Geoscientific Investigations Research Articles

Geoscientific investigations in search of tsunami deposits in the environs of the Agoulinitsa peatland, Kaiafas Lagoon and Kakovatos (Gulf of Kyparissia, western Peloponnese, Greece)

Geoscientific investigations in search of tsunami deposits in the environs of the Agoulinitsa peatland, Kaiafas Lagoon and Kakovatos (Gulf of Kyparissia, western Peloponnese, Greece)

Geoscientific investigation of a remanent anomaly - Teetulpa, South Australia

We investigate a small (100 metre width) 150 nT amplitude magnetic anomaly delineated in a high-resolution aeromagnetic survey in the Teetulpa Goldfield of the southern Flinders Ranges. We believe that the anomaly is due to a kimberlite pipe, part of a field already known in the general region. As is quite common with kimberlites, the magnetization is clearly dominated by remanence. Modelling the anomaly reveals that the source is very shallow, and would have outcropped at some stage. Follow-up ground geophysical, geochemical and biogeochemical investigations are planned to establish a methodology for integrated studies as follow-up to high resolution aeromagnetic surveys.

Automated stereo-photogrammetric DEM generation at high latitudes: Surface Extraction with TIN-based Search-space Minimization (SETSM) validation and demonstration over glaciated regions

Digital elevation models (DEMs) are critical to a wide range of geoscience investigations. High-latitude and polar regions are particularly challenging for automated, stereo-photogrammetric DEM extraction due to the abundance of surfaces that are low-contrast and repetitively textured, such as snow and shadowed terrain, and have discontinuities such as in crevasse fields, glacier calving faces or iceberg edges. Sub-meter, stereo-mode satellite imagery of high geometric and radiometric quality is becoming increasingly accessible, offering the potential for dramatically increasing the spatial coverage and quality of high-latitude DEMs. Here we demonstrate and validate automated DEMs generated from the Surface Extraction with Triangulated Irregular Network-based Search-space Minimization (SETSM) algorithm designed for these challenging terrains using only the satellite rational polynomial coefficients (RPCs). Comparison between 2-m DEMs created from WorldView image pairs and low-altitude LiDAR point clouds in west Greenland give DEM biases of less than 5 m, which is the maximum systematic RPC error. Co-registration with the LiDAR data reduces the DEM RMS error to ~20 cm, which is comparable to the uncertainty of the LiDAR data. We demonstrate SETSM’s automatic RPC refinement and bias reduction by successfully extracting a high-quality DEM from Pleiades stereo pair images with large RPC errors. Finally, we provide examples of SETSM DEMs that demonstrate their utility for a range of applications of interest to polar scientists.

Geoscientific investigations in search of tsunami deposits in the environs of the Agoulinitsa peatland, Kaiafas Lagoon and Kakovatos (Gulf of Kyparissia, western Peloponnese, Greece)

Geoscientific investigations in search of tsunami deposits in the environs of the Agoulinitsa peatland, Kaiafas Lagoon and Kakovatos (Gulf of Kyparissia, western Peloponnese, Greece)

地質環境調査におけるノウハウ及び意思決定プロセスの表出化

地質環境調査におけるノウハウ及び意思決定プロセスの表出化

A review of the ∼1600 Ma sedimentation, volcanism, and tectono-thermal events in the Singhbhum craton, Eastern India

The Palaeoproterozoic–Mesoproterozoic transition (∼1600 Ma) is a significant event in the Earth history as a global thermal perturbation affected the pre-1600 Ma landmasses. Like other cratonic blocks of the world, lithospheric thinning, sedimentation, magmatism, metamorphism and crustal melting/anatexis are associated with this significant geological event in the Singhbhum cratonic province of India. This paper is a review of sedimentological, magmatic and tectono-thermal events in the Singhbhum craton at ∼1600 Ma. The Palaeo-Mesoproterozoic sedimentation and volcanism in the Singhbhum craton took place in a terrestrial intracontinental rift setting. The available geochronological data are indicative of late Palaeoproterozoic to Neoproterozoic tectono-thermal events in the Chhotanagpur Granite Gneissic Complex (CGGC), an east–west trending arcuate belt of granite gneisses, migmatites and metasedimentary rocks. A detailed multidisciplinary geo-scientific investigation of the Dalma volcanic belt and the area to its north (Chandil Formation) and further north in CGGC will enable us to constrain the extant surface processes and crust-mantle interactions, the collision events between the North and South Indian cratonic blocks, and the position of India in the Columbia supercontinent.

Quantification of mineral behavior in four dimensions: Grain boundary and substructure dynamics in salt

Here we present the first four dimensional (time and three dimensional space resolved) experiment on a strongly deformed geological material. Results show that even complicated microstructures with large continuous and discontinuous changes in crystallographic orientation can be resolved quantitatively. The details that can be resolved are unprecedented and therefore the presented technique promises to become influential in a wide range of geoscientific investigations. Grain and subgrain scale processes are fundamental to mineral deformation and associated Earth Dynamics, and time resolved observation of these processes is vital for establishing an in‐depth understanding of the latter. However, until recently, in situ experiments were restricted to observations of two dimensional surfaces. We compared experimental results from two dynamic, in situ annealing experiments on a single halite crystal; a 2D experiment conducted inside the scanning electron microscope and a 3D X‐ray diffraction experiment. This allowed us to evaluate the possible effects of the free surface on grain and subgrain processes. The extent to which surface effects cause experimental artifacts in 2D studies has long been questioned. Our study shows that, although the nature of recovery processes are the same, the area swept by subgrain boundaries is up to 5 times larger in the volume than observed on the surface. We suggest this discrepancy is due to enhanced drag force on subgrain boundaries by thermal surface grooving. Our results show that while it is problematic to derive absolute mobilities from 2D experiments, derived relative mobilities between boundaries with different misorientation angles can be used.

An externalization of decision-making processes and logic structure in the geoscientific investigation, in the case of an investigation of uplift and denudation

An externalization of decision-making processes and logic structure in the geoscientific investigation, in the case of an investigation of uplift and denudation

Flow-types and lava emplacement history of Rajahmundry Traps, west of River Godavari, Andhra Pradesh

Rajahmundry Traps has been under geo-scientific investigations for over half a century; yet sketchy information is available on morphology and internal architecture of lavas. This study bridges this gap by describing the morphology of lava pile of Duddukuru area following Hawaiian scheme that relates a lava-type with a particular emplacement style.

Intervention of Electrical Resistance Tomography (ERT) in Resolving Hydrological Problems of a Semi Arid Granite Terrain of Southern India

Abstract Electrical Resistivity Tomography (ERT) has been used in association with several geohydrological, geotechnical and geophysical methods in resolving several site specific problems in hydrological science. Advancement in the field of computers and automation in the field of electronics has jointly resulted in the development of this geophysical innovation which has wide application in groundwater, environmental and engineering problems including monitoring of vadose zone water movement, steam injection etc. In this paper application of ERT in association with geohydrological and other exploration methods in resolving groundwater sustainability problem of a micro-watershed area in semi arid granite terrain is presented as three independent cases. In a hard rock terrain the probability of complexities in understanding the sub-surface lithology and its corresponding hydrological parameters are more. Hence appropriate resistivity survey configuration and suitable inversion of acquired data in congregation with other geo-scientific investigations were carried out to understand the site specific problem. The study demonstrated as 3 independent cases shows the usefulness of the ERT method in hydrological investigations, which is economic, efficient and less time consuming in comparison to the other exploration methods.

Preview: Geomechanics and Tunnelling 5/2011

AbstractProceedings of the 60th Geomechanics ColloquiumBenefits of geotechnical measurementsW. Schubert & B. Moritz: State of the art in evaluation and interpretation of displacement monitoring data in tunnels H. Walter & C. Kitzler: Duration and continuity of monitoring: wishful thinking and realityG. Barla & M. Alessio: Thorough geotechnical monitoring of a subway tunnel in service below rail link under construction in TorinoU. Maidl, M. Köhler & K. Schretter: Application of the observational method in TBM tunnellingM. Müllegger, G. Lenz & H. Laimer: Geotechnical monitoring as key safety management element at the Dürnstein/Wachau rock slideT. Pilgerstorfer, B. Moritz & A. Goricki: Assembling data from different sources to a coherent model: evaluation and interpretation of monitoring data from the instrumentation adit Paierdorf Accidents, lessons learned and their preventionA. Maier: Lessons learned from mine collaps Lassing?R. Poisel, R. Hofmann, A. Preh, T. Sausgruber & M. Schiffer: Lessons learned from Gschliefgraben mudslide (Austria)J. Hartley & R. Bashir: Shaft sinking experience in the Athabasca Basin and geoscientific investigations for future shaftsJ. Golser & E. Button: Experience in tunnelling in the Himalaya B. Moritz, J. Koinig & G.‐M. Vavrovsky: Geotechnical safety management during tunnelling – An efficient approach for minimising risk Criteria for the selection of construction M. Flora, W. Puprer & K. Bergmeister: Characteristics and potential for innovation of the tunnelling methods NATM, ADECO‐RS and TBMD. Bach, R. Hödl, J. Lemmerer & A. Vig: Risk analysis for the selection of the adequate tunnelling method for the Pummersdorf TunnelM. Spiegl & E. Schneider: Selection of tunnelling method by use of examplesH. Ehrbar, A. Sala & R. Wick: Criteria for the selection of tunnelling methods at the Gotthard Base TunnelM. John & G. Pilser: Criteria for selecting a tunnelling method using the first and second tube of the Pfänder Tunnel as exampleH. Wagner, G. Zwittnig, J. Daller & A. Fasching: Series of tunnels in Granitztal: Decision‐making process on tunnelling methodZ. Ekici, C. Rüegg, N. Salcher, O. Wagner & J. Weigl: Selection of the Tunnelling method for the new Semmering Base Tunnel Current large projectsM. Freitag, M. Larcher & A. Hager: The hydro power plant project HPP Reißeck IIB. Tauch, M. Reith & D. Handke: Shield tunnelling at the border area of experienceN. Reichard, J. Voringer & M. Rappold: Ortsumfahrung Hausmannstätten Tunnel Himmelreich – From exploration tunnel to completion of main tunnelM. Brunnerm & E. Enengl: Difficulties facing near‐surface tunnelling in creeping soilM. Weh & F. Bertholet: TBM‐advance in the main adit to the Nant de Drance pumped storage power plantC. Dulake: Crossrail – Design and construction

Geodynamical evolution of the transition zone of the Amundsen Sea (West Antarctica, the Southern Ocean)

The paper is based on the results of geoscience investigations conducted within the continental margin of the Amundsen Sea during the expeditions of the German research vessel “Polarstern”. The analysis and interpretation of the new data together with the geological and geophysical information available from the earlier studies of this region showed that the transition zone of the Amundsen Sea was formed as an Atlantic-type passive margin since the end of the Late Cretaceous to the present time. The tectonic-magmatic evolution of the continental margin has been significantly affected by the mantle-plume activity that led to the destruction of the continental and oceanic basement and to the formation of the Marie Byrd Seamount Province.

A deep rock laboratory in the Dellen impact crater

The Deep Rock Lab is a platform to establish a comprehensive subsurface bedrock characterization approach, by integrating site characterization techniques applied from different disciplines of geo-mechanics, geochemistry, hydrogeology, structural geology, lithology and geophysics, with consideration of the effects of coupled geological processes of importance for the understanding of groundwater renewal, continental shield deformations, engineering issues related to geological disposal of nuclear waste and CO2, and geothermal energy retrieval in crystalline rocks. The approach will focus on the physics and chemistry of crystalline rocks and groundwater with down-the-hole measurements of relevant variables, using and developing more efficient geo-scientific site investigation techniques for deep boreholes at a chosen site, and develop more advanced down-the-hole measurements and numerical modelling methods with more advanced inversion algorithms to help integrate data interpretations and object representations. The goal is to develop this platform into a long-term research facility that can be readily used by the scientific community for both subsurface fundamental and engineering-oriented research. Such a platform will be especially important for the education of PhD students for generations to come. The integrated drilling and research facility is suggested to be located at the Dellen site. This site has an impact crater with a large range of expected physical property changes with depth, complex and multiple thermal processes that have affected the bedrock, a favorable infrastructure and local supporting activities, and a large body of existing geo-scientific data.

Deformation, seismicity, and fluids: Results of the 2004/2005 water injection experiment at the KTB/Germany

During the past decades, the research into fluid‐controlled geodynamic processes in the upper crust of the Earth is put foreward regarding the stress accumulation, deformation, and seismicity. In a large‐scale injection experiment at the deep borehole site KTB (Kontinentale Tiefbohrung der Bundesrepublik Deutschland) in Germany, more than 84.000 m3 fresh water was injected in 4000 m depth over 10 months, and a lot of geoscientific investigations were connected to this injection test. The pore‐pressure change of more than 10 MPa yielded an induced deformation, which was detected by a tiltmeter array. The used five borehole tiltmeters of the ASKANIA type with a resolution of better than 1 nrad belong to the most sensitive tiltmeters worldwide. The poro‐elastic finite‐element modeling used for the interpretation of the observed tilts revealed an uplift of 3.1 mm above the injection point. Furthermore, it was shown that the induced stress and deformation fields depend mainly on the fluids inside the fault zones, particularly the SE2‐reflector which is the Franconian fault zone, and the local Nottersdorf fault: While the maximum pore pressure is concentrated close to the injection point at the SE2 zone, the maximum deformation of about 3 cm is located at the intersection line of both faults in 4 km depth. The area of the modeled maximum deformation is highly correlated with the region of the observed induced seismicity, thus linking seismicity and deformation. The connection of tilt observation and modeling provides a useful tool for the investigation of fluid coupled geoprocesses.

Geoscience and high-level nuclear waste disposal: the Nordic scene

In Norden, two countries, Sweden and Finland, are actively engaged in site investigations for the location of deep repositories for spent nuclear fuel from powerproducing nuclear reactors. These investigations are being carried out in crystalline rocks of the Fennoscandian Shield. In Sweden, a long history of site selection has led to the identification and investigation of two sites, Forsmark and Laxemar/Simpevarp, based on a strategy of combining favourable bedrock with consent by the local population. Surface-based geoscientific investigations of the two candidates, with extensive deep drilling, are now drawing to a close. A proposal as to which of the sites would be most suitable for the development of a deep repository will be submitted to the governmental regulatory authorities in 2009. In Finland, the site selection process was shorter and less politically controversial, and led to a Decision in Principle by the Finnish parliament, in May 2001, to develop a deep repository at the Olkiluoto site. The access tunnel to an underground rock characterisation facility at 400-500 m depth is at present under construction, accompanied by extensive geoscientific investigations in the subsurface. An application for a construction licence for a deep repository will be submitted in 2012. Although all sites are located in Precambrian crystalline rocks, the Swedish sites both lie in relatively homogeneous granitic rocks, whilst the Finnish site is located in an heterogeneous migmatite complex. The Nordic approach to high-level nuclear waste disposal in crystalline rock will be the theme of a Topical Symposium at the 33rd International Geological Congress at Oslo, in August 2008, and the three sites mentioned above will be the focus of Congress Excursion no. 14.

Geoscientific investigations for mapping the subsidence risk in an urban area

The geomorphological characteristics of the Salento peninsula (Puglia, south-eastern Italy) mean that movements of mass are extremely rare. These phenomena particularly affect certain coastal zones characterized by cliffs in rapid retreat and some unusual points in the hinterland in which collapses, generally linked to the development of karstic cavities, are common. These phenomena demonstrate the brittleness of some areas of the Salento and they constitute a restraint on the use of the territory itself. The town of Nardo is one of the sites at greatest geological risk in the Salento peninsula. In the last few decades, the historical centre of Nardo has been affected by a series of subsidence events, which have, in some cases, resulted in the partial collapse of buildings and road surfaces. These events have had both social repercussions, causing alarm and emergency situations, and economic repercussions in terms of the expense of restoration. In order to determine the causes of the ground subsidence events, integrated geophysical surveys were undertaken in the historical centre of Nardo. In addition, the historical succession of the subsidence events seen over the last 50 years was reconstructed, with the purpose of estimating the dimensions of the phenomenon and its possible relationship with specific environmental conditions (for instance intense precipitation). The study led to the production of a ground subsidence risk map of a sample area and made it possible to determine the real dimensions of the problem and to identify its causes.

Validation of ERS-1 and High-Resolution Satellite Gravity with in-situ Shipborne Gravity over the Indian Offshore Regions: Accuracies and Implications to Subsurface Modeling

Geoid and gravity anomalies derived from satellite altimetry are gradually gaining importance in marine geoscientific investigations. Keeping this in mind, we have validated ERS-1 (168 day repeat) altimeter data and very high-resolution free-air gravity data sets generated from Seasat, Geosat GM, ERS-1 and TOPEX/POSEIDON altimeters data with in-situ shipborne gravity data of both the Bay of Bengal and the Arabian Sea regions for the purpose of determining the consistencies and deviations. The RMS errors between high resolution satellite and ship gravity data vary from 2.7 to 6.0 mGal, while with ERS-1 data base the errors are as high as 16.5 mGal. We also have generated high resolution satellite gravity maps of different regions over the Indian offshore, which eventually have become much more accurate in extracting finer geological structures like 85° E Ridge, Swatch of no ground, Bombay High in comparison with ERS-1satellite-derived gravity maps. Results from the signal processing related studies over two specific profiles in the eastern and western offshore also clearly show the advantage of high resolution satellite gravity compared to the ERS-1 derived gravity with reference to ship gravity data.

The role of forensic geoscience in wildlife crime detection

The increase in both automation and precision in the analysis of geological materials has had significant impact upon forensic investigations in the last 10 years. There is however, a fundamental philosophical difference between forensic and geological enquiry. This paper presents the results of forensic geoscientific investigations of three cases of wildlife crime. Two cases involve the analysis of soils recovered after incidents of illegal badger baiting in the United Kingdom. The third case involves the illegal importation of Eleonora's Falcon ( Falco eleonorae) into the United Kingdom from the Mediterranean. All three cases utilise the analysis of soils by a variety of physical, chemical and biological techniques. These involve mineral and grain size analyses, cation and anion compositions, pH, organic content and pollen analysis. The independent analysis undertaken by specialists in each of these three main fields conclude firstly, that there is a significant similarity between sediments taken at the crime site at both badger setts and with sediments recovered from various spades, shovels and clothing belonging to suspects and secondly, that the soils analysed associated with the removal of the falcon eggs in the Mediterranean contained characteristics similar in many respects to the soils of the breeding areas of F. eleonorae on the cliffs of Mallorca. The use of these independent techniques in wildlife crime detection has great potential given the ubiquitous nature of soils and sediments found in association with wildlife sites.

New technology approach needed for mining industry

Rob Gordon of Quantec Geoscience, Toronto, Canada suggests that improved mining exploration results will only come with acceptance of new geoscience and other technology. Fundamental methodologies for mining exploration are finally benefiting from the precedent of the oil industry. The technologies used in 3D distributed seismic systems have now been applied to electrical earth imaging. Recent advances in digital signal processing and faster computers, coupled with the ability to collect very high resolution and deep geophysical data, means that physical property contrasts can now be discriminated from the surface with accuracy and depth penetration not previously seen. This provides new opportunities to further geoscientific investigation in mining environments at greater depths prior to drilling. Maximum value and more realizable returns are demanded from exploration expenditures today. Now the mining industry can systematically interrogate the ground in the search for orebodies while essentially sterilizing unfavourable ground in the process. In addition, as the oil sector continues to seek improvements in technology to increase exploration success rates, it has begun to experiment with electrical methods again. This technology should prove quite interesting to the forward looking groups in both sectors. Making a discovery is difficult and is arguably more difficult as undiscovered deposits today are more likely found at greater depths. The financial risk of deep drilling is hindering deep exploration. However, the mining industry has been traditionally slow to embrace new technology particularly if it is not easily understood or when the cost paradigm is out of sync with traditional spending habits regarding drilling versus other technologies. Drill targeting has to be more focused thereby providing better returns per metre drilled. In essence, high potential ground may gp be under-explored. Economists have often said a critical failure in exploration is the inefficiency even while targeting highly prospective regions. Today, imaging to depths of over 1500 m can assist with deeper exploration within favourable land packages. Moreover, technology can now provide a means to revitalize exploration in mature mining camps. A ‘bottom-up’ vs ‘top-down’ exploration process begins to address economic concerns about drilling risk and discovery rates.

Collision Tectonics between the Tarim Block (Basin) and the Northwestern Tibet Plateau: New Observations from a Multidisciplinary Geoscientific Investigation in the Western Kunlun Mountains

AbstractNew results from deep seismic reflection profiling, wide‐angle reflection‐refraction profiling and broadband seismic experiments reveal that a series of south‐dipping reflectors occur on the southern margin of the Tarim block (basin). However, it is these south‐dipping structures that are intercepted by another series of north‐dipping reflectors at depths from 30 to about 150 km beneath the foreland of the W Kunlun Mountains. No evidence from the above geophysical data as well as geochemical and surface geological data indicate the southward subduction of the Tarim block beneath the W Kunlun Mountains (NW Tibet plateau), forming the so‐called “two‐sided subduction” model for the Tibet plateau as proposed by previous studies. So the authors infer that the tectonic interaction between the Tarim block and the W Kunlun block was chiefly affected by a “horizontal compression in opposite directions”, which brought about “face‐to‐face contact” between these two lithospheric blocks and led to the thickening, shortening and densifying of the lithosphere. Hence a “delamination” was formed due to the gravitational instability created by the thickening and densifying; then alkaline basic volcanic rocks (mainly shoshonite series) was erupted along the northern margin of the Tibet plateau owing to the delamination. This inference for the formation of the alkaline basic volcanics has been confirmed by recent geochemical and petrological studies in Tibet, indicating that different contacts control different magmatic activities: the alkali basalts are always developed in the “horizontal shortening boundary (contact)” on the northern margin of the Tibet plateau, while the muscovite granite and two‐mica granite (leucogranite) in the “subductional contact” on the southern margin of the Tibet plateau.