Showing papers by "Geophysical Survey published in 2012"

An Early Mesozoic transcontinental palaeoriver in South China: evidence from detrital zircon U–Pb geochronology and Hf isotopes

Abstract: Detrital zircon geochronology reveals that Late Triassic–Early Jurassic fluvial sandstones from the major basins of the South China Craton have similar age patterns and define four populations at 2.6–2.4 Ga, 2.0–1.7 Ga, 850–700 Ma and 480–210 Ma. The late Palaeoproterozoic group is predominant in all of the five samples, and yielded remarkable age peaks at c . 1.85 Ga. These zircons have ϵ Hf (t) values between −22.5 and +3.6, suggesting derivation from reworked Archaean crust and minor juvenile crustal additions in the late Palaeoproterozoic. These characteristics differ from those of the Yangtze Block but correlate well with those of samples from the eastern Cathaysia Block. Palaeocurrent analysis of the Early Mesozoic sandstones shows predominant west- and NW-directed palaeoflows, supporting derivation of the sediments from the Cathaysia Block. The remarkable similarities in provenance signatures and spatial changes of lithofacies of the Triassic–Jurassic around the South China Craton delineate an east–west-trending sedimentary zone extending from Korea to West China. Accumulation of these sediments was probably related to the development of an active continental margin produced by westward subduction of the Palaeo-Pacific Plate. A c . 2000 km long westerly draining transcontinental palaeoriver probably had existed in the Early Mesozoic and fed the basins in Korea, South China and West China. Supplementary material: Sensitive high-resolution ion microprobe and laser ablation–inductively coupled plasma mass spectrometry zircon U–Th–Pb and Hf isotope data are available at www.geolsoc.org.uk/SUP18514.

Hand-held Radar Device With Direct Printing Based on Radar Input

Abstract: The disclosed technology includes a device and method of use for direct printing and ink or other marking, in conjunction with GPR techniques. In a most basic embodiment of the disclosed technology, a relevant date, time, filename, and other parameters are printed or otherwise physically exhibited on the measurement surface, so that RADAR files can be later attributed to a specific data collection site. In a more advanced embodiment of the disclosed technology, actual RADAR target information is printed, or otherwise physically exhibited, on the measurement surface, such as while measuring, or substantially while measuring, the surface and substrate beneath with GPR.

Realization of time-domain ultra wideband ground-penetrating radar using high speed accumulation and interpolated sampling

Abstract: Embodiments of the disclosed technology use high-speed interpolated (interdigitated) sampling for the specific purpose of GPR (Ground-Penetrating RADAR). This technology solves several issues associated with high-speed sampling in GPR which included 1) dynamic range limitations, 2) regulatory compliance issues, 3) sampler core offset error, and 4) timing errors. High-speed interpolated sampling GPR is implemented using a high-speed ADC in combination with trigger logic (such as an FPGA) and a programmable delay generator. The FPGA or other trigger logic generates a series of randomly dithered trigger pulses. A variable delay generator (or “Vernier”) is synchronously controlled in order to produce the fractional timing. The timing of the pulses is randomly or pseudo-randomly dithered, and the phase of the interpolation is shuffled in order to avoid producing discrete spectral lines in the radiated RADAR signal.

Monitoring Subsidence in Tianjin Area Using the Multi-Baseline D-InSAR Technique

Abstract: Subsidence has been affecting Tianjin since 1960s. It posed comprehensive detrimental effects on natural environment, the economy and society. Considering the actual monitoring demand for land subsidence in Tianjin area, multi-baseline D-InSAR technique was studied. Using the multi-baseline DInSAR technique more interferograms can be generated, which is useful for retrieving the subsidence velocity accurately. And then regression algorithm and least square method are used to deal with the time series to get deformation result. In this paper, the multi-baseline DInSAR technique is used to measure the subsidence velocity in Tianjin area. It can be concluded that the algorithm is effective and feasible especially in the study area.

Sedimentary environment of Carboniferous-Permian Amushan Formation in Wulanaobao area of Urad Rear Banner,Inner Mongolia

Abstract: Based on field section survey of Wulanaobao area in Inner Mongolia and an analysis of such sedimentary features as lithologic composition,stratigraphy,paleontology,sedimentary structure and petrology,the authors divided the section into three segmentsThe lower segment is braided river delta facies transformed into littoral facies,the middle segment is carbonate platform facies,and the upper segment is littoral and neritic faciesThese sedimentary features suggest that in the Carboniferous-Permian Amushan period this area was located at the edge of the basin and experienced transformation from continental facies to marine facies,belonging to an onlap deposition processIn addition,the research on sedimentary facies and the determination of marginal facies prove that in the Carboniferous-Permian period Ejin Banner and its adjacent areas constituted a rift basin from the angle of sedimentologyThe results of the research provide some evidence for the study of basin evolution and sedimentary facies

Characteristics and Genetic Significance of Skarn in the Gaerqiong Cu-Au Deposit,Ge'gyai,Tibet

Abstract: The petrologic and mineralogical characteristics of the skarn in the Gaerqiong copper-gold deposit were studied in this paper.The skarn is mainly distributed in the contact zone between marble and quartz diorite as well as granite porphyry.It is distributed vertically as the zoning of marble-silicified hornfels-skarnized marble-wollastonite skarn-diopside skarn-garnet skarn-quartz diorite.A study of petrochemical,rare earth and trace element characteristics of the skarn-type ore shows that the skarn is calcic skarn,which has characteristics of weak negative Eu anomalies and LREE enrichment as well as the enrichment of large ion lithophile elements such as Rb,Th,Cs and U and the depletion of high field strength elements such as Hf,Ti and Y.The geochemical characteristics of skarn are controlled and affected by marbles,quartz diorite and granite porphyry.It is held that the skarn is genetically closely related to marble,quartz diorite and granite porphyry.Based on a discussion on the formation background of the Bangonghu-Nujiang metallogenic belt and the temporal-spatial relationship,the authors consider that the Gaerqiong deposit is a magmatic hydrothermal contact metasomatic type ore deposit.

A Method for InSAR Baseline Refinement Based on CR

Abstract: Interferometric baseline plays a very important role in InSAR data processing, and it will directly affect the accuracy of interferometric result. Shuping area is covered by all of vegetation, so the coherence is very low. In Shuping area, it is very difficulty to generate clearly residue stripe to use the FFT method and to find natural coherence pixels points as GCP to refine the baseline to meet the need of monitoring the deformation accurately. But through CR stability phase information can be got. So It is also highlights to the apply CR in this region to refine the baseline parameters. In this article, the baseline got from coarse orbit file is regarded as initial value, and that got from precise orbit file is regarded as True. By comparing and analyzing the parameters of refined baseline with that of the precise baseline, it can be concluded that the refined method based on CRs is correct and feasible.

A simple method to determine permittivity and attenuation coefficient of media by holographic radar

Abstract: Permittivity and attenuation coefficient have an important role in a GPR survey. These are used as the key properties. The general values of these properties are fundamentally well known, however the values usually vary site by site, and accurate values are sometimes necessary for proper analysis. There is a characteristic phenomenon called the “zebra effect” in holographic radar images from the “Rascan” system. The zebra effect is expressed as continuous black and white stripes on a radar image produced by scanning over a slanting flat reflector. This study describes a method to determine permittivity and attenuation coefficient from the zebra effect stripes, with the method applied to various materials. While there is a slight ambiguity in determining exact values, it is a simple method, easily performed on-site, that can provide material property estimates for specific localities.

Design, Deploy and Signal Analysis of Different Types of CR

Abstract: In Shuping area, it is difficulty to find enough nature coherent targets to use InSAR technique to monitor the landslide. In order to solve the problem, CRs(Corner Reflectors) were used to improve the effectiveness of this technology. In this article Pyramidal Corner Reflector, Asymmetric Cubic Corner Reflector, Double Direction Asymmetric Cubic Corner Reflector are designed. In order to achieve maximum reflection intensity of CR, it's attitude must be carefully adjusted to match with the SAR imaging parameters exactly. After the CRs were deployed, the strong echo signals can be retrieved from SAR images. Analyzing the SAR image peak signals to locate the CR is the premise of differential processing. Through image location and phase analysis of ASAR and RADARSAT-2, the CRs’ signals can be recognition certainly. During the data processing of ASAR and PALSAR, the CRs can be regarded as ideal coherence target points.

Pre-eruption deformation caused by dike intrusion beneath Kizimen volcano, Kamchatka, Russia, observed by InSAR

Abstract: Interferometric synthetic aperture radar (InSAR) images reveal a pre-eruption deformation signal at Kizimen volcano, Kamchatka, Russia, where an ongoing eruption began in mid-November, 2010. The previous eruption of this basaltic andesite-to-dacite stratovolcano occurred in 1927–1928. InSAR images from both ascending and descending orbital passes of Envisat and ALOS PALSAR satellites show as much as 6 cm of line-of-sight shortening from September 2008 to September 2010 in a broad area centered at Kizimen. About 20 cm of opening of a nearly vertical dike provides an adequate fit to the surface deformation pattern. The model dike is approximately 14 km long, 10 km high, centered 13 km beneath Kizimen, and strikes NE–SW. Time-series analysis of multi-temporal interferograms indicates that (1) intrusion started sometime between late 2008 and July 2009, (2) continued at a nearly constant rate, and (3) resulted in a volume expansion of 3.2 × 107 m3 by September 2010, i.e., about two months before the onset of the 2010 eruption. Earthquakes located above the tip of the dike accompanied the intrusion. Eventually, magma pressure in the dike exceeded the confining strength of the host rock, triggering the 2010 eruption. Our results provide insight into the intrusion process that preceded an explosive eruption at a Pacific Rim stratovolcano following nearly a century of quiescence, and therefore have implications for monitoring and hazards assessment at similar volcanoes elsewhere.