scholarly journals Seismic imaging across fault systems in the Abitibi greenstone belt – an analysis of pre- and post-stack migration approaches in the Chibougamau area, Quebec, Canada

Solid Earth ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 1143-1164
Author(s):  
Saeid Cheraghi ◽  
Alireza Malehmir ◽  
Mostafa Naghizadeh ◽  
David Snyder ◽  
Lucie Mathieu ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Seismic Imaging ◽  
Massive Sulfide ◽  
The South ◽  
Element Analysis ◽  
Fault Systems ◽  
The North ◽  
Relative Contribution ◽  
Abitibi Subprovince ◽  
Seismic Reflection Profiles

Abstract. Two high-resolution seismic reflection profiles acquired north and south of Chibougamau, located in the northeast of the Abitibi subprovince of Canada, help understand historic volcanically hosted massive sulfide (VMS) deposits and hydrothermal Cu–Au mineralization found there. Major faults crossed by the profiles include the Barlow fault in the north and the Doda fault and the Guercheville fault in the south, all targets of this study that seeks to determine spatial relationships with a known metal endowment in the area. Common-offset DMO corrections and common-offset pre-stack time migrations (PSTMs) were considered. Irregularities of the trace midpoint distribution resulting from the crooked geometry of both profiles and their relative contribution to the DMO and PSTM methods and seismic illumination were assessed in the context of the complex subsurface architecture of the area. To scrutinize this contribution, seismic images were generated for offset ranges of 0–9 km using increments of 3 km. Migration of out-of-plane reflections used cross-dip element analysis to accurately estimate the fault dip. The seismic imaging shows the thickening of the upper-crustal rocks near the fault zones along both profiles. In the northern seismic reflection section, the key geological structures identified include the Barlow fault and two diffraction sets imaged within the fault zone that represent potential targets for future exploration. The south seismic reflection section shows rather a complicated geometry of two fault systems. The Guercheville fault observed as a subhorizontal reflector connects to a steeply dipping reflector. The Doda fault dips subvertical in the shallow crust but as a steeply dipping reflection set at depth. Nearby gold showings suggest that these faults may help channel and concentrate mineralizing fluids.

scholarly journals Seismic imaging across fault systems in the Abitibi greenstone belt – An analysis of pre- and post-stack migration approaches in the Chibougamau area, Quebec, Canada

2020 ◽  
Author(s):  
Saeid Cheraghi ◽  
Alireza Malehmir ◽  
Mostafa Naghizadeh ◽  
David Snyder ◽  
Lucie Mathieu ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Seismic Imaging ◽  
Massive Sulfide ◽  
Geological Structure ◽  
The South ◽  
Element Analysis ◽  
Fault Systems ◽  
The North ◽  
Relative Contribution ◽  
Abitibi Subprovince

Abstract. Two high-resolution seismic reflection profiles acquired north and south of Chibougamau, located in the northeast of the Abitibi subprovince of Canada help understand historic volcanic-hosted massive sulfide (VMS) deposits and hydrothermal Cu-Au mineralization found there. Major faults crossed by the profiles include the Barlow fault in the north and the Doda fault and the Guercheville fault in the south, all targets of this study that seeks to determine spatial relationships with known metal endowment in the area. Common-offset DMO corrections and common-offset pre-stack time migrations (PSTM) were considered. Irregularities of the trace midpoint distribution resulting from the crooked geometry of both profiles and their relative contribution to DMO and PSTM method and seismic illumination were assessed in the context of the complex subsurface architecture of the area. To scrutinize this contribution, seismic images were generated for offset ranges of 0–9 km using increments of 3 km. Migration of out-of-plane reflections used cross-dip element analysis to accurately estimate the fault dip. The seismic imaging shows the thickening of the upper crustal rocks near the fault zones along both profiles. In the north seismic reflection section, key geological structure identified include the Barlow fault and two diffraction sets imaged within the fault zone that represent potential targets for future exploration. The south seismic reflection section shows rather a complicated geometry of two fault systems. The Guercheville fault observed as a subhorizontal reflector connects to a steeply dipping reflector. The Doda fault dips subvertical in the shallow crust but as a steeply dipping reflection set at depth. Nearby gold showings suggest that these faults may help channel and concentrate mineralizing fluids.

Crustal geometry of the Abitibi Subprovince, in light of three-dimensional seismic reflector orientations

1998 ◽  
Vol 35 (5) ◽  
pp. 569-582 ◽  
Author(s):  
G Bellefleur ◽  
A J Calvert ◽  
M C Chouteau
Keyword(s):  
Seismic Reflection ◽  
Three Dimensional ◽  
Seismic Reflection Data ◽  
Volcanic Arc ◽  
The North ◽  
Reflection Data ◽  
Abitibi Subprovince ◽  
Seismic Reflection Profiles ◽  
Lower Crustal ◽  
Seismic Reflector

We provide precise estimates of reflector orientations beneath the Archean Abitibi Subprovince, using two distinct approaches based on Lithoprobe seismic reflection data. In the first, we use the dip of reflections observed on intersecting profiles to establish the three-dimensional orientation of reflective structures. In the second, the strikes and dips of reflectors are estimated in the crooked parts of seismic reflection profiles by calculating a measure of coherency along the traveltime trajectories defined by a particular azimuth, dip, depth, and medium velocity. Mid-crustal reflectors define two areas with distinctive geometry: reflectors beneath the southern Abitibi belt are oppositely dipping, and convergent at depth, providing a V-shape aspect to the greenstone rocks; other reflectors beneath the northern Abitibi belt are, in general, subparallel, dipping at an average of 30° toward the north. These north-dipping reflectors are partly disrupted by a low-reflectivity zone, which is attributed to rocks of the Opatica Subprovince, located underneath the northern Abitibi belt. Lower-crustal reflectors have a similar, shallowly north-dipping orientation throughout the Abitibi Subprovince. The geometry of the reflectors recovered is consistent with the different tectonic histories proposed for the southern and northern Abitibi assemblages, until common deformation during a north-south shortening event. Attitudes recovered in the northern Abitibi belt are consistent with tectonic scenarios involving underthrusting of Abitibi middle and lower crustal terranes beneath the Opatica belt, whereas the oppositely dipping reflectors recovered in the middle crust beneath the southern Abitibi belt could be representative of a rifted volcanic arc environment.

Control of Precambrian-to-Paleozoic orogenic trends on along-strike variations in Early Cretaceous continental rifts of the South Atlantic Ocean

2019 ◽  
Vol 7 (4) ◽  
pp. SH45-SH69 ◽  
Author(s):  
Kyle Reuber ◽  
Paul Mann
Keyword(s):  
Early Cretaceous ◽  
South Atlantic ◽  
Orogenic Belt ◽  
Deep Penetration ◽  
The South ◽  
The North ◽  
Continental Rifts ◽  
Rift Zones ◽  
Seismic Reflection Profiles ◽  
Orogenic Belts

The Early Cretaceous (135–130 Ma) continental rupture of Western Gondwana to form the South American and African plates closely paralleled the elongate trends of Precambrian and Paleozoic orogenic belts. These orogenic belts were produced as a result of the Neoproterozoic convergent and strike-slip assembly of Gondwana that redeformed during later, Paleozoic orogenic events. Continued continental rifting led to the formation of conjugate, South Atlantic volcanic passive margins whose widths vary from 55 to 180 km. Along-strike variations in crustal stretching, as measured from deep-penetration seismic reflection profiles, correlate with parallel and oblique orientations of rifts relative to the trend of the orogenic, basement fabric. Where orogenic fabric trends parallel to the north–south South Atlantic rift direction such as in the Dom Feliciano orogenic belt of Uruguay and Brazil and the Kaoko Uruguay/Brazil and Kaoko orogenic belt of Namibia, we observe narrow (55–90 km) rift zones with modest continental beta factors of 2.5–3.5 because smaller amounts of rifting were needed to stretch the weaker and parallel, orogenic, basement fabric. Where the basement fabric trends near-orthogonally to the north–south South Atlantic rift direction such as in the Salado suture of Southern Uruguay and the Damara Belt of Namibia, we observe wider (185–220 km) rift zones with higher beta factors of 4.3–5 because greater amounts of stretching were needed to rupture the orthogonal, orogenic, basement fabric. The rift-oblique Gariep Belt intersects the South Atlantic continental rupture at an intermediate angle (30°) and exhibits a predicted intermediate beta factor of 4.0. A compilation of published beta factors from 36 other rifted margins worldwide supports the same basement-trend-degree of stretching relationship that we have developed — with rift-parallel margins having lower beta factors in a range of 1.3–3.5 and rift-orthogonal or oblique margins having higher beta factors in a range of 4–8.

scholarly journals Grenville Foreland Deformation and Sedimentation in Southwest Ohio Indicated by Reprocessed Seismic Reflection Profiles near Middletown, Ohio, USA

2020 ◽  
Vol 120 (2) ◽  
pp. 39
Author(s):  
David J. Peterman ◽  
Ernest C. Hauser ◽  
Doyle R. Watts
Keyword(s):  
Cross Section ◽  
Seismic Reflection ◽  
Vertical Displacement ◽  
Reverse Fault ◽  
Seismic Line ◽  
The North ◽  
North American Craton ◽  
Tectonic Style ◽  
Seismic Reflection Profiles ◽  
Depositional Setting

The late Mesoproterozoic to early Neoproterozoic Middle Run Formation contains vital information about the crustal evolution of the North American Craton. Four reprocessed seismic reflection lines in the vicinity of the AK Steel facility in Middletown, Ohio, provide new insights into the structural and depositional setting of the Middle Run Formation in this region. A residual statics solution improved the resolution and coherency of reflections in these profiles that underlie the Cambrian Mount Simon Sandstone. Reprocessing revealed gently inclined, west-southwest-dipping reflectors and the occurrence of an angular unconformity between the Middle Run Formation and the overlying Paleozoic strata. The weak and discontinuous seismic reflection character of the Middle Run Formation in these seismic lines overlies a sequence of stronger parallel reflections that are like those observed on the eastward ODNR-1-88 seismic line located near core hole DGS 2627, the stratotype of the Middle Run Formation. This inferred thickness indicates that the basin in which the Middle Run Formation was deposited ranges from at least 670 to 1,128 m (2,200 to 3,700 ft) deep at the AK Steel area and dips gently west-southwest, which is in contrast with the moderate easterly dip observed on the ODNR-1-88 seismic line to the northeast. Correlation of these features across the 10 km (approximately 6 mi) cross-strike gap between the AK Steel lines and the ODNR-1-88 seismic line suggests the presence of a reverse fault with approximately 792 m (2,600 ft) of estimated vertical displacement. A regional cross section—including the WSU 1990 seismic line eastward of the ODNR-1-88 line—exhibits a faulted west-verging asymmetric syncline in near proximity to the Grenville Front. This cross section also shows that deformation of the Middle Run Formation and the underlying layered sequence exhibits a consistent tectonic style of reverse faulting and folding that developed in response to Grenville Front tectonism.

Seismic investigations of sedimentary structure in the northern Rockall Trough—a synopsis

1986 ◽  
Vol 88 ◽  
pp. 53-54
Author(s):  
R. J. Whittington ◽  
M. R. Dobson
Keyword(s):  
Seismic Reflection ◽  
Single Channel ◽  
Sedimentary Structure ◽  
The North ◽  
Air Gun ◽  
Late Tertiary ◽  
Rockall Trough ◽  
Seismic Reflection Profiles ◽  
Small Capacity ◽  
North Rockall Trough

Single channel, analogue, seismic reflection profiles using Sparker and small capacity Air gun sources were used to investigate late Tertiary and Quaternary sedimentation both around the margins and on the floor of the north Rockall Trough. The data complement, by being intermediate in penetration and resolution, previous seismic studies; particularly, they allow the upper 500 m of the sediment sequence to be examined in greater detail than hitherto.

ARCTIC OCEAN GEOPHYSICAL STUDIES: THE SOUTHERN HALF OF THE SIBERIA BASIN

Geophysics ◽  
1966 ◽  
Vol 31 (4) ◽  
pp. 683-710 ◽  
Author(s):  
Henry Kutschale
Keyword(s):  
Seismic Reflection ◽  
Magnetic Measurements ◽  
Abyssal Plain ◽  
Turbidity Currents ◽  
The North ◽  
Northern Half ◽  
Gravity Measurements ◽  
Southern Half ◽  
Basement Ridge ◽  
Seismic Reflection Profiles

In 1962, ice island Arlis II drifted over a portion of the southern half of the Siberia Basin. Depth recordings made between 81°N, 170°E and 82°30′N, 160°E show that the ocean floor in this area is an abyssal plain at about 2,825 m depth dissected by several interplain channels. This abyssal plain, here called the Wrangel Abyssal Plain, is bounded on the north by Arlis Gap, which joins it with the Siberia Abyssal Plain at about 3,946 m depth. The Siberia Abyssal Plain occupies the northern half of the Siberia Basin. Seismic reflection profiles show that a prominent subbottom basement ridge exists in the vicinity of Arlis Gap. This ridge strikes in an approximately northwest direction and appears to connect with Alpha Ridge, which bounds the Siberia Basin on the east and north, and with Lomonosov Ridge, which bounds the Siberia Basin on the west. The seismic reflection profiles also show that at least 3.5 km of subhorizontal, stratified sediments underlie Wrangel Abyssal Plain south of the ridge. Each layer within these sediments appears to correspond to a fossil surface of Wrangel Abyssal Plain. This thick sequence of stratified sediments shows the influence of the Asian continent, which bounds the Siberia Basin on the south, on sedimentation within the Siberia Basin. Presumably the buried basement ridge forms a dam which has permitted the accumulation of a thick sequence of sediments under the higher‐level Wrangel Abyssal Plain. Turbidity currents moving through Arlis Gap presumably carried the overflow of sediments from Wrangel Abyssal Plain into the lower‐level Siberia Abyssal Plain. The structure of the sediments suggests that the Siberia Basin has been free from deformation during the deposition of the sediments, except for possible broad crustal down warping. A crustal model based on the water depth measurements, seismic reflection profiles, gravity measurements, and magnetic measurements yields a crustal thickness of 15 km south of the buried ridge and 22 km under the ridge measured from sea level.

Constraints on Reelfoot Rift Evolution from a Reflection Seismic Profile in the Northern Rift

1992 ◽  
Vol 63 (3) ◽  
pp. 233-241 ◽  
Author(s):  
M.B. Goldhaber ◽  
C.J. Potter ◽  
C.D. Taylor
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Seismic Profile ◽  
Fault System ◽  
Seismic Reflection Profile ◽  
The South ◽  
Dome A ◽  
Reflection Seismic ◽  
The North ◽  
Northwestern Margin

Abstract An 82.8 km segment of a northwest-southeast trending seismic-reflection profile across the northernmost part of the Reelfoot rift shows that the Cambrian rift geometry there is quite distinct from that of the main part of Reelfoot rift to the south, and that of the Rough Creek graben to the east. The profile is within the area of intersection of the Reelfoot rift and Rough Creek graben and shows a systematic southeastward thickening of the Cambrian synrift clastic sequence with as much as 1940 meters of section present against the Pennyrile fault system as compared to 970 meters near the Lusk Creek and Shawneetown fault systems, towards the northwestern margin of the rift. This contrasts with the more symmetric rift pattern in the seismically active zone to the south, where the maximum thickness of synrift sediments is along the rift axis, and with an opposite sense of rift asymmetry in the Rough Creek graben, where the synrift sequence thickens to the north against the Rough Creek - Shawneetown fault. Reflection patterns in the vicinity of Hicks dome, a “cryptovolcano”, are consistent with the hypothesis that the dome originated by explosive release of mantle-derived gases associated with alkali volcanism. The seismic data also reveal that the fluorine mineralization in the area is associated with faults that offset basement; this is further evidence that deeply-derived fluids are significant in the geologic evolution of the area.

scholarly journals Cost-Effective Seismic Exploration: 2D Reflection Imaging at the Kylylahti Massive Sulfide Deposit, Finland

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 263 ◽  
Author(s):  
Suvi Heinonen ◽  
Michal Malinowski ◽  
Felix Hloušek ◽  
Gardar Gislason ◽  
Stefan Buske ◽  
...  
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Imaging Techniques ◽  
Mineral Exploration ◽  
Massive Sulfide ◽  
Seismic Profile ◽  
Seismic Exploration ◽  
Sulfide Deposit ◽  
Depth Imaging ◽  
Seismic Reflection Profiles

We show that by using an advanced pre-stack depth imaging algorithm it is possible to retrieve meaningful and robust seismic images with sparse shot points, using only 3–4 source points per kilometer along a seismic profile. Our results encourage the use of 2D seismic reflection profiling as a reconnaissance tool for mineral exploration in areas with limited access for active seismic surveys. We used the seismic data acquired within the COGITO-MIN project comprising two approximately 6 km long seismic reflection profiles at the polymetallic Kylylahti massive sulfide mine site in eastern Finland. The 2D seismic data acquisition utilized both Vibroseis and dynamite sources with 20 m spacing and wireless receivers spaced every 10 m. For both source types, the recorded data show clear first breaks over all offsets and reflectors in the raw shot gathers. The Kylylahti area is characterized by folded and faulted, steeply dipping geological contacts and structures. We discuss post-stack and pre-stack data processing and compare time and depth imaging techniques in this geologically complex Precambrian hardrock area. The seismic reflection profiles show prominent reflectors at 4.5–8 km depth utilizing different migration routines. In the shallow subsurface, steep reflectors are imaged, and within and underneath the known Kylylahti ultramafic body reflectivity is prominent but discontinuous.

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