96 research outputs found
Experimental Estimation of Compressional Velocities of a Series of Swedish Crystalline Rocks and Ores
Seismic methods in mineral exploration and mine planning: A general overview of past and present case histories and a look into the future.
Due to high metal prices and increased difficulties in finding shallower deposits, the exploration for and exploitation of mineral resources is expected to move to greater depths. Consequently, seismic methods will become a more important tool to help unravel structures hosting mineral deposits at great depth for mine planning and exploration. These methods also can be used with varying degrees of success to directly target mineral deposits at depth. We review important contributions that have been made in developing these techniques for the mining industry with focus on four main regions: Australia, Europe, Canada, and South Africa. A wide range of case studies are covered, including some that are published in the special issue accompanying this article, from surface to borehole seismic methods, as well as petrophysical data and seismic modeling of mineral deposits. At present, high-resolution 2D surveys mostly are performed in mining areas, but there is a general increasing trend in the use of 3D seismic methods, especially in mature mining camps
3D reflection seismic investigation for mine planning and exploration in the Kevitsa Ni-Cu-PGE deposit, Northern Finland
A 3D reflection seismic survey was conducted over an area of about 9 km2 at the Kevitsa Ni-Cu-PGE (platinum group elements) deposit, Northern Finland. The principal objective of the survey was to image major fault and fracture zones at depth. Understanding the geometry of these zones is important for designing a steep open-pit for mining. Initial processing results suggest that the 3D seismic survey has been successful in imaging both gently dipping and steeply dipping reflections as shallow as 50 ms (or about 150 m), many of which correlate with fault systems and lithological contacts observed at the surface. Several new target areas can be identified in the seismic data that require further investigations for their mineralization potential
Seismic imaging of dyke swarms within the SorgenfreiâTornquist Zone (Sweden) and implications for thermal energy storage
There is a great interest and demand for green-type
energy storage in Sweden for both short- and long-term (hours, days, weeks
and seasons) periods. While there are a number of approaches proposed (e.g.,
compressed air, geothermal and thermal), only a few have commercially been
demonstrated through upscaling projects. Among these, the thermal energy
storage (TES) that stores energy (excess heat or cold) in fluids is
particularly interesting. The excess energy can be stored underground in
excavated caverns and used for large district heating and cooling purposes
as well as for balancing and regulating electrical energy in power grids. For an
upscaling underground TES project within the Tornquist suture zone of
Scania in the southwest of Sweden, three high-resolution seismic profiles, each
approximately 1 km long, were acquired. Geologically, the site sits
within the southern margin of the RomeleÄsen fault zone in the
SorgenfreiâTornquist Zone (STZ), where dolerite dyke swarms of
CarboniferousâPermian age are observed striking in the SEâNW direction for
hundreds of kilometers both on land and in offshore seismic and magnetic data
(from Scania to Midland Valley in the UK). These dykes, 10â50 m thick, in the
nearby quarries (within both Precambrian gneiss and quartzite) express
themselves mostly in a subvertical manner. They can therefore act as a good water/fluid
barrier, which can be an important geological factor for any TES site. For
the data acquisition, combined cabled and wireless recorders were used to
provide continuity on both sides of a major road running in the middle of
the study area. Bedrock depressions are clearly depicted in the tomograms,
suggesting the possibility of zones of weaknesses, highly fractured and/or
weathered, in the bedrock and confirmed in several places by follow-up
boreholes. Several steeply dipping (60â65°) reflections were
imaged down to 400 m depth and interpreted to originate from dolerite dykes.
This interpretation is based on their orientations, strong amplitudes,
regular occurrences and correlation with downhole logging data. In addition,
groundwater flow measurements within the unconsolidated sediments and in
bedrock suggest steeply dipping structures are the dominant factor in
directing water mainly along a SEâNW trend, which is consistent with the
strike of the dyke swarm within the STZ. To provide further insight on the
origin of the reflections, even the historical crustal-scale offshore BABEL (Baltic and Bothnian Echoes from the Lithosphere)
lines (A-AA-AB) were revisited. Clear multiphase faults and signs of
intrusions or melt source in the lower crust are observed, as well as a Moho
step across the Tornquist zone. Overall, we favor that the reflections are
of dolerite origin and their dip component (i.e., not subvertical) may
imply a Precambrian basement (and dykes) tilting, block rotation, towards the NE
as a result of the RomeleÄsen reverse faulting. In terms of thermal
storage, these dykes then may be encountered during the excavation of the
site and can complicate underground water flow should they be used as a
fluid barrier in case of leakage.</p
Reflection Seismic Imaging for Mineral Exploration in the Sotiel-Coronada Area, Southwest Spain
Near Surface Geoscience Conference & Exhibition Online 2020This work explores the first results of the seismic data acquired in the Sotiel-Coronada mine
as part of the SIT4ME (Seismic Imaging Techniques for Mineral Exploration) project. In this
experiment, a multi-source seismic data-set was acquired at the end of 2018 in the Sotiel-
Coronada area of the Iberian Pyrite Belt (IPB) (southwest Spain). In the seismic experiment
presented, 653 seismic receivers were deployed distributed in a pseudo 3D grid and six
crooked lines across the study area. The sensors recorded c. 900 vibration points produced
by a 32 Tn vibrotruck.
Here, we present the stack results of the 2D seismic sections. Data from over 100 wells have
been incorporating to aid in the structural interpretation. The preliminary interpretation reveals
the complexity of this highly faulted ore-bearing area. Correlations between well log data
information and 2D seismic profiles, suggest the location of a potentially mineralized area. The
SIT4ME project has been funded by EIT Raw Materials (17024)
Arquitetura interlobĂĄtica de esker e feiçÔes hidrogeolĂłgicos relacionadas derivadas de uma combinação de sĂsmica de reflecção de alta resolução e tomografia de refração, Virttaankangas, sudoeste da FinlĂąndia
3-D reflection seismic imaging of the HontomĂn structure in the BasqueâCantabrian Basin (Spain)
The BasqueâCantabrian Basin of the northern Iberia Peninsula constitutes a unique example of a major deformation system, featuring a dome structure developed by extensional tectonics followed by compressional reactivation. The occurrence of natural resources in the area and the possibility of establishing a geological storage site for carbon dioxide motivated the acquisition of a 3-D seismic reflection survey in 2010, centered on the Jurassic HontomĂn dome. The objectives of this survey were to obtain a geological model of the overall structure and to establish a baseline model for a possible geological CO2 storage site. The 36 km 2 survey included approximately 5000 mixed (Vibroseis and explosives) source points recorded with a 25 m inline source and receiver spacing. The target reservoir is a saline aquifer, at approximately 1450 m depth, encased and sealed by carbonate formations. Acquisition and processing parameters were influenced by the rough topography and relatively complex geology. A strong near-surface velocity inversion is evident in the data, affecting the quality of the data. The resulting 3-D image provides constraints on the key features of the geologic model. The HontomĂn structure is interpreted to consist of an approximately 107 m2 large elongated dome with two major (WâE and NWâSE) striking faults bounding it. Preliminary capacity estimates indicate that about 1.2 Gt of CO2 can be stored in the target reservoirFunding for this Project has been partially provided by the Spanish Ministry of Industry, Tourism and Trade, through the CIUDEN-CSIC-Inst. Jaume Almera agreement (Characterization, Development and Validation of Seismic Techniques applied to CO2 Geological Storage Sites) and by the European Union through the Technology Demonstration Plant of Compostilla OXYCFB300 project (European Energy Programme for 534 Recovery). Additional support has been provided by Spanish Ministry of Education Science (CSD2006-00041), Generalitat de Catalunya (2009SGR006) and CSIC JAE-Doc postdoctoral research contract (E.S.).Peer Reviewe
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