GPS高程转换的一种改进算法

针对用拟合局部似大地水准面实现GPS高程转换的方法在山区大比例尺重力勘查领域难以推广应用的情况,提出GPS高程转换的一种改进算法,即利用基于重力似大地水准面推导的高程异常差公式将GPS测定的大地高差转换为正常高差,进而实现GPS高程的有效转换.通过算例分析表明,这种方法完全适用于大比例尺重力勘探工作.     

基于EGM2008模型的重力观测点GPS高程转换

在重力勘探工作中,重力成果的精度受重力观测点高程的影响尤为明显。在分析了EGM2008模型的精度基础上,提出一种基于该模型的重力观测点GPS高程转换方法,并利用某地区GPS水准资料,对转换方法的可行性进行验证分析,结果表明,这种方法完全适用于中小比例尺重力勘探工作。     

GPS 高程拟合转换正常高在重力勘探中的应用

GPS测量所提供的高程为相对于WGS-84椭球的大地高,而重力勘探中使用的是正常高.本文简要介绍了用多项式曲面拟合方法拟合高程异常的原理,并用水准仪测量的水准高程对拟合的正常高进行了精度评估,总结了采用GPS拟合高程在高精度重力勘探中的应用效果.     

浅水域及其边缘重力测点的地改问题

随着国民经济的发展,区域重力工作已由纯陆域扩展到了江、河、湖、滨海等浅水域及其边缘陆地地区,这对区域重力工作在方法技术上提出了新的要求。这类工作目前主要用于石油资源勘查,其布格异常总精度要求较高,一般为100～200×10~(-8)m.s~(-2),有的甚至高于100×10~(-8)m.s~(-2)。虽然其工作比例尺属区域重力范围,但精度要求之高已达到大比例尺重力工作的精度,一般称之为重力细测工作,具有两个特点: 作为区域重力工作,根据“五统一”的     

区域似大地水准面的二次精化及其软件实现

为了满足区域重力调查高精度测地工作的要求,实现不同坐标系之间的转换,通过区域似大地水准面的二次精化方法及开发的软件,将GPS大地高转换到正常高。采用实测26个水准点外检核精度,全区软件转换精度为±5.57 cm,完全满足重力测量中高程精度要求。     

GPS在1∶20万区域重力调查中的应用

近年来,在1∶20万区域重力调查工作中主要使用GPS确定重力测点的空间位置。GPS测量测得的是椭球高程,而我国重力测量求得的是水准高程。目前,野外工作中采用GPS基准站周围50km范围内忽略高程异常的办法进行重力测点高程的测量。文章介绍了GPS测量原理及我国常用的大地坐标系,根据连续5年在山区进行的1∶20万区域重力测量的实际资料,讨论了这种工作方法能达到的精度。     

重力近区地形改正精度探讨

在大比例尺重力勘探工作中,近区、中区地形改正误差对重力总精度影响较大。在实际工作中,近区域地形改正一般采用实测或用地形图读图计算;中区地形改正一般采用地形图读图计算,《大比例尺重力勘查规范》只考虑地形图高程精度对重力总精度的影响,忽略了地形图平面坐标精度对重力总精度影响。这里从锥形、扇形基本地形改正公式推导出发,探讨不同比例尺,不同高程,平面精度对重力总精度的影响,并提出了不同地形改正精度对地形图比例尺及高程,平面精度要求建议。     

GPS在1:20万区域重力调查中的应用

近年来，在1：20万区域重力调查工作中主要使用GPS确定重力测点的空间位置。GPS测量测得的是椭球高程，而我国重力测量求得的是水准高程．目前，野外工作中采用GPS基准站周围50km范围内忽略高程异常的办法进行重力测点高程的测量．文章介绍了GPS测量原理及我国常用的大地坐标系，根据连续5年在山区进行的1：20万区域重力测量的实际资料，讨论了这种工作方法能达到的精度。     

GPS技术在枣庄市城市控制测量中的应用

枣庄市城市控制测量项目采用现代大地测量的方法,利用D级GPS控制网作为测区首级控制网和精密水准点,选用20个点构成骨架网,按照GPS网的可靠性指标、精度指标、效率指标,进行优化设计;利用Trimble DINI12电子水准仪进行GPS四等水准联测,通过一定数量和分布均匀的GPS/水准点进行高程拟合.该项目了取得的成果精度,完全符合1∶500大比例尺测图的要求.     

CQG2000模型在青藏高原地区的精度检验及其对区域重力调查工作的意义

区域重力调查中,测点正常高的精度直接影响重力测量成果的精度。利用CQG2000似大地水准面模型对GPS测得的大地高程进行改算,可得到较高精度的正常高成果。然而,CQG2000似大地水准面模型在不同地区的精度和分辨率是不同的,在青藏高原地区精度相对差些。通过对CQG2000似大地水准面模型在青藏高原地区精度的实地检验,证实其在该地区的精度可以满足1:20万区域重力调查工作中求取测点正常高的精度需要。通过上述实验,总结出用CQG2000模型提高区域重力调查中GPS高程测量精度的方法,对区域重力调查工作有重要意义。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861