龙感湖近百年来沉积物磷的时空分布特征及其人类活动影响

湖泊沉积物蓄积的磷在湖泊环境发生变化(如pH值、Eh改变)时,往往能释放到水体,形成湖泊内源释放,造成湖泊富营养化。因此了解湖泊沉积物磷的蓄积特征,对于湖泊环境的治理和保护有重要意义。通过长江中游龙感湖不同部位钻孔的 210 Pb、沉积物磷和其他环境指标分析表明,近百年来东部湖区沉积速率明显大于西部湖区,北部湖区略大于南部湖区,人类活动在20世纪50年代后期主要通过修建水库和闸坝,改变龙感湖水系结构,也改变了龙感湖的物源供给,因而西部湖区沉积速率略有放缓,东部湖区变化不明显。龙感湖沉积物磷的浓度空间上表现为东部高于西部,这与不同物源磷的背景值相关,时间序列上近百年来呈上升趋势,上世纪50年代以来上升趋势更为明显。在确定沉积物磷背景值的基础上,由于人类活动导致的磷的增加量表明,20世纪50年代开始人类活动导致沉积物磷的增加量持续上升,20世纪70年代末开始增加幅度更大,这一特征与人类活动的方式有关。     

The Triassic age for oceanic eclogites in the Dabie orogen: Entrainment of oceanic fragments in the continental subduction

Low-temperature and high-pressure eclogites with an oceanic affinity in the western part of the Dabie orogen have been investigated with combined Lu–Hf and U–Pb geochronology. These eclogites formed over a range of temperatures (482–565 °C and 1.9–2.2 GPa). Three eclogites, which were sampled from the Gaoqiao country, yielded Lu–Hf ages of 240.7 ± 1.2 Ma, 243.3 ± 4.1 Ma and 238.3 ± 1.2 Ma, with a corresponding lower-intercept U–Pb zircon age of 232 ± 26 Ma. Despite the well-preserved prograde major- and trace-element zoning in garnets, these Lu–Hf ages mostly reflect the high-pressure eclogite-facies metamorphism instead of representing the early phase of garnet growth due to the occurrence of omphacite inclusions from core to rim and the shell effect. An upper-intercept zircon U–Pb age of 765 ± 24 Ma is defined for the Gaoqiao eclogite, which is consistent with the weighted-mean age of 768 ± 21 Ma for the country gneiss. However, the gneiss has not been subjected to successive high-pressure metamorphism. The new Triassic ages are likely an estimate of the involvement of oceanic fragments in the continental subduction.     

深源地震机理的新认识──反向裂隙断层作用

高温高压实验究表明，地幔矿物相交与深源地震有着密切的关系。在具有放热效应的橄榄石一尖晶石相变过程中形成的反向裂隙（ａｎｔｉｃｒａｃｈ）是诱发深源地震的主要原因；而发生在下地幔的相变作用（例如钛铁矿－钙钛矿相变）因其具有吸热效应的特征，不形成反向裂隙，从而导致深源地震终止于下地幔顶界。     

地质雷达在隧道检测中的应用

隧道施工完成后用常规方法很难对衬砌质量做出系统评价，地质雷达利用超高频脉冲电磁波探测目标介质的介电常数，很容易掌握砼衬砌结构的厚度、衬砌周围回填及空隙情况，围岩断层裂隙构造情况等，为工程技术评价提供依据。文章以实例，介绍了利用地质雷达对隧道进行检测所使用的仪器、工作参数及地质雷达资料处理解释步骤，并通过对几幅典型雷达图像进行分析介绍了不同异常结构在雷达剖面上的反映。     

An experimental study of effect of pre‐existing fabric on deformation of foliated mylonite at high temperature and pressure

We performed deformation experiments on a foliated mylonite under high temperature and pressure conditions in this study. To investigate the effect of pre‐existing fabric on the rheology of rocks, our samples were drilled from natural mylonite with the cylinder axis parallel to the foliation (PAR) and perpendicular to the foliation (PER). We performed 25 tests on seven PAR samples and 21 tests on seven PER samples at temperatures ranging from 600 to 890 °C, confining pressures ranging from 800 to 1400 MPa, and steady‐state strain rates of 1 × 10⁻⁴, 1 × 10⁻⁵ and 2.5 × 10⁻⁶ s⁻¹. In the temperatures of 600–700 °C, the deformation is accommodated by semi‐brittle flow, with the average stress exponent being 6–7 assuming power law flow; in the temperature range of 800–890 °C, deformation is mainly by plastic flow, with an average stress exponent of n = 3 and activation energies of Q = 354 ± 52 kJ/mol (PER and PAR samples). The experimental results show that the strengths of PER samples are higher than those of PAR samples. Deformation microstructures have been studied by optical and electron microscopy. The original foliation of PER samples is destroyed by deformation and replaced by a new foliation, but the deformation of PAR samples followed the original foliation. Electron backscatter diffraction (EBSD) measurements show a strong lattice preferred orientation (LPO) of the quartz c axis fabrics of the starting samples and deformed PER and PAR samples. However, the c axis fabric of quartz in experimentally deformed PER and PAR samples varied with temperature and strain rate is different from that seen in the starting mylonite sample. The initial quartz c axis fabric of the starting mylonite sample has been transformed into a new fabric during experimental deformation. Dehydration melting of biotite and hornblende occurred in both PER and PAR samples at temperatures of 800–890 °C. Copyright © 2014 John Wiley & Sons, Ltd.     

贵州煤田地质局技术队伍建设问题探讨

目前地质市场由计划经济转化为市场经济,市场的竞争究其本质是人才竞争。因此应该采取科学合理的技术人才资源管理方法和管理体制,以整体和局部、近期和长远为目标进行有计划、有步骤的技术队伍建设,注重从才培养,激励地质技术人员专业技能的提高,采用倾斜政策留住人才、招纳人才,只有这样贵州煤田地质局才能在不久的将来拥有一支精干、高效的地质专业技术队伍,确保全局乃至二级单位适应煤田地质市场的需要,保证全局科学、和谐健康有序的发展。     

Mesozoic tectonic evolution of the Southeast China Block: New insights from basin analysis

In order to better understand the Mesozoic tectonic evolution of Southeast China Block (SECB in short), this paper describes geological features of Mesozoic basins that are widely distributed in the SECB. The analyzed data are derived from a regional geological investigation on various Mesozoic basins and a recently compiled 1:1,500,000 geological map of Mesozoic–Cenozoic basins. Two types of basin are distinguished according to their tectonic settings, namely, the post-orogenic basin (Type I) and the intracontinental extensional basin (Type II); the latter includes the graben and the half-graben or faulted-depression basins. Our studies suggest that the formation of these basins connects with the evolution of geotectonics of the SECB. The post-orogenic basin (Type I) was formed in areas from the piedmont to the intraland during the interval from Late Triassic to Early Jurassic; and the formation of the intracontinental extensional basin (Type II) connects with an intracontinental crustal thinning setting in the Late Mesozoic. The graben basin was generated during the Middle Jurassic and is associated with a bimodal volcanic eruption; and the half-graben or faulted-depression basin, filled mainly by the rhyolite, tuff and sedimentary rocks during Early Cretaceous, is occupied by the Late Cretaceous–Paleogene red-colored terrestrial clastic rocks. We noticed that the modern outcrops of numerous granites and basins occur in a similar level, and the Mesozoic granitic bodies contact with the adjacent basins by large normal faults, suggesting that the modern landforms between granites and basins were yielded by the late crustal movement. The modern basin and range framework was settled down in the Cretaceous. Abundant sedimentary structures are found in the various basins, from that the deposited environments and paleo-currents are concluded; during the Late Triassic–Early Jurassic time, the source areas were situated to the north and northeast sides of the outcrop region. In this paper, we present the study results on one geological and geographical separating unit and two separating fault zones. The Wuyi orogenic belt is a Late Mesozoic paleo-geographically separating unit, the Ganjiang fault zone behaves as the western boundary of Early Cretaceous volcanic rocks, and the Zhenghe–Dapu fault zone separates the SE-China Coastal Late Mesozoic volcanic-sedimentary basins and the Wuyi orogenic belt. Finally, we discuss the geodynamic mechanisms forming various basins, proposing a three-stage model of the Mesozoic sedimentary evolution.     

Effect of shallow and narrow water on added mass of cylinders with various cross-sectional shapes

The sway, heave and roll added masses of three uniform cylinders with semi-circular, rectangular and triangular cross-sectional shapes in shallow and narrow water are numerically analysed. The method is based on simulation of the potential flow induced by the cylinder's mode of motion. The effects of shallow and narrow water on added mass are analysed and presented. It is concluded that the shallow and narrow water effects on added mass depend on the different cross-section shapes of the cylinders. In particular, the water depth effect on sway added mass is stronger than that on heave added mass while the narrow water effect on sway is weaker than that on heave. The shallow water effect on added mass tends to weaken the narrow water effect. Lastly the effect of shallow and narrow water on added mass on a rectangular cylinder is the strongest while that on a triangular cylinder is the weakest.     

秋季巴伦支海海温异常对冬季我国渤海冰情的可能影响

本文利用美国NCEP/NCAR逐月的再分析资料、HadISST海温、中国160台站气温和反映渤海冰情轻重的渤海冰情等级资料,研究了前秋巴伦支海海温异常对后期渤海冰情和东亚冬季风的影响,并对相关的物理过程进行分析。结果表明,前秋巴伦支海关键区海温与该区域海冰密集度呈显著的负相关,且具有较好的持续性,通过调节随后冬季向大气释放的热通量,引起后期环流变化。偏高(偏低)年冬季亚洲纬向环流偏弱(偏强),东亚大槽加深(减弱),东亚冬季风加强(减弱),我国东北、华北及西北地区地区显著偏冷(偏暖),这与冬季渤海海冰异常的强度和范围都偏大(小)及与之相联系的环流异常相一致。进一步的分析揭示了联系上游关键区海温变化与后期东亚地区气候异常的重要途径,前秋巴伦支海海温偏高会导致200 hPa高度场形成一个自西向东的波列形式,在东亚局地Hadley环流异常的作用下,加强了我国北方地区地表的北风异常。因此,前秋巴伦支海海温异常可以作为冬季渤海冰情的预报因子。