山东重大基础地质问题研究进展     

李洪奎  杨永波  耿科  曹丽丽 《岩石学报》2013,29(2):594-606

在1∶50万山东省大地构造相图编制和大地构造相综合研究的基础上,作者对山东重大基础地质问题提出了新的划分方案.山东地块是经多期增生和碰撞、镶嵌、叠覆而成的,其漫长的地质构造演化具明显的阶段性,可分为前南华纪、南华纪-中三叠世和晚三叠世-第四纪三大构造演化阶段.大地构造分区分为陆块区、造山系和叠加造山-裂谷系,划分出3个Ⅰ级构造单元、5个Ⅱ级构造单元、18个Ⅲ级构造单元和55个Ⅳ级构造单元.基于鲁东和鲁西地区在地层建造、岩浆活动、构造格局和成矿作用等存在的重大差异性,新厘定的渤海陆块作为华北陆块区之下的Ⅱ级构造单元.厘定大别-苏鲁造山带的北部边界、鲁西陆块与渤海陆块的边界.对古元古代荆山群、粉子山群形成的构造环境进行了深入探讨,认为是弧后盆地靠近大陆边缘一侧的构造背景,在古元古代晚期的造山过程中,粉子山群和荆山群等均卷入了造山过程,其中荆山群发生了深俯冲及高压麻粒岩相变质作用.胶东地区构造-岩浆事件和金矿成矿作用受控于特提斯、古亚洲洋和太平洋三大构造域,金矿形成于中生代构造体制转折和岩石圈减薄的动力学背景,与华北板块和扬子板块碰撞及太平洋板块的俯冲机制存在密切成因关系.  相似文献   

珠江三角洲晚第四纪沉积的OSL和¹⁴C年龄探讨   总被引：2，自引：0，他引：2       下载免费PDF全文

郭良田  王萍张珂盛强赵华  王成敏 《中国地质》2013,40(6):1842-1849

提要：珠江三角洲第四纪沉积的年代测定在三角洲的发育演化、古海平面变化以及断裂活动性研究等方面具有重要意义。对东江平原的7个钻孔岩心进行了14C和OSL测年以及孢粉和微体古生物分析。与前人主要根据14C年龄得到珠江三角洲沉积小于4万年的认识不同,OSL测年结果显示下部地层的年龄值为4.7~13.5万年。本文对年龄的信度以及晚第四纪两次海侵旋回的地层年代框架进行了初步分析,提出珠江三角洲地区第一次海侵旋回可能发生于距今4~10万年期间;在晚更新世与全新世两次海侵之间,三角洲地区长期暴露地表,出现较大跨度的地层缺失。  相似文献   

Holocene stratigraphic and morphological evolution of the Wandandian Creek delta,St Georges Basin,New South Wales     

C. A. Hopley  B. G. Jones 《Australian Journal of Earth Sciences》2013,60(6):991-1000

Subaerial exposure beside the Wandandian Creek channel during the last glacial maximum led to the development of red and orange mottling and, in some areas, produced a palaeosol over the Pleistocene land surface. Incision of the palaeo-Wandandian Creek, during the Late Pleistocene, formed a relatively deep steep-sided channel partially infilled with medium-grained fluvial sand. This palaeovalley became drowned as the post-glacial marine transgression impounded the western portion of St Georges Basin and the basal prodelta/lagoonal mud facies was deposited from ca 7 ka. The Wandandian Creek delta prograded down the palaeovalley and reached the study area ～3500 – 4000 years ago with the deposition of delta-front sandy silt and the overlying prograded sand facies. The subaerial portion of the delta is characterised by well-developed floodplains, levees, mouth bars and backswamps. Dredging in Wandandian Creek and land clearing for rural and urban development have had little long-term effect on the growth and morphology of Wandandian Creek delta.  相似文献   

近50 a来民勤绿洲-荒漠过渡带气候变化及沙尘天气特征     

马瑞  王继和  屈建军  刘虎俊  孙涛 《中国沙漠》2011,30(4):1031-1036

 根据近50 a民勤绿洲-荒漠过渡带气象和风沙观测资料,对过渡带温度、降水、蒸发量、相对湿度、风沙活动等气候要素进行了系统的分析。结果表明,近50 a过渡带平均增温率为0.009 ℃·a-1,20世纪80年代后增温显著,增温率高达0.025 ℃·a-1,增温主要发生于冬、春两季; 降水呈波动上升趋势且年际稳定性增强,近8 a与60年代相比,增加幅度达27.45%,增加主要发生于春、秋两季; 蒸发量减少,相对湿度线性增加; 受气候变化,沙尘暴在近50 a持续减少,而扬沙和浮尘天气与人为干扰关系密切,存在波动和反弹; 气候变化对过渡带退化植被的恢复与重建以及沙漠化的逆转将起到正面作用。  相似文献   

Understanding the adaptation deficit: Why are poor countries more vulnerable to climate events than rich countries?     

《Global Environmental Change》2014

Poor countries are more heavily affected by extreme weather events and future climate change than rich countries. One of the reasons for this is the so-called adaptation deficit, that is, limits in the ability of poorer countries to adapt. This paper analyses the link between income and adaptation to climate events theoretically and empirically. We postulate that the adaptation deficit may be due to two factors: A demand effect, whereby the demand for the good “climate security” increases with income, and an efficiency effect, which works as a spill-over externality on the supply-side: Adaptation productivity in high-income countries is enhanced because of factors like better public services and stronger institutions. Using panel data from the Munich Re natural catastrophe database we find strong evidence for a demand effect for adaptation to two climate-related extreme events, tropical cyclones and floods. Evidence on the efficiency effect is more equivocal. There are some indications that adaptation in rich countries might be more efficient, but the evidence is far from conclusive. The implication for research is that better data, in particular on adaptation effort, need to be collected to understand adaptation efficiency. In terms of policy, we conclude that inclusive growth policies (which boost adaptation demand) should be an important component of international efforts to close the adaptation deficit.  相似文献   

1961—2010年山西省极端气温年均发生频率的时空特征分析     

秦秀丽 《沙漠与绿洲气象(新疆气象)》2014,8(2):59-64

利用山西省61个气象站点逐日最高温度、最低温度资料,采用百分位值定义法、Mann原Kendall突变检验法和Morlet小波变换等方法,分析了山西省近50 a极端温度事件年均发生频率的时空特征,结果表明：1961年以来,山西省极端高温事件年均发生频率呈显著增加趋势,趋势为6.1 d/10 a,与此同时,极端低温事件年均发生频率呈显著减少趋势,且极端气温事件的变化存在明显的区域差异;极端高温和极端低温年均发生频率均发生了突变现象,变化趋势均在20世纪90年代以来更加显著;极端高温和极端低温事件年均发生频率均呈显著波动变化,在整个研究期间极端高温存在5～6a、4～8a显著周期,极端低温存在4～5a显著周期。  相似文献   

基于两步SVD变换的零偏VSP资料上下行波场分离方法          下载免费PDF全文

高磊  陈文超  王保利  高静怀 《地球物理学报》2013,56(5):1667-1675

垂直地震剖面(Vertical Seismic Profiling,VSP)资料处理中波场分离是关键问题之一.随着属性提取技术的发展,新的属性参数(例如Q值)提取技术对波场分离的保真性要求越来越高.本文改进了传统奇异值分解(Singular Value Decomposition,SVD)法,给出了一种对波场的动力学特征具有更好的保真性,可以作为Q值提取的预处理步骤的零偏VSP资料上下行波场分离方法.该方法通过两步奇异值分解变换实现:第一步,排齐下行波同相轴,利用SVD变换压制部分下行波能量;第二步,在剩余波场中排齐上行波同相轴,使用SVD变换提取上行波场.在该方法的实现过程中,压制部分下行波能量后的剩余波场中仍然存在较强的下行波干扰,使得上行波同相轴的排齐比较困难.本文给出了一种通过极大化多道数据线性相关程度(Maximize Coherence,MC)排齐同相轴的算法,在一定程度上解决了低信噪比下排齐同相轴的问题.将本文提出的方法用于合成数据和实际资料的处理,并与传统SVD法的处理结果进行对比,结果表明本文提出的波场分离方法具有良好的保真性,得到波场的质量明显优于传统SVD法.通过对本文方法和传统SVD法处理合成数据得到的下行波场提取Q值,然后进行对比可知,本文方法可以有效提高所提取Q值的准确性,适合作为Q值提取的预处理步骤.  相似文献   

测绘机构在突发公共事件中的应急地理信息服务探讨     

李姝祺 《北京测绘》2013,(2):91-93,96

简述突发公共卫生事件的含义、特点以及测绘部门在突发公共卫生事件中的任务与必要性,提出地理信息应急服务机制建设的建议,包括建立快速应急反应机制、应急服务网络系统和统一标准,资源共享等。  相似文献   

序列状态的林业资源时空数据模型研究     

夏凯  刘仁义  刘南  张国江  谢炯  张丰 《测绘学报》2013,42(3):433-439

对林业地理实体时空演变过程进行分析,认为林业地理实体的演变总体上是渐变和突变交替的时空过程,而且各专题属性和空间分布的演变类型和演变频率不尽相同。在此基础上,提出由序列快照和事件方法组合而成的序列状态时空表达方法,以状态集表达时空对象在生命周期内的演化历程,并针对林业数据的特点,采用面向对象的数据组织方式设计了林业资源时空数据模型。模型可对不同演变类型进行组合,并实现了对渐变和突变的统一表达,另外,模型也允许采用不确定数据以加强对渐变过程的表达。通过原型系统验证了模型的可行性。  相似文献   

Distinguishing human and climate influences on hydrological disturbance processes in the Columbia River,USA     

David A. Jay 《水文科学杂志》2013,58(7):1186-1209

Abstract

This paper distinguishes human and climate influences on the Columbia River streamflow disturbance regime, examines how this disturbance regime has changed over the last 150 years, and discusses downstream impacts. Flow management and withdrawal have greatly curtailed exceedence of the natural bankfull level of ～20 000 m³ s^-1. The frequency distribution of Columbia River flow has also changed. Sediment transport is positively correlated with streamflow standard deviation, and has been greatly reduced by flow regulation. Three kinds of spring freshet style have been identified; there are also three kinds of winter freshet. Flow regulation and regional climate warming have changed freshet styles and reduced maximum flows during the spring season. Downstream effects of hydrological alterations include increased salinity intrusion length, loss of shallow water habitat area during the freshet season, increased tides throughout most of the year, and a decrease in area of the Columbia River plume during spring and summer. Although climate changes and variations have played a substantial role in changing the hydrological disturbance regime, their influence is still less than that of human manipulation of the flow cycle.

Citation Jay, D. A. & Naik, P. K. (2011) Distinguishing human and climate influences on hydrological disturbance processes in the Columbia River, USA. Hydrol. Sci. J. 56(7), 1186–1209.  相似文献