3D seismic survey at the Millennium uranium deposit, Saskatchewan, Canada: Mapping depth to basement and imaging post-Athabasca structure near the orebody

A B S T R A C TThe primary economic uranium (U) mineralization indicators in the Athabasca Basin are the reactivated prominent basement deformation zones, basement alteration halos, and the overlying sandstone alteration halos enveloping the deposit. High-resolution seismic surveys, from the Shea Creek area, are investigated to assess the potential of the surface seismic reflection technique for detecting these key mineralization markers. Four seismic profiles identify ductile to highly brittle deformation features of the basement. One of the brittle deformation features is a southwest-dipping prominent reactivated shear zone comparable to basement structures hosting other known deposits in the basin. The Carswell meteor impact structure is also a conspicuous component of the Shea Creek regional structural regime. The seismic sections identify several features of the impact structure, including recognition that the dimensions of this structure are significantly larger than those estimated by previous geological studies. This larger area includes both the Cluff Lake mine and the Shea Creek U deposits, and it reveals that the basement was considerably disturbed by the impact and suggests the reactivation of the southwest-dipping shear zone. Complex trace analysis of the seismic sections provides detailed information about the lateral changes in the reflectivity properties of the unconformity interval, which is another key zone of interest for uranium exploration. Based mainly on velocity information, several sub-zones of clay alteration and silicification were identified within prominent fracture depth intervals: both in the sandstone and the basement. Thus, this study documents that these primary mineral indicators can be detected by the seismic method. Cross-plots of velocity versus density of well log data identify changes in lithological units such as unaltered basement, fractured/altered basement, unaltered sandstone, clay alterations in sandstone, and silicification in sandstone.

Section: Acoustic Properties – Mineralization Indicatorssupporting

confidence: 64%

“…; Juhojuntti et al . ; Hajnal et al . ); thus, numerous iterative processing steps are required to select the optimal signal processing procedures and to establish the best possible signal levels (Table ).…”

Section: Data Acquisition and Processingmentioning

confidence: 98%

Uranium mineralization indicators from seismic and well log data in the Shea Creek area at the southern margin of the Carswell impact structure, Athabasca Basin, Canada

Hajnal

Takács

Pandit

et al. 2015

“…, ; Bellefleur, Malehmir, and Müller ; Juhojuntti et al . ; Kukkonen et al . ; Malinowski, Schetselaar, and White ; White and Kjarsgaard ; Wood et al .…”

Section: Introductionmentioning

confidence: 99%

Integrated interpretation of 3D seismic data to enhance the detection of the gold‐bearing reef: Mponeng Gold mine, Witwatersrand Basin (South Africa)

Manzi

Cooper

Malehmir

et al. 2015

A B S T R A C TWe present an integrated approach to the seismic interpretation of one of the world's deepest gold ore body (Carbon Leader Reef) using three-dimensional seismic data, ultrasonic velocity measurements at elevated stresses, and modified instantaneous attribute analysis. Seismic wave velocities of the drill-core samples (quartzite, shale, and conglomeratic reef) from the mine are sensitive to uniaxial stress changes, i.e., they slowly increase with increasing pressure until they reach maximum value at ß25 MPa. For all the samples, seismic velocities are constant above 25 MPa, indicating a possible closure of microcracks at stress corresponding to 1.0 km-1.5 km. A reflection coefficient of 0.02 computed between hanging wall and footwall quartzites of the Carbon Leader Reef ore body suggests that it may be difficult to obtain a strong seismic reflection at their interface. Our modified seismic attribute algorithm, on the other hand, shows that the detection of the lateral continuity of the Carbon Leader Reef reflector can significantly be improved by sharpening the seismic traces. Three-dimensional seismic data reveal that faults with throws greater than 25 m that offset the Carbon Leader Reef can clearly be seen. Faults with throws less than 25 m but greater than 2-m throw were identified through horizon-based attribute analysis, while most dykes and sills with thickness less than 25 m were invisible. The detection of the lateral continuity of the Carbon Leader Reef reflector and its depth position is greatly improved by integrating the modified instantaneous attributes with controls from borehole observations. The three-dimensional visualization and effective interpretation of the Carbon Leader Reef horizon shows a host of structurally complex ore body blocks that may impact future shaft positioning and reduce its associated risks.

“…; Juhojuntti et al . ; Malinowski, Schetselaar, and White ; Malehmir and Bellefleur ; Malehmir et al . , , ,b, ; Manzi et al .…”

Section: Introductionmentioning

confidence: 99%

Delineating structures controlling sandstone‐hosted base‐metal deposits using high‐resolution multicomponent seismic and radio‐magnetotelluric methods: a case study from Northern Sweden

Malehmir

Wang

Lamminen

et al. 2015

Self Cite

A B S T R A C TOver the past few decades seismic methods have increasingly been used for the exploration of mineral, geothermal, and groundwater resources. Nevertheless, there have only been a few cases demonstrating the advantages of multicomponent seismic data for these purposes. To illustrate some of the benefits of three-component data, a test seismic survey, using 60 digital three-component sensors spaced between 2 m and 4 m and assembled in a 160 m-long prototype landstreamer, was carried out over shallow basement structures underlying mineralized horizons and over a magnetic lineament of unknown origin. Two different types of seismic sources, i.e., explosives and a sledgehammer, were used to survey an approximately 4 km-long seismic profile. Radio-magnetotelluric measurements were also carried out to provide constraints on the interpretation of the seismic data over a portion of the profile where explosive sources were used. Good quality seismic data were recorded on all three components, particularly when explosives were used as the seismic source. The vertical component data from the explosive sources image the top of the crystalline basement and its undulated/faulted surface at a depth of about 50 m-60 m. Supported by the radiomagnetotelluric results, however, shallower reflections are observed in the horizontal component data, one of them steeply dipping and associated with the magnetic lineament. The vertical component sledgehammer data also clearly image the crystalline basement and its undulations, but significant shear-wave signals are not present on the horizontal components. This study demonstrates that multicomponent seismic data can particularly be useful for providing information on shallow structures and in aiding mineral exploration where structural control on the mineralization is expected.