Discussion on the Cenozoic tectonic evolution and dynamics of southern Tibet

Opening-closing tectonics is a new idea for exploring the global tectonics, which holds that every tectonic movement of all materials and geological bodies on earth is characterized by opening and closing. The opening -closing tectonic view can be used to explain some geological phenomena developing in continents which cannot be reasonably explained by the theory of plate tectonics. Based on the available basic geological data and combining with the opening-closing view, we analyzed the divisions and characteristics of tectonic units in South Tibet, and propose that Tibet can be divided into gravitational detachment and detachment fault zones, which are superimposed thrust fault zones and reconstructed normal fault zones, respectively. Although the mainstream opinion believed that the Tibetan Plateau is formed by collision-compression orogenesis, field investigation revealed the existence of the Rongbu Temple normal fault in the1970s. We consider that the Rongbu Temple normal fault and the Main Central Thrust (MCT) were formed earlier than the South Tibet detachment fault, and the former two faults constitute the two boundaries of the southern Tibet extrusion structure. The South Tibet detachment fault partially superimposes on the MCT and manifests a relatively high angle in following the Rongbu Temple normal fault north of the Chomolangma. We suggest that the three fault systems are the products of different periods and tectonic backgrounds. The tectonic units, such as klippes and windows identified by previo us researchers in southern Tibet, belong to thrust fault system but usually have no obvious extrusion or thrust characteristics; however, they are characterized by missing strata columns as younger strata overlapping the older ones. These klippes and windows should be the results of later gravitational decollement and must be characterized as extensions and slips, respectively. Based on opening-closing theory, we suggest that since the Cenozoic the study area had undergone multistage development, which can be divided into the oceanic crust expansion (opening) and subduction (closing) and the continental collision (closing) and intracontinental extension (opening) stages. Geothermal energy from the deep earth, gravitational potential energy from the earth’s interior, and additional stress energy from tectonic movements, all played a key role in the multistage tectonic evolutionary process.     

Distribution and Ecological Risk Assessment of HCHs and DDTs in Surface Seawater and Sediment of the Mariculture Area of Jincheng Bay,China

The distribution of hexachlorocyclohexanes(HCHs) and dichlorodiphenyltrichloroethanes(DDTs) in the surface seawater and sediment of Jincheng Bay mariculture area were investigated in the present study. The concentration of total HCHs and DDTs ranged from 2.98 to 14.87 ng L-1 and were 0.032 ng L-1, respectively, in surface seawater, and ranged from 5.52 to 9.43 and from 4.11 to 6.72 ng g-1, respectively, in surface sediment. It was deduced from the composition profile of HCH isomers and DDT congeners that HCH residues derived from a mixture of technical-grade HCH and lindane whereas the DDT residues derived from technical-grade DDT and dicofol. Moreover, both HCH and DDT residues may mainly originate from historical inputs. The hazard quotient of α-HCH, β-HCH, γ-HCH and δ-HCH to marine species was 0.030, 0.157, 3.008 and 0.008, respectively. It was estimated that the overall probability of adverse biological effect from HCHs was less than 5%, indicating that its risk to seawater column species was low. The threshold effect concentration exceeding frequency of γ-HCH, p,p'-DDD, p,p'-DDE and p,p'-DDT in sediment ranged from 8.3% to 100%, and the relative concentration of the HCH and DDT mixture exceeded their probable effect level in sediment. These findings indicated that the risk to marine benthos was high and potentially detrimental to the safety of aquatic products, e.g., sea cucumber and benthic shellfish.     

基于波动方程的广义屏叠前深度偏移

地震波传播算子的计算效率和精度是制约三维叠前深度偏移的关键因素. 广义屏传播算子(GSP, Generalized Screen Propagator)是一种在双域中实现的广角单程波传播算子. 这一方法略去了在非均匀体之间发生的交混回响,但它可以正确处理包括聚焦、衍射、折射和干涉在内的各种多次前向散射现象. 通过背景速度下的相移和扰动速度下的陡倾角校正,广义屏算子能够适应地层速度的强烈横向变化. 这种算子可以直接应用于炮集叠前偏移,通过将广义屏算子作用于双平方根方程,还可以获得一种高效率、高精度的炮检距域叠前深度偏移方法,用于二维共炮检距道集和三维共方位角道集的深度域成像. 本文首先简述了炮检距域广义屏传播算子的理论,进而讨论了共照射角成像(CAI, Common Angle Imaging)条件,由此给出各个不同照射角(炮检距射线参数)下的成像结果,进而得到共照射角像集. 由于照射角和炮检距的对应关系,共照射角像集又为偏移速度分析和AVO(振幅随炮检距变化)分析等提供了有力工具.     

Studies on hemolysis of hemolysin produced by Synechocystis sp. PCC 6803

Hemolysin produced by various bacteria,may destroy erythrocyte membranes via a pore-forming mechanism,a deter-gent action,or a lipase activity.Previous to this experiment,the mode of action used by cyanobacterial hemolysin had not been re-ported.To characterize the action mode of hemolysin produced by the wild-type strain of Synechocystis sp.PCC6803,hemolysis of erythrocytes originating from human,mouse,sheep,rabbit and goldfish was studied.The erythrocytes of mouse,sheep and rabbit were sensitive,while those of human and fish were resistant,to this hemolysin.Using rabbit erythrocytes,it was shown that hemoly-sis occurred in two steps:a binding step within the first 10 min of treatment and a lytic step after 30 min.Both binding and lysis were highly temperature-dependent.Effects of erythrocyte density on hemolysis suggest that the hemolysin might target erythrocytes via a multiple-hit mechanism.In the osmotic protection experiment,all tested osmotic protectants,with molecular diameters ranging from 0.9 ?5.66 nm,failed to effectively inhibit hemolysis.Scanning electron micrographs showed that the hemolysin caused protuberances or echinocytes in rabbit erythrocytes,and then disrupted and ruptured the erythrocytes.Characteristics of hemolysis showed distinct differences from other pore-forming mechanisms,suggesting that this hemolysin might act through a detergent-like or lipase mecha-nism,rather than a pore-forming mechanism.     

ON THE POSSIBLE CHANGES OF THE SOLAR DIFFERENTIAL ROTATION DURING THE ACTIVITY CYCLE DETERMINED USING MICROWAVE LOW-BRIGHTNESS-TEMPERATURE REGIONS AND Hα FILAMENTS AS TRACERS

The solar rotation rate obtained using the microwave Low-brightness-Temperature Regions (LTRs) as tracers in the heliographic range ± 55° from the years 1979–1980, 1981–1982, 1987–1988, and 1989–1991 varied from 3% to 4% in medium latitudes, and below 1% at the equator. Using H filaments as tracers at higher latitudes from the years 1979, 1980, 1982, 1984, and 1987, the solar rotation rate variation was between 2% and 8%. This represents an upper limit on the rotation rate variation during the solar activity cycle. Such changes could be caused by short-lived, large-scale velocity patterns on the solar surface. The Sun revealed a higher rotation rate on the average during the maxima of the solar activity cycles 21 and 22, i.e., in the periods 1979–1980 and 1989–1991, respectively, which differs from the rotation rates (lower on the average) in some years, 1981–1982 and 1987–1988, between the activity maximum and minimum (LTR data). Simultaneous comparison of rotation rates from LTRs and H filament tracings was possible in very limited time intervals and latitude bands only, and no systematic relationship was found, although the rotation rates determined by LTRs were mostly smaller than the rotation rates determined by H filaments. The errors obtained by applying different fitting procedures of the LTR data were analyzed, as well as the influence of the height correction. Finally, the north–south asymmetry in the rotation rate investigated by LTRs indicates that the southern solar hemisphere rotated slower in the periods under consideration, the difference being about 1%. The reliability of all obtained results is discussed and a comparison with other related studies was performed.     

带梯度项的半线性椭圆型方程正径向整大解的存在性

本文研究带梯度项的半线性椭圆型方程正径向整大解的存在性.先利用Banach不动点定理和反证法得出正径向解的局部及整体存在性,进而得到正径向整大解的存在性结论.结果发现,正径向整大解的存在性依赖于梯度项的系数符号和指数的范围.     

大豆异黄酮对鱼类生长作用的研究进展

大豆异黄酮是广泛存在于大豆中的一类非甾族杂环多酚类化合物,它对鱼类生长的作用还未得到一致结论,这限制了大豆蛋白源鱼饲料的开发利用。本文综述了大豆异黄酮对鱼类生长的影响及其可能的作用机制,展望了该领域的研究方向,以期为鱼粉蛋白源替代提供参考依据。     

蓝罗非鱼鳞片表面结构的扫描电镜观察

运用扫描电镜技术对蓝罗非鱼侧线上鳞、侧线下鳞和侧经鳞进行了形态结构的观察。研究结果表明,蓝罗非鱼体表睛属栉鳞,外形呈近圆形,分为顶区、基区和侧区三个部分;顶区边缘具细小齿状棘突,区内分布有癌状或棒状突起;基区具有清晰致密的鳞纹和放射状排列的鳞沟,年轮线处鳞纹密集排列;侧区较为平滑,无明显的鳞沟;侧线鳞具有粗壮的侧线管口。     

统一地址赋能社会治理的关键技术

统一地址的概念于近些年才被提出,其主要本质和意义是在充分尊重现有各部门行业标准地址的基础上,作为社会治理要素有效关联融合的"桥梁",为摸清底数、精准施策等精细治理工作提供支撑,是测绘地理信息技术在社会治理数字化、智能化领域的创新应用.本文针对统一地址在建设过程中的关键技术进行初步研究,并简单介绍了杭州市的实际应用情况.     

西天山伊犁地块北缘早石炭世硅化木的发现及其意义

在西天山伊犁地块北缘琼阿希河谷中首次发现硅化木,对硅化木的基本特征进行了描述。根据地层中腕足、珊瑚化石的鉴定结果,将地层的时代定为早石炭世维宪期,因此该硅化木的产出层位为下石炭统阿克沙克组。硅化木产于阿克沙克组底部黑色薄层状泥岩、粉砂岩中,这套岩性组合形成于扇三角洲前缘水下分流间湾。伊犁地块北缘阿克沙克组底部扇三角洲沉积环境的确定和硅化木化石的发现说明：研究区早石炭世维宪期不是一套连续的海相沉积,而是陆相—海陆过渡相沉积,研究区所处的地理位置距离古陆地不远。这一发现对于重新认识伊犁地块早石炭世古地理和古构造格局具有重要意义。