deformation, where N120° E lineaments and E–W faults anastomose on both sides of the intersection. The fracture zone developed within an extensional regime, which facilitated the formation of oceanic transverse ridges parallel to the fracture zone and depressions attributed to pull-apart basins, bounded by normal and strike-slip faults.On the multichannel seismic (MCS) profiles, the igneous crust is well stratified, with numerous discontinuous high-amplitude reflectors and many irregular diffractions at the top, and a thicker layer below. The latter has sparse and weak reflectors, although it locally contains strong, dipping reflections. A bright, slightly undulating reflector observed below the spreading center axial valley at about 0.75 s (twt) depth in the igneous crust is interpreted as an indication of the relict axial magma chamber. Deep, high-amplitude subhorizontal and slightly dipping reflections are observed between 1.8 and 3.2 s (twt) below sea floor, but are preferentially located at about 2.8–3.0 s (twt) depth. Where these reflections are more continuous they may represent the Mohorovicic seismic discontinuity. More locally, short (2–3 km long), very high-amplitude reflections observed at 3.6 and 4.3 s (twt) depth below sea floor are attributed to an interlayered upper mantle transition zone. The MCS profiles also show a pattern of regularly spaced, steep-inclined reflectors, which cut across layers 2 and 3 of the oceanic crust. These reflectors are attributed to deformation under a transpressional regime that developed along the SFZ, shortly after spreading ceased at the WSR. Magnetic anomalies 5 to 5 E may be confidently identified on the flanks of the WSR. Our spreading model assumes slow rates (ca. 10–20 mm/yr), with slight asymmetries favoring the southeastern flank between 5C and 5, and the northwestern flank between 5 and extinction. The spreading rate asymmetry means that accretion was slower during formation of the steeper, shallower, southeastern flank than of the northwestern flank.     

红树林海岸的沉积物输运和碳沉降特征

Mangroves play an important role in sequestering carbon and trapping sediments. However, the effectiveness of such functions is unclear due to the restriction of knowledge on the sedimentation process across the vegetation boundaries. To detect the effects of mangrove forests on sediment transportation and organic carbon sequestration, the granulometric and organic carbon characteristics of mangrove sediments were investigated from three vegetation zones of four typical mangrove habitats on the Leizhou Peninsula coast. Based on our results, sediment transport was often "environmentally sensitive" to the vegetation friction. A transition of the sediment transport mode from the mudflat zone to the interior/fringe zone was often detected from the cumulative frequency curve. The vegetation cover also assists the trapping of material, resulting in a significantly higher concentration of organic carbon in the interior surface sediments. However, the graphic parameters of core sediments reflected a highly temporal variability due to the sedimentation process at different locations. The sediment texture ranges widely from sand to mud, although the sedimentary environments are restricted within the same energy level along the fluvial-marine transition zone. Based on the PCA results, the large variation was mainly attributed to either the mean grain size features or the organic carbon features. A high correlation between the depth and δ13C value also indicated an increasing storage of mangrove-derived organic carbon with time.     

应用ArcGIS软件缩编1:5万土地利用现状图方法的探讨

1:5万土地利用现状图缩编主要是对第二次全国土地调查数据的面状要素和线性要素进行合并或改变其表现方式,利用制图综合的方法将小于规范要求上图面积的图斑合并到相邻图斑或将宽度小于规范要求的道路、河流等线性要素改用线状符号表示,在上述数据处理过程中需要较多的人工操作,因此本文针对1︰5万土地利用现状图数据缩编过程中如何运用ArcGIS软件,从提高缩编工作效率方面进行讨论,提出针对面状要素和线性要素处理的两种方法,从而提高工作效率。     

Paleo- and Neoproterozoic magmatic and tectonometamorphic evolution of the Isla Cristalina de Rivera (Nico Pérez Terrane, Uruguay)

The Isla Cristalina de Rivera crystalline complex in northeastern Uruguay underwent a multistage magmatic and metamorphic evolution. Based on SHRIMP U–Pb zircon, Th–U–Pb monazite (CHIME-EPMA method) and K–Ar age data from key units several events can be recognized: (1) multistage magmatism at 2,171–2,114?Ma, recorded on zircon of the granulitic orthogneisses and their 2,093–2,077?Ma overgrowths; (2) a distinct amphibolite facies metamorphism at ~1,980?Ma, recorded by monazite; (3) greenschist facies reworking and shearing at ca. 606?Ma (monazite and K–Ar on muscovite) along the Rivera Shear Zone, and finally (4) intrusion of the post-tectonic Sobresaliente and Las Flores granites at around 585?Ma. Lithological similarities, geographic proximity and coeval magmatic and metamorphic events indicate a similar tectonometamorphic evolution for the Isla Cristalina de Rivera, the Valentines Block in Uruguay and the Santa María Chico Granulitic Complex in southern Brazil, since at least 2.1?Ga.     

Putative Meteoritic Craters in Río Cuarto (Central Argentina) Interpreted as Eolian Structures

Ten oblong aligned depressions in the Río Cuarto area (provincia de Córdoba, Argentina) were supposed to be the result of very-low-angle Holocene meteoroid impacts. However, we consider that authors that studied the structures did not demonstrated their extraterrestrial origin. We suggest that an eolian origin for the structures of Río Cuarto is more likely. Actually, these landforms integrate large systems of similar deflation/accumulation geoforms aligned according to predominant winds during different periods.     

四川盆地基底断裂对长兴组生物礁的控制作用研究

四川盆地长兴组生物礁油气藏是国内外该类型油气藏的一个典型代表。在前人主要针对川东北地区提出台地边缘是生物礁发育有利部位的基础上,从盆地更广的尺度,结合国内外已有实例,着重从基底断裂角度,分析了其对生物礁发育的影响与控制作用。结果表明,盆地内长兴组发育有大量NE和NW向深大断裂,地层、岩相和构造证据均反映这些断裂在晚二叠世处于正断活动期,并形成了台—槽相间和台内棋盘格状堑垒构造格局。基底正断活动通过对古地理的影响来实现对生物礁的控制,生物礁受张性正断层上升盘"断隆"控制,分布于基底断裂古上升盘断阶处,如环海槽的台地边缘和台地内部断垒周缘。因此,除已获得重大突破的"环海槽礁滩气藏富气带"外,在台地内部靠基底断裂带附近,礁滩也可能发育,可作为今后油气勘探重点考虑的对象。这一研究新认识有助于拓展区域油气勘探思路,并为生物礁型油气成藏理论研究提供新的参考信息。     

The Precision Analysis of the Chinese VLBI Network in Probe Delay Measurement

We propose a Very Long Baseline Interferometry(VLBI)precision evaluation method for probe delay measurement,so as to investigate the error contributions from di...     

逆转座子序列插入——海湾扇贝过氧化物还原酶V 第1 内含子分析

根据海湾扇贝(Argopecten irradians)过氧化物还原酶V(AiPrxV)的cDNA序列和部分基因组DNA序列设计引物,采用基因组步移方法扩增获得其第1内含子(I1)完整序列,并通过Blast比对、DNAMAN和RepFind搜索进行序列分析。AiPrxV I1长8 565bp,占AiPrxV基因全长的68%,AT%显著高于GC%。在5 900-6 700bp的区域中包含了不完整的编码区,经分析与文昌鱼、海胆的逆转录酶有极高的相似性,其N端与多种动植物逆转座子的逆转录酶C端具有相似特征。此外,发现AiPrxV I1中包含283个重复序列,在3 500-4 000bp和6 800-7 200bp区域尤为密集。以上特点提示海湾扇贝过氧化物还原酶V第1内含子可能是由一个非长末端重复元件逆转座子(non-LTR retrotransposons)插入,逐渐演变而形成的。