East-west crustal structure and ?down-bowing? Moho under the northern Tibet revealed by wide-angle seismic profile

2002 ◽  
Vol 45 (6) ◽  
pp. 550 ◽  
Author(s):  
Zhongjie ZHANG
Keyword(s):  
Crustal Structure ◽  
Seismic Profile ◽  
Wide Angle ◽  
Northern Tibet ◽  
East West

Seismic reflection constraints from Lithoprobe line 29 on the upper crustal structure of the northern Abitibi greenstone belt

1995 ◽  
Vol 32 (2) ◽  
pp. 128-134 ◽  
Author(s):  
Gilles Bellefleur ◽  
Arthur Barnes ◽  
Andrew Calvert ◽  
Claude Hubert ◽  
Marianne Mareschal
Keyword(s):  
Crustal Structure ◽  
Greenstone Belt ◽  
Seismic Reflection ◽  
Volcanic Rocks ◽  
Seismic Profile ◽  
Median Filtering ◽  
Abitibi Greenstone Belt ◽  
Geological Information ◽  
Additional Constraints ◽  
East West

Detailed reprocessing of east–west Lithoprobe seismic reflection line 29 includes cross-dip analysis to improve the continuity of the reflectors and median filtering to attenuate shear wave refractions. The interpretation provides additional constraints on the tectonic models of northern Abitibi, but cannot be used to invalidate either of the two models recently presented for the area. However, the seismic profile defines a large east-dipping faulted contact between the Brouillan tonalite and the volcanic rocks exposed west of the intrusion. The moderate dip of the reflectors and their extensive lateral continuity, combined with geological information, provide evidence for an east-dipping thrust sequence and suggest an allochthonous origin for the Brouillan tonalite. The maximum thickness of the volcanic sequence in the northern Abitibi greenstone belt is 8 km, but could be as low as 4 km if Opatica orthogneisses are considered to underthrust northern Abitibi. The mid-crustal reflections confirm the east–west continuity of south-vergent imbrications also observed on a north–south reflection line (28) through northern and central Abitibi. Breakage and displacement of some mid-crustal reflectors may define a west-to-east thrust sequence of sense opposite to that which thrust the Brouillan pluton over the volcanic rocks.

scholarly journals Crustal structure of the Eratosthenes Seamount, Cyprus and S. Turkey from an amphibian wide-angle seismic profile

2017 ◽  
Vol 700-701 ◽  
pp. 32-59 ◽  
Author(s):  
Christian Feld ◽  
James Mechie ◽  
Christian Hübscher ◽  
Jeremy Hall ◽  
Stelios Nicolaides ◽  
...  
Keyword(s):  
Crustal Structure ◽  
Seismic Profile ◽  
Wide Angle

Deep crustal structure across a young passive margin from wide-angle and reflection seismic data (The SARDINIA Experiment) – II. Sardinia’s margin

2015 ◽  
Vol 186 (4-5) ◽  
pp. 331-351 ◽  
Author(s):  
Alexandra Afilhado ◽  
Maryline Moulin ◽  
Daniel Aslanian ◽  
Philippe Schnürle ◽  
Frauke Klingelhoefer ◽  
...  
Keyword(s):  
Crustal Structure ◽  
Passive Margin ◽  
Data Sets ◽  
Wide Angle ◽  
Seismic Velocities ◽  
The West ◽  
Reflection Seismic ◽  
Gulf Of Lion ◽  
Deep Crustal Structure ◽  
Domain Iii

Abstract Geophysical data acquired on the conjugate margins system of the Gulf of Lion and West Sardinia (GLWS) is unique in its ability to address fundamental questions about rifting (i.e. crustal thinning, the nature of the continent-ocean transition zone, the style of rifting and subsequent evolution, and the connection between deep and surface processes). While the Gulf of Lion (GoL) was the site of several deep seismic experiments, which occurred before the SARDINIA Experiment (ESP and ECORS Experiments in 1981 and 1988 respectively), the crustal structure of the West Sardinia margin remains unknown. This paper describes the first modeling of wide-angle and near-vertical reflection multi-channel seismic (MCS) profiles crossing the West Sardinia margin, in the Mediterranean Sea. The profiles were acquired, together with the exact conjugate of the profiles crossing the GoL, during the SARDINIA experiment in December 2006 with the French R/V L’Atalante. Forward wide-angle modeling of both data sets (wide-angle and multi-channel seismic) confirms that the margin is characterized by three distinct domains following the onshore unthinned, 26 km-thick continental crust : Domain V, where the crust thins from ~26 to 6 km in a width of about 75 km; Domain IV where the basement is characterized by high velocity gradients and lower crustal seismic velocities from 6.8 to 7.25 km/s, which are atypical for either crustal or upper mantle material, and Domain III composed of “atypical” oceanic crust. The structure observed on the West Sardinian margin presents a distribution of seismic velocities that is symmetrical with those observed on the Gulf of Lion’s side, except for the dimension of each domain and with respect to the initiation of seafloor spreading. This result does not support the hypothesis of simple shear mechanism operating along a lithospheric detachment during the formation of the Liguro-Provencal basin.

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