The Sask Craton and Hearne Province margin: seismic reflection studies in the western Trans-Hudson Orogen

2005 ◽  
Vol 42 (4) ◽  
pp. 403-419 ◽  
Author(s):  
Z Hajnal ◽  
J Lewry ◽  
D White ◽  
K Ashton ◽  
R Clowes ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Regional Tectonic ◽  
Detachment Zone ◽  
Tectonic Development ◽  
Seismic Images ◽  
Basal Detachment

A three-dimensional model of the regional crustal architecture of the western Trans-Hudson Orogen, based on the interpretation of 590 km of deep-sounding seismic reflection data and a comparable length of existing seismic reflection information, is presented. The seismic images identify the regional geometry of the basal detachment zone (Pelican thrust) that separates juvenile allochthonous terranes from the underlying Archean microcontinent (Sask craton). The Sask Craton is inferred to have a minimum spatial extent of over 100 000 km2 with an associated crustal root that extends for 200 km along strike. During terminal collision, complete convergence of the Rae–Hearne and Superior continental blocks was precluded by the presence of the Sask Craton, resulting in the preservation of anomalous amounts of oceanic and associated sedimentary juvenile material. Along regional tectonic strike, consistency of crustal structure across the Rae–Hearne margin – Reindeer zone boundary is established. Several phases of tectonic development, including multistage subduction and continent–continent collision, are inferred for the western margin of the orogen. A bright, shallow (2–3.5 s two-way traveltime) band of reflectivity (Wollaston Lake reflector) imaged over ~150 000 km2 area is inferred to be a large post-orogenic mafic intrusion. A highly reflective, well-defined and structurally disturbed Moho discontinuity is mapped throughout the western Trans-Hudson Orogen. The present-day crustal architecture of the western Trans-Hudson Orogen is described in terms of the tectonic evolution within the region.

scholarly journals 3-D seismic images of an extensive igneous sill in the lower crust

Geology ◽  
2019 ◽  
Vol 47 (8) ◽  
pp. 729-733 ◽  
Author(s):  
T. Wrona ◽  
C. Magee ◽  
H. Fossen ◽  
R.L. Gawthorpe ◽  
R.E. Bell ◽  
...  
Keyword(s):  
North Sea ◽  
Lower Crust ◽  
Seismic Reflection ◽  
Three Dimensional ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Igneous Intrusions ◽  
Northern North Sea ◽  
Seismic Images ◽  
East West

Abstract When continents rift, magmatism can produce large volumes of melt that migrate upwards from deep below the Earth’s surface. To understand how magmatism impacts rifting, it is critical to understand how much melt is generated and how it transits the crust. Estimating melt volumes and pathways is difficult, however, particularly in the lower crust where the resolution of geophysical techniques is limited. New broadband seismic reflection data allow us to image the three-dimensional (3-D) geometry of magma crystallized in the lower crust (17.5–22 km depth) of the northern North Sea, in an area previously considered a magma-poor rift. The subhorizontal igneous sill is ∼97 km long (north-south), ∼62 km wide (east-west), and 180 ± 40 m thick. We estimate that 472 ± 161 km3 of magma was emplaced within this intrusion, suggesting that the northern North Sea contains a higher volume of igneous intrusions than previously thought. The significant areal extent of the intrusion (∼2700 km2), as well as the presence of intrusive steps, indicate that sills can facilitate widespread lateral magma transport in the lower crust.

Crustal structure and surface zonation of the Canadian Appalachians: implications of deep seismic reflection data

1989 ◽  
Vol 26 (2) ◽  
pp. 305-321 ◽  
Author(s):  
François Marillier ◽  
Charlotte E. Keen ◽  
Glen S. Stockmal ◽  
Garry Quinlan ◽  
Harold Williams ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Three Dimensional ◽  
Surface Expression ◽  
Seismic Profiles ◽  
Crust And Upper Mantle ◽  
Seismic Reflection Data ◽  
Central Block ◽  
Reflection Data ◽  
Lower Crustal ◽  
Canadian Appalachians

In 1986, 1181 km of marine seismic reflection data was collected to 18–20 s of two-way traveltime in the Gulf of St. Lawrence area. The seismic profiles sample all major surface tectono-stratigraphic zones of the Canadian Appalachians. They complement the 1984 deep reflection survey northeast of Newfoundland. Together, the seismic profiles reveal the regional three-dimensional geometry of the orogen.Three lower crustal blocks are distinguished on the seismic data. They are referred to as the Grenville, Central, and Avalon blocks, from west to east. The Grenville block is wedge shaped in section, and its subsurface edge follows the form of the Appalachian structural front. The Grenville block abuts the Central block at mid-crustal to mantle depths. The Avalon block meets the Central block at a steep junction that penetrates the entire crust.Consistent differences in the seismic character of the Moho help identify boundaries of the deep crustal blocks. The Moho signature varies from uniform over extended distances to irregular with abrupt depth changes. In places the Moho is offset by steep reflections that cut the lower crust and upper mantle. In other places, the change in Moho elevation is gradual, with lower crustal reflections following its form. In all three blocks the crust is generally highly reflective, with no distinction between a transparent upper crust and reflective lower crust.In general, Carboniferous and Mesozoic basins crossed by the seismic profiles overlie thinner crust. However, a deep Moho is found at some places beneath the Carboniferous Magdalen Basin.The Grenville block belongs to the Grenville Craton; the Humber Zone is thrust over its dipping southwestern edge. The Dunnage Zone is allochthonous above the opposing Grenville and Central blocks. The Gander Zone may be the surface expression of the Central block or may be allochthonous itself. There is a spatial analogy between the Avalon block and the Avalon Zone. Our profile across the Meguma Zone is too short to seismically distinguish this zone from the Avalon Zone.

scholarly journals Entrainment and abrasion of megaclasts during submarine landsliding and their impact on flow behaviour

2018 ◽  
Vol 477 (1) ◽  
pp. 223-240 ◽  
Author(s):  
D. M. Hodgson ◽  
H. L. Brooks ◽  
A. Ortiz-Karpf ◽  
Y. Spychala ◽  
D. R. Lee ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Three Dimensional ◽  
Submarine Landslides ◽  
Seismic Reflection Data ◽  
Karoo Basin ◽  
Reflection Data ◽  
Seabed Topography ◽  
Flow Evolution ◽  
Basal Shear ◽  
Process Product

AbstractMany mass transport complexes (MTCs) contain up to kilometre-scale (mega)clasts encased in a debritic matrix. Although many megaclasts are sourced from the headwall areas, the irregular basal shear surfaces of many MTCs indicate that megaclast entrainment during the passage of flows into the deeper basin is also common. However, the mechanisms responsible for the entrainment of large blocks of substrate, and their influence on the longitudinal behaviour of the associated flows, have not been widely considered. We present examples of megaclasts from exhumed MTCs (the Neuquén Basin, Argentina and the Karoo Basin, South Africa) and MTCs imaged in three-dimensional seismic reflection data (Magdalena Fan, offshore Colombia and Santos Basin, offshore Brazil) to investigate these process–product interactions. We show that highly sheared basal surfaces are well developed in distal locations, sometimes extending beyond their associated deposit. This points to deformation and weakening of the substrate ahead of the flow, suggesting that preconditioning of the substrate by distributed shear ahead of, and to the side of, a mass flow could result in the entrainment of large fragments. An improved understanding of the interactions between flow evolution, seabed topography, and the entrainment and abrasion of megaclasts will help to refine estimates of run-out distances, and therefore the geohazard potential of submarine landslides.

Inversion of the Proterozoic Wernecke basin during tectonic development of the Racklan Orogen, northwest Canada

1994 ◽  
Vol 31 (3) ◽  
pp. 447-457 ◽  
Author(s):  
Marlene Dredge Mitchelmore ◽  
Frederick A. Cook
Keyword(s):  
Seismic Reflection ◽  
Sedimentary Rocks ◽  
Drill Hole ◽  
Seismic Reflection Data ◽  
Potential Field Data ◽  
Eastern Front ◽  
Reflection Data ◽  
Tectonic Development ◽  
Mackenzie Mountains ◽  
Middle Proterozoic

New deep seismic reflection data coupled with regional stratigraphic correlations, drill-hole information, and potential field data are interpreted to provide images of Middle Proterozoic Wernecke Supergroup (meta-)sedimentary layers that were uplifted during tectonic development of the ca. 0.9–1.3 Ga Racklan Orogen in Canada's western Northwest Territories. The reflection data are located at the eastern front of the Mackenzie Mountains portion of the Canadian Cordillera and on the western flank of the Fort Simpson structural trend that is a prominent Proterozoic structure in the subsurface throughout the region. Along three parallel profiles, layers that are correlated with thick Wernecke Supergroup sedimentary rocks produce prominent reflections between about 3.0 and 9.0 s (about 7.5 and 23 km) that were arched prior to deposition of younger Proterozoic (probably Mackenzie Mountains Supergroup) and Phanerozoic sedimentary rocks. The strata are considered to be Wernecke basin sedimentary rocks that were uplifted during deformation associated with the development of the Racklan Orogen.

INTEGRATED TECHNIQUES FOR DETERMINING THE VELOCITY FUNCTION IN THE SEISMIC REFLECTION: EXAMPLE OF LOW SIGNAL-TO-NOISE DATA

2016 ◽  
Vol 34 (2) ◽  
Author(s):  
Rodrigo Francis Revorêdo ◽  
Carlos César Nascimento da Silva
Keyword(s):  
Seismic Reflection ◽  
Signal To Noise Ratio ◽  
Hydrocarbon Exploration ◽  
Velocity Analysis ◽  
Signal To Noise ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Noise Data ◽  
Quality And Reliability ◽  
Seismic Images

ABSTRACT. In the hydrocarbon exploration activities, the reprocessing of old seismic reflection data, acquired with few channels and with low signal-to-noise ratio, is commonly undertaken to ameliorate the quality and reliability of the seismic images...Keywords: seismic processing, velocity analysis, CVS. RESUMO. É comum na exploração de hidrocarbonetos o reprocessamento de dados sísmicos antigos, por vezes com um baixo número de canais e baixa razão sinal/ruído, com o objetivo de gerar uma imagem de melhor qualidade e confiabilidade quando comparada àquelas já existentes...Palavras-chave: processamento sísmico, análise de velocidades, CVS. 

Sign in / Sign up

Export Citation Format

Share Document