scholarly journals Lava Block Rotation around Vertical Axis Inferred from Remanence Directions of Miocene Yoka Formation, Southwest Japan.

1992 ◽  
Vol 44 (1) ◽  
pp. 55-63 ◽  
Author(s):  
Masanori SAKAMOTO
Keyword(s):  
Vertical Axis ◽  
Block Rotation ◽  
Southwest Japan ◽  
Lava Block

Multicomponent magnetizations in Nipissing diabase near Temagami, Ontario, and structural and thermal history of the Grenville Front

1989 ◽  
Vol 26 (3) ◽  
pp. 467-478 ◽  
Author(s):  
Hironobu Hyodo ◽  
David J. Dunlop
Keyword(s):  
Country Rock ◽  
Unknown Origin ◽  
Vertical Axis ◽  
Hydrothermal Activity ◽  
Natural Remanent Magnetization ◽  
Lake Area ◽  
Block Rotation ◽  
History Of ◽  
Tectonic Rotation ◽  
Late Stages

The Nipissing diabase (ND), sampled 2 km northwest of the Grenville Front near Temagami, Ontario, has four distinct components of natural remanent magnetization (NRM). The lowest unblocking temperature (TUB) component is attributed to the present Earth's field, whereas the second lowest TUB component is due to overprinting during the late stages of the Grenvillian Orogeny (~900 Ma). Similar Grenvillian overprint directions of NRM are found in Archean (~2600 Ma) country rock. The second highest TUB component (B) has an unknown origin. Low-temperature demagnetization (LTD) reveals that this component is significantly contaminated by overlap with the Grenvillian overprint and with the highest TUB component (A). If the A NRM is primary, its direction should agree with previously published ND poles after structural correction for subvertical tilting of sites. However, the structurally corrected A direction does not agree with known ND primary directions without additional rotation about a vertical axis. This may indicate sequential block rotation and tilting or could be caused by a single tectonic rotation about an inclined axis. The ND in the Temagami area shows a variety of characteristic magnetizations, which may reflect a complicated structural history and (or) hydrothermal activity before Grenvillian uplift, whereas west of Lake Temagami and in the Wanapitei Lake area ND results agree with the previously reported N1 paleopole. This contrast suggests quite different tectonic histories east and west of Lake Temagami.

Fault reconstructions using aeromagnetic data in the Great Bear magmatic zone, Northwest Territories, Canada

2014 ◽  
Vol 51 (10) ◽  
pp. 927-942 ◽  
Author(s):  
Nathan Hayward ◽  
Louise Corriveau
Keyword(s):  
Iron Oxide ◽  
Vertical Axis ◽  
Fault System ◽  
Aeromagnetic Data ◽  
Block Rotation ◽  
Magmatic Arc ◽  
The North ◽  
Copper Gold ◽  
Great Bear Magmatic Zone ◽  
Transcurrent Faults

The Great Bear magmatic zone, located in Wopmay orogen, is a 1.875–1.84 Ga belt, 450 km long by 100 km wide of volcanic and allied plutonic rocks interpreted as a Paleoproterozoic magmatic arc. The belt, which contains economically important mineralization, was folded and subsequently cut by a swarm of northeast-striking transcurrent faults, which are part of a regional conjugate fault system interpreted to result from terminal collision of the Nahanni – Fort Simpson terrane. Fault reconstructions based on the interpretation of aeromagnetic data and geological maps provide first-order models of deformation mechanisms associated with, and the configuration of the Great Bear magmatic zone prior to, its dissection by northeast-striking transcurrent faults. The models show that vertical axis block rotation (plane strain) of ∼4.5° can explain fault offsets in the south, but that greater rotation is required to explain many of the displacements in the north. However, offsets on transcurrent faults that border the Camsell River district are greater than can be explained by vertical axis block rotation model alone and may include a component of Mesoproterozoic contractional deformation associated with the Racklan–Forward orogeny. Following reconstruction, iron oxide alkali alteration and associated mineralization, which pre-date transcurrent faulting, form a pair of northerly trending zones on the east and west margins of the belt. We suggest that these zones, whose exposure is related to broad synclinal folding of some of the oldest rocks in the Great Bear magmatic zone, are where iron oxide copper–gold (IOCG)-targeted exploration efforts should be focused on these areas in both outcrop and subcrop.

scholarly journals Modelling role of basement block rotation and strike-slip faulting on structural pattern in cover units of fold-and-thrust belts

2016 ◽  
Vol 153 (5-6) ◽  
pp. 827-844 ◽  
Author(s):  
HEMIN KOYI ◽  
FARAMARZ NILFOUROUSHAN ◽  
KHALED HESSAMI
Keyword(s):  
Vertical Axis ◽  
Strike Slip ◽  
Block Rotation ◽  
Northern Iran ◽  
Fault Movement ◽  
Structural Pattern ◽  
Basement Faults ◽  
Thrust Belts ◽  
Basement Fault ◽  
Southwestern Iran

AbstractA series of scaled analogue models are used to study (de)coupling between basement and cover deformation. Rigid basal blocks were rotated about a vertical axis in a ‘bookshelf’ fashion, which caused strike-slip faulting along the blocks and in the overlying cover units of loose sand. Three different combinations of cover–basement deformations are modelled: (i) cover shortening before basement fault movement; (ii) basement fault movement before cover shortening; and (iii) simultaneous cover shortening with basement fault movement. Results show that the effect of the basement faults depends on the timing of their reactivation. Pre- and syn-orogenic basement fault movements have a significant impact on the structural pattern of the cover units, whereas post-orogenic basement fault movement has less influence on the thickened hinterland of the overlying belt. The interaction of basement faulting and cover shortening results in the formation of rhombic structures. In models with pre- and syn-orogenic basement strike-slip faults, rhombic blocks develop as a result of shortening of the overlying cover during basement faulting. These rhombic blocks are similar in appearance to flower structures, but are different in kinematics, genesis and structural extent. We compare these model results to both the Zagros fold-and-thrust belt in southwestern Iran and the Alborz Mountains in northern Iran. Based on the model results, we conclude that the traces of basement faults in cover units rotate and migrate towards the foreland during regional shortening. As such, these traces do not necessarily indicate the actual location or orientation of the basement faults which created them.

scholarly journals Sigmoidal normal faults and evidence for vertical-axis block rotation in an oblique convergent margin: A 3D seismic example from offshore Colombia

2021 ◽  
Vol 40 (12) ◽  
pp. 923-930
Author(s):  
Pedro A. Galindo ◽  
Lidia Lonergan
Keyword(s):  
Shear Zone ◽  
Vertical Axis ◽  
Fault Zones ◽  
Normal Displacement ◽  
Normal Faults ◽  
3D Seismic ◽  
Block Rotation ◽  
Plan View ◽  
Seismic Reflection Data ◽  
Reflection Data

Sigmoidal fold and fault geometries are typical kinematic indicators of strike-slip fault zones. We document kilometer-scale, normal faults with sigmoidal plan-view geometries within the dextral pull-apart Bahia Basin, at the rear of the obliquely convergent South Caribbean Deformed Belt, offshore Colombia. Using 3D seismic reflection data calibrated to wells, closely spaced, low-displacement, planar normal faults are mapped within the Miocene strata. A series of seismic horizontal (time) slices and computed seismic attributes are used to interpret the 3D configuration of these faults. The closely spaced faults display an east–west trend with a progressive rotation into a northwest–southeast trend. In map view, the fault traces curve toward their tips, describing a sigmoidal-Z geometry that terminates at discrete northeast–southwest-trending fault zones. The structures observed may correspond to either tension fractures, which form theoretically at 45°, or antithetic shear fractures with normal displacement formed at 50°–70° to the boundaries of a dextral shear zone. These scenarios lead to a clockwise block rotation of between 20° and 40° within the shear zone. This study shows the first example of vertical-axis block rotations observed offshore in the western end of the South Caribbean margin and is an important example of the use of 3D seismic data to identify rotations where paleomagnetic studies are not available.

Albian syndepositional block rotation and its geological consequences, Basque–Cantabrian Basin (western Pyrenees)

2013 ◽  
Vol 150 (6) ◽  
pp. 986-1001 ◽  
Author(s):  
LUIS MIGUEL AGIRREZABALA ◽  
JAUME DINARÈS-TURELL
Keyword(s):  
Slip Rate ◽  
Vertical Axis ◽  
Strike Slip ◽  
Block Rotation ◽  
Minimum Block ◽  
Magmatic Intrusions ◽  
Axis Rotation ◽  
High Level ◽  
Basque Cantabrian Basin ◽  
Dextral Strike Slip

AbstractStratigraphic, structural, palaeocurrent and palaeomagnetic analyses of Upper Albian deep-water deposits in and around the Deba block (Northern Iberia) are presented. Results indicate an anticlockwise vertical-axis rotation of this block by 35° during a maximum time span of c. 1 Ma (Late Albian intra-C. auritus ammonite Subzone). This Albian syndepositional block rotation is interpreted to be the consequence of the coeval activity of conjugate major sinistral strike-slip faults and minor (antithetic) dextral strike-slip faults, which border the Deba block. On the base of conservative estimations, a minimum block-rotation rate of 35° Ma−1 and a sinistral strike-slip rate of 1.2 km Ma−1 are calculated. As a consequence of the interaction of the rotated Deba block with adjacent non-rotated blocks, its corners experienced coeval transpressive (NW and SE corners) and transtensional deformations (SW and, possibly, NE corners). At the transtensional SW corner, two domal high-reflective seismic structures have been recorded and interpreted as high-level magmatic laccoliths. These magmatic intrusions triggered the development of a mineralizing hydrothermal system, which vented to the Late Albian seafloor warm to hot hydrocarbon-rich fluids. Vented hydrocarbon was generated from Albian organic-rich sediments by contact alteration with hydrothermal fluids.

Spatial Representations as an Emergent Feature of Perceptual Processing

2010 ◽  
Vol 24 (3) ◽  
pp. 161-172 ◽  
Author(s):  
Edmund Wascher ◽  
C. Beste
Keyword(s):  
Common Ground ◽  
Event Related Potentials ◽  
Vertical Axis ◽  
Relevant Information ◽  
Sources Of Information ◽  
Integrated Network ◽  
Perceptual Maps ◽  
Emergent Feature ◽  
Related Potentials ◽  
Selection Of

Spatial selection of relevant information has been proposed to reflect an emergent feature of stimulus processing within an integrated network of perceptual areas. Stimulus-based and intention-based sources of information might converge in a common stage when spatial maps are generated. This approach appears to be inconsistent with the assumption of distinct mechanisms for stimulus-driven and top-down controlled attention. In two experiments, the common ground of stimulus-driven and intention-based attention was tested by means of event-related potentials (ERPs) in the human EEG. In both experiments, the processing of a single transient was compared to the selection of a physically comparable stimulus among distractors. While single transients evoked a spatially sensitive N1, the extraction of relevant information out of a more complex display was reflected in an N2pc. The high similarity of the spatial portion of these two components (Experiment 1), and the replication of this finding for the vertical axis (Experiment 2) indicate that these two ERP components might both reflect the spatial representation of relevant information as derived from the organization of perceptual maps, just at different points in time.

Calculating the aerodynamics of vertical axis wind turbines

2012 ◽  
Vol 34 (3) ◽  
pp. 169-184 ◽  
Author(s):  
Hoang Thi Bich Ngoc
Keyword(s):  
Wind Turbine ◽  
Incidence Angle ◽  
Vertical Axis ◽  
Rotor Blades ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Velocity Triangle ◽  
Relationship Of ◽  
The Relationship

Vertical axis wind turbine technology has been applied last years, very long after horizontal axis wind turbine technology. Aerodynamic problems of vertical axis wind machines are discussible. An important problem is the determination of the incidence law in the interaction between wind and rotor blades. The focus of the work is to establish equations of the incidence depending on the blade azimuth, and to solve them. From these results, aerodynamic torques and power can be calculated. The incidence angle is a parameter of velocity triangle, and both the factors depend not only on the blade azimuth but also on the ratio of rotational speed and horizontal speed. The built computational program allows theoretically selecting the relationship of geometric parameters of wind turbine in accordance with requirements on power, wind speed and installation conditions.

Characterization of groundwater based on δ2H, δ18O and Cl− concentration beneath the Osaka Plain, Southwest Japan

2019 ◽  
Vol 53 (4) ◽  
pp. 235-247
Author(s):  
Tsuyoshi Shintani ◽  
Harue Masuda ◽  
Kaori Okazaki ◽  
Emilie Even ◽  
Masahiko Ono ◽  
...  
Keyword(s):  
Southwest Japan
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