Calcite twinning strains associated with Laramide uplifts, Wyoming Province

ABSTRACT We report the results of 167 calcite twinning strain analyses (131 limestones and 36 calcite veins, n = 7368 twin measurements)t from the Teton–Gros Ventre (west; n = 21), Wind River (n = 43), Beartooth (n = 32), Bighorn (n = 32), and Black Hills (east; n = 11) Laramide uplifts. Country rock limestones record only a layer-parallel shortening (LPS) strain fabric in many orientations across the region. Synorogenic veins record both vein-parallel shortening (VPS) and vein-normal shortening (VNS) fabrics in many orientations. Twinning strain overprints were not observed in the limestone or vein samples in the supracrustal sedimentary veneer (i.e., drape folds), thereby suggesting that the deformation and uplift of Archean crystalline rocks that form Laramide structures were dominated by offset on faults in the Archean crystalline basement and associated shortening in the midcrust. The twinning strains in the pre-Sevier Jurassic Sundance Formation, in the frontal Prospect thrust of the Sevier belt, and in the distal (eastern) foreland preserve an LPS oriented approximately E-W. This LPS fabric is rotated in unique orientations in Laramide uplifts, suggesting that all but the Bighorn Mountains were uplifted by oblique-slip faults. Detailed field and twinning strain studies of drape folds identified second-order complexities, including: layer-parallel slip through the fold axis (Clarks Fork anticline), attenuation of the sedimentary section and fold axis rotation (Rattlesnake Mountain), rotation of the fold axis and LPS fabric (Derby Dome), and vertical rotations of the LPS fabric about a horizontal axis with 35% attenuation of the sedimentary section (eastern Bighorns). Regional cross sections (E-W) across the Laramide province have an excess of sedimentary veneer rocks that balance with displacement on a detachment at 30 km depth and perhaps along the Moho discontinuity at 40 km depth. Crustal volumes in the Wyoming Province balance when deformation in the western hinterland is included.

Curved, Expanded and Inclined Diffraction Patterns of Grating--Rotating Grating Around Three Axes (1)

The orientation-dependence of the interference/diffraction patterns of the 1D-double slit/1D-grating and 2D-cross-double slit/2D-cross-grating experiments have been studied experimentally and theoretically. However, the above experiments were limited to certain orientations, namely rotating around either one axis or two axes. In this article, the 3-axis-rotation apparatus is proposed/made, which can rotate the 1D-double slit/2D-cross-double slit and 1D-grating/2D-cross-grating, CW and CCW respectively, 00-3600 around three axes independently and sequentially. By this apparatus, the orientation-dependence of the patterns is systematically studied. Moreover, the experiments can be performed easily. Then we show that the photons, before landing on the detector/screen, behave as particles. The above observed phenomena provide the comprehensive information to theoretical study of the double slit/grating experiments. We suggest that the complete mathematical model should contain three rotation angles as parameters. Furthermore, the phenomena have potential applications.

Theoretical investigation of active listening behavior based on the echolocation of CF-FM bats

Bats perceive the three-dimensional (3D) environment by emitting ultrasound pulses from their nose or mouth and receiving echoes through both ears. To detect the position of a target object, it is necessary to know the distance and direction of the target. Certain bat species synchronize the movement of their pinnae with pulse emission, and it is this behavior that enables 3D direction detection. However, the significance of bats’ ear motions remains unclear. In this study, we construct a model of an active listening system including the motion of the ears, and conduct mathematical investigations to clarify the importance of ear motion in 3D direction detection. The theory suggests that only certain ear motions, namely three-axis rotation, accomplish accurate and robust 3D direction detection. Our theoretical analysis also strongly supports the behavior whereby bats move their pinnae in the antiphase mode. In addition, we provide the conditions for ear motions to ensure accurate and robust direction detection, suggesting that simple shaped hearing directionality and well-selected uncomplicated ear motions are sufficient to achieve precise and robust 3D direction detection. Our findings and mathematical approach have the potential to be used in the design of active sensing systems in various engineering fields.

Efficient SAR Azimuth Ambiguity Reduction in Coastal Waters Using a Simple Rotation Matrix: The Case Study of the Northern Coast of Jeju Island

Azimuth ambiguities, or ghosts on SAR images, represent one of the main obstacles for SAR applications involving coastal monitoring activities such as ship detection. While most previous methods based on azimuth antenna pattern and direct filtering are effective for azimuth ambiguity suppression, they may not be effective for fast cruising small ships. This paper proposes a unique approach for the reduction of azimuth ambiguities or ghosts in SAR single-look complex (SLC) images using a simple rotation matrix. It exploits the fact that the signal powers of azimuth ambiguities are concentrated on narrow bands, while those of vessels or other true ground targets are dispersed over broad bands. Through sub-aperture processing and simple axis rotation, it is possible to concentrate the dispersed energy of vessels onto a single axis while the ghost signal powers are dispersed onto three different axes. Then, the azimuth ambiguities can be easily suppressed by a simple calculation of weighted sum and difference, while preserving vessels. Applied results achieved by processing TerrSAR-X SLC images are provided and discussed. An optimum weight of 0.5 was determined by Receiver Operating Characteristic (ROC) analysis. Capabilities of ship detection from the test image were significantly improved by removing 93% of false alarms. Application results demonstrate its high performance of ghost suppression. This method can be employed as a pre-processing tool of SAR images for ship detection in coastal waters.

Neogene Evolution of the Pacific - Australia Plate Boundary Zone in NE Marlborough, South Island, New Zealand

<p>Six new palaeomagnetic localities in NE Marlborough, sampled from Late Cretaceous - Early Tertiary Amuri Formation and Middle Miocene Waima Formation, all yield clockwise declination anomalies of 100 - 150 degrees. Similarity in the magnitude of all new declination anomalies and integration of these results with previous data implies that clockwise vertical-axis rotation of this magnitude affected the entire palaeomagnetically sampled part of NE Marlborough (an area of ~700sq. km) after ~18 Ma. Previous palaeomagnetic sampling constrains this rotation to have occurred before ~7 Ma. The regional nature of this rotation implies that crustal-scale vertical-axis rotations were a fundamental process in the Miocene evolution of the Pacific - Australia plate boundary in NE South Island. The Flags Creek Fault System (FCFS) is a fold-and-thrust belt that formed in marine conditions above a subduction complex that developed as the Pacific - Australia plate boundary propagated through Marlborough in the Early Miocene. Thin-skinned fault offset accommodated at least 20 km of horizontal shortening across a leading-edge imbricate fan. Mesoscopic structures in the deformed belt indicate thrust vergence to the southeast. The palaeomagnetically-determined regional clockwise vertical axis rotation of ~100 degrees must be undone in order to evaluate this direction in the contemporary geographic framework of the thrust belt. Therefore the original transport direction of the thrust sheets in the FCFS was to the NE, in accordance with NE-SW plate motion vector between the Pacific and Australian plates during the Early Miocene. The two new palaeomagnetic localities that are within ~3 km of the active dextral strike-slip Kekerengu Fault have the highest clockwise declination anomalies (up to 150 degrees). Detailed structural mapping suggests that the eastern ends of the FCFS are similarly clockwise-rotated, by an extra 45 degrees relative to the regional average, to become south-vergent in proximity to the Kekerengu Fault. This structural evidence implies the presence of a zone of Plio-Pleistocene dextral shear and vertical-axis rotation within 2-3 km of the Kekerengu Fault. Local clockwise vertical-axis rotations of up to 50 degrees are inferred to have accrued in this zone, and to have been superimposed on the older, regional. ~100 degrees Miocene clockwise vertical-axis rotation. The Late Quaternary stratigraphy of fluvial terraces in NE Marlborough has been revised by the measurement of five new optically stimulated luminescence (OSL) dates on loess. This new stratigraphy suggests that the latest aggradation surface in the Awatere Valley (the Starborough-1 terrace) is, at least locally, ~9 ka old, several thousand years younger than the previous 16 ka thermoluminescence age for the same site. This new surface abandonment age implies that terrace-building events in NE Marlborough lasted well after the last glacial maximum (~17 ka). The timing of terrace aggradation in this peri-glacial region is compared with oxygen isotope data. Downstream transport of glacially derived sediment at the time of maximum deglaciation/warming is concluded to be the primary influence on the aggradation of major fill terraces in coastal NE Marlborough. This interpretation is generally applicable to peri-glacial central New Zealand. Patterns of contemporary uplift and directions of landscape tilting have been analysed by assessing the rates of stream incision and by the evolution of drainage networks over a wide tract of NE Marlborough that includes the termination of the dextral strike-slip Clarence Fault. Relative elevations of differentially aged terraces suggests an increase in rates of incision over the last ~10 ka. Uplift is highest in the area immediately surrounding the fault tip and is generally high where Torlesse basement rocks are exposed. Independently derived directions of Late Quaternary tilting of the landscape display a similar pattern of relative uplift in a broad dome to the north and west of the fault tip. This pattern of uplift suggests dissipation of strike-slip motion at the Clarence Fault tip into a dome-shaped fold accommodating: 1) crustal thickening (uplift) and 2) up to 44 degrees of vertical-axis rotation of a ~40 km2 crustal block, relative to more inland domains, into which the fault terminates. The distribution of incision rates is compared with the pattern of crustal thickening predicted by elastic models of strike-slip fault tips. The observed pattern and spatial extent of uplift generally conforms with the distribution of thickening predicted by the models, although the rate of incision/uplift over the last ~120 ka has been variable. These differences may be due to variability in the strike-slip rate of the Clarence Fault, superimposition of the regional uplift rate or to interaction with nearby fault structures not accounted for in the models.</p>

Neogene Evolution of the Pacific - Australia Plate Boundary Zone in NE Marlborough, South Island, New Zealand

<p>Six new palaeomagnetic localities in NE Marlborough, sampled from Late Cretaceous - Early Tertiary Amuri Formation and Middle Miocene Waima Formation, all yield clockwise declination anomalies of 100 - 150 degrees. Similarity in the magnitude of all new declination anomalies and integration of these results with previous data implies that clockwise vertical-axis rotation of this magnitude affected the entire palaeomagnetically sampled part of NE Marlborough (an area of ~700sq. km) after ~18 Ma. Previous palaeomagnetic sampling constrains this rotation to have occurred before ~7 Ma. The regional nature of this rotation implies that crustal-scale vertical-axis rotations were a fundamental process in the Miocene evolution of the Pacific - Australia plate boundary in NE South Island. The Flags Creek Fault System (FCFS) is a fold-and-thrust belt that formed in marine conditions above a subduction complex that developed as the Pacific - Australia plate boundary propagated through Marlborough in the Early Miocene. Thin-skinned fault offset accommodated at least 20 km of horizontal shortening across a leading-edge imbricate fan. Mesoscopic structures in the deformed belt indicate thrust vergence to the southeast. The palaeomagnetically-determined regional clockwise vertical axis rotation of ~100 degrees must be undone in order to evaluate this direction in the contemporary geographic framework of the thrust belt. Therefore the original transport direction of the thrust sheets in the FCFS was to the NE, in accordance with NE-SW plate motion vector between the Pacific and Australian plates during the Early Miocene. The two new palaeomagnetic localities that are within ~3 km of the active dextral strike-slip Kekerengu Fault have the highest clockwise declination anomalies (up to 150 degrees). Detailed structural mapping suggests that the eastern ends of the FCFS are similarly clockwise-rotated, by an extra 45 degrees relative to the regional average, to become south-vergent in proximity to the Kekerengu Fault. This structural evidence implies the presence of a zone of Plio-Pleistocene dextral shear and vertical-axis rotation within 2-3 km of the Kekerengu Fault. Local clockwise vertical-axis rotations of up to 50 degrees are inferred to have accrued in this zone, and to have been superimposed on the older, regional. ~100 degrees Miocene clockwise vertical-axis rotation. The Late Quaternary stratigraphy of fluvial terraces in NE Marlborough has been revised by the measurement of five new optically stimulated luminescence (OSL) dates on loess. This new stratigraphy suggests that the latest aggradation surface in the Awatere Valley (the Starborough-1 terrace) is, at least locally, ~9 ka old, several thousand years younger than the previous 16 ka thermoluminescence age for the same site. This new surface abandonment age implies that terrace-building events in NE Marlborough lasted well after the last glacial maximum (~17 ka). The timing of terrace aggradation in this peri-glacial region is compared with oxygen isotope data. Downstream transport of glacially derived sediment at the time of maximum deglaciation/warming is concluded to be the primary influence on the aggradation of major fill terraces in coastal NE Marlborough. This interpretation is generally applicable to peri-glacial central New Zealand. Patterns of contemporary uplift and directions of landscape tilting have been analysed by assessing the rates of stream incision and by the evolution of drainage networks over a wide tract of NE Marlborough that includes the termination of the dextral strike-slip Clarence Fault. Relative elevations of differentially aged terraces suggests an increase in rates of incision over the last ~10 ka. Uplift is highest in the area immediately surrounding the fault tip and is generally high where Torlesse basement rocks are exposed. Independently derived directions of Late Quaternary tilting of the landscape display a similar pattern of relative uplift in a broad dome to the north and west of the fault tip. This pattern of uplift suggests dissipation of strike-slip motion at the Clarence Fault tip into a dome-shaped fold accommodating: 1) crustal thickening (uplift) and 2) up to 44 degrees of vertical-axis rotation of a ~40 km2 crustal block, relative to more inland domains, into which the fault terminates. The distribution of incision rates is compared with the pattern of crustal thickening predicted by elastic models of strike-slip fault tips. The observed pattern and spatial extent of uplift generally conforms with the distribution of thickening predicted by the models, although the rate of incision/uplift over the last ~120 ka has been variable. These differences may be due to variability in the strike-slip rate of the Clarence Fault, superimposition of the regional uplift rate or to interaction with nearby fault structures not accounted for in the models.</p>

Torque force in the kinesin stroke drives coupled yaw axis and orbital rotations of kinesin coated gold nanorods

Kinesin motor domains generate impulses of force and movement that have both translational and rotational components, raising the question of how the rotational component contributes to motor function. We used a new assay in which kinesin-coated gold nanorods (kinesin-GNRs) move on suspended microtubules, for three plus-end-directed kinesins: single-headed KIF1A, dimeric ZEN-4 and single-headed kinesin-1. Polarization of the light scattered by all three types of kinesin-GNRs periodically oscillated as they orbited the microtubule along a left-handed helical trajectory. Our analyses revealed that each kinesin-GNR unidirectionally rotates about its yaw axis as it translocates, and that the period of this yaw-axis rotation corresponds to two periods of its left-handed helical orbit around the microtubule axis. Stochastic simulations suggest that the yaw-axis rotation enhances biased lateral displacement of the kinesin team. Our study reveals biaxial rotation as a new mode of motility in kinesin teams that helps the team to sidestep obstacles.