粤东梅州地区1：5万区调主要成果与进展

在粤东梅州地区完成的1：5万区域地质调查,对区内地层进行了多重划分和对比研究,理清了地层层序;将“兴梅混合岩田”解体为变质表壳岩和变质深成岩;采用双重填图法,查明了火山岩相、火山机构分布特征,划分了火山活动旋回;对侵入岩进行重新划分和研究,首次将永和北．三枫侵入体解体为超基性、中性和中酸性侵入岩;对构造形迹进行调查研究...     

非零偏移距声地层剖面多次波的时距分析及压制示例

基于对符合二维观测的模型中非零偏移距全程多次波时距关系的理论分析可知:无论地下反射界面为水平的还是倾斜的,非零偏移距的全程n次多次波的旅行时总是小于相应一次波旅行时的n倍,但非零偏移距与零偏移距全程多次波的时距差异,随偏移距的增大而增大,而随探测深度的增大而减小。基于该理论分析结论,对在零偏移距假设下计算的多次波旅行时先行调整,使其与非零偏移距的多次波旅行时相对应后再进行压制处理,可获得更高质量的声地层剖面。     

基于频率差异的多次波识别

从简化的海洋地震勘探的基本模型出发,根据一次波和多次波的传播所经介质品质因子的不同,通过理论分析和数值实验证明了随着传播时间的增加,一次波的主频可明显低于同一时间段的海水鸣震主频;提出了将多次波的传播时间和相应主频结合起来判别多次波的"时间-频率识别模式"。实际资料的处理实验表明:与传统的"时间识别模式"相比,基于"时间-频率识别模式"的多次波衰减,可在压制多次波的同时较好地保持有效信号的基本特征。     

Memory in place

Geographers and psychologists both seek to understand people's behaviour and their cognitive and emotional lives so it is somewhat surprising that there has not been more theoretical cross‐fertilisation of the two disciplines. ‘On time, place and happiness’ is a rare but welcome exception, showing how research in social‐cognitive psychology might usefully clarify thinking about temporality, place and well‐being. This commentary examines several additional human memory phenomena that geographers might like to consider in their theorising about these matters.     

多元均生函数模型及其在短期气候预测中的应用

在原均生数模型的基础上，对模型进行改进，首次引入预报因子变量，建立一个多元的均生函数模型。它适应于气温、降水、热带气旋个数等多种要素预报。新建的多元均生函数模型包含了原模型的优点。而且比原有均生函数模型具有更物理基础。     

Spatial evolution and growth mechanism of urban networks in western China: A multi-scale perspective

Journal of Geographical Sciences - Globalization and informatization promote the evolution of urban spatial organization from a hierarchical structure mode to a network structure mode, forming a...     

Pyrite paragenesis and multiple sulfur isotope distribution in late Archean and early Paleoproterozoic Hamersley Basin sediments

The sulfur isotope record in late Archean and early Paleoproterozoic rocks is of considerable importance because it provides evidence for changes in early Earth atmospheric oxygen levels and potentially constrains the origin and relative impact of various microbial metabolisms during the transition from an anoxic to oxic atmosphere. Mass independently fractionated (MIF) sulfur isotopes reveal late Archean and early Paleoproterozoic sulfur sources in different pyrite morphologies in Western Australia's Hamersley Basin. Multiple sulfur isotope values in late Archean pyrite vary according to morphology. Fine grained pyrite has positive sulfur MIF, indicating a reduced elemental sulfur source, whereas pyrite nodules have negative sulfur MIF, potentially derived from soluble sulfate via microbial sulfate reduction. The Hamersley Basin δ³⁴S–Δ³³S record suggests that the extent of oxygenation of the surface ocean fluctuated through the Late Archean from at least 2.6 Ga, more than 150 million yr before the Great Oxidation Event. In the early Paleoproterozoic, there is less distinction between pyrite morphologies with respect to sulfur isotope fractionation, and pyrite from the Brockman Iron Formation trends toward modern sulfur isotope values. An important exception to this is the strong negative MIF recorded in layer parallel pyrite in Paleoproterozoic carbonate facies iron formation. This may suggest that deeper water hydrothermal environments remained anoxic while shallower water environments became more oxidised by the early Paleoproterozoic. The results of the current study indicate that sulfide paragenesis is highly significant when investigating Archean and early Paleoproterozoic multiple sulfur isotope compositions and sulfur sources.     

Complex multiple cosmogenic nuclide concentration and histories in the arid Rio Lluta catchment,northern Chile

Terrestrial cosmogenic nuclide (TCN) concentrations measured in river sediments can be used to estimate catchment‐wide denudation rates. By investigating multiple TCN the steadiness of sediment generation, transport and depositional processes can be tested. Measurements of ¹⁰Be, ²¹Ne and ²⁶Al from the hyper‐ to semi‐arid Rio Lluta catchment, northern Chile, yield average single denudation rates ranging from 12 to 75 m Myr^–1 throughout the catchment. Paired nuclide analysis reveals complex exposure histories for most of the samples and thus the single nuclide estimates do not exclusively represent catchment‐wide denudation rates. The lower range of single nuclide denudation rates (12–17 m Myr^–1), established with the noble gas ²¹Ne, is in accordance with palaeodenudation rates derived from ²¹Ne/¹⁰Be and ²⁶Al/¹⁰Be ratio analysis. Since this denudation rate range is measured throughout the system, it is suggested that a headwater signal is transported downstream but modulated by a complex admixture of sediment that has been stored and buried at proximal hillslope or terrace deposits, which are released during high discharge events. That is best evidenced by the stable nuclide ²¹Ne, which preserves the nuclide concentration even during storage intervals. The catchment‐wide single ²¹Ne denudation rates and the palaeodenuation rates contrast with previous TCN‐derived erosion rates from bedrock exposures at hillslope interfluves by being at least one order of magnitude higher, especially in the lower river course. These results support earlier studies that identified a coupling of erosional processes in the Western Cordillera contrasting with decoupled processes in the Western Escarpment and in the Coastal Cordillera. Copyright © 2008 John Wiley & Sons, Ltd.     

测井声波时差反演重构技术研究及应用

利用测井声波时差、自然电位和伽玛重构声波时差,分析了以上3种曲线结果对地质体响应方面的机制差异,给出了这些曲线的深度相对移动校正的方法。研究了多条测井曲线去噪的协方差矩阵特征向量滤波方法。在此基础上,利用小波多尺度分解技术进行声波时差曲线重构。在分析这3种测井曲线不同尺度小波分解结果的信号和噪音特点后,利用相邻分解尺度相关滤波技术,对各种曲线的小尺度(高频)分解结果进行滤波处理。为保证重构声波曲线的真实性,深入分析了多曲线、多尺度分解结果的冗余性(相关性)问题;利用特征值技术,对高频多尺度分解分量进行了非相关(正交)分析,最后实现了声波时差曲线的重构,并对重构结果与钻井岩心录井资料进行了对比验证,重构后的声波曲线在区分砂、泥岩性分辨率方面具有明显的提高     

基于波场外推压制水层多次波

重点讨论了基于克希霍夫积分的波场外推方法预测水层多次波的方法原理及具体的数值实现.自适应减法是波动方程方法压制多次波的另一个重要方面,考虑到Monk提出的带约束的互均衡化算法在复杂模型情况下压制效果不是很理想,本文对其算法进行了改进,提出了基于矩形窗和海宁(hanning)窗的分段匹配算法,模型算例的处理结果表明,改进后的算法具有一定的优越性.