Crosshole seismic imaging for sulfide orebody delineation near Sudbury, Ontario, Canada

Geophysics ◽  
2000 ◽  
Vol 65 (6) ◽  
pp. 1900-1907 ◽  
Author(s):  
Joe Wong
Keyword(s):  
Cost Effective ◽  
Massive Sulfide ◽  
P Wave ◽  
Mining Operations ◽  
Seismic Surveys ◽  
Ore Bodies ◽  
P Wave Velocity ◽  
Sulfide Ore ◽  
First Arrival ◽  
Discrete Layer

Crosshole seismic instrumentation based on a piezoelectric source and hydrophone detectors were used to gather seismograms between boreholes at the McConnell orebody near Sudbury, Ontario. High‐frequency seismograms were recorded across rock sections 50 to 100 m wide containing a continuous zone of massive sulfide ore. First‐arrival traveltimes obtained from a detailed scan were used to create a P-wave velocity tomogram that clearly delineated the ore zone. Refraction ray tracing on a discrete layer model confirmed the main features of the tomogram. The survey demonstrated that it is possible to conduct cost‐effective, high‐resolution crosshole seismic surveys to delineate ore bodies on a scale useful for planning mining operations.

scholarly journals P-wave velocity measurements for preliminary assessments of the mineralization in seafloor massive sulfide mini-cores during drilling operations

2017 ◽  
Vol 226 ◽  
pp. 316-325 ◽  
Author(s):  
Giovanni Spagnoli ◽  
Bradley A. Weymer ◽  
Marion Jegen ◽  
Erik Spangenberg ◽  
Sven Petersen
Keyword(s):  
Wave Velocity ◽  
Massive Sulfide ◽  
P Wave ◽  
Velocity Measurements ◽  
P Wave Velocity ◽  
Drilling Operations ◽  
Seafloor Massive Sulfide

Field trials of a seismoelectric method for detecting massive sulfides

Geophysics ◽  
1995 ◽  
Vol 60 (2) ◽  
pp. 365-373 ◽  
Author(s):  
Anton W. Kepic ◽  
Michael Maxwell ◽  
R. Don Russell
Keyword(s):  
Electromagnetic Radiation ◽  
Acoustic Waves ◽  
Seismic Energy ◽  
Field Trials ◽  
P Wave ◽  
Massive Sulfides ◽  
P Wave Velocity ◽  
Electromagnetic Emissions ◽  
First Arrival ◽  
Exploration Tool

An underground test of a seismoelectric prospecting method for massive sulfides was performed at the Mobrun Mine (Rouyn‐Noranda, Quebec) in June 1991. The method is based upon the conversion of seismic energy to high‐frequency pulses of electromagnetic radiation by sulfide minerals. The delay between shot detonation and detection of the electromagnetic radiation gives a one‐way traveltime for the acoustic wave to reach the zone of seismoelectric conversion, which when combined with P‐wave velocity allows the shot‐to‐ore zone distance to be calculated. A 0.22-kg explosive charge located within 50 m of the orebody provided the seismic excitation, and the resulting electromagnetic emissions were received by electric dipole and induction‐coil antennas. First‐arrival information from a 35‐shot survey above an orebody, the 1100 lens, provides firm evidence that short duration pulses of electromagnetic radiation are produced by the passage of acoustic waves through the orebody. The survey also demonstrated that seismoelectric conversions could be induced at shot‐to‐orebody distances of 50 m and detected at distances of up to 150 m from the orebody. Areas of seismoelectric conversion are highlighted in sections produced by plotting the position of seismic wavefronts during signal reception. The sections show anomalies that correlate with the known structure and location of the orebody and demonstrate the potential of using this seismoelectric phenomenon as an exploration tool.

The structural architecture of the Whataroa Valley at the Alpine Fault (New Zealand) from first-arrival tomography and reflection imaging using an extended 3D VSP survey

2020 ◽  
Author(s):  
Vera Lay ◽  
Stefan Buske ◽  
Sascha Barbara Bodenburg ◽  
Franz Kleine ◽  
John Townend ◽  
...  
Keyword(s):  
New Zealand ◽  
Seismic Data ◽  
Average Velocity ◽  
Velocity Model ◽  
P Wave ◽  
3D Seismic ◽  
Data Set ◽  
Alpine Fault ◽  
P Wave Velocity ◽  
First Arrival

<p>The Alpine Fault along the West Coast of the South Island (New Zealand) is a major plate boundary that is expected to rupture in the next 50 years, likely as a magnitude 8 earthquake. The Deep Fault Drilling Project (DFDP) aims to deliver insight into the geological structure of this fault zone and its evolution by drilling and sampling the Alpine Fault at depth.  </p><p>Here we present results from a 3D seismic survey around the DFDP-2 drill site in the Whataroa Valley where the drillhole penetrated almost down to the fault surface. Within the glacial valley, we collected 3D seismic data to constrain valley structures that were obscured in previous 2D seismic data. The new data consist of a 3D extended vertical seismic profiling (VSP) survey using three-component receivers and a fibre optic cable in the DFDP-2B borehole as well as a variety of receivers at the surface.</p><p>The data set enables us to derive a reliable 3D P-wave velocity model by first-arrival travel time tomography. We identify a 100-460 m thick sediment layer (average velocity 2200±400 m/s) above the basement (average velocity 4200±500 m/s). Particularly on the western valley side, a region of high velocities steeply rises to the surface and mimics the topography. We interpret this to be the infilled flank of the glacial valley that has been eroded into the basement. In general, the 3D structures implied by the velocity model on the upthrown (Pacific Plate) side of the Alpine Fault correlate well with the surface topography and borehole findings.</p><p>A reliable velocity model is not only valuable by itself but it is also required as input for prestack depth migration (PSDM). We performed PSDM with a part of the 3D data set to derive a structural image of the subsurface within the Whataroa Valley. The top of the basement identified in the P-wave velocity model coincides well with reflectors in the migrated images so that we can analyse the geometry of the basement in detail.</p>

Transient electromagnetic surveys in the Okiep district

Geophysics ◽  
1992 ◽  
Vol 57 (5) ◽  
pp. 736-744 ◽  
Author(s):  
M. J. Maher
Keyword(s):  
Time Constant ◽  
Massive Sulfide ◽  
Sulfide Mineralization ◽  
Limited Size ◽  
Modern Times ◽  
Transient Electromagnetic ◽  
Diamond Drilling ◽  
Ore Bodies ◽  
Sulfide Ore ◽  
Massive Sulfide Mineralization

In the Okiep District early miners produced massive sulfide ore from some five deposits. Some of these deposits later contributed to the reserves of disseminated ore mined during modern times. It is unreasonable to assume that all of the massive sulfide bodies present within the area are intersected by the erosion surface and thus were discovered by the early miners. Consequently, blind massive sulfide ore bodies could be present and may have large quantities of disseminated ore associated with them. The transient electromagnetic method is ideally suited to exploring for massive sulfide bodies, and six test surveys were carried out at various sites in the district. Four of these surveys were unsuccessful whereas, at the remaining two sites, excellent anomalies were recorded. At Ezelsfontein East Extension an anomaly was recorded indicative of a massive sulfide body at shallow depth and of generally flat attitude. This anomaly has a time constant of 15 ms and the interpreted body was confirmed by a limited diamond drilling program. A deep, flat‐lying conductor was interpreted from the TEM results at Fonteintjie West Prospect. This anomaly, with a time constant of 0.6 ms, has limited size. Diamond drilling confirmed the presence of submassive to massive sulfide mineralization at this locale. Neither of these two drilled prospects had economic mineralization.

Seismic refraction signatures for massive sulfide ore bodies

1982 ◽  
Author(s):  
Laric V. Hawkins ◽  
Robert J. Whiteley
Keyword(s):  
Seismic Refraction ◽  
Massive Sulfide ◽  
Ore Bodies ◽  
Sulfide Ore

Characterizing an unstable mountain slope using shallow 2D and 3D seismic tomography

Geophysics ◽  
2006 ◽  
Vol 71 (6) ◽  
pp. B241-B256 ◽  
Author(s):  
Bjoern Heincke ◽  
Hansruedi Maurer ◽  
Alan G. Green ◽  
Heike Willenberg ◽  
Tom Spillmann ◽  
...  
Keyword(s):  
Rock Mass ◽  
Seismic Refraction ◽  
P Wave ◽  
Fracture Zones ◽  
Mountain Slope ◽  
Low Field ◽  
P Wave Velocity ◽  
First Arrival ◽  
Mobile Segment ◽  
2D And 3D

As transport routes and population centers in mountainous areas expand, risks associated with rockfalls and rockslides grow at an alarming rate. As a consequence, there is an urgent need to delineate mountain slopes susceptible to catastrophic collapse in a safe and noninvasive manner. For this purpose, we have developed a 3D tomographic seismic refraction technique and applied it to an unstable alpine mountain slope, a significant segment of which is moving at [Formula: see text] toward the adjacent valley floor. First arrivals recorded across an extensive region of the exposed gneissic rock mass have extraordinarily low apparent velocities at short [Formula: see text] to long [Formula: see text] shot-receiver offsets. Inversion of the first-arrival traveltimes produces a 3D tomogram that reveals the presence of a huge volume of very-low-quality rock with ultralow to very low P-wave velocities of [Formula: see text]. These values are astonishingly low compared to the average horizontal P-wave velocity of [Formula: see text] determined from laboratory analyses of intact rocks collected at the investigation site. The extremely low field velocities likely result from the ubiquitous presence of dry cracks, fracture zones, and faults on a wide variety of scales. They extend to more than [Formula: see text] depth over a [Formula: see text] area that encompasses the mobile segment of the mountain slope, which is transected by a number of actively opening fracture zones and faults, and a large part of the adjacent stationary slope. Although hazards related to the mobile segment have been recognized since the last major rockslides affected the mountain in 1991, those related to the adjacent low-quality stationary rock mass have not.

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