Pub Date : 2024-02-08DOI: 10.1134/s1075701523080068
V. E. Glushkova, I. S. Peretyazhko, E. A. Savina, E. A. Khromova
Abstract
This paper reports the olivine-group minerals from melilite–nepheline paralavas of two combustion metamorphic (CM) complexes of Mongolia. The paralavas formed by thermal alterations of sedimentary rocks due to multistage modern and ancient (since the Quaternary) wild coal fires. The decomposition products of the olivine solid solution into Ca-bearing fayalite and kirschsteinite have been found in paralavas of the Khamaryn–Khural–Khiid CM complex. Apart from these minerals, members of isomorphic series forsterite–fayalite, and monticellite–kirschsteinite, and simplectite-like intergrowths of kirschsteinite with nepheline were identified in the paralavas of the Nyalga CM complex. The studied minerals differ in structural features, Mg# value, and crystallization temperature as a consequence of local variations in formation conditions and composition of silica-undersaturated Ca-rich mafic melts initial for melilite–nepheline paralavas. The olivines of the monticellite–kirschsteinite series reaching 86 mol % of kirschsteinite end-member occur only in paralavas bearing xenoliths of thermally modified carbonate-silicate sedimentary rocks. The crystallization of these olivines together with gehlenitic melilite took place through interaction between mafic paralava melts and xenoliths of marly limestones with large variations in content of silicate (clay–feldspar) admixture.
摘要 本文报告了蒙古两个燃烧变质岩群（CM）熔融-涅盘状副岩体中的橄榄石族矿物。这些副岩是由现代和远古（自第四纪以来）多级野煤火引起的沉积岩热变形成的。在 Khamaryn-Khural-Khiid CM 复合体的副岩中发现了橄榄石固溶体的分解产物，即含 Ca 的法叶腊石和基氏石。除这些矿物外，在聂雅嘎 CM 矿群的副岩体中还发现了同构系列的芒硝-法安石、芒硝-钾长石，以及钾长石与霞石的类单斜辉石互生。所研究的矿物在结构特征、Mg#值和结晶温度方面存在差异，这是因为形成条件和富含二氧化硅-过饱和钙的黑云母熔体成分的局部变化导致了黑云母-霞石副熔岩的形成。只有在热改造碳酸盐-硅酸盐沉积岩的副岩中才会出现蒙脱石-柯氏橄榄石系列橄榄石，其中柯氏橄榄石的终成体含量高达 86 摩尔%。这些橄榄石与gehlenitic melilite的结晶是在黑云母副熔岩熔体与硅酸盐（粘土长石）掺杂物含量变化较大的泥质灰岩侧晶之间的相互作用下形成的。
{"title":"Olivine-Group Minerals from Melilite–Nepheline Paralavas of Combustion Metamorphic Complexes of Mongolia","authors":"V. E. Glushkova, I. S. Peretyazhko, E. A. Savina, E. A. Khromova","doi":"10.1134/s1075701523080068","DOIUrl":"https://doi.org/10.1134/s1075701523080068","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This paper reports the olivine-group minerals from melilite–nepheline paralavas of two combustion metamorphic (CM) complexes of Mongolia. The paralavas formed by thermal alterations of sedimentary rocks due to multistage modern and ancient (since the Quaternary) wild coal fires. The decomposition products of the olivine solid solution into Ca-bearing fayalite and kirschsteinite have been found in paralavas of the Khamaryn–Khural–Khiid CM complex. Apart from these minerals, members of isomorphic series forsterite–fayalite, and monticellite–kirschsteinite, and simplectite-like intergrowths of kirschsteinite with nepheline were identified in the paralavas of the Nyalga CM complex. The studied minerals differ in structural features, Mg# value, and crystallization temperature as a consequence of local variations in formation conditions and composition of silica-undersaturated Ca-rich mafic melts initial for melilite–nepheline paralavas. The olivines of the monticellite–kirschsteinite series reaching 86 mol % of kirschsteinite end-member occur only in paralavas bearing xenoliths of thermally modified carbonate-silicate sedimentary rocks. The crystallization of these olivines together with gehlenitic melilite took place through interaction between mafic paralava melts and xenoliths of marly limestones with large variations in content of silicate (clay–feldspar) admixture.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140881550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-08DOI: 10.1134/s1075701523080056
B. B. Gerasimov
Abstract
Typomorphic features of placer gold are carriers of important information necessary for reconstruction of the formation history of gold placers and can be used as mineralogical criteria to search primary sources. The internal structure of grains of native gold is one of the most informative features. Internal structures of gold grains from modern placers and Early Permian conglomerates in the northeast of the Siberian Platform are studied. Structural etching of native gold was performed using the reagent (HCl + HNO3 + FeCl3⋅6H2O + CrO3 + thiurea + water). It was found that the well-rounded high-grade gold grains from modern placers experienced repeated redeposition through intermediate reservoirs. The discovery of slightly rounded gold grains, the internal structure of which bear no signs of exogenous transformation indicates that they were supplied to the modern alluvium from a nearby primary source. Apo-carbonate hydrothermal–metasomatic formations with the disseminated gold-sulfide mineralization were identified in the course of gold-ore exploration.
{"title":"Internal Structures of Placer Gold Grains As Prospecting Indicators of Primary Gold Sources in the Northeast of the Siberian Platform","authors":"B. B. Gerasimov","doi":"10.1134/s1075701523080056","DOIUrl":"https://doi.org/10.1134/s1075701523080056","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Typomorphic features of placer gold are carriers of important information necessary for reconstruction of the formation history of gold placers and can be used as mineralogical criteria to search primary sources. The internal structure of grains of native gold is one of the most informative features. Internal structures of gold grains from modern placers and Early Permian conglomerates in the northeast of the Siberian Platform are studied. Structural etching of native gold was performed using the reagent (HCl + HNO<sub>3</sub> + FeCl<sub>3</sub>⋅6H<sub>2</sub>O + CrO<sub>3</sub> + thiurea + water). It was found that the well-rounded high-grade gold grains from modern placers experienced repeated redeposition through intermediate reservoirs. The discovery of slightly rounded gold grains, the internal structure of which bear no signs of exogenous transformation indicates that they were supplied to the modern alluvium from a nearby primary source. Apo-carbonate hydrothermal–metasomatic formations with the disseminated gold-sulfide mineralization were identified in the course of gold-ore exploration.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140881554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1134/s107570152307005x
V. G. Krivovichev, K. A. Kuksa, P. B. Sokolov, O. Yu. Marakhovskaya, M. E. Klimacheva
Abstract
A comparative study of the mineral-species distribution by various systems in evaporites from the Inder deposit (Kazakhstan) and in marbles of the Luc Yen deposit in North Vietnam, as well as a comparison of these locations in the distribution of species-defining elements, has been conducted. The obtained data show that both locations are almost identical in the set of species-defining elements (O, H, Si, Ca, S, Al, Na, Mg, K, C, F, Cl, and B), but slightly differ only in the Luc Yen marble enrichment in Al, Si, C, and F. The differences in the mineral abundance between evaporites and metamorphic rocks are due to landscape environments and physicochemical conditions of their formation. A comprehensive analysis of the evaporite and marble mineralogy with the identification of species-defining elements (mineral systems) may provide an objective basis for the assumption that evaporites with minor terrigenous material rocks were involved into the formation of ruby and gem spinel deposits.
摘要 对 Inder 矿床（哈萨克斯坦）蒸发岩和越南北部 Luc Yen 矿床大理石中各种系统的矿物物种分布进行了比较研究，并对这些地点的物种定义元素分布进行了比较。获得的数据表明，两地的物种定义元素（O、H、Si、Ca、S、Al、Na、Mg、K、C、F、Cl 和 B）几乎完全相同，仅在 Luc Yen 大理石中 Al、Si、C 和 F 的富集程度略有不同。蒸发岩和大理岩矿物学的综合分析，以及物种定义元素（矿物系统）的鉴定，可为红宝石和宝石尖晶石矿床形成过程中涉及蒸发岩和少量原生物质岩石的假设提供客观依据。
{"title":"Marble-Hosted Gem Spinel Deposits from Luc Yen District, North Vietnam: Mineral Systems and Some Aspects of Genesis","authors":"V. G. Krivovichev, K. A. Kuksa, P. B. Sokolov, O. Yu. Marakhovskaya, M. E. Klimacheva","doi":"10.1134/s107570152307005x","DOIUrl":"https://doi.org/10.1134/s107570152307005x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A comparative study of the mineral-species distribution by various systems in evaporites from the Inder deposit (Kazakhstan) and in marbles of the Luc Yen deposit in North Vietnam, as well as a comparison of these locations in the distribution of species-defining elements, has been conducted. The obtained data show that both locations are almost identical in the set of species-defining elements (O, H, Si, Ca, S, Al, Na, Mg, K, C, F, Cl, and B), but slightly differ only in the Luc Yen marble enrichment in Al, Si, C, and F. The differences in the mineral abundance between evaporites and metamorphic rocks are due to landscape environments and physicochemical conditions of their formation. A comprehensive analysis of the evaporite and marble mineralogy with the identification of species-defining elements (mineral systems) may provide an objective basis for the assumption that evaporites with minor terrigenous material rocks were involved into the formation of ruby and gem spinel deposits.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139755588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1134/s1075701523070152
N. V. Zubkova, N. V. Chukanov, D. A. Varlamov, M. F. Vigasina, I. V. Pekov, D. A. Ksenofontov, D. Yu. Pushcharovsky
Abstract
The crystal structure of a mineral of the cancrinite group with an aluminosilicate framework of the marinellite type and a dominant sulfite group ({text{SO}}_{3}^{{2 - }}) in one of the extraframework sites in the liottite cavity is studied. The studied mineral is derived from a paleovolcano near Magliano (Lazio, Italy) and is one of the major rock-forming phases of the leucite–nepheline syenite. The divergence factor was R = 5.71% for 6819 independent reflections with I > 2σ(I). The studied mineral is trigonal, space group is P31c, and the unit cell parameters are a = 12.87267(18), c = 31.7393(5) Å, V = 4554.75(15) Å3. The crystal chemical formula Na29.78K11.82Ca6.40(Si36Al36O144)(SO4)6(SO3)2Cl2(OH)0.40⋅3.98H2O (Z = 1), which is based on the results of XRD structure analysis, is consistent with electron-microprobe data. The presence of the ({text{SO}}_{3}^{{2 - }}) anion was confirmed by the Raman spectrum.
{"title":"A Sulfite-Bearing Analog of Marinellite","authors":"N. V. Zubkova, N. V. Chukanov, D. A. Varlamov, M. F. Vigasina, I. V. Pekov, D. A. Ksenofontov, D. Yu. Pushcharovsky","doi":"10.1134/s1075701523070152","DOIUrl":"https://doi.org/10.1134/s1075701523070152","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The crystal structure of a mineral of the cancrinite group with an aluminosilicate framework of the marinellite type and a dominant sulfite group <span>({text{SO}}_{3}^{{2 - }})</span> in one of the extraframework sites in the liottite cavity is studied. The studied mineral is derived from a paleovolcano near Magliano (Lazio, Italy) and is one of the major rock-forming phases of the leucite–nepheline syenite. The divergence factor was <i>R</i> = 5.71% for 6819 independent reflections with <i>I</i> > 2σ(<i>I</i>). The studied mineral is trigonal, space group is <i>P</i>31<i>c</i>, and the unit cell parameters are <i>a</i> = 12.87267(18), <i>c</i> = 31.7393(5) Å, <i>V</i> = 4554.75(15) Å<sup>3</sup>. The crystal chemical formula Na<sub>29.78</sub>K<sub>11.82</sub>Ca<sub>6.40</sub>(Si<sub>36</sub>Al<sub>36</sub>O<sub>144</sub>)(SO<sub>4</sub>)<sub>6</sub>(SO<sub>3</sub>)<sub>2</sub>Cl<sub>2</sub>(OH)<sub>0.40</sub>⋅3.98H<sub>2</sub>O (<i>Z</i> = 1), which is based on the results of XRD structure analysis, is consistent with electron-microprobe data. The presence of the <span>({text{SO}}_{3}^{{2 - }})</span> anion was confirmed by the Raman spectrum.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139755658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1134/s1075701523070061
S. V. Krivovichev
Abstract
Density functional theory (DFT) has been used with CRYSTAL14 program to optimize hydrogen atom positions in the crystal structure of parascorodite Fe(AsO4)⋅2H2O. It has been shown that taking into account hydrogen bonding, the structure forms six-membered asymmetrical cycles –Fe1–O1–H1…O3–As–O2– and eight-membered cycles –Fe1–O1–H2…O2–Fe1–O2…H2–O1– with lateral topological symmetry. Calculation of the structural complexity parameters for scorodite and parascorodite and their comparison with thermodynamic characteristics shows that the Fe(AsO4)⋅2H2O polymorph modifications correspond well to Goldsmith’s rule that states that metastable transitional polymorphs are structurally simpler than thermodynamically stable phases. Scorodite is a stable phase, whereas parascorodite is metastable, which agrees well with the conclusions made in the previous works. Crystallization of parascorodite under natural conditions of oxidation zones of ore-mineral deposits may occur due to the high speed of its nucleation as a metastable phase, i.e., due to the kinetic stabilization of its structure.
{"title":"Hydrogen Bonding in Parascorodite and Relative Stability of Fe(AsO4)⋅2H2O Polymorphs","authors":"S. V. Krivovichev","doi":"10.1134/s1075701523070061","DOIUrl":"https://doi.org/10.1134/s1075701523070061","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Density functional theory (DFT) has been used with CRYSTAL14 program to optimize hydrogen atom positions in the crystal structure of parascorodite Fe(AsO<sub>4</sub>)⋅2H<sub>2</sub>O. It has been shown that taking into account hydrogen bonding, the structure forms six-membered asymmetrical cycles –Fe1–O1–H1<sup>…</sup>O3–As–O2– and eight-membered cycles –Fe1–O1–H2<sup>…</sup>O2–Fe1–O2<sup>…</sup>H2–O1– with lateral topological symmetry. Calculation of the structural complexity parameters for scorodite and parascorodite and their comparison with thermodynamic characteristics shows that the Fe(AsO<sub>4</sub>)⋅2H<sub>2</sub>O polymorph modifications correspond well to Goldsmith’s rule that states that metastable transitional polymorphs are structurally simpler than thermodynamically stable phases. Scorodite is a stable phase, whereas parascorodite is metastable, which agrees well with the conclusions made in the previous works. Crystallization of parascorodite under natural conditions of oxidation zones of ore-mineral deposits may occur due to the high speed of its nucleation as a metastable phase, i.e., due to the kinetic stabilization of its structure.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139763049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1134/s1075701523070024
M. S. Avdontceva, S. V. Krivovichev, M. G. Krzhizhanovskaya, V. N. Bocharov, N. S. Vlasenko, D. V. Spiridonova
Abstract
The crystal chemical peculiarities of cacoxenite from the Těškov quarry (Bohemia, Czech Republic) are studied using single crystal X-ray analysis and thermal X-ray analysis, electron-microprobe analysis, and infrared (IR) and Raman spectroscopy. The crystal structure of cacoxenite (hexagonal system, sp. gr. P63/m, a = 27.5677(4) Å, c = 10.5364(3) Å, V = 6934.64(16) Å3) is refined to R1 = 0.052 by 4637 independent reflections. The crystal structure is based on two independent structural blocks, which form an open-framework (the minimum free pore diameter is 15.1 Å). The crystal structure of cacoxenite is stable up to 190°C. The empirical formula of the mineral (based on 17 P atoms) is (({text{Fe}}_{{19.98}}^{{3 + }})Al4.97)Σ24.95O6(PO4)17(OH8.52Cl3.48)Σ12(H2O)24⋅ nH2O (n ∼ 50). The most intense bands of IR and Raman spectra in a range from 400 to 1200 cm–1 correspond to stretching and bending vibration modes of the phosphate groups. The presence of water in the structure is confirmed by the presence of an intense band in the IR spectrum in the area of 1624 cm–1 (O–H vibrations), as well as the absorption band with maximum of 3357 cm–1, which corresponds to stretching vibrations of the Fe(Al)–OH bond and H2O molecules. The calculation of structural complexity of cacoxenite for the framework without H-corrections and with the addition of framework-related H-positions shows a very complex structure of the mineral (2312.464 bit/cell).
摘要 利用单晶 X 射线分析和热 X 射线分析、电子探针分析、红外光谱和拉曼光谱，研究了 Těškov 采石场（捷克共和国波希米亚）出产的埃克森石的晶体化学特性。通过 4637 次独立反射，将可可碱石（六方体系，sp. gr. P63/m，a = 27.5677(4) Å，c = 10.5364(3) Å，V = 6934.64(16) Å3）的晶体结构细化为 R1 = 0.052。该晶体结构基于两个独立的结构块，它们形成了一个开放框架（最小自由孔径为 15.1 Å）。可可碱石的晶体结构在 190°C 以下都很稳定。该矿物的经验公式（基于 17 个 P 原子）为 (({{Fe}}_{{19.98}}^{{3 + }})Al4.97)Σ24.95O6(PO4)17(OH8.52Cl3.48)Σ12(H2O)24⋅ nH2O (n ∼ 50)。红外光谱和拉曼光谱中 400 至 1200 cm-1 范围内最强烈的波段对应于磷酸基团的伸展和弯曲振动模式。在红外光谱中，1624 cm-1（O-H 振动）区域存在一条强波段，以及最大值为 3357 cm-1 的吸收波段（对应于 Fe(Al)-OH 键和 H2O 分子的伸缩振动）证实了结构中水的存在。在不进行 H 校正和添加与框架相关的 H 位置的情况下，对卡考氙石框架结构复杂性的计算显示，该矿物的结构非常复杂（2312.464 位/单元）。
{"title":"Cacoxenite—a Complex Phosphate with a Modular Structure","authors":"M. S. Avdontceva, S. V. Krivovichev, M. G. Krzhizhanovskaya, V. N. Bocharov, N. S. Vlasenko, D. V. Spiridonova","doi":"10.1134/s1075701523070024","DOIUrl":"https://doi.org/10.1134/s1075701523070024","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The crystal chemical peculiarities of cacoxenite from the Těškov quarry (Bohemia, Czech Republic) are studied using single crystal X-ray analysis and thermal X-ray analysis, electron-microprobe analysis, and infrared (IR) and Raman spectroscopy. The crystal structure of cacoxenite (hexagonal system, sp. gr. <i>P</i>6<sub>3</sub>/<i>m</i>, <i>a</i> = 27.5677(4) Å, <i>c</i> = 10.5364(3) Å, <i>V</i> = 6934.64(16) Å<sup>3</sup>) is refined to <i>R</i><sub>1</sub> = 0.052 by 4637 independent reflections. The crystal structure is based on two independent structural blocks, which form an open-framework (the minimum free pore diameter is 15.1 Å). The crystal structure of cacoxenite is stable up to 190°C. The empirical formula of the mineral (based on 17 P atoms) is (<span>({text{Fe}}_{{19.98}}^{{3 + }})</span>Al<sub>4.97</sub>)<sub>Σ24.95</sub>O<sub>6</sub>(PO<sub>4</sub>)<sub>17</sub>(OH<sub>8.52</sub>Cl<sub>3.48</sub>)<sub>Σ12</sub>(H<sub>2</sub>O)<sub>24</sub>⋅ <i>n</i>H<sub>2</sub>O (<i>n</i> ∼ 50). The most intense bands of IR and Raman spectra in a range from 400 to 1200 cm<sup>–1</sup> correspond to stretching and bending vibration modes of the phosphate groups. The presence of water in the structure is confirmed by the presence of an intense band in the IR spectrum in the area of 1624 cm<sup>–1</sup> (O–H vibrations), as well as the absorption band with maximum of 3357 cm<sup>–1</sup>, which corresponds to stretching vibrations of the Fe(Al)–OH bond and H<sub>2</sub>O molecules. The calculation of structural complexity of cacoxenite for the framework without H-corrections and with the addition of framework-related H-positions shows a very complex structure of the mineral (2312.464 bit/cell).</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139763053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1134/s1075701523070127
S. S. Ugap’eva, A. E. Molotkov, S. A. Gromilov, V. P. Afanasiev, A. D. Pavlushin, A. P. Eliseev, V. I. Popov
Abstract
This paper reports new study data on structural features of polycrystalline diamonds (yakutites) from placers of the Anabar diamondiferous region obtained by X-ray and optical spectroscopy. All studied samples are fine-grained (up to 1 μm) polycrystals. The diffractograms of most samples show reflexes related to lonsdaleite defects in the diamond structure. Yakutites are inhomogeneous: diffractograms of different parts of diamond aggregates show different reflections of texture and micrograins with a monocrystalline structure. A “bell” in the single-phonon region of IR spectra indicates defects in the crystal structure of yakutites and a significant structural stress. An aggregated nitrogen line is absent in the photoluminescence spectra of yakutites, likely due to the fact that they were ejected outside the crater after the solid-phase synthesis stage and were relatively rapidly cooled down.
摘要 本文报告了通过 X 射线和光学光谱法获得的关于阿纳巴尔金刚石产区块矿中多晶金刚石 （雅库特岩）结构特征的新研究数据。研究的所有样品都是细粒度（最多 1 μm）多晶体。大多数样品的衍射图都显示出与金刚石结构中龙氏石缺陷有关的反射。雅库特岩是不均匀的：金刚石集合体不同部分的衍射图显示出不同的纹理反射和单晶结构的微晶粒。红外光谱单声子区域的 "钟声 "表明雅库特岩的晶体结构存在缺陷，结构应力很大。白云石的光致发光光谱中没有聚集氮线，这可能是由于白云石在固相合成阶段之后被喷射到陨石坑外，并相对迅速地冷却下来。
{"title":"Texture and Structure Features of Yakutites from Placers of the Anabar Diamondiferous Region","authors":"S. S. Ugap’eva, A. E. Molotkov, S. A. Gromilov, V. P. Afanasiev, A. D. Pavlushin, A. P. Eliseev, V. I. Popov","doi":"10.1134/s1075701523070127","DOIUrl":"https://doi.org/10.1134/s1075701523070127","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This paper reports new study data on structural features of polycrystalline diamonds (yakutites) from placers of the Anabar diamondiferous region obtained by X-ray and optical spectroscopy. All studied samples are fine-grained (up to 1 μm) polycrystals. The diffractograms of most samples show reflexes related to lonsdaleite defects in the diamond structure. Yakutites are inhomogeneous: diffractograms of different parts of diamond aggregates show different reflections of texture and micrograins with a monocrystalline structure. A “bell” in the single-phonon region of IR spectra indicates defects in the crystal structure of yakutites and a significant structural stress. An aggregated nitrogen line is absent in the photoluminescence spectra of yakutites, likely due to the fact that they were ejected outside the crater after the solid-phase synthesis stage and were relatively rapidly cooled down.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139755674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1134/s1075701523070048
Yu. L. Gulbin, I. A. Abdrakhmanov, I. M. Gembitskaya, E. A. Vasiliev
Abstract
The Bunger Hills, East Antarctica occupies an area of about 300 km2 and is underlain by large Neoarchean tonalite–granite orthogneiss bodies in the southern part and a Paleoproterozoic volcanosedimentary sequence, buckled into isoclinal folds and metamorphosed to the granulite facies, in the northern. The sequence is intruded by large syncollisional charnockite plutons and consists predominantly of strongly migmatized garnet–sillimanite–cordierite paragneisses (metapelitic granulites). A characteristic feature of the mineral composition of these rocks is the paragenesis of Zn-poor spinel and quartz. The P–T conditions for the equilibrium of these two minerals are 6–7 kbar and 970–1030°C as estimated with the method of isochemical phase diagrams and 985–1005°C, as calculated with the aid of Ti-in-quartz thermobarometry (Huang and Audétat, 2012). Quartz contains needle-shaped microinclusions less than 1 μm in thickness aligned along the [0001] direction and evenly distributed throughout the quartz grains. According to data of electron-probe analysis, they are heterogeneous and consist of rutile and spinel (hercynite) intergrowths. The available data suggest that the genesis of the microinclusions is related to the exsolution process and the diffusion of structural impurities in quartz (Al, Fe, and Ti) in the direction of parallel translation-slip zones (10(bar {1})10), along which the high-temperature plastic deformations of quartz took place during the postpeak stage. The appearance of spinel in the microparagenesis of the oxides of the Al–Fe–Mg–Ti system is interpreted as a result of the processes synchronous with the intracrystal diffusion: the open-system diffusion of Mg atoms along the weakness zones of the quartz lattice or the infiltration of Mg-rich fluids along the microscopic cleavage planes formed as a result of hydrofracturing.
{"title":"Oriented Microinclusions of Al–Fe–Mg–Ti Oxides in Quartz from Metapelitic Granulites of the Bunger Hills, East Antarctica","authors":"Yu. L. Gulbin, I. A. Abdrakhmanov, I. M. Gembitskaya, E. A. Vasiliev","doi":"10.1134/s1075701523070048","DOIUrl":"https://doi.org/10.1134/s1075701523070048","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The Bunger Hills, East Antarctica occupies an area of about 300 km<sup>2</sup> and is underlain by large Neoarchean tonalite–granite orthogneiss bodies in the southern part and a Paleoproterozoic volcanosedimentary sequence, buckled into isoclinal folds and metamorphosed to the granulite facies, in the northern. The sequence is intruded by large syncollisional charnockite plutons and consists predominantly of strongly migmatized garnet–sillimanite–cordierite paragneisses (metapelitic granulites). A characteristic feature of the mineral composition of these rocks is the paragenesis of Zn-poor spinel and quartz. The <i>P–T</i> conditions for the equilibrium of these two minerals are 6–7 kbar and 970–1030°C as estimated with the method of isochemical phase diagrams and 985–1005°C, as calculated with the aid of Ti-in-quartz thermobarometry (Huang and Audétat, 2012). Quartz contains needle-shaped microinclusions less than 1 μm in thickness aligned along the [0001] direction and evenly distributed throughout the quartz grains. According to data of electron-probe analysis, they are heterogeneous and consist of rutile and spinel (hercynite) intergrowths. The available data suggest that the genesis of the microinclusions is related to the exsolution process and the diffusion of structural impurities in quartz (Al, Fe, and Ti) in the direction of parallel translation-slip zones (10<span>(bar {1})</span>10), along which the high-temperature plastic deformations of quartz took place during the postpeak stage. The appearance of spinel in the microparagenesis of the oxides of the Al–Fe–Mg–Ti system is interpreted as a result of the processes synchronous with the intracrystal diffusion: the open-system diffusion of Mg atoms along the weakness zones of the quartz lattice or the infiltration of Mg-rich fluids along the microscopic cleavage planes formed as a result of hydrofracturing.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139755664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1134/s1075701523070140
E. A. Vasilev, A. A. Kudriavtsev, I. V. Klepikov, A. V. Antonov
Abstract
Diamond crystals of various morphological types, including carbonado, were studied by the electron backscatter diffraction method. Cases of inhomogeneities of different natures were revealed: interpenetrant and mechanical twins, incoherent intergrowth, and splitting growth. Differences in the distribution pattern of boundary angles for different types of inhomogeneities have been shown: predominantly discrete in intergrowths, continuous distribution of low-angle boundaries in ballas diamonds, and continuous random distribution in carbonado. It has been shown that Rose channels in diamond arise as a result of etching at the intersection of mechanical twins. The revealed mechanical twins have a thickness of 60–600 nm.
{"title":"Diversity of the Structure of Diamond Crystals and Aggregates: Electron Backscatter Diffraction Data","authors":"E. A. Vasilev, A. A. Kudriavtsev, I. V. Klepikov, A. V. Antonov","doi":"10.1134/s1075701523070140","DOIUrl":"https://doi.org/10.1134/s1075701523070140","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Diamond crystals of various morphological types, including carbonado, were studied by the electron backscatter diffraction method. Cases of inhomogeneities of different natures were revealed: interpenetrant and mechanical twins, incoherent intergrowth, and splitting growth. Differences in the distribution pattern of boundary angles for different types of inhomogeneities have been shown: predominantly discrete in intergrowths, continuous distribution of low-angle boundaries in ballas diamonds, and continuous random distribution in carbonado. It has been shown that Rose channels in diamond arise as a result of etching at the intersection of mechanical twins. The revealed mechanical twins have a thickness of 60–600 nm.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139763060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1134/s1075701523070139
K. L. Ushakova, M. V. Charykova, V. G. Krivovichev, N. M. Efimenko, N. V. Platonova, V. N. Bocharov, A. S. Mazur
Abstract
The purpose of this work was to synthesize hexahydrate aluminum selenite Al2(SeO3)3⋅6H2O (analogous to the mineral alfredopetrovite) and study its solubility in water. Al2(SeO3)3⋅6H2O is synthesized from AlCl3 and Na2SeO3 solutions at room temperature and atmospheric pressure. The obtained samples were studied using powder diffractometry, infrared and Raman spectroscopy, energy-dispersive X-ray microanalysis, nuclear magnetic resonance spectroscopy, and complex thermal analysis. Solubility was determined by isothermal saturation in ampoules at 25°C. Solubility products were calculated using Geochemist’s Workbench software package (GMB 9.0, SpecE8 program). As a result of the calculation, the average value logKsp[Al2(SeO3)3⋅6H2O] = –28.3 ± 0.5 was obtained. An Eh–pH diagram is constructed for the Al–Se–H2O system, which was used to analyze the stability of alfredopetrovite in near-surface conditions.
{"title":"Thermodynamics of Arsenates, Selenites, and Sulfates in the Oxidation Zone of Sulfide Ores. XV. Synthetic Analog of Alfredopetrovite: Composition, Properties, and Stability Limits","authors":"K. L. Ushakova, M. V. Charykova, V. G. Krivovichev, N. M. Efimenko, N. V. Platonova, V. N. Bocharov, A. S. Mazur","doi":"10.1134/s1075701523070139","DOIUrl":"https://doi.org/10.1134/s1075701523070139","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The purpose of this work was to synthesize hexahydrate aluminum selenite Al<sub>2</sub>(SeO<sub>3</sub>)<sub>3</sub>⋅6H<sub>2</sub>O (analogous to the mineral alfredopetrovite) and study its solubility in water. Al<sub>2</sub>(SeO<sub>3</sub>)<sub>3</sub>⋅6H<sub>2</sub>O is synthesized from AlCl<sub>3</sub> and Na<sub>2</sub>SeO<sub>3</sub> solutions at room temperature and atmospheric pressure. The obtained samples were studied using powder diffractometry, infrared and Raman spectroscopy, energy-dispersive X-ray microanalysis, nuclear magnetic resonance spectroscopy, and complex thermal analysis. Solubility was determined by isothermal saturation in ampoules at 25°C. Solubility products were calculated using Geochemist’s Workbench software package (GMB 9.0, SpecE8 program). As a result of the calculation, the average value logKsp[Al<sub>2</sub>(SeO<sub>3</sub>)<sub>3</sub>⋅6H<sub>2</sub>O] = –28.3 ± 0.5 was obtained. An Eh–pH diagram is constructed for the Al–Se–H<sub>2</sub>O system, which was used to analyze the stability of alfredopetrovite in near-surface conditions.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139755662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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