川滇西部上新世以来构造地貌:断裂控制的盆地发育及对于远程陆内构造过程的约束

青藏高原隆升、周边地貌形成是新生代时期印度-欧亚板块碰撞后的重要响应。在滇西北地区发育了一系列由晚新生代(上新世以来)活动断裂所控制的盆地,例如宾川盆地、洱海盆地、鹤庆盆地、弥渡盆地等。宾川盆地是近南北向程海左行走滑断裂在走滑剪切作用下产生的北西向正断层和北东向走滑断层共同作用而形成的一个较大的拉分盆地。洱海盆地是由两组陡立的共轭张剪性(Transtensional)断层组限定的,为一伸展断陷盆地,总体上反映了近E-W向的区域伸展。滇西北地区发育的其它晚新生代盆地,如弥渡盆地、鹤庆盆地、剑川盆地等,也为区域走滑断裂及其分支断裂所控制,并且这些分支断裂在区域上为一组NE-SW和NW-SE向的共轭正断裂,反映了该区域近E-W向的伸展。将藏东南三江地区发育的活动断裂按照其走向分为三组:(1)NW-SE走向的断裂,如红河断裂、无量山-营盘山断裂等;(2)近N-S向断裂系,以程海断裂、小江断裂等为代表;(3)NE-SW走向的断裂,如丽江-剑川断裂、鹤庆-洱源断裂和南定河断裂等。这些断裂的震源机制解表明地震断裂活动性或者是走滑性质或者是伸展属性,它们的组合型式也揭示出藏东南三江地区在上新世以来表现为近E-W向的伸展。区域上,在藏东北部地区发育的断层构造组合普遍反映了以近E-W向挤压为主导的应力场。推测这一现象为上新世以来藏东地区上地壳围绕喜马拉雅东构造结做顺时针旋转所致,区域上受印度-欧亚会聚过程中印度板块顺时针旋转诱发的差异性应力场制约。     

不同时间尺度上的热带海气耦合扰动

本文从热带地球流体运动的物理特征出发,建立了适合热带地区特点的海气耦合模式方程组并对之进行了系统的尺度分析,指出时间尺度不同的运动其受控的物理过程各异。基于这种时间尺度的差异,我们有可能将不同时间尺度的运动分开来研究。计算结果表明,去掉海洋中的波动过程,仅仅考虑与海洋表面温度场的变化相联系的扰动形式会对耦合系统及耦合扰动的性质造成很大影响。由此看来,Ｎｅｅｌｉｎ所谓的“快波极限”不是一种好的近似。     

西太平洋副热带高压对华北地区降水蒸发差的影响

采用小波相关和交叉小波变换等方法, 分析了西太平洋副热带高压脊线和北界位置变化对华北地区降水蒸发差的影响。结果表明, 2000年以来华北区南部的水资源短缺问题有所缓解, 但以北京为中心的华北区东北部仍处于持续缺水期; 华北地区降水蒸发差与副热带高压脊线及北界位置变化相关密切, 存在年际和年代际尺度的显著相关振荡, 与副热带高压脊线的年代际尺度相关凝聚性最强; 时域中年际尺度相关存在局部化特征, 年代际尺度相关具有阶段性。分析认为, 2000年以来副热带高压脊线和北界位置偏北并维持反气旋型环流, 有利于水汽向华北输送, 使得华北降水增多, 是近年来华北中南部降水蒸发差增大的主要原因; 而东亚季风减弱不利于西南气流的水汽输送, 以及蒙古高原显著增暖导致蒸发增大等因素, 使得华北东北部仍处于持续缺水期。     

THERMAL FORCING IMPACTS OF THE EASTERLY VORTEX ON THE EAST-WEST SHIFT OF THE SUBTROPICAL ANTICYCLONE OVER WESTERN PACIFIC OCEAN

By employing the NCEP/NCAR reanalysis data sets(1 000 to 10 hPa,2.5°× 2.5°),the thermal forcing impacts are analyzed of an easterly vortex(shortened as EV) over the tropical upper troposphere on the quasi-horizontal movement of the Western Pacific Subtropical Anticyclone(shortened as WPS A) during 22-25 June 2003.The relevant mechanisms are discussed as well.It is shown that the distribution and intensity of the non-adiabatic effect near the EV result in the anomalous eastward retreat of the WPSA.The WPSA prefers extending to the colder region,i.e.,it moves toward the region in which the non-adiabatic heating is weakening or the cooling is strengthening.During the WPSA retreat,the apparent changes of non-adiabatic heating illustrate the characteristics of enhanced cooling in the east side of the EV.Meanwhile,the cooling in the west side exhibits a weakened eastward trend,most prominently at 300 hPa in the troposphere.The evidence on the factors causing the change in thermal condition is found:the most important contribution to the heating-rate trend is the vertical transport term,followed in turn by the local change in the heating rate term and the horizontal advection term.As a result,the atmospheric non-adiabatic heating generated by the vertical transport and local change discussed above is mainly connected to the retreat of the WPSA.     

Contrast in stress–strain history during exhumation between high- and ultrahigh-pressure metamorphic units in the Western Alps: Microboudinage analysis of piemontite in metacherts

Our analyses of microboudinage structures of piemontite grains embedded within six samples of metachert, one collected from an ultrahigh-pressure (UHP) metamorphic unit at Lago di Cignana in Italy of the Western Alps, and the other five from surrounding high-pressure (HP) metamorphic units in Italy and France, have revealed that the structures are all symmetrical in type, and were presumably produced in coaxial strain fields. Stress–strain analyses of the microboudinaged grains revealed significant contrasts in the stress and strain histories of the UHP and HP metamorphic units, with the differential stress recorded by the UHP sample being unequivocally lower than that recorded by the five HP samples. In addition, our analyses showed that the UHP sample underwent stress-relaxation during microboudinage, whereas the five HP samples did not. On the basis of these observations and analyses we discuss the mechanical decoupling of the UHP and HP units that led to different histories in differential stress between the units during exhumation of the Western Alps.     

Experimental Study of a Command Governor Adaptive Depth Controller for an Unmanned Underwater Vehicle

Unmanned Underwater Vehicles (UUVs) are increasingly being used in advanced applications that require them to operate in tandem with human divers and around underwater infrastructure and other vehicles. These applications require precise control of the UUVs which is challenging due to the non-linear and time varying nature of the hydrodynamic forces, presence of external disturbances, uncertainties and unexpected changes that can occur within the UUV’s operating environment. Adaptive control has been identified as a promising solution to achieve desired control within such dynamic environments. Nevertheless, adaptive control in its basic form, such as Model Reference Adaptive Control (MRAC) has a trade-off between the adaptation rate and transient performance. Even though, higher adaptation rates produce better performance they can lead to instabilities and actuator fatigue due to high frequency oscillations in the control signal. Command Governor Adaptive Control (CGAC) is a possible solution to achieve better transient performance at low adaptation rates. In this study CGAC has been experimentally validated for depth control of a UUV, which is a unique challenge due to the unavailability of full state measurement and a greater thrust requirement. These in turn leads to additional noise from state estimation, time-delays from input noise filters, higher energy expenditure and susceptibility to saturation. Experimental results show that CGAC is more robust against noise and time-delays and has lower energy expenditure and thruster saturation. In addition, CGAC offers better tracking, disturbance rejection and tolerance to partial thruster failure compared to the MRAC.     

西太平洋暖池热含量变化与东亚冬季风关系

利用 1955-2003 年 NCEP\NCAR 再分析资料和美国 Scripps 海洋研究所环境数据分析中心 ( JEDAC ) 提供的冬季热含量资料,采用小波分析、相关及合成分析等方法, 分析了西太平洋暖池热含量变化特征及其与东亚冬季风关系.结果表明,西太平洋暖池热含量与东亚冬季风有着非常密切的联系,当西太平洋暖池热含量异常偏高时,对流层低层在菲律宾及以东洋面形成一个异常的气旋性环流,中国大陆上空形成一个异常的反气旋性环流,从而使得东亚冬季风在东南区加强,西北区减弱.     

The impact of extreme turbidity events on the nursery function of a temperate European estuary with regulated freshwater inflow

Estuaries are used as nursery grounds by numerous marine species despite being usually subject to strong anthropogenic disturbances. Abundances of marine recruits (fish and crustacean decapods) and their main prey (mysids) were monitored by monthly sampling, from June 1997 to February 2009, in the lower reaches of the Guadalquivir estuary (SW Spain). During that period, unusually high and persistent turbidity events (HPTEs) were observed twice. Both HPTEs started with strong and sudden freshwater discharges after relatively long periods of very low freshwater inflow. Data from this time-series were used to test the hypothesis that HPTEs may negatively impact the nursery function of estuaries either by decreasing prey availability or by decreasing survival/arrival of marine recruits. During HPTEs, the commonest mysid (Mesopodopsis slabberi), a key species in the estuarine food web, showed a significant decrease in abundance. Likewise, some marine recruits that prey on M. slabberi and whose peaks of abundance within the estuary occur in summer–autumn (Engraulis encrasicolus and Pomadasys incisus) were less abundant during HPTEs. It is also suggested that HPTEs might have triggered a shift in the distribution of the most euryhaline prey (Neomysis integer) and predator (Dicentrarchus punctatus and Crangon crangon) species, towards more saline waters. This could have contributed to an increase in the inter-specific competition (for food/habitat) within the estuarine nursery area. The results discussed in this study call attention to the need to reduce as much as possible the anthropogenic pressures that may stimulate the occurrence of high and persistent turbidity events (HPTEs) in order to preserve the nursery function of temperate estuaries.     

辽宁地区金矿类型、成矿规律及找矿方向

详细叙述了辽西地区各金矿类型的地质特征和成矿规律,并指出其找矿方向。     

Petrogenesis and sedimentary environment of silicate in Late Paleozoic in Kala area of Western Sichuan Province

In order to study the sedimentary environment characteristics of the Late Paleozoic in Kala area of Western Sichuan Province, the authors have conducted the petrological and geochemical analyses of the widely distributed silicate in Qiongyi Formation of Lower Carboniferous and Kawenggou Formation of Upper Permian. The results show that the silicate in the study area belongs to the pure siliceous rocks, with a continuous supply of land-based materials during the deposition process. The average Al/(Al+Fe+Mn) ratio is 0.62, and the silicate shows a biogenic origin by the Al-Fe-Mn diagram. The ratios of Al₂O₃/ (Al₂O₃+ Fe₂O₃), Th/U, Th/Sc, (La/Ce)_N and (La/Yb)_N and tectonic environment discriminant diagram demonstrate that the silicate developed in a shallow-slope depesitional environment in the continental margin. The Ce_anom value is -0.04 to 0.07, and it gradually increases from the Carboniferous to the Permian period, indicating the water body is in an anoxic environment with gradually increasing reducibility. The Garz--Litang basin opened in the Carboniferous period, in accordance with the regional geological evolution, and it continued to expand during the Permian period, with the gradually increasing depth of the seawater within the sedimentary basins.