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   

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   

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   

The British Cartographic Society Awards 2006     

none 《The Cartographic journal》2013,50(3):266-274

Abstract

While graphic variables in 2D maps have been extensively investigated, 4D cartography is still a widely unexplored field. In this paper, we investigate the usefulness of 4D maps (three spatial dimensions plus time) for cartographically illustrating spatio-temporal environmental phenomena. The presented approach focuses mostly on explorative research rather than on enhancement and extension of existing methods and principles. The user study described in the paper shows that 4D cartography is not a well-explored research area and that many experienced map users try to apply their knowledge from 2D maps to 4D dynamic visualisations. Thus, in order to foster the discussion within the community, we formulated several basic research questions for the area of 4D cartography, which range from methods for representing time in 4D visualisations and understanding the temporal context to finding generic methods to achieve optimized temporal generalisation and a consistent definition of graphical variables for 3D and 4D.  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   

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   

自动检测地震事件筛选方法研究     

唐伟  刘俊民  王海军  王晓明  石建芳  唐恒专  王燕  李靓  刘哲函 《地震地磁观测与研究》2013,34(3)

重点介绍禁核试北京国家数据中心研究的自动检测地震事件筛选方法.通过分析自动检测事件关联台站分布的合理性、关联台站的类型、关联信号参数的可靠性、多频带平均能量比等方法,判断自动检测事件的真伪.以国际数据中心审核公报事件为参考,研究的筛选方法可有效筛除43％自动检测虚假事件,使得自动检测误检率降低13％,并保持较低的误筛选率.此筛选方法可对国际数据中心以及禁核试北京国家数据中心不同处理平台的自动检测事件进行筛选分析.  相似文献   

珠江三角洲西缘晚第四纪沉积演化和最大海侵古岸线的重建     

周良  王洋  杜学斌  卜建军  吴俊  吕万军  刘秀娟 《沉积学报》2022,40(1):119-135

第四纪以来,受全球气候和海平面变化影响,海岸带地区发生了一系列强烈的海陆相互作用和海侵—海退等地质事件,包含了丰富的沉积环境演化和海平面变化等信息.选用珠江三角洲西缘台山地区的30个地质钻孔,通过14C、光释光、地球化学特征、底栖有孔虫、磁化率数据,建立了晚更新世以来的地层框架,重建了最大海侵古岸线的位置.研究结果表明...  相似文献   

Total sediment budget of a transgressive barrier-spit,Skallingen, SW Denmark: A review     

Christian Christiansen  Troels Aagaard  Jesper Bartholdy  Merete Christiansen  Jørgen Nielsen  Niels Nielsen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):107-126

Average sea-level rise in the northern part of the Danish Wadden Sea has been 1.3 mm a^?1 during the last 100 years but during the last 25 years a rise of 4.2 mm a^?1 was observed. Concurrent with the recent sea-level rise the Skallingen barrier spit has migrated landward by 3–5 m a^?1. Long term sediment budgets for each of the morphological units involved in the migration are reviewed (e.g. onshore in the shore face +90.000 m³ a^?1, longshore -641.000 m³ a^?1, foredunes +65,000 m³ a^?1, overwash fan including shorenormal dunes +11,000 m³ a^?1, spit terminus -96,000 m³ a^?1, tidal flat + 10,000 m³ a^?1 and backbarrier salt marsh +33,000 m³ a^?1) and used to establish the relative importance of sediment transport processes involved in barrier migration. Strong interannual variations exist in the long term budget making evaluation of barrier behaviour based on short term measurements doubtful. In a cross shore sense the barrier spit is accreting in spite of the sea level rise. This is specially pronounced at an active overwash fan. However, due to substantial sediment losses to longshore transport the barrier, gets narrower and shorter during its transgressive behaviour. This may indicate that preservation of barriers in the geological record during rapid sea level rise is promoted when sediment loss to longshore transport is insignificant.  相似文献   

Three-dimensional digital imaging of environmental data: selection of gridding parameters     

Carol A. EDDY  B. Looney 《International journal of geographical information science》2013,27(2):165-172

Abstract. Three-dimensional imaging is a powerful technique for the visualization and interpretation of environmental data. The success of the process is linked to careful, technically-justifiable selection of variable parameters during the gridding and imaging process. The impacts of various approaches to gridding and possible setting of parameters on the final image and volume calculations were examined by generating alternative images for a very well characterized contaminated site in layered coastal plain sediments. To image properly scattered data collected at close intervals in wells from layered geological media, a higher grid density in the z direction is required along with a weighting factor to emphasize the influence of data in the x and y directions. For steeply-varying contaminant concentration data, the best results were obtained by gridding the log of the property value; an anti-log transformation is carried out to restore property values to the correct value before the visualization file is prepared. The techniques and recommendations made in this article were designed for modelling contaminant values with very steep gradients dispersed in a strongly anisotropic media. These recommendations may not apply directly to other sites but the process of selecting parameters should be similar.  相似文献