不同定位模式下北斗单基站CORS定位精度分析

单基站CORS相对于多基站CORS具有成本低、建设时间短等优点.本文对北斗系统单基站RTD/RTK定位模型进行分析研究,并通过对实测数据对算法进行分析验证,RTD定位在东方向精度可以达到0.3 m,北方向精度可以达到0.4 m,高程精度可以达到0.8 m.RTK定位在平面精度可以达到1 cm,高程精度可以达到3 cm,可以满足不同类型的导航定位需求.     

地基合成孔径雷达技术研究与初步应用

阐述了地基合成孔径雷达测量的技术原理和应用方向,归纳了地基雷达形变测量的主要技术流程.通过实地测试验证其精度,地基合成孔径雷达技术具备探测毫米-亚毫米级形变信息的能力,地基雷达设备稳定可靠,具有广泛的应用前景.最后揭示地基合成孔径雷达技术在变形监测及预警中的问题,同时提出下一步的工作安排.     

南阿尔金地区早古生代中酸性侵入岩的岩石成因及其对构造演化的指示意义

南阿尔金造山带位于塔里木盆地和柴达木盆地之间,是中国西北地区重要的俯冲-碰撞杂岩带,其早古生代构造演化过程是近年来的研究热点之一,然而,洋壳俯冲的时限一直存在争议。本文对茫崖石英二长岩开展岩石学、地球化学、锆石U-Pb年代学和锆石Lu-Hf同位素地球化学研究,探讨其岩石成因及成岩时的构造环境。样品显示高碱、富钾、低钛、贫铁及Nd-Ta-Ti异常等与钾玄岩相似的地球化学特征,成岩年龄为511～495 Ma, ε_Hf(t)主要为-3.51～-0.08,少量介于0.04～1.69之间。我们认为俯冲洋壳到达角闪岩相边界时释放大量水并上升进入地幔楔,导致地幔楔橄榄岩发生角闪石化交代作用,由于地幔楔沿俯冲带向下拖曳而温度升高,角闪石化橄榄岩熔融形成的熔体在上升过程诱发上地壳物质部分熔融,壳源岩浆混合少量幔源岩浆形成了石英二长岩,该期花岗岩是对造山带从大洋岛弧环境向活动大陆边缘过渡的岩石学响应。因此,南阿尔金洋壳可能在约517 Ma前已经开始俯冲。     

Geochemical characterization of Archaean amphibolites from the eastern part of Anshan–Benxi iron producing area,northeastern China: implication for tectonic setting of BIFs

The Anshan–Benxi iron producing area, which is located at the northeastern margin of the North China Craton, is the main distribution area of Archaean BIFs in China. In their eastern part, including the Gongchangling and Waitoushan deposits, BIFs mainly are hosted in the Archaean middle Anshan Group. Amphibolites are widely distributed in the iron‐bearing rock series, reflecting the tectonic setting of BIFs. Amphibolites not only have MORB‐like compositional characteristics, but also have island arc‐like ones, and they are consistent with back‐arc basin basalts (BABB). In the study area, the protolith of amphibolites belongs to Okinawa‐type BABB; it indicates that tectonic setting of BIFs is the intra‐continental back‐arc basin. In the study area, the formation of sedimentary basins for BIFs had been associated with oceanic plate subduction. Amphibolites from Gongchangling deposit are characterized by relative enrichments in LILE and LREE, and depletions in HFSE. This indicates that they had a relatively large influence of subduction in their formation. Amphibolites from Waitoushan deposit are characterized by relative enrichments in LILE without conspicuous depletions in HFSE, indicating relatively low subduction rates. Copyright © 2015 John Wiley & Sons, Ltd.     

Secular period decreasing of detached chromospherically active binaries

The long-term orbital period changes of a large sample of detached chromospherically active binaries (CABs) were studied. Eleven such systems were found to be undergoing secular period decreases with the rates of ?6.3×10^?9 to ?1.1×10^?6 days per year. The period decreasing rates are found to vary depending on the orbital period. The longer the orbital period is, the more rapidly the period decreases. Following Stepien (Mon. Not. R. Astron. Soc. 274:1019, 1995), the period decreasing rate predicted by angular momentum loss (AML) caused by magnetic wind is computed for each system. A comparison between the observed and calculated period decreasing rates shows that the former values are obviously larger than the latter by 1–3 orders of magnitude. It suggests that the magnetic wind is not likely the determinant mechanism driving the AML in these systems. Finally, the orbital angular momentum (AM) and the rate of AML, $\dot{J}$ , are computed for each system. It shows that the AM have a similar change with the orbital period like dP/dt does, but $\log\dot{J}/J$ presents no strict changing with the kinematical ages.     

An inflection in the rate of early mid-Holocene eustatic sea-level rise: A new sea-level curve from Singapore

This study presents a sea-level curve from 9500 to 6500 cal BP for the farfield location of Singapore, on the Sunda Shelf in southeast Asia. The curve is based on more than 50 radiocarbon dates from elevations of +1.43 m to −15.09 m representing sea-level index points in intertidal mangrove and shallow marine sediments deposited by sea-level rise accompanying deglaciation. The results indicate that mean sea level rose rapidly from around −17 m at 9500 cal BP to around −3 m by 8000 cal BP. After this time, the data suggest (but do not unequivocally prove) that the rate of sea-rise slowed for a period of 300–500 years centred on 7700 cal BP, shortly after the cessation of meltwater input to the oceans from the northern hemisphere. Renewed sea-level rise amounting to 3–5 m began around 7400 cal BP and was complete by 7000 cal BP. The existence of an inflection in the rate of sea-level rise, with a slow-down centred on 7700 cal BP, is broadly consistent with other available sea-level curves over this interval and is supported by evidence of stable shorelines and delta initiation elsewhere at this time, as well as evidence of comparatively rapid retreat of the West Antarctic ice sheet beginning around 7500 cal BP. ‘Stepped’ sea-level rise occurring shortly after 7500 cal BP and also earlier during deglaciation may have served to focus significant post-glacial episodes of human maritime/coastal dispersal, into comparatively narrow time intervals.     

Bungalows, mansions and shophouses: Encounters in architourism

In architourism, tourists are attracted to places because of iconic buildings. Increasingly, non-iconic buildings of vernacular architectural styles are also appreciated by visitors as a way to authentically experience a place. This paper explores architourism in Malaysia and Singapore through the lens of historic boutique hotels. Geographical discourses in and methodologies of architectural geography are used to interrogate what these hotels mean for guests and hoteliers, and the effects on them too. Empirical findings deepen understanding of architourism through examining how ‘producers’ create culturally authentic environments in boutique hotels, and how ‘consumers’ utilise hotels to experience local cultures. The dual focus on production and consumption is in-line with critical architectural geography’s insistence on exploring the rhetoric of building design as well as the realities of their everyday uses and users.     

Estimation of aseismic crustal-strain using radon precursors of the 2003 <Emphasis Type="Italic">M</Emphasis> 6.8, 2006 <Emphasis Type="Italic">M</Emphasis> 6.1, and 2008 <Emphasis Type="Italic">M</Emphasis> 5.0 earthquakes in eastern Taiwan

Aseismic crustal-strain signals prior to the 2003 Mw 6.8 Chengkung, 2006 Mw 6.1 Taitung, and 2008 Mw 5.0 Antung earthquakes with epicenters located 20, 55 and 11 km, respectively, from the Antung radon-monitoring station have been calculated using the radon anomalies recorded. Specifically, radon decreased from background levels of 791 ± 46, 762 ± 57, and 735 ± 48 pCi/L to minima of 326 ± 9, 371 ± 9, and 480 ± 43 pCi/L prior to the 2003, 2006, and 2008 earthquakes, respectively. The estimated aseismic crustal-strain maxima at the Antung hot spring during the rock dilation stage were 3.6, 2.7, and 1.3 ppm, respectively. The v-shaped radon pattern recognized in all three anomalies is valuable for detecting the aseismic strain precursory to disastrous earthquakes in the Antung hot spring which is situated in a brittle fractured aquifer of limited recharge surrounded by ductile mudstone.     

地震纵波技术预测煤层瓦斯富集区的探讨与实践

基于国内外煤层瓦斯富集的岩石物理及地球物理响应的研究成果,提出了以煤层反射波振幅、频率及衰减等动力学特征变化为主要研究对象的地震纵波预测技术方案;探讨了利用叠后Gamma拟合声波约束反演、频谱分解属性分析和叠前AVO反演、弹性阻抗反演等纵波技术预测煤层瓦斯富集性的理论依据及实现方法。上述技术在沁水盆地进行了预测尝试,其获得的含气性预测成果与探井实测的瓦斯富集情况基本吻合,初步证明了上述纵波预测技术方法在开展煤层瓦斯富集区研究方面的可行性和有效性。