Help Centre. Track My Order. My Wishlist Sign In Join. Be the first to write a review. Share This eBook:. Add to Wishlist. Instant Download. Description eBook Details Click on the cover image above to read some pages of this book! The Prodigal Sun Evergence. The Dying Light Evergence. Killswitch Crossover Series. City of Pearl The Wess'har Wars. King's Wrath Valisar Book Three. On the other hand, the hot-spotting technique can predict present positions of hotspots if the absolute plate motion is given. Therefore we can undertake iterative calculations using the two methods.
This hybrid method enables us to determine accurate finite rotation poles for the Pacific plate solely from geometry of Hawaii, Louisville and Easter Crough -Line hotspot tracks from around 70 Ma to present. Information of ages can be independently assigned to the model after the poles and rotation angles are determined. We did not detect any inter-hotspot motion from the geometry of these Pacific hotspot tracks using this method. Its orientation was influenced by the inherited Pan-African collisional system and related lithospheric fabric. We present the kinematics of ER derived from compilation of geodetic velocities, focal mechanism inversions, structural data analysis, and construction of geological profiles.
This deviation between GPS velocity trajectories and orientation of incremental extensional strain is developed due to left lateral transtensional deformation. Small amount of vertical axis blocks rotation, sinistral strike slip faults and dyke intrusions in the rift accommodate the transtensional deformation. Comparison between the two reference frames shows different kinematics in ER and also Africa and Somalia plate motion both in magnitude and direction.
Plate spreading direction in shallow HSRF i.
Shearing and extension across the plate boundary zone contribute both to the style of deformation and overall kinematics in the rift. We conclude that the observed long wavelength kinematics and tectonics are consequences of faster SW ward motion of Africa than Somalia in the shallow HSRF. This reference frame seems more consistent with the geophysical and geological constraints in the Rift. Absolute plate motions and true polar wander in the absence of hotspot tracks.
The motion of continents relative to the Earth's spin axis may be due either to rotation of the entire Earth relative to its spin axis--true polar wander--or to the motion of individual plates. In order to distinguish between these over the past Myr since the formation of the Pangaea supercontinent , we present here computations of the global average of continental motion and rotation through time in a palaeomagnetic reference frame. Two components are identified: a steady northward motion and, during certain time intervals, clockwise and anticlockwise rotations, interpreted as evidence for true polar wander.
We find approximately 18 degrees anticlockwise rotation about Myr ago and the same amount of clockwise rotation about Myr ago. In both cases the rotation axis is located at about degrees W, 0 degrees N, near the site that became the North American-South American-African triple junction at the break-up of Pangaea. This was followed by approximately 10 degrees clockwise rotation about Myr ago, followed again by the same amount of anticlockwise rotation about Myr ago, with a rotation axis in both cases approximately degrees E in the reconstructed area of North Africa and Arabia.
These rotation axes mark the maxima of the degree-two non-hydrostatic geoid during those time intervals, and the fact that the overall net rotation since Myr ago is nearly zero is an indication of long-term stability of the degree-two geoid and related mantle structure. We propose a new reference frame, based on palaeomagnetism, but corrected for the true polar wander identified in this study, appropriate for relating surface to deep mantle processes from Myr ago until hotspot tracks can be used about Myr ago.
Boschman, L. A positive wave speed anomaly interpreted as the Cocos slab stretches from the uppermost mantle at the Middle America trench in the west, to the lowermost mantle below the Atlantic in the east.
The length and continuity of this slab indicates long-lived, uninterrupted eastward subduction of the attached Cocos Plate and its predecessor, the Farallon Plate. The geological record of Mexico contains Triassic to present day evidence of subduction, of which the post-Late Cretaceous phase is of continental margin-style. Interpretations of the pre-Upper Cretaceous subduction-related rock assemblages are under debate, and vary from far-travelled exotic intra-oceanic island arc character to in-situ extended continental margin origin.
This suggests that these rock assemblages were part of the overriding plate and were perhaps only separated from the North American continent by temporal fore- or back-arc spreading.
The entire Triassic-present day subduction record, and hence, reconstructed trench location, can therefore be linked to the Cocos slab, which provides control on longitudinal plate motion of North America since the time of Pangea. Compared to the latest state of the art mantle frames, in which longitudes are essentially unconstrained for pre-Cretaceous times, our reconstructed absolute position of North America requires a significant westward longitudinal shift for Mesozoic times. Towards absolute plate motions constrained by lower-mantle slab remnants.
Since the first reconstruction of the supercontinent Pangaea, key advances in plate tectonic reconstructions have been made1. On the absolute meaning of motion. Directory of Open Access Journals Sweden.
Full Text Available The present manuscript aims to clarify why motion causes matter to age slower in a comparable sense, and how this relates to relativistic effects caused by motion. A fresh analysis of motion , build on first axiom, delivers proof with its result, from which significant new understanding and computational power is gained. A review of experimental results demonstrates, that unaccelerated motion causes matter to age slower in a comparable, observer independent sense.
Whilst focusing on this absolute effect, the present manuscript clarifies its context to relativistic effects, detailing their relationship and incorporating both into one consistent picture. The presented theoretical results make new predictions and are testable through suggested experiment of a novel nature. The manuscript finally arrives at an experimental tool and methodology, which as far as motion in ungravitated space is concerned or gravity appreciated, enables us to find the absolute observer independent picture of reality, which is reflected in the comparable display of atomic clocks.
The discussion of the theoretical results, derives a physical causal understanding of gravity, a mathematical formulation of which, will be presented.
In Search of the Alter Dom (Antares Cluster Trilogy) - Kindle edition by Jack Challis. Download it once and read it on your Kindle device, PC, phones or tablets. In Search of the Alter Dom (Antares Cluster Trilogy) eBook: Jack Challis: Amazon .in: Kindle Store.
Keywords: Kinematics, Gravity, Atomic clocks, Cosmic microwave background. Plate motions and plate stresses are widely assumed as the surface expression of mantle convection. The generation of plate tectonics from mantle convection has been studied for many years. Lithospheric thickening or ridge push and slab pull forces are commonly accepted as the major driving forces for the plate motions. However, the importance of the lower mantle to plate stresses and plate motions remains less clear. Here, we use the joint modeling of lithosphere and mantle dynamics approach of Wang et al.
Absolute values of deviatoric stresses are determined by the body force distributions GPE gradients and traction magnitudes applied at the base of the lithosphere. We use the same relative viscosity model that Ghosh et al. This distribution of absolute values of lithosphere viscosities defines the magnitudes of surface motions. In this procedure, the dynamic model first satisfies the internal constraint of no-net-rotation of motions. The model viscosity field is then scaled by the single factor until we achieve a root mean square RMS minimum between computed surface motions and the kinematic no-net-rotation NNR model of Kreemer et al.
We compute plate stresses and plate motions from recently published global tomography models over 70 based on Wang et al. We find that RMS misfits are significantly reduced when details of lower mantle structure from the latest tomography models are added to models that contain only upper and mid-mantle density distributions.
One of the key reasons is that active upwelling from the Large Low Shear. Chemel, A. We cross-match objects from several different astronomical catalogs to determine the absolute proper motions of stars within the arcmin radius fields of Milky-Way globular clusters with the accuracy of mas yr Cluster members are photometrically identified by selecting horizontal- and red-giant branch stars on color-magnitude diagrams, and the mean absolute proper motions of the clusters with a typical formal error of about 0. Five distant clusters have higher-than-escape velocities, most likely due to large errors of computed transversal velocities, whereas the computed orbits of all other clusters remain bound to the Galaxy.
Unlike previously published results, we find the bar to affect substantially the orbits of most of the clusters, even those at large Galactocentric distances, bringing appreciable chaotization, especially in the portions of the orbits close to the Galactic center, and stretching out the orbits of some of the thick-disk clusters. The Hawaii-Emperor and Louisville hotspot tracks have long dominated the data set constraining absolute plate motion models.
According to plate reconstructions these LIPs were constructed near all-ridge triple junctions, thus potential plume-ridge interactions need to be clarified before these LIPs can be used to define an absolute mantle reference frame. In contrast, the volcanoes of the third group Wake, Marshall, Magellan did erupt truly intra- plate and we therefore argue that this group provides a constraint on plate motion beyond 80 Ma that is independent of plume-ridge interactions.
Backtracking each volcano through its age to its original eruptive location and using compositional color-coding, reveals groupings and patterns that vary by plate motion model, while the temporal patterns of backtracked locations inform us about potential plume motions. Plate motions and deformations from geologic and geodetic data. Research effort on behalf of the Crustal Dynamics Project focused on the development of methodologies suitable for the analysis of space-geodetic data sets for the estimation of crustal motions , in conjunction with results derived from land-based geodetic data, neo-tectonic studies, and other geophysical data.
These methodologies were used to provide estimates of both global plate motions and intraplate deformation in the western U. Results from the satellite ranging experiment for the rate of change of the baseline length between San Diego and Quincy, California indicated that relative motion between the North American and Pacific plates over the course of the observing period during to were consistent with estimates calculated from geologic data averaged over the past few million years. This result, when combined with other kinematic constraints on western U.