A natural example of crystal-plastic deformation enhancing the incorporation of water into quartz

Water content of quartz in and around a greenschist facies mylonitic shear zone located in the western Adirondacks was analyzed by micro-FTIR spectroscopy. The shear zone is within a pegmatitic dike, which cuts across a granitic gneiss. The thickness of the shear zone varies along strike from 15 cm wide and encompassing all of the pegmatite dike at its northern most exposure to 5 cm wide approximately 10 m south, along strike. Microstructures, including quartz ribbons and recrystallized grains, indicate quartz and feldspar within the mylonite underwent dislocation creep. Infrared spectral analysis was carried out using a Nicolet micro-FTIR on mylonitic quartz ribbons, pegmatitic quartz and gneissic quartz. A small aperture size (56 μm by 50 μm) for the IR beam allowed optically clear regions of the quartz grains to be analyzed without any contribution from grain boundaries. The smallest dimension of the quartz ribbons is 0.3 mm, whereas the pegmatitic quartz has a grain size of 3 to 5 cm. Results show mylonitic quartz ribbons contain the most water (320 H:10⁶ Si average, range of 50 to 1120 H:10⁶ Si); pegmatite quartz contains much less water (30 H:10⁶ Si average, range of 20–40 H:10⁶ Si) and the gneissic quartz contained an intermediate amount (200 H:10⁶ Si average, range of 20 to 870 H:10⁶ Si). These data indicate that water was preferentially incorporated into the deformed quartz ribbons.     

基于EEMD方法的河南省倒春寒时空分布分析

根据1961-2014年河南省100个站3-4月的逐日气温资料,以及河南省倒春寒标准,建立倒春寒发生次数的时间序列,采用集合经验模态分解(EEMD)、Mann-Kendall等方法研究了河南省倒春寒时空分布特征。结果表明,河南倒春寒发生次数基本上呈现出自西南向东北逐渐增多的空间格局,2~3级倒春寒发生次数呈现出北少南多的空间格局。河南整个中部地区发生倒春寒的总次数较多,并且也会发生较为严重的倒春寒。通过EEMD分析,IMF1模态和趋势项基本反映了倒春寒的演变规律。河南倒春寒的年发生次数有一个明显的准5 a周期振荡,且发生次数呈明显的减少趋势。2000年和2005年为突变点,在春季增暖的气候背景下倒春寒年发生次数开始减少。     

1906-2015年武汉市温度变化序列重建与初步分析

本文利用1906-2015年武汉月平均最高与最低气温资料,重建了过去110年武汉市年平均气温距平序列,分析了其年代际尺度的变化特征。主要结论为：①过去110年武汉市经历了“暖—冷—暖”3个多年代际波动,其中1906-1946年与1994-2015年气候相对温暖,1947-1993年则气候相对寒冷;②在多年代尺度上,武汉市存在多次显著增温和降温过程,其中增温速率最快的30年和50年分别出现在1980-2009年和1960-2009年;最快降温速率则出现在1928-1957年和1925-1974年;③过去110年武汉市年均温发生了3次跃变,其中由冷转暖的跃变出现在20世纪20年代初和90年代中后期,而由暖转冷的跃变则出现在40年代;④武汉市年均温变化与全球/北半球和中国的变化趋势基本一致,但变幅偏大。此外,全球增暖停滞现象在武汉市最近十几年也有所体现。     

新疆北疆地表水资源时空分布及变化特征初探

采用经验正交函数展开分析了新疆北疆地表水资源的时空分布特征，将北疆地表水资源序列由２５０ａ延长到４１２ａ，并首次提出了将两个来自不同树轮年表的重建序列进行合并所应满足的条件。分析了４１２ａ来北疆地表水资源的突变与渐变特征，对其形成了一些新认识，较之以前的工作取得了一些新进展。     

提取断层位移突变信息的一种方法与实践

本文提出了一种适合于跨断层形变测量数据处理的相对分析平差原理,并应用突变论方法分析了相对位移突变及其稳定性问题,实例验证了方法的正确性。     

Fault-zone structure and weakening processes in basin-scale reverse faults: The Moonlight Fault Zone,South Island,New Zealand

The >200 km long Moonlight Fault Zone (MFZ) in southern New Zealand was an Oligocene basin-bounding normal fault zone that reactivated in the Miocene as a high-angle reverse fault (present dip angle 65°–75°). Regional exhumation in the last c. 5 Ma has resulted in deep exposures of the MFZ that present an opportunity to study the structure and deformation processes that were active in a basin-scale reverse fault at basement depths. Syn-rift sediments are preserved only as thin fault-bound slivers. The hanging wall and footwall of the MFZ are mainly greenschist facies quartzofeldspathic schists that have a steeply-dipping (55°–75°) foliation subparallel to the main fault trace. In more fissile lithologies (e.g. greyschists), hanging-wall deformation occurred by the development of foliation-parallel breccia layers up to a few centimetres thick. Greyschists in the footwall deformed mainly by folding and formation of tabular, foliation-parallel breccias up to 1 m wide. Where the hanging-wall contains more competent lithologies (e.g. greenschist facies metabasite) it is laced with networks of pseudotachylyte that formed parallel to the host rock foliation in a damage zone extending up to 500 m from the main fault trace. The fault core contains an up to 20 m thick sequence of breccias, cataclasites and foliated cataclasites preserving evidence for the progressive development of interconnected networks of (partly authigenic) chlorite and muscovite. Deformation in the fault core occurred by cataclasis of quartz and albite, frictional sliding of chlorite and muscovite grains, and dissolution-precipitation. Combined with published friction and permeability data, our observations suggest that: 1) host rock lithology and anisotropy were the primary controls on the structure of the MFZ at basement depths and 2) high-angle reverse slip was facilitated by the low frictional strength of fault core materials. Restriction of pseudotachylyte networks to the hanging-wall of the MFZ further suggests that the wide, phyllosilicate-rich fault core acted as an efficient hydrological barrier, resulting in a relatively hydrous footwall and fault core but a relatively dry hanging-wall.     

黄河源区土壤温湿和大气参量变化特征

利用中国科学院西北生态环境资源研究院玛曲土壤温湿观测网2008-2009年、2013-2014年数据验证了3套再分析资料ERA-Interim,CFSR（Climate Forecast System Reanalysis）和JRA-55（Japanese 55-year Reanalysis）在黄河源区的适用性,结合中国气象数据网玛曲气象站1980-2014年观测资料与CLM4.5（Community Land Model 4.5）进一步分析了黄河源区近35年气候变迁、土壤温湿分布和变化,结果表明:CFSR能够较好地描绘黄河源区土壤湿度变化,ERA-Interim对于土壤温度刻画能力更强,JRA-55效果较差;35年来气温、土壤温湿总体呈上升趋势且发生突变;近年来10 cm土壤温湿有暖干化趋势,降水量稍有增加,土壤冷季冻结周期变短,暖季持续时间拉长;CLM4.5模拟精度高,能够较好地刻画源区土壤温湿变化细节,两湖及黄河周边暖季为冷湿中心,冷季为暖干中心。     

Transition of Tidal Waves from the East to South China Seas over the Taiwan Strait: Influence of the Abrupt Step in the Topography

Observations of tidal waves between the East and South China Seas (ECS and SCS) over the Taiwan Strait (TS) suggest that the diurnal tides simply appear as one southward-propagating wave from the ECS to the SCS through the TS. The semidiurnal tides, however, behave differently in that they appear as a southward-propagating Kelvin wave in the western TS and a nearly standing wave in the eastern TS, and then diminish rapidly over the shallow shoal in the southern TS. A smaller-domain model, with sea-level boundary conditions derived from a larger-domain tidal model, was first used to simulate tides in the TS to an overall percentage of accuracy of about 90%. Subsequent numerical experiments and theoretical analysis revealed that the southward-propagating semidiurnal tides to be impeded and then reflected as they arrive at an abrupt, deepened step in the topography of the southern TS. This reflection enhances the amplitudes of the incident semidiurnal tides and contributes to the formation of a nearly standing wave in the eastern TS. The southward-propagating diurnal tides in the TS are connected by the diurnal tides in the northern SCS when the amplitudes of the two tide systems are comparable and their phases nearly equal at the step. This revised version was published online in July 2006 with corrections to the Cover Date.     

Abrupt changes in the discharge and sediment load of the Pearl River,China

The abrupt changes in the streamflow and sediment load at nine hydrological stations of the Pearl River basin were systematically analysed by using the simple two‐phase linear regression scheme and the coherency analysis technique. Possible underlying causes were also discussed. Our study results indicated that abrupt changes in the streamflow occurred mainly in the early 1990s. The change points were followed by significant decreasing streamflow. Multiscale abrupt behaviour of the sediment load classified the hydrological stations into two groups: (1) Xiaolongtan, Nanning and Liuzhou; and (2) Qianjiang, Dahuangjiangkou, Wuzhou, Gaoyao, Shijiao and Boluo. The grouped categories implied obvious influences of water reservoirs on the hydrological processes of the Pearl River. On the basis of analysis of the locations and the construction time of the water reservoirs, and also the time when the change points occurred, we figured out different ways the water reservoirs impacted the hydrological processes within the Pearl River basin. As for the hydrological variation along the mainstream of the Pearl River, the water reservoirs have considerable influences on both the streamflow and sediment load variations; however, more influences seemed to be exerted on the sediment load transport. In the North River, the hydrological processes seemed to be influenced mainly by climate changes. In the East River, the hydrological variations tended to be impacted by the water reservoirs. The study results also indicated no fixed modes when we address the influences of water reservoirs on hydrological processes. Drainage area and regulation behaviour of the water reservoirs should be taken into account. The results of this study will be of considerable importance for the effective water resources management of the Pearl River basin under the changing environment. Copyright © 2011 John Wiley & Sons, Ltd.     

全新世千百年尺度气候波动机制

全新世（11. 7 ka BP）作为最年轻的地质年代,其气候变化相对晚更新世冰期稳定,但仍存在千百年尺度的气候波动。造成这些气候波动的可能有多种原因,但至今还没有统一的认识。这一时期的气候变化与人类发展有密切的关系,因此其短尺度的气候变化越来越受到学界的关注,已经开展了大量的研究。通过对文献资料分析,综述了全新世千百年尺度的气候突变的原因。全新世早期温度普遍升高主要与太阳活动变化有关,期间冰盖消融与海洋环流作用引起百年尺度的气候事件。全新世中期气温最高,但也发现多次干冷气候事件,主要为冰川活动导致。全新世晚期温度降低,主要是以火山活动导致的气候变冷。其他因素如地球轨道参数、潮汐作用、冰川作用、海洋环流等在全新世各个时期对气候造成影响。