Pub Date : 2019-04-01DOI: 10.1016/j.crte.2018.11.006
Nejib Jemmali , Larbi Rddad , Fouad Souissi , Emmanuel John M. Carranza
Jebel Mecella and Sidi Taya F–(BaPbZn) deposits are located within the Fluorite Zaghouan Province (NE Tunisia). The mineralization occurs along the unconformity surface between the Jurassic limestones and Upper Cretaceous rocks. The mineralization consists mainly of fluorite, barite, sphalerite, and galena. The δ34S values of barite at Jebel Mecella (14.8–15.4‰) and at Sidi Taya (21.6–22.2‰) closely match those of the Triassic evaporites and Messinian seawater, respectively. The range of δ34S values of galena and sphalerite in both deposits (−6.9 to +2.4‰) suggests the involvement of thermochemical sulfate reduction and possibly organically-bound sulfur in the generation of sulfur. Lead isotope data with 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of 18.893–18.903, 15.684–15.699, and 38.850–38.880, respectively suggests a single homogeneous source reservoir of Paleozoic age and/or the homogenization of the Paleozoic–Cretaceous multireservoir-derived fluids along their long migration paths to the loci of deposition during the Alpine orogeny.
{"title":"The ore genesis of the Jebel Mecella and Sidi Taya FBa (ZnPb) Mississippi Valley-type deposits, Fluorite Zaghouan Province, NE Tunisia, in relation to Alpine orogeny: Constraints from geological, sulfur, and lead isotope studies","authors":"Nejib Jemmali , Larbi Rddad , Fouad Souissi , Emmanuel John M. Carranza","doi":"10.1016/j.crte.2018.11.006","DOIUrl":"10.1016/j.crte.2018.11.006","url":null,"abstract":"<div><p>Jebel Mecella and Sidi Taya F–(Ba<img>Pb<img>Zn) deposits are located within the Fluorite Zaghouan Province (NE Tunisia). The mineralization occurs along the unconformity surface between the Jurassic limestones and Upper Cretaceous rocks. The mineralization consists mainly of fluorite, barite, sphalerite, and galena. The <em>δ</em><sup>34</sup>S values of barite at Jebel Mecella (14.8–15.4‰) and at Sidi Taya (21.6–22.2‰) closely match those of the Triassic evaporites and Messinian seawater, respectively. The range of <em>δ</em><sup>34</sup>S values of galena and sphalerite in both deposits (−6.9 to +2.4‰) suggests the involvement of thermochemical sulfate reduction and possibly organically-bound sulfur in the generation of sulfur. Lead isotope data with <sup>206</sup>Pb/<sup>204</sup>Pb, <sup>207</sup>Pb/<sup>204</sup>Pb, and <sup>208</sup>Pb/<sup>204</sup>Pb ratios of 18.893–18.903, 15.684–15.699, and 38.850–38.880, respectively suggests a single homogeneous source reservoir of Paleozoic age and/or the homogenization of the Paleozoic–Cretaceous multireservoir-derived fluids along their long migration paths to the loci of deposition during the Alpine orogeny.</p></div>","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.crte.2018.11.006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43868665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-01DOI: 10.1016/j.crte.2019.01.001
Mohammad El Hajj , Nicolas Baghdadi , Nicolas Labrière , Jean-Stéphane Bailly , Ludovic Villard
The aim of this paper is to map the aboveground biomass (AGB) in Gabon. First, a random forest (RF) model that relates reference AGB values to remote sensing (RS)-derived variables (mainly radar and optical images) was built, and the significant predictive variables were determined. Second, the built RF model was applied to the significant RS-derived variables to predict AGB across Gabon. The results showed that the overall RMSE (Root Mean Square Error) on the RS-derived AGB map with a spatial resolution of 50 m was 63.3 t/ha (R2 = 0.53).
To improve the accuracy of the RS-derived AGB map, the integration of LiDAR data provided by the Geoscience Laser Altimeter System (GLAS) onboard the Ice Cloud and Land Elevation Satellite (ICESat) was investigated. First, an RF model that relates reference AGB values to GLAS-derived metrics and a DEM (Digital Elevation Model) was built. Second, the calibrated RF model was applied to obtain a spatially distributed estimation of AGB (GLAS footprints geolocation) covering forested areas in Gabon, with a density of 0.13 footprints/km2. Third, the semivariogram of residuals (RS-derived AGB map – GLAS-derived AGB “surrogate AGB”) was computed. Later, a regression kriging interpolation was performed by taking into account the spatial structure of residuals to provide a continuous residual map. Finally, the RS-derived AGB map and the residual map were summed, and a final AGB map was obtained. The results showed that the integration of GLAS surrogate AGB data slightly improves the accuracy of the RS-derived AGB map only for AGB values lower than 100 t/ha (bias and RMSE reduced by 13.9 and 10 t/ha, respectively).
{"title":"Mapping of aboveground biomass in Gabon","authors":"Mohammad El Hajj , Nicolas Baghdadi , Nicolas Labrière , Jean-Stéphane Bailly , Ludovic Villard","doi":"10.1016/j.crte.2019.01.001","DOIUrl":"10.1016/j.crte.2019.01.001","url":null,"abstract":"<div><p>The aim of this paper is to map the aboveground biomass (AGB) in Gabon. First, a random forest (RF) model that relates reference AGB values to remote sensing (RS)-derived variables (mainly radar and optical images) was built, and the significant predictive variables were determined. Second, the built RF model was applied to the significant RS-derived variables to predict AGB across Gabon. The results showed that the overall RMSE (Root Mean Square Error) on the RS-derived AGB map with a spatial resolution of 50 m was 63.3 t/ha (<em>R</em><sup>2</sup> = 0.53).</p><p>To improve the accuracy of the RS-derived AGB map, the integration of LiDAR data provided by the Geoscience Laser Altimeter System (GLAS) onboard the Ice Cloud and Land Elevation Satellite (ICESat) was investigated. First, an RF model that relates reference AGB values to GLAS-derived metrics and a DEM (Digital Elevation Model) was built. Second, the calibrated RF model was applied to obtain a spatially distributed estimation of AGB (GLAS footprints geolocation) covering forested areas in Gabon, with a density of 0.13 footprints/km<sup>2</sup>. Third, the semivariogram of residuals (RS-derived AGB map – GLAS-derived AGB “surrogate AGB”) was computed. Later, a regression kriging interpolation was performed by taking into account the spatial structure of residuals to provide a continuous residual map. Finally, the RS-derived AGB map and the residual map were summed, and a final AGB map was obtained. The results showed that the integration of GLAS surrogate AGB data slightly improves the accuracy of the RS-derived AGB map only for AGB values lower than 100 t/ha (bias and RMSE reduced by 13.9 and 10 t/ha, respectively).</p></div>","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.crte.2019.01.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47510807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the first seismic measurements of serpentinite of Bou Azzer ophiolite, central Anti-Atlas of Morocco, including seismic velocities and anisotropy. Two serpentinite samples collected from the Ait Ahmane fault zone were analyzed in order to define the mineralogical and seismic features of the natural serpentinite of the Bou Azzer ophiolite. The mineralogical features were investigated using microscopic observation and Raman spectroscopy, while the seismic features were performed using an Electron Backscatter Diffraction (EBSD) instrument. Microscopy and spectroscopy analyses confirmed that the investigated serpentinite suffers from a variable degree of serpentinization, and the antigorite is the dominant variety of serpentine minerals in the study area. The crystal preferred orientation (CPO) results show that the axis [001] of the antigorite deformation is aligned subnormal to the foliation, while the axis [010] is mostly aligned subparallel to the lineation. The seismic anisotropy results are depending on serpentine amount in the rock samples. The sample with a low serpentine amount (30%) shows lowest P- and S-wave anisotropy (Vp = 7.2% and AVs = 6.55%), while the sample with a high amount of serpentine (85%) presents highest P-wave and S-wave anisotropy (Vp = 8.6% and AVs = 11.06%). Consequently, the results indicate that seismic anisotropy increases when increasing the antigorite amount.
{"title":"Mineralogical and seismic properties of serpentinite of Ait Ahmane fault zone of Bou Azzer ophiolite, central Anti-Atlas of Morocco","authors":"Mohamed Bhilisse , Hassan Admou , Ali Aydda , Lhou Maacha","doi":"10.1016/j.crte.2019.01.002","DOIUrl":"10.1016/j.crte.2019.01.002","url":null,"abstract":"<div><p>This paper presents the first seismic measurements of serpentinite of Bou Azzer ophiolite, central Anti-Atlas of Morocco, including seismic velocities and anisotropy. Two serpentinite samples collected from the Ait Ahmane fault zone were analyzed in order to define the mineralogical and seismic features of the natural serpentinite of the Bou Azzer ophiolite. The mineralogical features were investigated using microscopic observation and Raman spectroscopy, while the seismic features were performed using an Electron Backscatter Diffraction (EBSD) instrument. Microscopy and spectroscopy analyses confirmed that the investigated serpentinite suffers from a variable degree of serpentinization, and the antigorite is the dominant variety of serpentine minerals in the study area. The crystal preferred orientation (CPO) results show that the axis [001] of the antigorite deformation is aligned subnormal to the foliation, while the axis [010] is mostly aligned subparallel to the lineation. The seismic anisotropy results are depending on serpentine amount in the rock samples. The sample with a low serpentine amount (30%) shows lowest P- and S-wave anisotropy (<em>Vp</em> = 7.2% and <em>AVs</em> = 6.55%), while the sample with a high amount of serpentine (85%) presents highest P-wave and S-wave anisotropy (<em>Vp</em> = 8.6% and <em>AVs</em> = 11.06%). Consequently, the results indicate that seismic anisotropy increases when increasing the antigorite amount.</p></div>","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.crte.2019.01.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48426143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-01DOI: 10.1016/j.crte.2019.04.001
Jean Malburet
This is the publication of a pli cacheté (sealed letter) submitted to the French Academy of Sciences in 1918 by Jean Malburet (amateur astronomer, 1879–1955). The subject is “On the period of solar activity maxima”. If not reclaimed for 100 years, such sealed letters are opened and analysed by members of the Academy. This letter was considered sufficiently interesting to be published in Comptes rendus Geoscience, along with a descriptive comment of its contents and some of the subsequent history of the ideas put forward in that sealed contribution. In 1918, J. Malburet proposed that “triple syzygies” (alignments) of the planets Jupiter, Venus, and the Earth (with some smaller influence of Mercury) caused tides on the Sun that imposed on our star the observed periodicity (or rather quasi-periodicity) of 11 years. Thanks to contacts with the author’s grandson, two subsequent (1918 and 1925) papers were found, whereas Nicola Scafetta (pers. comm.) pointed out a 1927 criticism of the paper by H.M. Losh. The topic is still an active one today, as witnessed for example by papers by Scafetta, 2012a, Scafetta, 2012b, Scafetta, 2016). The handwritten text of the sealed letter has been typed for easier access to readers and is placed after a short analysis. French has been used throughout this as this is the language of the letter.
{"title":"Sur la période des maxima d’activité solaire","authors":"Jean Malburet","doi":"10.1016/j.crte.2019.04.001","DOIUrl":"10.1016/j.crte.2019.04.001","url":null,"abstract":"<div><p>This is the publication of a <em>pli cacheté</em> (sealed letter) submitted to the French Academy of Sciences in 1918 by Jean Malburet (amateur astronomer, 1879–1955). The subject is “On the period of solar activity maxima”. If not reclaimed for 100 years, such sealed letters are opened and analysed by members of the Academy. This letter was considered sufficiently interesting to be published in <em>Comptes rendus Geoscience</em>, along with a descriptive comment of its contents and some of the subsequent history of the ideas put forward in that sealed contribution. In 1918, J. Malburet proposed that “triple syzygies” (alignments) of the planets Jupiter, Venus, and the Earth (with some smaller influence of Mercury) caused tides on the Sun that imposed on our star the observed periodicity (or rather quasi-periodicity) of 11 years. Thanks to contacts with the author’s grandson, two subsequent (1918 and 1925) papers were found, whereas Nicola Scafetta (pers. comm.) pointed out a 1927 criticism of the paper by H.M. Losh. The topic is still an active one today, as witnessed for example by papers by <span>Scafetta, 2012a</span>, <span>Scafetta, 2012b</span>, <span>Scafetta, 2016</span>). The handwritten text of the sealed letter has been typed for easier access to readers and is placed after a short analysis. French has been used throughout this as this is the language of the letter.</p></div>","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.crte.2019.04.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47188770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-01DOI: 10.1016/j.crte.2018.11.005
Arsalan Ghorbanian, Mahmod Reza Sahebi, Ali Mohammadzadeh
This study suggests a novel approach to the retrieval of soil surface parameters using a single-acquisition single-configuration synthetic-aperture radar (SAR) system. Soil surface parameters such as soil moisture and surface roughness are key elements for many environmental studies, including Earth surface water cycles, energy exchange, agriculture, and geology. Remote sensing techniques, especially SAR data, are commonly used to retrieve such soil surface parameters over large areas. Several backscattering models have been proposed for soil surface parameters retrieval from SAR data. However, commonly, these backscattering models require multi configuration SAR data, including multi-polarization, multi-frequency, and multi-incidence angle. Here we propose a methodology that employs single-acquisition single-configuration SAR data for the retrieval of soil surface parameters. The originality is to use single-acquisition single-configuration SAR data to retrieve the soil surface parameters using an optimization approach by the genetic algorithm (GA); we have used the modified Dubois model (MDM) in HH polarization as the backscattering model. Three HH polarization and C band data sets from Quebec (Radarsat-1), Ontario (SIR-C), and Oklahoma (AIRSAR) were analyzed. The retrieved values of soil moisture and soil surface roughness were then compared to ground truth measurements with corresponding parameters. We employed diverse criteria, including the mean absolute error (MAE), the root mean square error (RMSE), the coefficient of performance (CP), and the correlation coefficient to investigate the performance of the proposed methodology. This analysis suggests the capability of the GA for the retrieval of soil surface parameters. Based on our findings, this method presents a viable alternative approach to the retrieval of soil surface parameters when only single-acquisition single-configuration SAR data is available.
{"title":"Optimization approach to retrieve soil surface parameters from single-acquisition single-configuration SAR data","authors":"Arsalan Ghorbanian, Mahmod Reza Sahebi, Ali Mohammadzadeh","doi":"10.1016/j.crte.2018.11.005","DOIUrl":"10.1016/j.crte.2018.11.005","url":null,"abstract":"<div><p>This study suggests a novel approach to the retrieval of soil surface parameters using a single-acquisition single-configuration synthetic-aperture radar (SAR) system. Soil surface parameters such as soil moisture and surface roughness are key elements for many environmental studies, including Earth surface water cycles, energy exchange, agriculture, and geology. Remote sensing techniques, especially SAR data, are commonly used to retrieve such soil surface parameters over large areas. Several backscattering models have been proposed for soil surface parameters retrieval from SAR data. However, commonly, these backscattering models require multi configuration SAR data, including multi-polarization, multi-frequency, and multi-incidence angle. Here we propose a methodology that employs single-acquisition single-configuration SAR data for the retrieval of soil surface parameters. The originality is to use single-acquisition single-configuration SAR data to retrieve the soil surface parameters using an optimization approach by the genetic algorithm (GA); we have used the modified Dubois model (MDM) in HH polarization as the backscattering model. Three HH polarization and C band data sets from Quebec (Radarsat-1), Ontario (SIR-C), and Oklahoma (AIRSAR) were analyzed. The retrieved values of soil moisture and soil surface roughness were then compared to ground truth measurements with corresponding parameters. We employed diverse criteria, including the mean absolute error (MAE), the root mean square error (RMSE), the coefficient of performance (CP), and the correlation coefficient to investigate the performance of the proposed methodology. This analysis suggests the capability of the GA for the retrieval of soil surface parameters. Based on our findings, this method presents a viable alternative approach to the retrieval of soil surface parameters when only single-acquisition single-configuration SAR data is available.</p></div>","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.crte.2018.11.005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44316057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The sound velocity of Fe3C was measured at pressures from 33 to 86 GPa and at ambient and high temperatures up to 2300 K using inelastic X-ray scattering (IXS) from laser-heated samples in diamond anvil cells (DACs). The compressional velocity (VP) and density of Fe3C at room temperature were observed to follow a linear relationship (Birch's law). The temperature dependency of Birch's law was not clearly observed and can be ignored. Birch's law for Fe3C is expressed by: . The result indicates that VP and VS (shear velocity) of the preliminary reference Earth model (PREM) inner core at the Inner Core Boundary (ICB) were by 12% and 48% smaller than those of Fe3C, which could be accounted for by the premelting effect by analogy from pure Fe or by partial melting of the Fe–Fe3C mixture in the inner core.
{"title":"Sound velocity of Fe3C at high pressure and high temperature determined by inelastic X-ray scattering","authors":"Suguru Takahashi , Eiji Ohtani , Tatsuya Sakamaki , Seiji Kamada , Hiroshi Fukui , Satoshi Tsutsui , Hiroshi Uchiyama , Daisuke Ishikawa , Naohisa Hirao , Yasuo Ohishi , Alfred Q.R. Baron","doi":"10.1016/j.crte.2018.09.005","DOIUrl":"10.1016/j.crte.2018.09.005","url":null,"abstract":"<div><p>The sound velocity of Fe<sub>3</sub>C was measured at pressures from 33 to 86<!--> <!-->GPa and at ambient and high temperatures up to 2300<!--> <!-->K using inelastic X-ray scattering (IXS) from laser-heated samples in diamond anvil cells (DACs). The compressional velocity (<em>V</em><sub>P</sub>) and density of Fe<sub>3</sub>C at room temperature were observed to follow a linear relationship (Birch's law). The temperature dependency of Birch's law was not clearly observed and can be ignored. Birch's law for Fe<sub>3</sub>C is expressed by: <span><math><mrow><msub><mi>V</mi><mtext>P</mtext></msub><mo>=</mo><mn>1.09</mn><mfenced><mrow><mo>±</mo><mn>0.14</mn></mrow></mfenced><mo>×</mo><mi>ρ</mi><mo>−</mo><mn>1.79</mn><mfenced><mrow><mo>±</mo><mn>1.26</mn></mrow></mfenced></mrow></math></span>. The result indicates that <em>V</em><sub>P</sub> and <em>V</em><sub>S</sub> (shear velocity) of the preliminary reference Earth model (PREM) inner core at the Inner Core Boundary (ICB) were by 12% and 48% smaller than those of Fe<sub>3</sub>C, which could be accounted for by the premelting effect by analogy from pure Fe or by partial melting of the Fe–Fe<sub>3</sub>C mixture in the inner core.</p></div>","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.crte.2018.09.005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48441207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-02-01DOI: 10.1016/j.crte.2018.06.011
Kamil M. Bulatov , Pavel V. Zinin , Yulia V. Mantrova , Aleksey A. Bykov , Maksim I. Gaponov , Alexsandr S. Machikhin , Ivan A. Troyan , Igor B. Kutuza
In this report, we demonstrate that combining the laser heating system in a diamond anvil cell (LH-DAC) with a tandem acoustic-optical tunable filter (LH-DAC–TAOTF) allows for the simultaneous measurement of (a) the relative infrared (IR, 1070 nm) power distribution on a specimen surface in the DAC; (b) the temperature distribution under laser heating of a specimen under high-pressure in a DAC; it also (c) provides an opportunity to control the shape of the IR laser spot on the surface of the heated specimen. The effect of the π-shaper on the shape and the position of the focus of the IR laser beam on a specimen using a TAOTF is also presented. For a 10× long-working distance objective, the smallest diameter of the IR laser was found to be around 10 μm, when the focal plane coincides with that of the imaging optical system of LH-DAC. The highest diameter of the IR laser was shown to be 20 μm when the rim of the π-shaper was set at 3 μm. It is demonstrated also that the TAOFT not only permits to measure the two-dimensional (2-D) distribution of the IR laser power, but also allows for the alignment of the laser before each heating event at different pressures.
{"title":"Simultaneous measurements of the two-dimensional distribution of infrared laser intensity and temperature in a single-sided laser-heated diamond anvil cell","authors":"Kamil M. Bulatov , Pavel V. Zinin , Yulia V. Mantrova , Aleksey A. Bykov , Maksim I. Gaponov , Alexsandr S. Machikhin , Ivan A. Troyan , Igor B. Kutuza","doi":"10.1016/j.crte.2018.06.011","DOIUrl":"10.1016/j.crte.2018.06.011","url":null,"abstract":"<div><p>In this report, we demonstrate that combining the laser heating system in a diamond anvil cell (LH-DAC) with a tandem acoustic-optical tunable filter (LH-DAC–TAOTF) allows for the simultaneous measurement of (a) the relative infrared (IR, 1070<!--> <!-->nm) power distribution on a specimen surface in the DAC; (b) the temperature distribution under laser heating of a specimen under high-pressure in a DAC; it also (c) provides an opportunity to control the shape of the IR laser spot on the surface of the heated specimen. The effect of the π-shaper on the shape and the position of the focus of the IR laser beam on a specimen using a TAOTF is also presented. For a 10× long-working distance objective, the smallest diameter of the IR laser was found to be around 10<!--> <!-->μm, when the focal plane coincides with that of the imaging optical system of LH-DAC. The highest diameter of the IR laser was shown to be 20<!--> <!-->μm when the rim of the π-shaper was set at 3<!--> <!-->μm. It is demonstrated also that the TAOFT not only permits to measure the two-dimensional (2-D) distribution of the IR laser power, but also allows for the alignment of the laser before each heating event at different pressures.</p></div>","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.crte.2018.06.011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43667250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-02-01DOI: 10.1016/j.crte.2018.07.007
Fei Qin , Xiang Wu , Shan Qin , Dongzhou Zhang , Vatali B. Prakapenka , Steven D. Jacobsen
We present a synchrotron-based, single-crystal X-ray diffraction and Raman spectroscopy study of natural green dioptase (Cu6Si6O18·6H2O) up to ∼30 GPa at room temperature. The lattice parameters of dioptase exhibit continuous compression behavior up to ∼14.5 GPa, whereupon a structural transition is observed. Pressure–volume data below 14.5 GPa were fitted to a second-order Birch–Murnaghan equation of state with V0 = 1440(2) Å3 and K0 = 107(2) GPa, with K0′ = 4(fixed). The low-pressure form of dioptase exhibits anisotropic compression with axial compressibility βa > βc in a ratio of 1.14:1.00. Based on the diffraction data and Raman spectroscopy, the new high-pressure phase could be regarded as a dehydrated form of dioptase in the same symmetry group. Pressure-induced dehydration of dioptase contributes broadly to our understanding of the high-pressure crystal chemistry of hydrous silicates containing molecular water groups.
{"title":"Pressure-induced dehydration of dioptase: A single-crystal X-ray diffraction and Raman spectroscopy study","authors":"Fei Qin , Xiang Wu , Shan Qin , Dongzhou Zhang , Vatali B. Prakapenka , Steven D. Jacobsen","doi":"10.1016/j.crte.2018.07.007","DOIUrl":"10.1016/j.crte.2018.07.007","url":null,"abstract":"<div><p>We present a synchrotron-based, single-crystal X-ray diffraction and Raman spectroscopy study of natural green dioptase (Cu<sub>6</sub>Si<sub>6</sub>O<sub>18</sub>·6H<sub>2</sub>O) up to ∼30<!--> <!-->GPa at room temperature. The lattice parameters of dioptase exhibit continuous compression behavior up to ∼14.5<!--> <!-->GPa, whereupon a structural transition is observed. Pressure–volume data below 14.5<!--> <!-->GPa were fitted to a second-order Birch–Murnaghan equation of state with <em>V</em><sub>0</sub> <!-->=<!--> <!-->1440(2) Å<sup>3</sup> and <em>K</em><sub>0</sub> <!-->=<!--> <!-->107(2) GPa, with <em>K</em><sub>0</sub>′<!--> <!-->=<!--> <!-->4(fixed). The low-pressure form of dioptase exhibits anisotropic compression with axial compressibility <em>β</em><sub><em>a</em></sub> <!-->><!--> <em>β</em><sub><em>c</em></sub> in a ratio of 1.14:1.00. Based on the diffraction data and Raman spectroscopy, the new high-pressure phase could be regarded as a dehydrated form of dioptase in the same symmetry group. Pressure-induced dehydration of dioptase contributes broadly to our understanding of the high-pressure crystal chemistry of hydrous silicates containing molecular water groups.</p></div>","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.crte.2018.07.007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41826181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A technique for density measurement under high pressure and high temperature was developed using the X-ray absorption imaging method combined with an externally heated diamond anvil cell. The densities of solid and liquid In were measured in the pressure and temperature ranges of 3.2–18.6 GPa and 294–719 K. The densities obtained through the X-ray absorption imaging method were in good agreement (less than 2.0% difference) with those obtained through X-ray diffraction. Based on the measured density, the isothermal bulk modulus of solid In is determined as 48.0 ± 1.1−40.9 ± 0.8 GPa at 500 K, assuming K′ = 4 to 6. The compression curve of liquid In approaches that of solid In at higher pressures and does not cross over the solid compression curve in the measurement range. The present technique enables us to determine the densities of both solids and liquids precisely in a wide pressure and temperature range.
{"title":"Development of density measurement for metals at high pressures and high temperatures using X-ray absorption imaging combined with externally heated diamond anvil cell","authors":"Yusaku Takubo , Hidenori Terasaki , Tadashi Kondo , Shingo Mitai , Seiji Kamada , Takumi Kikegawa , Akihiko Machida","doi":"10.1016/j.crte.2018.04.002","DOIUrl":"10.1016/j.crte.2018.04.002","url":null,"abstract":"<div><p>A technique for density measurement under high pressure and high temperature was developed using the X-ray absorption imaging method combined with an externally heated diamond anvil cell. The densities of solid and liquid In were measured in the pressure and temperature ranges of 3.2–18.6<!--> <!-->GPa and 294–719<!--> <!-->K. The densities obtained through the X-ray absorption imaging method were in good agreement (less than 2.0% difference) with those obtained through X-ray diffraction. Based on the measured density, the isothermal bulk modulus of solid In is determined as 48.0<!--> <!-->±<!--> <!-->1.1−40.9<!--> <!-->±<!--> <!-->0.8<!--> <!-->GPa at 500<!--> <!-->K, assuming <em>K</em>′<!--> <!-->=<!--> <!-->4 to 6. The compression curve of liquid In approaches that of solid In at higher pressures and does not cross over the solid compression curve in the measurement range. The present technique enables us to determine the densities of both solids and liquids precisely in a wide pressure and temperature range.</p></div>","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.crte.2018.04.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43953747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}