STRUCTURAL CHARACTERISTICS AROUND THE FRONTAL THRUST ALONG THE NANKAI TROUGH REVEALED BY RED RELIEF IMAGE MAPPING AND SEISMIC REFLECTION SURVEY

2017 ◽  
Author(s):  
Mikiya Yamashita ◽  
◽  
Ayako Nakanishi ◽  
Gregory F. Moore ◽  
Shuichi Kodaira ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Nankai Trough ◽  
Structural Characteristics ◽  
Image Mapping

scholarly journals The Wishbone Ridge at the Chatham Rise Intersection: Structural Characteristics and Tectonic Implications

2021 ◽  
Author(s):  
◽  
Rachel Barrett
Keyword(s):  
New Zealand ◽  
Seismic Reflection ◽  
Structural Characteristics ◽  
Gravity Data ◽  
Large Igneous Province ◽  
Magnetic Data ◽  
The West ◽  
Satellite Gravity ◽  
Gondwana Margin ◽  
Seismic Reflection Profiles

<p>Geophysical data show that the West Wishbone Ridge, offshore of eastern New Zealand, is best described as having previously been a crustal transform fault, which first propagated along the eastern margin of the Hikurangi Plateau as subduction along the New Zealand sector of the Gondwana margin began to slow and reorientate between 105 and 101 Ma. Variation in the strike of the West Wishbone Ridge has resulted in contrasting compressional and extensional zones along the ridge. These regimes reflect the direction of strike offset from the direction of fault propagation, and constrain the sense of motion along the West Wishbone Ridge as having been dextral.  We find evidence that Cretaceous subduction along the Chatham Rise margin extended east of the margin offset at 174°W that marks the edge of Hikurangi Plateau subduction beneath the margin. Rotation of the Chatham Rise margin between 105 and 101 Ma was accommodated by westward broadening of the extensional zone of deformation associated with the West Wishbone Ridge near its intersection with the Chatham Rise. The amount of offset along the ridge indicates that significant transform motion along the West Wishbone Ridge south of ~40.5°S ceased ca. 101 Ma, coeval with the cessation of spreading of the Osbourn Trough, and of subduction of the Hikurangi Plateau.  Additionally, we find anomalously thick oceanic crust adjacent to the WWR and north of the Hikurangi Plateau (>12 km thick). This is attributed to the proximity of this crust to the Hikurangi Plateau Large Igneous Province.  The results of this study are based on seismic reflection and magnetic data recently collected during the 2016 R/V Sonne survey SO-246, as well as previously collected seismic reflection profiles and satellite gravity data.</p>

scholarly journals Along-strike variations in protothrust zone characteristics at the Nankai Trough subduction margin

Geosphere ◽  
2021 ◽  
Author(s):  
Hannah L. Tilley ◽  
Gregory F. Moore ◽  
Mikiya Yamashita ◽  
Shuichi Kodaira
Keyword(s):  
High Resolution ◽  
Strain Localization ◽  
Seismic Reflection ◽  
Deformation Band ◽  
Nankai Trough ◽  
Accretionary Prism ◽  
Fault Propagation ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Surface Slopes

Significant along-strike changes in the protothrust zone at the toe of the Nankai Trough accretionary prism were imaged in new high-resolution seismic reflection data. The width of the protothrust zone varies greatly along strike; two spatially discrete segments have a wide protothrust zone (∼3.3–7.8 km, ∼50–110 protothrusts), and two segments have almost no protothrust zone (∼0.5–2.8 km, &lt;20 protothrusts). The widest protothrust zone occurs in the region with the widest and thickest sediment wedge and subducting turbidite package, both of which are influenced by basement topography. The trench wedge size and lithology, the lithology of the subducting section, and the basement topography all influence the rate of consolidation in the trench wedge, which we hypothesize is an important control over the presence and width of the protothrust zone. We conclude that protothrusts are fractures that form from shear surfaces in deformation band clusters as the trench fill sediment is consolidated. Strain localization occurs at sites with a high density of protothrusts, which become the probable locations of future frontal thrust propagation. The frontal thrust may propagate forward with a lower buildup of strain where it is adjacent to a wide protothrust zone than at areas with a narrow or no protothrust zone. This is reflected in the accretionary prism geometry, where wide protothrust zones occur adjacent to fault-propagation folds with shallow prism toe surface slopes.

Structural Characteristics of some Sedimentary Basins in Northern Baffin Bay

1973 ◽  
Vol 10 (8) ◽  
pp. 1267-1278 ◽  
Author(s):  
C. E. Keen ◽  
D. L. Barrett
Keyword(s):  
Seismic Reflection ◽  
Magnetic Measurements ◽  
Structural Characteristics ◽  
Gravity Data ◽  
Seismic Refraction ◽  
Sedimentary Basins ◽  
Structural Features ◽  
Ocean Basin ◽  
Normal Faults ◽  
Baffin Bay

Geophysical measurements along tracks crossing some of the main structural features of the northern Baffin Bay shelf are described. The data consist of seismic reflection, seismic refraction, gravity, and magnetic measurements. Results in four areas—Lancaster Sound, Melville Bay, Smith Sound and Jones Sound—are presented. Magnetic and gravity data are used to define the extent of sedimentary basins in these areas. Seismic reflection measurements delineate the structural characteristics of the upper 2 km of the sedimentary strata and allow comparisons between them to be made. Seismic refraction measurements show that the upper 2 km of sediment exhibit low velocities—less than 3.2 km/s. Little deformation of the sediments is observed in any of these areas, however, the strata in Lancaster Sound and in the Melville Bay graben appear to have experienced less faulting than those in Jones Sound and Smith Sound. Normal faults are characteristic of the latter two areas. Jones Sound is a structurally complex area and is filled by a lesser thickness of sediments than is found in the other basins. These sediments are terminated near the entrance to the sound by Precambrian basement. A deeper sedimentary basin occupies Smith Sound and trends across the Nares Strait lineament. Although the data are insufficient to allow a detailed structural analysis of the strata in these regions, we speculate that the differences in sedimentary structures can be related to the formation of the Baffin Bay ocean basin.

Evolution of the Nankai Trough décollement from the trench into the seismogenic zone: Inferences from three-dimensional seismic reflection imaging

Geology ◽  
2004 ◽  
Vol 32 (4) ◽  
pp. 273 ◽  
Author(s):  
Nathan L. Bangs ◽  
Thomas H. Shipley ◽  
Sean P.S. Gulick ◽  
Gregory F. Moore ◽  
Shinichi Kuromoto ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Nankai Trough ◽  
Three Dimensional ◽  
Seismogenic Zone ◽  
Reflection Imaging
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