Revealing microstructural properties of shocked and tectonically deformed zircon from the Vredefort impact structure: Raman spectroscopy combined with SEM microanalyses

2021 ◽  
Author(s):  
Elizaveta Kovaleva ◽  
Dmitry A. Zamyatin
Keyword(s):  
Raman Spectroscopy ◽  
Raman Band ◽  
Impact Structure ◽  
Chemical Mapping ◽  
Deformation Bands ◽  
Electron Backscattered Diffraction ◽  
Granite Sample ◽  
Deformation Features ◽  
Ebsd Technique ◽  
Deformation Patterns

ABSTRACT Finite deformation patterns of accessory phases can indicate the tectonic regime and deformation history of the host rocks and geological units. In this study, tectonically deformed, seismically deformed, and shocked zircon grains from a granite sample from the core of the Vredefort impact structure were analyzed in situ, using a combination of Raman spectroscopy, backscatter electron (BSE) imaging, electron backscattered diffraction (EBSD) mapping, electron probe microanalyses (EPMA), energy-dispersive X-ray spectroscopy (EDS) qualitative chemical mapping, and cathodoluminescence (CL) imaging. We aimed to reveal the effects of marginal grain-size reduction, planar deformation bands (PDBs), and shock microtwins on the crystal structure and microchemistry of zircon. Deformation patterns such as PDBs, microtwins, and subgrains did not show any significant effect on zircon crystallinity/metamictization degree or on the CL signature. However, the ratio of Raman band intensities B1g (1008 cm–1) to Eg (356 cm–1) slightly decreased within domains with low misorientation. The ratio values were affected in shocked grains, particularly in twinned domains with high misorientation. B1g/Eg ratio mapping combined with metamictization degree mapping (full width at half maximum of B1g peak) suggest the presence of shock deformation features in zircon; however, due to the lower spatial resolution of the method, they must be used in combination with the EBSD technique. Additionally, we discovered anatase, quartz, goethite, calcite, and hematite micro-inclusions in the studied zircon grains, with quartz and anatase specifically being associated with strongly deformed domains of shocked zircon crystals.

scholarly journals Distinguishing ice β-XV from deep glassy ice VI: Raman spectroscopy

2019 ◽  
Vol 21 (28) ◽  
pp. 15452-15462 ◽  
Author(s):  
Alexander V. Thoeny ◽  
Tobias M. Gasser ◽  
Thomas Loerting
Keyword(s):  
Raman Spectroscopy ◽  
Raman Band

Evidence for the existence of D2O-ice β-XV is given by the observation of its librational Raman band at 380 cm−1.

scholarly journals Redistribution of germanium during dynamic recrystallization of sphalerite

Geology ◽  
2019 ◽  
Vol 48 (3) ◽  
pp. 236-241 ◽  
Author(s):  
Alexandre Cugerone ◽  
Bénédicte Cenki-Tok ◽  
Emilien Oliot ◽  
Manuel Muñoz ◽  
Fabrice Barou ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Background Level ◽  
Microstructural Characterization ◽  
Ore Deposits ◽  
Chemical Mapping ◽  
Low Carbon ◽  
Rare Metals ◽  
Green Technologies ◽  
Electron Backscattered Diffraction ◽  
Spatial Redistribution

Abstract Rare metals are essential to the development of the “green” technologies that are at the core of low-carbon societies. In nature, these metals are frequently present in trace amounts scattered in base metal ore deposits, but the physico-chemical processes that are responsible for their concentration into strategic minerals are still poorly understood. Based on laser-induced breakdown spectroscopy (LIBS), coupled with electron backscattered diffraction (EBSD) analysis, this study shows that plastic deformation and subsequent syntectonic recrystallization of sphalerite (zinc sulfide, ZnS) led to the spatial redistribution of germanium (Ge): from a background level of a few hundreds of parts per million in undeformed primary sphalerite to tens of weight-percent in neocrystallized Ge minerals. During dynamic recrystallization, Ge is likely released from the crystal lattice of parent sphalerite and subsequently concentrated in Ge minerals, leaving behind a Ge-depleted, recrystallized sphalerite matrix. Identifying how rare metals concentrate through deformation and syntectonic recrystallization at the mineral scale is essential to understand the spatial redistribution and localization at the deposit scale. This study highlights the importance of coupling in situ chemical mapping analysis with macro- and microstructural characterization when targeting rare metals in deformed ore.

ARSENIC-INDUCED DOWNSHIFT OF RAMAN BAND POSITIONS FOR PYRITE

2020 ◽  
Vol 115 (7) ◽  
pp. 1589-1600
Author(s):  
Qiaoqiao Zhu ◽  
Nigel J. Cook ◽  
Guiqing Xie ◽  
Benjamin P. Wade ◽  
Cristiana L. Ciobanu
Keyword(s):  
Raman Spectroscopy ◽  
Environmental Science ◽  
Raman Band ◽  
Eastern China ◽  
Chemical Properties ◽  
Minor Element ◽  
Minor Elements ◽  
Band Position ◽  
Wide Range ◽  
The Impact

Abstract Pyrite commonly incorporates a wide range of trace and minor elements, which in turn may modify some of the mineral’s physical and chemical properties. Published band position data for the Raman spectra of pyrite show a wide variation, and the relationship between band position and the trace/minor element incorporation in pyrite is poorly constrained until now. This prompted a case study on pyrite with varying As content from the Shizilishan Sr-(Pb-Zn) deposit, eastern China, combining electron probe microanalysis with Raman spectroscopy. Results show a significant correlation, with a major downshift (~10 cm–1) of the positions of all three Raman bands with increase of As content from below 0.05 to 4.89 wt % in pyrite. This phenomenon is attributed to increased bond lengths and local distortions within an expanded pyrite crystal structure. Results highlight the potential that Raman spectroscopy offers to estimate the contents of trace/minor elements—especially As—in pyrite. Given that substitution of As into pyrite often facilitates co-incorporation of both economically useful (Au) and environmentally significant elements (Hg and Tl), Raman methodology could provide valuable, rapid assessment of pyrite chemistry in both gold deposit exploration and environmental science, although the impact of laser heating and mechanical polishing needs to be avoided or effectively reduced. Raman spectroscopy may also find a valuable future role within semiautomated multispectral analytical platforms that can generate close- to-real-time geologic information on freshly drilled core directly at the drill site or in outcrop.

DRX in 7050 Aluminum Alloy during Constraint Deformation Processing at High Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 647-650
Author(s):  
Liang Zhen ◽  
W.H. Hu ◽  
Wen Zhu Shao ◽  
J.Z. Chen ◽  
Xin Mei Zhang ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Qualitative Description ◽  
Electron Backscattered Diffraction ◽  
Quantitative Characterization ◽  
Deformation Processing ◽  
Direct Extrusion ◽  
Solution Treated ◽  
7050 Aluminum Alloy ◽  
Ebsd Technique

Combined extrusion experiment (including direct and indirect extrusion) at 440 for large amount of deformation was carried out with the solution treated AA7050 aluminum alloy. Qualitative description and quantitative characterization were conducted employing electron backscattered diffraction (EBSD) technique on the microstructure of typical regions with different filler contents. These characteristic regions were filled at the following stages: ahead of filling (AF), beginning of filling (BF), mid stage of filling (MF) and the end of filling (EF). EBSD results showed that recrystallization fraction during direct extrusion were 8.3%, 13.5%, 9.3% and 11.2%, for AF, BF, MF and EF, respectively. Recrystallization fraction during indirect extrusion were 15.5%, 9.1% 5.2% and 9.9%，for AF, BF, MF and EF, respectively. It shows that the mode and the amount of deformation played an important role in DRX. DRX grains were formed continuously during direct extrusion, while during indirect extrusion, fewer DRX grains generated, and only originally generated DRX grains grew larger gradually.

Comparison of Experimental and Computational Aspects of Grain Growth in Al-Foil

2000 ◽  
Vol 652 ◽  
Author(s):  
Melik C. Demirel ◽  
Andrew P. Kuprat ◽  
Denise C. George ◽  
Bassem S. El-Dasher ◽  
Neil N. Carlson ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Three Dimensional ◽  
Interface Energy ◽  
Grain Structure ◽  
Electron Backscattered Diffraction ◽  
Boundary Properties ◽  
Ebsd Technique ◽  
Columnar Grain ◽  
Grain Boundary Motion

ABSTRACTGrain boundary and crystallographic orientation information of an Al-foil with a columnar grain structure is characterized by Electron Backscattered Diffraction (EBSD) technique. The starting microstructure and grain boundary properties are implemented as an input for the three- dimensional grain growth simulation. In the computational model, minimization of the interface energy is the driving force for the grain boundary motion. The computed evolved microstructure is compared with the final experimental microstructure, after annealing at 550 °C. Good agreement is observed between the experimentally obtained microstructure and the simulated microstructure. The constitutive description of the grain boundary properties was based on a 1- parameter characterization of the variation in mobility with misorientation angle.

Raman Spectroscopy: An Exploratory Study to Identify Post-Radiation Cell Survival

2020 ◽  
Vol 74 (5) ◽  
pp. 553-562
Author(s):  
Kshama Pansare ◽  
Saurav Raj Singh ◽  
Venkatavaradhan Chakravarthy ◽  
Neha Gupta ◽  
Arti Hole ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Cell Viability ◽  
Cell Survival ◽  
Cell Line ◽  
Cell Lines ◽  
Clonogenic Assay ◽  
Early Stage ◽  
Raman Band ◽  
Breast Adenocarcinoma ◽  
Linear Discriminant

Resistance to radiotherapy has been an impediment in the treatment of cancer, and the inability to detect it at an early stage further exacerbates the prognosis. We have assessed the feasibility of Raman spectroscopy as a rapid assay for predicting radiosensitivity of cancer cells in comparison to the conventional biological assays. Cell lines derived from breast adenocarcinoma (MCF7), gingivobuccal squamous cell carcinoma (ITOC-03), and human embryonic kidney (HEK293) were subjected to varying doses of ionizing radiation. Cell viability of irradiated cells was assessed at different time points using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and Raman spectroscopy, and colony-forming capability was evaluated by clonogenic assay. Radiosensitivity observed using MTT assay was limited by the finding of similar cell viability in all the three cell lines 24 h post-irradiation. However, cell survival assessed using clonogenic assay and principal component linear discriminant analysis (PC-LDA) classification of Raman spectra showed correlating patterns. Irradiated cells showed loss of nucleic acid features and enhancement of 750 cm−1 peak probably attributing to resonance Raman band of cytochromes in all three cell lines. PC-LDA analysis affirmed MCF7 to be a radioresistant cell line as compared to ITOC-03 and HEK293 to be the most radiosensitive cell line. Raman spectroscopy is shown to be a rapid and alternative assay for identification of radiosensitivity as compared to the gold standard clonogenic assay.

Corroboration of Structural Properties of Dy2O3-TiO2 Nanocomposites through X-Ray Diffraction and Raman Spectroscopy

2017 ◽  
Vol 17 ◽  
pp. 127-130
Author(s):  
J. Dhanalakshmi ◽  
D. Pathinettam Padiyan
Keyword(s):  
Raman Spectroscopy ◽  
Crystallite Size ◽  
Structural Properties ◽  
Oxygen Vacancies ◽  
Raman Band ◽  
Anatase Phase ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Weight Percentage

Dy2O3-TiO2 nanocomposites with different weight percentage (0, 2, 4, 8 & 10)Dy were synthesized bysol-gel method and named as 0DT, 2DT, 4DT, 6DT, 8DT and 10DT. The structural properties of these nanocomposites are characterized by X-ray diffraction (XRD) and Raman spectroscopy. XRD results show that Dy2O3-TiO2 nanocomposites have anatase phase with tetragonal structure. The average crystallite size of the Dy2O3-TiO2 nanocomposites lies between 10 to 18 nm.Coupling of Dy with TiO2 shifts the Raman band to higher wavenumber side indicating the creation of oxygen vacancies in the TiO2 lattice.

Zircon Microstructures Record Deformation History of Shock- and Tectonically-generated Pseudotachylites: a Case Study from the Vredefort Impact Structure, South Africa

2019 ◽  
Vol 60 (12) ◽  
pp. 2529-2546 ◽  
Author(s):  
E Kovaleva ◽  
M S Huber ◽  
G Habler ◽  
D A Zamyatin
Keyword(s):  
Tectonic Deformation ◽  
Impact Structure ◽  
Deformation Bands ◽  
Deformation History ◽  
Meteorite Impacts ◽  
History Of ◽  
Tectonic Settings ◽  
New Criterion

Abstract High-strain rate deformation can cause in situ melting of rocks, resulting in the formation of dark, micro- to nanocrystalline pseudotachylite veins. On Earth, pseudotachylite veins form during meteorite impacts, large landslides, and earthquakes. Within the Vredefort impact structure, both impact-generated and (pre-impact) tectonically-generated pseudotachylite veins have been described, but are challenging to distinguish. Here, we demonstrate a genetic distinction between two pseudotachylite veins from Vredefort by studying their petrography, degree of recrystallization and deformation, cross-cutting relationships and the deformation microstructures in associated zircon. We conclude that Vein 1 is pre-impact and tectonically-generated, and Vein 2 is impact-generated. In agreement, zircon microstructures in Vein 1 contain planar deformation bands (PDBs), attributed to tectonic deformation, whereas zircon microstructures in Vein 2 reveal microtwin lamellae, indisputable evidence of shock metamorphism. Thus, deformation microstructures in zircon may provide a new criterion for distinguishing the genetic origin of pseudotachylite veins. Zircons that have been removed from their context (i.e., alluvial or detrital zircon, zircon from Lunar breccia) should be interpreted with caution in terms of their deformation history. For example, zircon with PDBs cannot reliably be used as a marker for shock deformation, because this feature has been shown to form in purely tectonic settings.

137 Chemical mapping of developing atherosclerotic plaques in APOE∗3 Leiden transgenic mice by Raman spectroscopy

1997 ◽  
Vol 130 ◽  
pp. S36
Author(s):  
T.J. Römer ◽  
J.E Brennan ◽  
G.J. Puppels ◽  
K. van Dijk ◽  
B.J.M. van Vlijmen ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Transgenic Mice ◽  
Atherosclerotic Plaques ◽  
Chemical Mapping

Microcomputer Controlled Flash Photometry with Submicrosecond Resolution and Raman Spectroscopy

1983 ◽  
Vol 37 (2) ◽  
pp. 203-207 ◽  
Author(s):  
Zvi Meiri ◽  
Yaakov Berezin ◽  
Avraham Shemesh ◽  
Benjamin Ehrenberg
Keyword(s):  
Raman Spectroscopy ◽  
Data Collection ◽  
Fluorescence Spectroscopy ◽  
Time Resolution ◽  
Raman Band ◽  
Photon Counting ◽  
Direct Memory Access ◽  
Memory Access ◽  
Access Mode ◽  
Light Flashes

The interfacing of two spectrophotometric systems to an Apple II microcomputer is described. The first is a flash photometric setup in which light flashes are formed either with a chopper wheel, or with an acousto-optic modulator which is activated by the microcomputer. Spectroscopic transients are monitored with a time resolution as short as 250 ns, by counting photon pulses into the computer's memory in the fast direct memory access mode. The formation half-times of the M412 intermediate in the photocycle of bacteriorhodopsin were measured in H2O and in D2O using the characteristic Raman band of this species, and are 68 ± 2 and 300 ± 5 μs, respectively. A microcomputer-controlled Raman spectrometer, in which the Apple II is interfaced to a Spex monochromator and the photon counting electronics, is also described. These microcomputer-controlled configurations provide simple and inexpensive setups for data collection in flash photometry and Raman and fluorescence spectroscopy.

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