Shock‐metamorphic microstructures in quartz grains from Albian sandstones from the Tin Bider impact structure, Algeria

2021 ◽  
Author(s):  
Fazia Kassab ◽  
Ludovic Ferrière ◽  
Djelloul Belhai
Keyword(s):  
Impact Structure ◽  
Quartz Grains

Shocked quartz grains from the Målingen structure, Sweden-Evidence for a twin crater of the Lockne impact structure

2014 ◽  
Vol 49 (6) ◽  
pp. 1076-1082 ◽  
Author(s):  
C. Alwmark ◽  
S. Alwmark-Holm ◽  
J. Ormö ◽  
E. Sturkell
Keyword(s):  
Impact Structure ◽  
Shocked Quartz ◽  
Quartz Grains

The Cleanskin impact structure, Northern Territory and Queensland, Australia: A reconnaissance study

2021 ◽  
Author(s):  
T. Kenkmann ◽  
P.W. Haines ◽  
I.P. Sweet ◽  
K. Mitchell
Keyword(s):  
Remote Sensing ◽  
Northern Territory ◽  
Impact Structure ◽  
Impact Event ◽  
Deformation Features ◽  
Apparent Diameter ◽  
The Impact ◽  
Planar Deformation Features ◽  
Impact Origin ◽  
Quartz Grains

ABSTRACT We report on the Cleanskin structure (18°10′00″S, 137°56′30″E), situated at the border between the Northern Territory and Queensland, Australia, and present results of preliminary geological fieldwork, microscopic analyses, and remote sensing. The Cleanskin structure is an eroded complex impact structure of ~15 km apparent diameter with a polygonal outline caused by two preexisting regional fault sets. The structure has a central uplift of ~6 km diameter surrounded by a rather shallow ring syncline. Based on stratigraphy, the uplift in the center may not exceed ~1000 m. The documentation of planar deformation features (PDFs), planar fractures (PFs), and feather features (FFs) in quartz grains from sandstone members of the Mesoproterozoic Constance Sandstone confirms the impact origin of the Cleanskin structure, as proposed earlier. The crater was most likely eroded before the Cambrian and later became buried beneath Cretaceous strata. We infer a late Mesoproterozoic to Neoproterozoic age of the impact event. In this chapter, the Cleanskin structure is compared with other midsized crater structures on Earth. Those with sandstone-dominated targets show structural similarities to the Cleanskin structure.

scholarly journals The Keurusselkä impact structure, Finland-Impact origin confirmed by characterization of planar deformation features in quartz grains

2010 ◽  
Vol 45 (3) ◽  
pp. 434-446 ◽  
Author(s):  
Ludovic FERRIÈRE ◽  
Selen RAISKILA ◽  
Gordon R. OSINSKI ◽  
Lauri J. PESONEN ◽  
Martti LEHTINEN
Keyword(s):  
Impact Structure ◽  
Planar Deformation ◽  
Deformation Features ◽  
Planar Deformation Features ◽  
Impact Origin ◽  
Quartz Grains

scholarly journals Shocked quartz in distal ejecta from the Ries impact event (Germany) found at ~ 180 km distance, near Bernhardzell, eastern Switzerland

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sanna Holm-Alwmark ◽  
Carl Alwmark ◽  
Ludovic Ferrière ◽  
Matthias M. M. Meier ◽  
Sofie Lindström ◽  
...  
Keyword(s):  
Impact Structure ◽  
Impact Cratering ◽  
Impact Ejecta ◽  
Deformation Features ◽  
Different Depths ◽  
Shocked Quartz ◽  
Depositional Age ◽  
Impact Events ◽  
Planar Deformation Features ◽  
Quartz Grains

AbstractImpact ejecta formation and emplacement is of great importance when it comes to understanding the process of impact cratering and consequences of impact events in general. Here we present a multidisciplinary investigation of a distal impact ejecta layer, the Blockhorizont, that occurs near Bernhardzell in eastern Switzerland. We provide unambiguous evidence that this layer is impact-related by confirming the presence of shocked quartz grains exhibiting multiple sets of planar deformation features. Average shock pressures recorded by the quartz grains are ~ 19 GPa for the investigated sample. U–Pb dating of zircon grains from bentonites in close stratigraphic context allows us to constrain the depositional age of the Blockhorizont to ~ 14.8 Ma. This age, in combination with geochemical and paleontological analysis of ejecta particles, is consistent with deposition of this material as distal impact ejecta from the Ries impact structure, located ~ 180 km away, in Germany. Our observations are important for constraining models of impact ejecta emplacement as ballistically and non-ballistically transported fragments, derived from vastly different depths in the pre-impact target, occur together within the ejecta layer. These observations make the Ries ejecta one of the most completely preserved ejecta deposit on Earth for an impact structure of that size.

The Effects of Drying Techniques on Clay-Rich Soil Texture

1974 ◽  
Vol 32 ◽  
pp. 466-467
Author(s):  
T. G. Naymik
Keyword(s):  
Critical Point ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Drying Methods ◽  
Air Drying ◽  
Freeze Dried ◽  
Critical Point Drying ◽  
Set Up ◽  
The Relationship ◽  
Quartz Grains

Three techniques were incorporated for drying clay-rich specimens: air-drying, freeze-drying and critical point drying. In air-drying, the specimens were set out for several days to dry or were placed in an oven (80°F) for several hours. The freeze-dried specimens were frozen by immersion in liquid nitrogen or in isopentane at near liquid nitrogen temperature and then were immediately placed in the freeze-dry vacuum chamber. The critical point specimens were molded in agar immediately after sampling. When the agar had set up the dehydration series, water-alcohol-amyl acetate-CO2 was carried out. The objectives were to compare the fabric plasmas (clays and precipitates), fabricskeletons (quartz grains) and the relationship between them for each drying technique. The three drying methods are not only applicable to the study of treated soils, but can be incorporated into all SEM clay soil studies.

SEM study of quartz grains from recent sediments: Western Iraq

1990 ◽  
Vol 48 (4) ◽  
pp. 860-861
Author(s):  
F. Al-Kufaishi
Keyword(s):  
Factor Loading ◽  
Fault System ◽  
Clay Material ◽  
Crustal Material ◽  
Factor Analyses ◽  
Five Factors ◽  
Sem Study ◽  
Recent Sediments ◽  
Quartz Grains ◽  
Positive Factor

Two localities (Al-Marij and Laik) were selected to investigate the type of Quartz Grains from crustal material formed by evaporation of waters discharged by springs in Hit area, western Iraq, Previous studies on the crustal material (1,2) showed that the water discharged by these springs are associated with Abu-Jir fault system which run parallel to the Euphrates river,Factor analyses of the crustal and soil materials (50 samples analysed for 16 variables)(2) showed five factors; the first factor includes SiO2, Al2O3 and TiO2 with positive factor loading, and CaO, L.O.I. with negative loading and hence lead to the conclusion that the distribution of these variables is a reflection of transported clay material.This study concentrates on the use of SEM to investigate the contribution of Quartz grains found in the crustal material on two selected sites.

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