Getting the inside story: using computed X-ray tomography to study inclusion trails in garnet porphyroblasts

2005 ◽  
Vol 90 (11-12) ◽  
pp. ea1-ea17 ◽  
Author(s):  
C. R. Huddlestone-Holmes
Keyword(s):  
Garnet Porphyroblasts ◽  
X Ray ◽  
Inclusion Trails ◽  
Study Inclusion

scholarly journals Microstructure characteristics of the ganet-bearing schist from Nam Co formation, Son La area, Song Ma suture zone, Northwestern Vietnam

2021 ◽  
Vol 62 (1) ◽  
pp. 64-72
Author(s):  
Hau Vinh Bui ◽  
Hai Thanh Tran ◽  
Thanh Xuan Ngo ◽  
Chi Kim Thi Ngo ◽  
Keyword(s):  
Mineral Assemblage ◽  
Suture Zone ◽  
Nam Co ◽  
Garnet Porphyroblasts ◽  
Microstructure Characteristics ◽  
Inclusion Trails ◽  
Compositional Zonation

The garnet-bearing schists of the Nam Co formation have an identical mineral assemblage consisting of garnet, chlorte, albite, quartz and muscovite, together with accessory apatite, zircon, monazite, xenotime, and ilmenite. An aggregate of muscovite and chlorite defines the major foliations (Sn). Both albite and garnet occur as a porphyroblast, ranging in size 0.2÷1 mm and 0.5÷1.2 mm, respectively. Albite porphyroblasts commonly have the curved to sigmoidal inclusion trails defined by graphitic materials (Sn-1). Garnet porphyroblasts in the sample is generally characterized by paucity of inclusions and retrograde corona of bitotite and chlorite. Garnet also occurs as an inclusion within albite porphyroblast. Porphyroblastic garnet shows the compositional zonation typified by a bell-shaped spessartine profile balanced by increasing almandine from core to rim. Whereas, inclusion garnet is homogeneous compositions with rich in almandin and poor in spessatin, pyrop and grossula. All the above microstructures suggest two deformation and metamorphic stages (M1 and M2) that were affected to politic rocks of the Nam Co formation, Song Ma suture zone.

scholarly journals The formation mechanism of garnet porphyroblast in quartz schist, Namche Barwa, east Himalaya

2013 ◽  
Vol 46 ◽  
Author(s):  
Zhihui Cai ◽  
Hui Cao
Keyword(s):  
Suture Zone ◽  
Electron Backscattered Diffraction ◽  
Garnet Porphyroblasts ◽  
Shear Sense ◽  
The Matrix ◽  
Yarlung Tsangpo ◽  
Namche Barwa ◽  
Growth Zoning ◽  
Inclusion Trails ◽  
Garnet Porphyroblast

The quartz schist in the Indus-Yarlung Tsangpo suture zone, from Namche Barwa, east Himalaya undergone extensive mylonization with well developed, foliation and lineation; its S-C fabric, "σ" and "δ" type porphyroblasts and asymmetrical folds indicate the northwestward normal slip ductile shear deformation. The electron backscattered diffraction (EBSD) data, lattice preferred orientation (LPO) patterns for quartzes in the matrix foliation (or external foliation, S) and inclusion-trails in the rim of the garnet porphyroblasts (S) both show a top-to-NW (normal) shear sense. While LPO patterns for quartzes of the inclusion-trails in the garnet porphyroblast cores (S) show an opposite shear sense (top-to-SE). The garnet compositional zonation indicates a growth zoning characteristic from energy dispersive spectroscopy (EDS) analysis. By connecting the inclusion-trails in garnet cores, an initial foliation trace with asymmetrical fold shape can be obtained. It suggests that these garnet porphyroblasts with snov, ball structure formed on the asymmetrical folds by the rotation of external shear sense rather than the rotation of garnet porphyroblasts. Gamet porphyroblast with snowball structure proposed that the rocks from the lndus Yarlung Tsangpo suture zone west side of the Namche Barwa syntaxis have undergone southeastward thrusting and later followed by northwestward normal slipping.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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