scholarly journals Strength models of the terrestrial planets and implications for their lithospheric structure and evolution

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ikuo Katayama
Keyword(s):  
Internal Structure ◽  
Large Scale ◽  
Frictional Coefficient ◽  
Ductile Deformation ◽  
Terrestrial Planets ◽  
Brittle Strength ◽  
Lithospheric Deformation ◽  
Plastic Strength ◽  
Power Law Creep ◽  
Strength Models

AbstractKnowledge of lithospheric strength can help to understand the internal structure and evolution of the terrestrial planets, as surface topography and gravity fields are controlled mainly by deformational features within the lithosphere. Here, strength profiles of lithosphere were calculated for each planet using a recently updated flow law and taking into account the effect of water on lithospheric deformation. Strength is controlled predominantly by brittle deformation at shallow depths, whereas plastic deformation becomes dominant at greater depths through its sensitivity to temperature. Incorporation of Peierls creep, in which strain rate is exponentially dependent on stress, results in the weakening of plastic strength at higher stress levels, and the transition from brittle to ductile deformation shifts to shallower depths than those calculated using conventional power-law creep. Strength in both the brittle and ductile regimes is highly sensitive to the presence of water, with the overall strength of the lithosphere decreasing markedly under wet conditions. The markedly low frictional coefficient of clay minerals results in a further decrease in brittle strength and is attributed to expansion of the brittle field. As plastic strength is influenced by lithology, a large strength contrast can occur across the crust–mantle boundary if deformation is controlled by ductile deformation. Effective elastic thickness for the terrestrial planets calculated from the rheological models indicates its close dependence on spatiotemporal variations in temperature and the presence of water. Although application of the strength models to observed large-scale surface deformational features is subject to large extrapolation and uncertainties, I emphasize the different sensitivity of these features to temperature and water, meaning that quantifying these features (e.g., by data from orbiting satellites or rovers) should help to constrain the internal structure and evolution of the terrestrial planets.

scholarly journals Fault model of the 2012 doublet earthquake, near the up-dip end of the 2011 Tohoku-Oki earthquake, based on a near-field tsunami: implications for intraplate stress state

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Tatsuya Kubota ◽  
Ryota Hino ◽  
Daisuke Inazu ◽  
Syuichi Suzuki
Keyword(s):  
Stress State ◽  
Frictional Coefficient ◽  
Fault Model ◽  
Japan Trench ◽  
Time Interval ◽  
Depth Range ◽  
Seismic Zone ◽  
Bending Stress ◽  
Normal Faulting ◽  
Brittle Strength

AbstractOn December 7, 2012, an earthquake occurred within the Pacific Plate near the Japan Trench, which was composed of deep reverse- and shallow normal-faulting subevents (Mw 7.2 and 7.1, respectively) with a time interval of ~10 s. It had been known that the stress state within the plate was characterized by shallow tensile and deep horizontal compressional stresses due to the bending of the plate (bending stress). This study estimates the fault model of the doublet earthquake utilizing tsunami, teleseismic, and aftershock data and discusses the stress state within the incoming plate and spatiotemporal changes seen in it after the 2011 Tohoku-Oki earthquake. We obtained the vertical extents of the fault planes of deep and shallow subevents as ~45–70 km and ~5 (the seafloor)–35 km, respectively. The down-dip edge of the shallow normal-faulting seismic zone (~30–35 km) deepened significantly compared to what it was in 2007 (~25 km). However, a quantitative comparison of the brittle strength and bending stress suggested that the change in stress after the Tohoku-Oki earthquake was too small to deepen the down-dip end of the seismicity by ~10 km. To explain the seismicity that occurred at a depth of ~30–35 km, the frictional coefficient in the normal-faulting depth range required would have had to be ~0.07 ≤ μ ≤ ~0.2, which is significantly smaller than the typical friction coefficient. This suggests the infiltration of pore fluid along the bending faults, down to ~30–35 km. It is considered that the plate had already yielded to a depth of ~35 km before 2011 and that the seismicity of the area was reactivated by the increase in stress from the Tohoku-Oki earthquake.

Large-scale topography of Io: Implications for internal structure and heat transfer

1988 ◽  
Vol 15 (6) ◽  
pp. 581-584 ◽  
Author(s):  
Robert W. Gaskell ◽  
Stephen P. Synnott ◽  
Alfred S. McEwen ◽  
Gerald G. Schaber
Keyword(s):  
Heat Transfer ◽  
Internal Structure ◽  
Large Scale

scholarly journals Triaxial experiments on iceberg and glacier ice

1995 ◽  
Vol 41 (139) ◽  
pp. 528-540 ◽  
Author(s):  
R. E. Gagnon ◽  
P. H. Gammon
Keyword(s):  
Large Scale ◽  
Freezing Point ◽  
Shear Plane ◽  
Confining Pressure ◽  
Ductile Deformation ◽  
Dominant Factor ◽  
Stick Slip ◽  
Glacier Ice ◽  
Confining Pressures ◽  
The Mean

Abstract Triaxial experiments, at confining pressures in the range 0–13.79 MPa, have been performed on glacial ice collected from four icebergs and one glacier. Tests were conducted at strain rates in the range of 5 × 10−5 to 5 × 10−5s−1 and at four temperatures in the range of −1° to −16°C. Depending on test conditions, the ice failed by one of four possible modes ductile deformation, due to extensive non-interacting microcracks; fracture along a shear plane followed by continuous or stick-slip sliding; large-scale brittle fracture; and combined ductile and shear-plane fracture and slip The strength Increased with decreasing temperature, increasing strain rate up to 5 × 10−3s−1 and increasing confining pressure at the lower temperatures. The strength at 5 × 10−2s−1 was lower than at 5 × 10−3s−1 probably because extension and interaction of microcracks is enhanced at the higher rate. For higher confining pressures at −1°C, the strength decreased due to freezing-point depression. The ice from the different sources exhibited different mean uniaxial compressive strengths. The mean number of air bubbles per unit volume correlated with the mean uniaxial compressive strengths and this may be the dominant factor distinguishing the strengths of the various ice types.

scholarly journals Next Generation Transit Survey (NGTS)

2013 ◽  
Vol 8 (S299) ◽  
pp. 311-312
Author(s):  
Peter J. Wheatley ◽  
Don L. Pollacco ◽  
Didier Queloz ◽  
Heike Rauer ◽  
Christopher A. Watson ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Internal Structure ◽  
Bulk Composition ◽  
Terrestrial Planets ◽  
Next Generation

AbstractThe Next Generation Transit Survey (NGTS) is a new ground-based survey for transiting exoplanets. Our primary goal is to find the first statistically-significant sample of Neptunes and super-Earths that are bright enough for radial velocity confirmation. By measuring precise masses and radii we will constrain the bulk composition and internal structure of planets that span the transition between the gas giants and terrestrial planets. Our brightest exoplanets will also be suitable for atmospheric characterisation with large facilities such as the VLT, JWST and the E-ELT. NGTS construction began in June 2013, and the survey is due to commence in 2014.

A Modeling Method of Equipment Systems Based on UPDM

2014 ◽  
Vol 571-572 ◽  
pp. 490-496
Author(s):  
Wen Bo Jing ◽  
Yong Ming Gao ◽  
Xue Bo Zhang
Keyword(s):  
Internal Structure ◽  
Systems Engineering ◽  
Large Scale ◽  
System Modeling ◽  
Modeling Method ◽  
Systems Modeling ◽  
Executable Model

For large-scale equipment systems whose elements and internal structure are complex, traditional systems engineering methods can’t meet the requirements of the system modeling. In this paper, a kind of modeling method based on UPDM is developed to solve the complexity of equipment systems. This paper proceeds as follow. Firstly, analyze the mission of equipment systems; secondly, using a variety of views product describes the equipment systems; then, validate the systems structure by generating an executable model. Finally, an experiment about equipment systems modeling of space weaponry indicates the modeling method based on UPDM is effective.

Interplay between folding and ductile shearing in the Proterozoic crust of the Muskoka – Parry Sound region, central Ontario

1987 ◽  
Vol 24 (8) ◽  
pp. 1507-1525 ◽  
Author(s):  
W. M. Schwerdtner
Keyword(s):  
Large Scale ◽  
Lake Huron ◽  
Ductile Deformation ◽  
Boundary Fault ◽  
Crustal Thinning ◽  
Front Boundary ◽  
Ductile Shearing ◽  
Structural Signature ◽  
Reverse Shearing ◽  
East West

Grenville gneiss of the central Georgian Bay region was subjected to ductile deformation that produced narrow mylonite zones as well as three sets of superimposed folds differing greatly in structural signature, size, and orientation. Some mylonite zones are concordant to gneissosity and are repeatedly folded, others cut gneissosity and postdate the folding. Gneissosity was generated as a regionally subhorizontal feature, either by crustal thinning or, like the early mylonite zones, by low-angle reverse shearing. An attempt is made to account for the initially subhorizontal gneissosity, the mylonite zones, and the folds in a regime of large-scale reverse shearing that strikes parallel to the Grenville Front.Upright northwest–southwest to north–south buckle folds dominate the map pattern and are subperpendicular to the reverse Grenville Front boundary fault. These set-2 folds cannot be attributed to reverse simple shearing but require a large component of east–west compression. Such stress could have been generated in a northwest–southeast zone of sinistral ductile shear caused by temporary locking of the southern segment of the Grenville Front boundary fault (now under Lake Huron).All structural facts can be explained without large differential translations of crustal slices. For example, most discordances in the regional gneissosity pattern could have been created by décollement and repeated buckling. Detailed geobarometry and petrologic studies may be required to settle the question of large-scale thrusting within the Grenville gneiss terrane.

Structural and metamorphic relationships between the Mount Ida and Monashee Groups at Mara Lake, British Columbia

1982 ◽  
Vol 19 (2) ◽  
pp. 288-307 ◽  
Author(s):  
Kent C. Nielsen
Keyword(s):  
British Columbia ◽  
Large Scale ◽  
Ductile Deformation ◽  
Late Triassic ◽  
Second Phase ◽  
The West ◽  
Late Mesozoic ◽  
The North ◽  
Phase Deformation ◽  
Metamorphic Core

Mara Lake, British Columbia straddles the boundary between the Monashee Group on the east and the Mount Ida Group on the west. Correlation of units across the southern end of Mara Lake indicates lithologic continuity between parts of the groups. Both groups have experienced four phases of deformation. Phases one and two are tight and recumbent, trending to the north and to the west, respectively. Phases three and four are open to closed and upright, trending northwest and northeast, respectively. Second-phase deformation includes large-scale tectonic slides that separate areas of consistent vergence. Slide surfaces are folded by third- and fourth-phase structures and outline domal outcrop patterns. Metamorphic grade increases from north to south along the west side of Mara Lake. Calc-silicate reactions involving the formation of diopside are characteristic. From west to east increasing grade is evident in the reaction of muscovite + quartz producing sillimanite + K-feldspar + water. These prograde reactions are related to relative position in the second-phase structure. The highest grade is located near the lowest slide surface. Greenschist conditions accompanied phase-three deformation. Fourth phase is characterized by hydrothermal alteration, brittle fracturing, and local faulting. First-phase deformation appears to be pre-Late Triassic whereas second and third phases are post-Late Triassic and pre-Cretaceous. The fourth phase is part of a regional Tertiary event. The third folding event is correlated with the development of the Chase antiform and the second-phase folding is related to the pervasive east–west fabric of the Shuswap Complex. The timing of these events indicates that the metamorphic core zone of the eastern Cordillera was relatively rigid during the late Mesozoic foreland thrust development. Ductile deformation significantly preceded thrusting and developed a fabric almost at right angles to the trend of the thrust belt.

scholarly journals A LARGE SCALE QUASI-CRYSTALLINE LAMELLAR LATTICE IN CHLOROPLASTS OF THE GREEN ALGA ZYGNEMA

1970 ◽  
Vol 45 (3) ◽  
pp. 522-531 ◽  
Author(s):  
Robert J. Mclean ◽  
George F. Pessoney
Keyword(s):  
Internal Structure ◽  
Green Alga ◽  
Thylakoid Membrane ◽  
Large Scale ◽  
Three Dimensional ◽  
Prolamellar Body ◽  
Dimensional Lattice ◽  
Filamentous Green Alga ◽  
Prolamellar Bodies ◽  
Single Membrane

A quasi-crystalline lamellar lattice was observed in chloroplasts of the filamentous green alga Zygnema. The lattice does not appear in the cells until cultures are at the end of the log phase of growth. Pseudograna are also present and become more numerous towards the middle of the log phase. The three-dimensional lattice superficially resembles the configuration of cubic prolamellar bodies but is about 10 times larger and is entirely different in internal structure. The lattice is composed of one or two appressed thylakoids in a stroma matrix which is bounded on each side by a single thylakoid membrane. This multilayered sandwich of membranes and matrix occupies a position equivalent to the single membrane of a cubic prolamellar body.

scholarly journals Magneto-asteroseismology of massive magnetic pulsators

2016 ◽  
Vol 12 (S329) ◽  
pp. 146-150
Author(s):  
B. Buysschaert ◽  
C. Neiner ◽  
C. Aerts
Keyword(s):  
Magnetic Field ◽  
Internal Structure ◽  
Hybrid Method ◽  
Large Scale ◽  
Massive Star ◽  
Mixing Processes ◽  
Large Scale Magnetic Field ◽  
Stellar Pulsations

AbstractSimultaneously and coherently studying the large-scale magnetic field and the stellar pulsations of a massive star provides strong complementary diagnostics suitable for detailed stellar modelling. This hybrid method is called magneto-asteroseismology and permits the determination of the internal structure and conditions within magnetic massive pulsators, for example the effect of magnetism on non-standard mixing processes. Here, we overview this technique, its requirements, and list the currently known suitable stars to apply the method.

Sign in / Sign up

Export Citation Format

Share Document