Geological structure and acoustic properties of sediments in Effingham Inlet

Thesis written for Oceanography 445

Geology and Geological Structure of the Alberta and Saskatchewan Plains

Alberta, responsible for ninety per cent of Canada's output, had, by 1947 entered into her fifth year of production decline. Only ten per cent of Canada's oil requirements were secured from home fields. Ninety per cent had to be imported, mainly from the United States. How long could imports be maintained on present levels? During the year, the United States had started rationing; in one sector of its domain. Would this become general? If so, what was the answer for Canada?

The geological structure of the north-west Highlands of Scotland.

Plates XL-LII each accompanied by leaf with descriptive letterpress.

Applied geology. A treatise on the industrial relations of geological structure; and on the nature, occurrence, and uses of substances derived from geological sources.

Available on demand as hard copy or computer file from Cornell University Library.

Acadian geology. The geological structure, organic remains, and mineral resources of Nova Scotia, New Brunswick, and Prince Edward Island.

"Geological bibliography of the Acadian provinces," p. 9-13.

Geological map of Geltinger Birk, western Baltic Sea, Germany

The geological structure of a Holocene sand spit system and the adjacent Weichselian glacial deposits in the northeastern part of Schleswig-Holstein have been investigated and presented in a geological map. Thin meltwater deposits overlie the glacial tills in the area of the former Beverö lsland in the west. To its north and northeast, the modern Sand spit system is present. Its basal transgression horizon is composed mainly of gravels and boulders, and directly overlie the Pleistocene deposits. Further up the succession, fine graind sands are present, in turn overlain by the coarser grained sands of the barrier bar. To the east, under the protection of the sand spit, gyttyas and peats which sometimes attain large thicknesses have been deposited under lacustrinellagoonal conditions. Closer to the shore, these sediments are covered by marine sands.

Simulation of Vibration Caused by Blasting for a Layered Slope

Recent studies showed that vibration caused by blasting mainly reflects the property of geological structure itself neighboring the blasting center. Different vibration signals can be collected for different geological structures under blasting. Hence, vibration signal can be used to identify geological structure, especial for a slope with a weak layer. As the geological structure for a practical slope is usually complicated, the simulation of vibration caused by blasting should be carried out first. Generally, the material in a certain zone near the blasting center will undergo damage, so the physical model to simulate this region is the most concerned. In this paper, the damaged zone near blasting center is neglected, and the blasting load can be considered being applied on the interface between the damaged zone and undamaged zone. Regarding the relations between the weight of explosive, the size of damaged zone, and the dynamic loading to propagate out away, the vibration caused by blasting for a practical layered slope is simulated. Compared with the measured signal in site, it can be seen that the simulating result is in well agreement with that of practical testing. The results also indicate that the farther the testing point apart from the blasting center, the more accurate the simulation is.

The ionic composition of surface waters in the English Lake District, related to bedrock geology, with some singular facts and speculation on the existence of mineral-rich groundwaters

This article is based on a survey of tarns conducted mainly in the summers of 1983 to 1985, plus a survey made in the winter of 1985, in which streams were sampled on the wide variety of rock-types occurring on the fringes of the Lake District. Differences in composition of major ions and their concentrations in the surface waters of Cumbria reflect the complex geological structure of the region. At altitudes above 300 m, on Borrowdale Volcanics and Skiddaw Slates, surface waters are derived from atmospheric precipitation, with additional inputs of some ions - especially calcium and bicarbonate - from catchment rocks and soils. In some of the low-lying large lakes on the fringes of the central fells, water composition is also dominated by inputs from upper catchments; examples are Wastwater, Ullswater and Haweswater. However in other lakes there is evidence (Derwentwater and Bassenthwaite Lake) of inputs from saline groundwater.

Padrões geoacústicos de fundo e sub-fundo na Baía de Sepetiba: implicações no conhecimento da geologia do holoceno

A Baía de Sepetiba, localizada entre a Baía de Guanabara e a Baía de Ilha Grande, Estado do Rio de Janeiro, está inserida em um cenário estratégico para o desenvolvimento econômico do Estado. Isto ocorre devido ao aumento da concentração populacional, que está diretamente relacionado com o turismo, com a presença de portos e de áreas industriais. Sendo assim, se faz necessário estudar sua estrutura geológica e dinâmica sedimentar para entender sua evolução ao longo do tempo e para uma utilização mais racional desta área. Utilizando-se da sísmica rasa de alta resolução e da sonografia de varredura lateral juntamente com dados pretéritos de amostragem superficial de sedimentos, o presente trabalho tem como objetivo principal analisar sua geologia holocênica. A investigação, em subsuperfície, da geologia estrutural e sedimentar dessa baía, através da interpretação de 09 perfis sísmicos, baseada na determinação de diferentes tipos de ecotexturas, revelou a presença de diferentes pacotes sedimentares depositados ao longo do Holoceno. Ao todo, foram encontrados 15 tipos de ecotexturas perfazendo 14 camadas sedimentares, que estão relacionados em 4 Grupos de acordo com sua distribuição. Já a investigação em superfície através dos registros sonográficos, baseada nos diferentes graus de reflexão acústica (backscattering) e parametrizada pelos dados de amostragem direta pretérita, identificou 6 padrões sonográficos distintos. Com isso foi confeccionado um novo mapa de distribuição textural dos sedimentos superficiais da Baía de Sepetiba. Com a correlação dos dados de sísmica rasa com os dados sonográficos, foi possível ainda sugerir a provável existência de neotectonismo na área de estudo.

Gas hydrate occurrence on the continental slope of the northern South China Sea

High-resolution multi-channel seismic data and geological samples were collected during two research cruises of the R/V FENDOU 4 in 1999 and 2000. Studies on these data and samples together with results from sites 1143-1145 and 1148 of ODP Leg 184 suggest that the geological structure on the continental slope of the northern South China Sea is favorable for the formation of gas hydrates. Bottom simulating reflectors (BSRs) and geochemical anomalies which indicate the existence of gas hydrates have been recognized in sediments of the Xisha Trough, the Dongsha Rise and the accretionary wedge of the Manila subduction zone. These gas hydrates are generated by two different mechanisms depending on the tectonic regime and the seismic and geochemical characteristics. The first applies to the passive continental margin of the nor-them South China Sea on the Dongsha Rise and in the Xisha Trough. The gas hydrates are associated with diapiric structures, active faults, slumps and gravity flows as well as high Late Cenozoic sedimentation rates. Their seismic expression includes BSRs, seismic blanking zones and velocity anomalies. The second mechanism is operative on the active continental margin along the Manila subduction zone, especially in the accretionary wedge. Here, gas hydrate occurrence is marked by widespread BSRs and acoustic 'pull-down' possibly related to the existence of free gas in the sediments beneath the BSR. The thickness of the seismic blanking zones averages 250 m, suggesting that the stable gas hydrate zone has about the same thickness. (c) 2005 Elsevier Ltd. All rights reserved.

承德公路隧道围岩分级与塌方机理分析

During tunnel constriction the classification of rock mass is widely used in tunnel design and construction. Moreover it offers the base information about tunnel investment and security. The quick classification of rock mass is very important for not delaying tunnel construction. Nowadays the tunnel engineers usually use initial survey files which are obtained by probe drilling to design a tunnel. It brings the problem that initial surrounding rock classification is usually much different from the real condition during the tunnel construction. Because initial surrounding rock lack credibility, it need us to make real time surrounding rock classification during the tunnel construction, and feed back the result to designers and constructors. Therefore, to find a quick wall rock classification method is very important not only for the time limit for a project but also for not delaying tunnel construction. Not all but many tunnels and underground constructions do suffer form collapse during the period of construction. Although accidental collapse in a large project in civil and geotechnical engineering sometimes appears to be a local event, if it occurred, it can bring about casualties, disrupted，production, construction delay, environmental damage, capital cost etc，therefore, it has been a difficult problem ,both in theory and in practice, establishing how to prevent underground structures form collapse and how to handle such an event in case in occurs. It is important to develop effective solutions and technical measures to prevent and control the collapse. According to the tunnel collapse occurred in Cheng De this paper analyze the main collapse mechanism leading to tunnel collapse and summon up the disposal method when collapse happened. It may be useful for tunnel construction in Cheng De in future. This paper is base on tunnel surrounding rock classification and tunnel support tasks during the tunnel construction in Cheng De area. It aims at solving 4 important problems in tunnel design and construction. 1) The relationship between rock rebound strength and rock single axle compression strength. First we go to the face wall and do rebound test on the tunnel face, then we chose some pieces of rock and do point loading test. Form the tests record we try to find the relationship between rock rebound strength and rock single axle compression strength. 2) The relationship between the value [BQ] and the value Q. First in order to obtain the information of rock character, rock strength, degree of weathering, the structure of rock mass, the joint condition, underground water condition and so on, we go to the tunnel face to do field investigation. And then we use two kinds of rock classification method to make surrounding rock classification. Base on the works above, finally we analyze the relationship between the value [BQ] and the value Q. 3) Sum up the mechanism leading to tunnel collapse and it disposal method in Cheng De area According to the tunnel collapse occurred in Cheng De this paper analyze the main reasons leading to the tunnel collapse and sum up the disposal method when collapse happened. 4) Obtain the properties of steel frame grid by numerical simulation. First we establish the 3D numeral model of steel frame grid by ADINA, and then find the mechanics properties by numerical simulation in ADINA. Second Based on the rock mass geological structure model, we established steel frame grid numeral model which is installed in the tunnel by FLAC3D and simulated the progress of tunnel construction. We hope that the support effect in tunnel can be evaluated from the numerical simulation.

华北及周边地区层析成像研究

Our study deals with the high resolution body wave tomography in North china and adjacent areas(30°N-43°N，100°E-130°E), where earthquakes occurred many times in history and has a very complicated geological structure. 6870 events recorded at 273 digital seismic stations from CDSN during 1996－2002 and stations settled by Seislab of IGCAS in Bohai Bay area, including 1382 local earthquakes and 5488 teleseismic earthquakes are used in this study. In the data we used, the average number of received stations is greater than 5, the error of picking up direct arrival time is 0.1－0.5s. Before the inversion, we use Checkerboard method to confirm the reliability of result of Local events; use Restoring Resolution Test to confirm the reliability of result of teleseismic events. We also analyzed the effect of different parameters in the inversion. Based the analysis above, the model used in this paper is divided into small blocks with a dimension of 0.33°in the latitude and longitude directions and 5km、15km、30km in depth, and initial velocity model. Using pseudobending method to calculate the ray traveling path, LSQR algorithm to inverse, finally, we got the body velocity images below 25km and above 480km in this area using Joint- inversion with local events and teleseismic events. We made the conclusion at last: (1)at top zone of the south of Sichuan Basin , there exits low velocity anomalies, below 40km is the high velocity zone extend to 300km; (2) Above the 40km of Ordos block exits low velocity zone, while below 40km until 240km, the high velocity anomalies are interlaced by low velocity anomalies. Below 300km, the anomalies are unclear any more; (3) On the whole, the velocity structure below 400km on the mantle transition zone of Eastern China area shows its changes from low velocity to high velocity.

复杂介质中地震波场数值模拟研究——基于广义正交多项式迭积微分算子法

In this paper, we propose a new numerical modeling method – Convolutional Forsyte Polynomial Differentiator (CFPD), aimed at simulating seismic wave propagation in complex media with high efficiency and accuracy individually owned by short-scheme finite differentiator and general convolutional polynomial method. By adjusting the operator length and optimizing the operator coefficient, both global and local informations can be easily incorporated into the wavefield which is important to invert the undersurface geological structure. The key issue in this paper is to introduce the convolutional differentiator based on Forsyte generalized orthogonal polynomial in mathematics into the spatial differentiation of the first velocity-stress equation. To match the high accuracy of the spatial differentiator, this method in the time coordinate adopts staggered grid finite difference instead of conventional finite difference to model seismic wave propagation in heterogeneous media. To attenuate the reflection artifacts caused by artificial boundary, Perfectly Matched Layer (PML) absorbing boundary is also being considered in the method to deal with boundary problem due to its advantage of automatically handling large-angle emission. The PML formula for acoustic equation and first-order velocity-stress equation are also derived in this paper. There is little difference to implement the PML boundary condition in all kind of wave equations, but in Biot media, special attenuation factors should be taken. Numerical results demonstrate that the PML boundary condition is better than Cerjan absorbing boundary condition which makes it more suitable to hand the artificial boundary reflection. Based on the theories of anisotropy, Biot two-phase media and viscous-elasticity, this paper constructs the constitutive relationship for viscous-elastic and two-phase media, and further derives the first-order velocity-stress equation for 3D viscous-elastic and two-phase media. Numerical modeling using CFPD method is carried out in the above-mentioned media. The results modeled in the viscous-elastic media and the anisotropic pore elastic media can better explain wave phenomena of the true earth media, and can also prove that CFPD is a useful numerical tool to study the wave propagation in complex media.

隐伏金矿床预测中的地震勘探险方法

Based on brief introduction of seismic exploration and it's general developing situation, the seismic exploration method in field work implementation and some problems frequently encountered in field, which should be pay attention to, are analyzed in detail. The most economic field work techniques are emphasized. Then the seismic data processing flow and it's interpretation technique about the processing results are presented. At last four examples of seismic prospecting in gold deposits are showed. The main conclusions of our research are: 1. Seismic prospecting technique is a very efficient method in the prediction of concealed gold deposits. With appropriate application, it can absolutely reflect the detail underground geological structure in the condition of rugged area and complicated geological environment. 2. The field geometry should be designed and changed according to different kinds of objective exploration depth and ground situation. The best field implementing parameters which include offset, the distance between two adjacent traces, the quantity of dynamite and the depth of hole for explosion, should be determined with examination. Only this way, the high quality original seismic data can be gotten. 3. In seismic data processing, the edition of invalid trace and source gather, signal enhancement, velocity analysis and migration are the key steps. It has some different points with conventional processing and needs a new processing flow and methods which is suitable to the data acquired in rugged area and complicated geological environment. 4. The new common reflection area stacking method in crooked line data processing is an efficient method to improve the signal to noise ratio of seismic data The innovations of our research work are: 1. In the areas which were considered to be forbidden zone, we implement the seismic exploration in several gold deposits in China through our application. All acquire distinguished effects. This show the seismic exploration method is a new effective method in the prediction of concealed gold deposits. 2. We developed a set of seismic field work techniques and data processing which is suitable to complex environment, especially find a effective method in stacking and noise elimination in crooked line data processing. 3. In the field of seismic profile interpretation, through our research work, we are convinced of that: in different kinds of geological condition, the seismic reflection character are not same. For example the lava, the intrusion rock and sediment layers are different in the character of reflection structure and strength. So we accumulate some experience about seismic data interpretation in the area of gold deposits.

青藏高原东部电性结构特征及地球动力学意义

As the largest and highest plateau on the Earth, the Tibetan Plateau has been a key location for understanding the processes of mountain building and plateau formation during India-Asia continent-continent collision. As the front-end of the collision, the geological structure of eastern Tibetan Plateau is very complex. It is ideal as a natural laboratory for investigating the formation and evolution of the Tibetan Plateau. Institute of Geophysics, Chinese Academy of Sciences (CAS) carried out MT survey from XiaZayii to Qingshuihe in the east part of the plateau in 1998. After error analysis and distortion analysis, the Non-linear Conjugate Gradient inversion(NLCG), Rapid Relaxation Inversin (RRI) and 2D OCCAM Inversion algorithms were used to invert the data. The three models obtained from 3 algorithms provided similar electrical structure and the NLCG model fit the observed data better than the other two models. According to the analysis of skin depth, the exploration depth of MT in Tibet is much more shallow than in stable continent. For example, the Schmucker depth at period 100s is less than 50km in Tibet, but more than 100km in Canadian Shield. There is a high conductivity layer at the depth of several kilometers beneath middle Qiangtang terrane, and almost 30 kilometers beneath northern Qiangtang terrane. The sensitivity analysis of the data predicates that the depth and resistivity of the crustal high conductivity layer are reliable. The MT results provide a high conductivity layer at 20~40km depth, where the seismic data show a low velocity zone. The experiments show that the rock will dehydrate and partially melt in the relative temperature and pressure. Fluids originated from dehydration and partial melting will seriously change rheological characteristics of rock. Therefore, This layer with low velocity and high conductivity layer in the crust is a weak layer. There is a low velocity path at the depth of 90-110 km beneath southeastern Tibetan Plateau and adjacent areas from seismology results. The analysis on the temperature and rheological property of the lithosphere show that the low velocity path is also weak. GPS measurements and the numerical simulation of the crust-mantle deformation show that the movement rate is different for different terranes. The regional strike derived from decomposition analysis for different frequency band and seismic anisotropy indicate that the crust and upper mantle move separately instead of as a whole. There are material flow in the eastern and southeastern Tibetan Plateau. Therefore, the faults, the crustal and upper mantle weak layers are three different boundaries for relatively movement. Those results support the "two layer wedge plates" geodynamic model on Tibetan formation and evolution.