J. Majzlan, M. Števko, J. Plášil, J. Sejkora, E. Dachs
Secondary minerals, especially phosphates and arsenates of copper and zinc, form a group of phases with astonishing variability in crystal structures and chemical composition. Some of these minerals are more common than others and one has to ask whether the abundance is linked to their thermodynamic stability or rather to geochemical constraints. In this work, we used calorimetric techniques to determine the thermodynamic properties of synthetic olivenite [Cu 2 (AsO 4 )(OH)], zincolivenite [Cu 0.95 Zn 1.05 (AsO 4 )(OH)], adamite [Zn 2 (AsO 4 )(OH)], ludjibaite [Cu 5 (PO 4 ) 2 (OH) 4 ], natural strashimirite [(Cu 7.75 Zn 0.09 ) 7.84 (AsO 4 ) 3.89 (SO 4 ) 0.11 (OH) 3.79 ·5H 2 O], and a slavkovite sample dehydrated
{"title":"Thermodynamics of the Cu, Zn, and Cu-Zn phases: zincolivenite, adamite, olivenite, ludjibaite, strashimirite, and slavkovite","authors":"J. Majzlan, M. Števko, J. Plášil, J. Sejkora, E. Dachs","doi":"10.3190/jgeosci.367","DOIUrl":"https://doi.org/10.3190/jgeosci.367","url":null,"abstract":"Secondary minerals, especially phosphates and arsenates of copper and zinc, form a group of phases with astonishing variability in crystal structures and chemical composition. Some of these minerals are more common than others and one has to ask whether the abundance is linked to their thermodynamic stability or rather to geochemical constraints. In this work, we used calorimetric techniques to determine the thermodynamic properties of synthetic olivenite [Cu 2 (AsO 4 )(OH)], zincolivenite [Cu 0.95 Zn 1.05 (AsO 4 )(OH)], adamite [Zn 2 (AsO 4 )(OH)], ludjibaite [Cu 5 (PO 4 ) 2 (OH) 4 ], natural strashimirite [(Cu 7.75 Zn 0.09 ) 7.84 (AsO 4 ) 3.89 (SO 4 ) 0.11 (OH) 3.79 ·5H 2 O], and a slavkovite sample dehydrated","PeriodicalId":15957,"journal":{"name":"Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47905255","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}
A. Kasatkin, I. Pekov, R. Škoda, N. Chukanov, F. Nestola, A. Agakhanov, A. Kuznetsov, N. N. Koshlyakova, J. Plášil, S. N. Britvin
{"title":"Fluorpyromorphite, Pb5(PO4)3F, a new apatite-group mineral from Sukhovyaz Mountain, Southern Urals, and Tolbachik volcano, Kamchatka","authors":"A. Kasatkin, I. Pekov, R. Škoda, N. Chukanov, F. Nestola, A. Agakhanov, A. Kuznetsov, N. N. Koshlyakova, J. Plášil, S. N. Britvin","doi":"10.3190/jgeosci.368","DOIUrl":"https://doi.org/10.3190/jgeosci.368","url":null,"abstract":"","PeriodicalId":15957,"journal":{"name":"Journal of Geosciences","volume":"1 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42682510","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}
V. Rapprich, V. Janoušek, T. Hroch, J. Míková, V. Erban, F. Legesa, Z. Pécskay, P. Halodová
A group of pyroclastic cones is dispersed in the North Chamo Volcanic Field, i.e. in the northern surroundings of the Chamo Lake and over neighbouring part of the Nech Sar plains (southern termination of the Main Ethiopian Rift). The activity of scattered cinder cones was partly coeval with that of Tosa Sucha Volcano (Calabrian), but continued also after Tosa Sucha’s extinction until Middle Pleistocene ( c. 0.5 Ma). Whereas scoria cones on the Nech Sar plains displayed a rather simple Strombolian eruptive style, the cones located within the northern part of Chamo Lake were characterized by more complex evolution. Ganjulle scoria cone, with a uniform olivine basalt composition, started with a Surtseyan-style eruption, which turned into Strombolian as the volcano grew above the water level. An even more complex history was documented for the Ganta cone. Compositional zoning of pyroclastic rocks is explained by zoned-chamber exhaustion. The transition from magmatic to phreatomagmatic style of the eruption was then most likely linked to syn-eruptive subsidence of the area on the Chamo Lake banks. Subsequent transition back to Strombolian style reflected the growth of the cone above water level. The Sr–Nd–Pb isotopes, together with major-element-based thermodynamic modelling, demonstrate that magmas parental to the North Chamo alkaline volcanic rocks (alkali basalt, through trachybasalt and trachyandesite to trachyte) evolved initially by closed-system fractionation of olivine, later joined by clinopyroxene, spinel and calcic plagioclase. The subsequent stage was characterized by a substantial ( c. 25% by mass) assimilation of country-rock felsic igneous material, perhaps corresponding to the Paleogene ignimbrites.
{"title":"Eruptive and magmatic evolution of North Chamo Volcanic Field (southern Ethiopia)","authors":"V. Rapprich, V. Janoušek, T. Hroch, J. Míková, V. Erban, F. Legesa, Z. Pécskay, P. Halodová","doi":"10.3190/jgeosci.365","DOIUrl":"https://doi.org/10.3190/jgeosci.365","url":null,"abstract":"A group of pyroclastic cones is dispersed in the North Chamo Volcanic Field, i.e. in the northern surroundings of the Chamo Lake and over neighbouring part of the Nech Sar plains (southern termination of the Main Ethiopian Rift). The activity of scattered cinder cones was partly coeval with that of Tosa Sucha Volcano (Calabrian), but continued also after Tosa Sucha’s extinction until Middle Pleistocene ( c. 0.5 Ma). Whereas scoria cones on the Nech Sar plains displayed a rather simple Strombolian eruptive style, the cones located within the northern part of Chamo Lake were characterized by more complex evolution. Ganjulle scoria cone, with a uniform olivine basalt composition, started with a Surtseyan-style eruption, which turned into Strombolian as the volcano grew above the water level. An even more complex history was documented for the Ganta cone. Compositional zoning of pyroclastic rocks is explained by zoned-chamber exhaustion. The transition from magmatic to phreatomagmatic style of the eruption was then most likely linked to syn-eruptive subsidence of the area on the Chamo Lake banks. Subsequent transition back to Strombolian style reflected the growth of the cone above water level. The Sr–Nd–Pb isotopes, together with major-element-based thermodynamic modelling, demonstrate that magmas parental to the North Chamo alkaline volcanic rocks (alkali basalt, through trachybasalt and trachyandesite to trachyte) evolved initially by closed-system fractionation of olivine, later joined by clinopyroxene, spinel and calcic plagioclase. The subsequent stage was characterized by a substantial ( c. 25% by mass) assimilation of country-rock felsic igneous material, perhaps corresponding to the Paleogene ignimbrites.","PeriodicalId":15957,"journal":{"name":"Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46582105","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}
P. Hanžl, V. Janoušek, K. Hrdličková, D. Buriánek, O. Gerel, B. Altanbaatar, J. Hora, P. Čoupek
The Trans-Altai Zone in the southern tract of the Central Asian Oceanic Belt is composed of Early Palaeozoic oceanic crust preserved in Ordovician to Devonian ophiolite fragments and Devonian–Carboniferous igneous arcs. The Edren and Baaran subzones at the NW tip of the Trans-Altai Zone were intruded by Late Palaeozoic plutons that have been examined by the combined geochronological and geochemical study. Mississippian subduction-related plutons intruded Devonian and Carboniferous volcano-sedimentary sequences in two magmatic pulses. The older, Tournaisian plutons (dated at 352 ± 1 and 347 ± 4 Ma) occur in both subzones; the younger Visean/Serpukhovian ones (331 ± 1 Ma) are found only at the northern boundary of the Edren Subzone. All Mississippian rocks are high-K calc-alkaline and characterised by a strong enrichment of hydrous fluid mobile lithophile elements over conservative Nb, Ta and Ti relative to normal mid-ocean ridge basalts. Low 87 Sr/ 86 Sr i (~ 0.7035–0.7038) and highly positive ε iNd values (+ 6.6 to + 5.2) suggest a relatively juvenile parental magma source with a short mean crustal residence. This corresponds well with the age of scarce inherited zircons, none of which is older than 530 Ma. The Early Permian post-tectonic plutons intruded the shallow crust of the Baaran Subzone (Devonian–Carboniferous flysch and Early Carboniferous volcanic arc). The prominent concentric body of the Aaj Bogd Pluton is composed of monzodiorites to monzogabbros (284 ± 1 and 294 ± 3 Ma) in its centre, surrounded by granite with syenite (282 ± 1 Ma) in the main mass of the pluton. Whole-rock Sr–Nd isotopic ratios match those of Carboniferous magmatic rocks, while trace-element patterns point to an intra-plate origin influenced by a fertile asthenospheric mantle component. On the other hand, the slightly older (290 ± 1 Ma) quartz syenites to alkali feldspar granites in the Baaran Subzone have spurious arc-like geochemistry inherited from their arc-related crustal source(s). Regional distribution of the numerous oval-shaped Early Permian alkaline post-orogenic plutons, some with A 2 -type granite affinity, follows the major Permian strike-slip zones spanning from the Dulate Arc in the west to the Khan Bogd Pluton in the east. These late, transcurrent zones apparently played an important role in late-orogenic magma generation, ascent and emplacement.
{"title":"From magmatic arc to a post-accretionary setting: Late Palaeozoic granitoid plutons in the northwestern Trans-Altai Zone, Mongolia","authors":"P. Hanžl, V. Janoušek, K. Hrdličková, D. Buriánek, O. Gerel, B. Altanbaatar, J. Hora, P. Čoupek","doi":"10.3190/jgeosci.366","DOIUrl":"https://doi.org/10.3190/jgeosci.366","url":null,"abstract":"The Trans-Altai Zone in the southern tract of the Central Asian Oceanic Belt is composed of Early Palaeozoic oceanic crust preserved in Ordovician to Devonian ophiolite fragments and Devonian–Carboniferous igneous arcs. The Edren and Baaran subzones at the NW tip of the Trans-Altai Zone were intruded by Late Palaeozoic plutons that have been examined by the combined geochronological and geochemical study. Mississippian subduction-related plutons intruded Devonian and Carboniferous volcano-sedimentary sequences in two magmatic pulses. The older, Tournaisian plutons (dated at 352 ± 1 and 347 ± 4 Ma) occur in both subzones; the younger Visean/Serpukhovian ones (331 ± 1 Ma) are found only at the northern boundary of the Edren Subzone. All Mississippian rocks are high-K calc-alkaline and characterised by a strong enrichment of hydrous fluid mobile lithophile elements over conservative Nb, Ta and Ti relative to normal mid-ocean ridge basalts. Low 87 Sr/ 86 Sr i (~ 0.7035–0.7038) and highly positive ε iNd values (+ 6.6 to + 5.2) suggest a relatively juvenile parental magma source with a short mean crustal residence. This corresponds well with the age of scarce inherited zircons, none of which is older than 530 Ma. The Early Permian post-tectonic plutons intruded the shallow crust of the Baaran Subzone (Devonian–Carboniferous flysch and Early Carboniferous volcanic arc). The prominent concentric body of the Aaj Bogd Pluton is composed of monzodiorites to monzogabbros (284 ± 1 and 294 ± 3 Ma) in its centre, surrounded by granite with syenite (282 ± 1 Ma) in the main mass of the pluton. Whole-rock Sr–Nd isotopic ratios match those of Carboniferous magmatic rocks, while trace-element patterns point to an intra-plate origin influenced by a fertile asthenospheric mantle component. On the other hand, the slightly older (290 ± 1 Ma) quartz syenites to alkali feldspar granites in the Baaran Subzone have spurious arc-like geochemistry inherited from their arc-related crustal source(s). Regional distribution of the numerous oval-shaped Early Permian alkaline post-orogenic plutons, some with A 2 -type granite affinity, follows the major Permian strike-slip zones spanning from the Dulate Arc in the west to the Khan Bogd Pluton in the east. These late, transcurrent zones apparently played an important role in late-orogenic magma generation, ascent and emplacement.","PeriodicalId":15957,"journal":{"name":"Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49463058","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}
Stibioústalečite , Cu 12 (Sb 2 Te 2 )Se 13 , was approved as a new mineral species from the Ústaleč mine, 15 km west of Horažďovice, SW Bohemia, Czech Republic. It occurs as metallic anhedral grains up to 0.1–0.3 mm in size, dark grey in color, in a calcite gangue. It is directly associated with hakite-(Hg), berzelianite, the not-yet approved phase Cu 12 (As 2 Te 2 ) Se 13 and uraninite. Stibioústalečite is brittle, with an indistinct cleavage and a conchoidal fracture; the calculated density is 5.676 g/cm 3 . In reflected light, stibioústalečite is isotropic, and grey in color; internal reflections were not observed. Reflectance data for the four COM wavelengths in air are [λ (nm): R (%)]: 470: 33.3; 546: 33.2; 589: 33.1; 650: 33.0. Electron microprobe analysis for holotype material (grain used for single-crystal X-ray study) gave (in wt. % – average of 7 spot analyses): Cu 34.10, Ag 1.22, Fe 0.04, Zn 0.09, Hg 0.33, Sb 9.39, As 0.70, Te 12.41, S 3.76, Se 37.59, total 99.63. On the basis of (As + Sb + Te) = 4 atoms per formula unit ( apfu ), the empirical formula of stibioústalečite is M (2) (Cu 5.75 Ag 0.25 ) Σ6 M (1) (Cu 5.93 Hg 0.04 Zn 0.03 Fe 0.02 ) Σ6.02 X (3) (Te 2.12 Sb 1.68 As 0.20 ) Σ4 (Se 10.36 S 2.55 ) Σ12.91 . The ideal formula is Cu 6 Cu 6 (Sb 2 Te 2 ) Se 13 , which requires Cu 33.33, Sb 10.64 Te 11.16 Se 44.87, total 100 wt. %. Stibioústalečite is cubic, I 4̄ 3 m , with unit-cell parameters a = 10.828(4) Å, V = 1269.6(9) Å 3 , Z = 2. The crystal structure of stibioústalečite was studied by singlecrystal X-ray diffraction data and it is isotypic with other members of the tetrahedrite group. The mineral is named after its type locality Ústaleč and its chemical composition, being the (Sb/Te) end-member in the possible ústalečite series.
Stibioústalečite, Cu 12 (Sb 2 Te 2)Se 13，是在捷克波希米亚西南部Horažďovice以西15 km处的Ústaleč矿区发现的一种新矿物。在方解石脉石中以金属四面体颗粒的形式出现，大小可达0.1-0.3毫米，颜色为深灰色。它与hakite-(Hg)、白绿石、尚未批准的Cu 12 (As 2 Te 2) Se 13和铀矿直接相关。Stibioústalečite脆性，有不明显的解理和贝壳状断裂;计算密度为5.676 g/ cm3。在反射光中，stibioústalečite是各向同性的，呈灰色;没有观察到内部反射。四个COM波长在空气中的反射率数据为[λ (nm): R (%)]: 470: 33.3;546: 33.2;589: 33.1;650: 33.0。纯型材料(用于单晶x射线研究的颗粒)的电子探针分析(wt % -平均7点分析):Cu 34.10, Ag 1.22, Fe 0.04, Zn 0.09, Hg 0.33, Sb 9.39, As 0.70, Te 12.41, S 3.76, Se 37.59，总计99.63。根据(As + Sb + Te) = 4个原子/分子式单位(apfu)， stibioústalečite的经验公式为M (2) (Cu 5.75 Ag 0.25) Σ6 M (1) (Cu 5.93 Hg 0.04 Zn 0.03 Fe 0.02) Σ6.02 X (3) (Te 2.12 Sb 1.68 As 0.20) Σ4 (Se 10.36 S 2.55) Σ12.91。理想的配方为Cu 6 Cu 6 (Sb 2 Te 2) Se 13，需要Cu 33.33, Sb 10.64, Te 11.16, Se 44.87，总量为100 wt. %。Stibioústalečite为立方，I 4 × 3 m，单位胞参数a = 10.828(4) Å， V = 1269.6(9) Å 3, Z = 2。通过单晶x射线衍射数据研究了stibioústalečite的晶体结构，发现其与四面体族的其他成员具有同型性。该矿物以其类型位置Ústaleč和化学成分命名，是可能的ústalečite系列中的(Sb/Te)端元。
{"title":"Stibioústalečite, Cu6Cu6(Sb2Te2)Se13, the first Te-Se member of tetrahedrite group, from the Ústaleč, Czech Republic","authors":"J. Sejkora, J. Plášil, E. Makovicky","doi":"10.3190/jgeosci.359","DOIUrl":"https://doi.org/10.3190/jgeosci.359","url":null,"abstract":"Stibioústalečite , Cu 12 (Sb 2 Te 2 )Se 13 , was approved as a new mineral species from the Ústaleč mine, 15 km west of Horažďovice, SW Bohemia, Czech Republic. It occurs as metallic anhedral grains up to 0.1–0.3 mm in size, dark grey in color, in a calcite gangue. It is directly associated with hakite-(Hg), berzelianite, the not-yet approved phase Cu 12 (As 2 Te 2 ) Se 13 and uraninite. Stibioústalečite is brittle, with an indistinct cleavage and a conchoidal fracture; the calculated density is 5.676 g/cm 3 . In reflected light, stibioústalečite is isotropic, and grey in color; internal reflections were not observed. Reflectance data for the four COM wavelengths in air are [λ (nm): R (%)]: 470: 33.3; 546: 33.2; 589: 33.1; 650: 33.0. Electron microprobe analysis for holotype material (grain used for single-crystal X-ray study) gave (in wt. % – average of 7 spot analyses): Cu 34.10, Ag 1.22, Fe 0.04, Zn 0.09, Hg 0.33, Sb 9.39, As 0.70, Te 12.41, S 3.76, Se 37.59, total 99.63. On the basis of (As + Sb + Te) = 4 atoms per formula unit ( apfu ), the empirical formula of stibioústalečite is M (2) (Cu 5.75 Ag 0.25 ) Σ6 M (1) (Cu 5.93 Hg 0.04 Zn 0.03 Fe 0.02 ) Σ6.02 X (3) (Te 2.12 Sb 1.68 As 0.20 ) Σ4 (Se 10.36 S 2.55 ) Σ12.91 . The ideal formula is Cu 6 Cu 6 (Sb 2 Te 2 ) Se 13 , which requires Cu 33.33, Sb 10.64 Te 11.16 Se 44.87, total 100 wt. %. Stibioústalečite is cubic, I 4̄ 3 m , with unit-cell parameters a = 10.828(4) Å, V = 1269.6(9) Å 3 , Z = 2. The crystal structure of stibioústalečite was studied by singlecrystal X-ray diffraction data and it is isotypic with other members of the tetrahedrite group. The mineral is named after its type locality Ústaleč and its chemical composition, being the (Sb/Te) end-member in the possible ústalečite series.","PeriodicalId":15957,"journal":{"name":"Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44140597","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}
Gülin GENÇOG˘LU Korkmaz, H. Kurt, Kürşad Asan, Maurizio Petrelli, Matthew Leybourne
This study investigates the mantle source characteristics of the Quaternary Karapınar Basalts from the southwestern part of the Cappadocia Volcanic Province (CVP) in Central Anatolia using a combination of whole-rock and olivine major-and trace-element geochemistry as well as olivine oxygen isotope composition. Petrographic features and trace element distributions demonstrate that the Karapınar basalts can be classified into two sub-groups as basalt-1 (KB1/ alkaline–calc-alkaline) and basalt-2 (KB2/calc-alkaline). Although these two types of basalts are petrographically, texturally and geochemically different, they exhibit similar “orogenic type” incompatible trace element patterns in MORB-normalized diagrams. KB1 basalts are relatively primitive (e.g., up to 12 wt. % MgO) and calc-alkaline to mildly alkaline (Ne-normative content up to 5 %) in character, whereas KB2 basalts are enclave-bearing, calc-alkaline (hypersthene-normative plus quartz or olivine) ones with the more evolved composition. The most primitive olivine from the KB1 exhibits normal zoning, from core compositions of Fo 89 to rim compositions of Fo 86, with a concomitant decreasing in Ni and increasing MnO and CaO contents. On the contrary, the KB2 olivines show both inverse and normal zoning in terms of CaO and MnO contents. Moreover, the studied olivine phenocrysts have enriched rims and/or growth zones in Li, Zn, Cr, Ti, Sc, and V contents, which indicates a source containing recycled continental crust and/or magma recharging processes. The olivine from the most primitive samples (KB1; MgO > 10 wt. %) has high Zn/Fe, Fe/Mn, Co, Zn, Ni, Ca, and low Mn/Zn, Co/Fe values indicating melt addition from a pyroxenitic source. Calculations based on the olivine chemistry indicate that the most primitive nepheline normative KB1 rocks originated from the melting of mixed pyroxenitic-peridotitic source that shows the average proportion of ~70 % and ~30 %, respectively. The mean δ 18 O values of olivine phenocrysts (+ 6.4 ‰; n = 8) from the Karapınar basaltic rocks are higher than typical mantle olivine (+ 5.1–5.4 ‰) but overlap known OIB-EMII sources (+ 5.4–6.1 ‰). Collected data indicate that the Karapınar basalts are the mixing products of partial melts from mantle peridotite and metasomatic pyroxenite generated by the reaction of the subducted oceanic slab-derived melts with the surrounding peridotite, related to the convergence system of the Eurasian and Afro–Arabian plates.
{"title":"The role of peridotite and pyroxenite melts in the origin of the Karapınar basalts, Cappadocia Volcanic Province, Central Anatolia","authors":"Gülin GENÇOG˘LU Korkmaz, H. Kurt, Kürşad Asan, Maurizio Petrelli, Matthew Leybourne","doi":"10.3190/jgeosci.362","DOIUrl":"https://doi.org/10.3190/jgeosci.362","url":null,"abstract":"This study investigates the mantle source characteristics of the Quaternary Karapınar Basalts from the southwestern part of the Cappadocia Volcanic Province (CVP) in Central Anatolia using a combination of whole-rock and olivine major-and trace-element geochemistry as well as olivine oxygen isotope composition. Petrographic features and trace element distributions demonstrate that the Karapınar basalts can be classified into two sub-groups as basalt-1 (KB1/ alkaline–calc-alkaline) and basalt-2 (KB2/calc-alkaline). Although these two types of basalts are petrographically, texturally and geochemically different, they exhibit similar “orogenic type” incompatible trace element patterns in MORB-normalized diagrams. KB1 basalts are relatively primitive (e.g., up to 12 wt. % MgO) and calc-alkaline to mildly alkaline (Ne-normative content up to 5 %) in character, whereas KB2 basalts are enclave-bearing, calc-alkaline (hypersthene-normative plus quartz or olivine) ones with the more evolved composition. The most primitive olivine from the KB1 exhibits normal zoning, from core compositions of Fo 89 to rim compositions of Fo 86, with a concomitant decreasing in Ni and increasing MnO and CaO contents. On the contrary, the KB2 olivines show both inverse and normal zoning in terms of CaO and MnO contents. Moreover, the studied olivine phenocrysts have enriched rims and/or growth zones in Li, Zn, Cr, Ti, Sc, and V contents, which indicates a source containing recycled continental crust and/or magma recharging processes. The olivine from the most primitive samples (KB1; MgO > 10 wt. %) has high Zn/Fe, Fe/Mn, Co, Zn, Ni, Ca, and low Mn/Zn, Co/Fe values indicating melt addition from a pyroxenitic source. Calculations based on the olivine chemistry indicate that the most primitive nepheline normative KB1 rocks originated from the melting of mixed pyroxenitic-peridotitic source that shows the average proportion of ~70 % and ~30 %, respectively. The mean δ 18 O values of olivine phenocrysts (+ 6.4 ‰; n = 8) from the Karapınar basaltic rocks are higher than typical mantle olivine (+ 5.1–5.4 ‰) but overlap known OIB-EMII sources (+ 5.4–6.1 ‰). Collected data indicate that the Karapınar basalts are the mixing products of partial melts from mantle peridotite and metasomatic pyroxenite generated by the reaction of the subducted oceanic slab-derived melts with the surrounding peridotite, related to the convergence system of the Eurasian and Afro–Arabian plates.","PeriodicalId":15957,"journal":{"name":"Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49420061","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}
Iwona KORYBSKA-SADŁO, Adam Szuszkiewicz, Marta Prell, Piotr Gunia
Aerugite Ni 8.5 (AsO 4 ) 2 As 5+ O 8 and xanthiosite Ni 3 (AsO 4 ) 2 , two rare anhydrous arsenates, have been identified in a historic sample from Johanngeorgenstadt, Saxony, Germany. The minerals have been characterized through scanning electron microscopy, electron microprobe analysis and Raman spectroscopy for the first time. They are mostly dark-green (aerugite) to light-green (xanthiosite) fine-grained or microcrystalline crusts on a quartz matrix in association with barite, bunsenite, dolomite, and rooseveltite. Aerugite forms up to 200 μm large pseudo-hexagonal platy crystals, whereas xanthiosite forms short prisms to nearly equant forms, often with indistinct, poorly-developed and rounded faces. The chemical composition of the two minerals can be expressed by the empirical formulas: (Ni 7.92 Co 0.52 Cu 0.06 ) Σ8.50 (As 1.00 O 4 ) 2 As 1.00 O 8 with traces of Bi (aerugite, mean of 4 analyses, based on 32 oxygens) and (Ni 2.85 Co 0.12 Cu 0.03 ) Σ3.00 (As 1.00 O 4 ) 2 (xanthiosite, mean of 5 analyses, based on 32 oxygens). The Raman spectra of both minerals lack bands related to OH stretching vibrations and are dominated by antisymmetric ν 3 and symmetric ν 1 As–O vibrations in AsO 4 polyhedra centered at 817, 846 and 886 cm –1 in the case of aerugite and at 786, 808, 826 and 843 cm –1 in xanthiosite. Bands from stretching vibrations As-O in AsO 4 polyhedra are located at 728 and 735 cm –1 in aerugite and are slightly displaced to 726 and 747 cm –1 in xanthiosite. The Raman spectrum of aerugite also contains well-defined 692, 675 and 658 cm –1 bands due to the stretching mode of NiO 6 octahedra, a broad feature at 576 cm –1 probably from a number of modes connected with AsO 6 octahedra. On the other hand, the xanthiosite spectrum displays a number of low-intensity, well-defined bands related to antisymmetric ν 4 and ν 2 symmetric bending vibrations in AsO 4 below 700 cm –1 as well as to lattice vibrational modes and Ni-O interactions below 250 cm –1 . Locally, the interstices between xanthiosite grains are filled with cryptocrystalline mass with the mean chemical composition of (K 0.90 Ba 0.01 ) Σ0.91 (Ni 2.86 Co 0.11 Cu 0.05 ) Σ3.02 (As 1.00 O 4 )(As 2.1 O 7 ) with traces of Na (mean of 7 analyses, based on 11 oxygens). The recorded Raman spectrum, with a strongly overlapping xanthiosite-related signal, lacks bands of water molecules or OH groups and contains bands related to the As–O–As vibration modes attributed to pyroarsenate As 2 O 7 groups. Although it was impossible to obtain more detailed data on crystal structure, we suggest this is the first reported natural occurrence of KNi 3 (AsO 4 )(As 2 O 7 ) phase.
在德国萨克森州Johanngeorgenstadt的一份历史样品中，发现了两种罕见的无水砷酸盐绿柱石Ni8.5（AsO4）2As5+O8和黄硫石Ni3（AsO4）2。首次通过扫描电子显微镜、电子探针分析和拉曼光谱对这些矿物进行了表征。它们大多为深绿色（绿柱石）至浅绿色（黄硫石）细粒或微晶结壳，位于石英基质上，与重晶石、辉玄岩、白云石和绿柱石有关。绿柱石形成高达200μm的大型伪六方片状晶体，而黄硫石形成短棱柱，形状几乎相等，通常具有模糊、发育不良和圆形的表面。这两种矿物的化学组成可以用经验公式表示：（Ni 7.92 Co 0.52 Cu 0.06）∑8.50。这两种矿物的拉曼光谱都缺乏与OH伸缩振动相关的谱带，并且在砷铁矿的情况下，以817、846和886 cm–1为中心的AsO4多面体中，以反对称的Γ3和对称的Γ1 As–O振动为主，在黄硫矿的情况下为786、808、826和843 cm–1。AsO4多面体中拉伸振动As-O的谱带在绿柱石中分别位于728和735 cm–1处，在黄硫石中分别略微位移到726和747 cm–1。由于NiO6八面体的拉伸模式，绿柱石的拉曼光谱还包含明确的692、675和658 cm–1波段，这是576 cm–2的一个广泛特征，可能来自与AsO6八面的许多模式。另一方面，在700 cm–1以下的AsO4中，黄硫石光谱显示出许多低强度、定义明确的谱带，这些谱带与反对称的Γ4和Γ2对称弯曲振动有关，也与250 cm–1下方的晶格振动模式和Ni-O相互作用有关。局部而言，黄硫矿颗粒之间的间隙充满了隐晶质，其平均化学组成为（K0.90 Ba 0.01）∑0.91（Ni 2.86 Co 0.11 Cu 0.05）∑3.02（As 1.00 O4）（As 2.1 O7），并含有微量Na（基于11种氧的7次分析的平均值）。记录的拉曼光谱具有强烈重叠的黄硫酸盐相关信号，缺乏水分子或OH基团的谱带，并且包含与焦砷酸盐As 2 O 7基团的As–O–As振动模式相关的谱带。虽然无法获得更详细的晶体结构数据，但我们认为这是首次报道KNi3（AsO4）（As2O7）相的自然出现。
{"title":"Chemical composition and Raman spectroscopy of aerugite, xanthiosite, and a natural analog of KNi3(AsO4)(As2O7) from Johanngeorgenstadt, Germany","authors":"Iwona KORYBSKA-SADŁO, Adam Szuszkiewicz, Marta Prell, Piotr Gunia","doi":"10.3190/jgeosci.361","DOIUrl":"https://doi.org/10.3190/jgeosci.361","url":null,"abstract":"Aerugite Ni 8.5 (AsO 4 ) 2 As 5+ O 8 and xanthiosite Ni 3 (AsO 4 ) 2 , two rare anhydrous arsenates, have been identified in a historic sample from Johanngeorgenstadt, Saxony, Germany. The minerals have been characterized through scanning electron microscopy, electron microprobe analysis and Raman spectroscopy for the first time. They are mostly dark-green (aerugite) to light-green (xanthiosite) fine-grained or microcrystalline crusts on a quartz matrix in association with barite, bunsenite, dolomite, and rooseveltite. Aerugite forms up to 200 μm large pseudo-hexagonal platy crystals, whereas xanthiosite forms short prisms to nearly equant forms, often with indistinct, poorly-developed and rounded faces. The chemical composition of the two minerals can be expressed by the empirical formulas: (Ni 7.92 Co 0.52 Cu 0.06 ) Σ8.50 (As 1.00 O 4 ) 2 As 1.00 O 8 with traces of Bi (aerugite, mean of 4 analyses, based on 32 oxygens) and (Ni 2.85 Co 0.12 Cu 0.03 ) Σ3.00 (As 1.00 O 4 ) 2 (xanthiosite, mean of 5 analyses, based on 32 oxygens). The Raman spectra of both minerals lack bands related to OH stretching vibrations and are dominated by antisymmetric ν 3 and symmetric ν 1 As–O vibrations in AsO 4 polyhedra centered at 817, 846 and 886 cm –1 in the case of aerugite and at 786, 808, 826 and 843 cm –1 in xanthiosite. Bands from stretching vibrations As-O in AsO 4 polyhedra are located at 728 and 735 cm –1 in aerugite and are slightly displaced to 726 and 747 cm –1 in xanthiosite. The Raman spectrum of aerugite also contains well-defined 692, 675 and 658 cm –1 bands due to the stretching mode of NiO 6 octahedra, a broad feature at 576 cm –1 probably from a number of modes connected with AsO 6 octahedra. On the other hand, the xanthiosite spectrum displays a number of low-intensity, well-defined bands related to antisymmetric ν 4 and ν 2 symmetric bending vibrations in AsO 4 below 700 cm –1 as well as to lattice vibrational modes and Ni-O interactions below 250 cm –1 . Locally, the interstices between xanthiosite grains are filled with cryptocrystalline mass with the mean chemical composition of (K 0.90 Ba 0.01 ) Σ0.91 (Ni 2.86 Co 0.11 Cu 0.05 ) Σ3.02 (As 1.00 O 4 )(As 2.1 O 7 ) with traces of Na (mean of 7 analyses, based on 11 oxygens). The recorded Raman spectrum, with a strongly overlapping xanthiosite-related signal, lacks bands of water molecules or OH groups and contains bands related to the As–O–As vibration modes attributed to pyroarsenate As 2 O 7 groups. Although it was impossible to obtain more detailed data on crystal structure, we suggest this is the first reported natural occurrence of KNi 3 (AsO 4 )(As 2 O 7 ) phase.","PeriodicalId":15957,"journal":{"name":"Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44364857","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}
V. F. Embui, Cheo Emmanuel, Suh, Bernd Lehmann, Lukáš Ackerman
We present Mo isotope data for molybdenite from the Ekomédion U–Mo prospect, SW Cameroon, a Late Neoproterozoic granite–pegmatite–quartz vein system. Disseminated and veinlet-controlled molybdenite in granite and pegmatitic pods yields a narrow range of δ 98 Mo values from – 0.06 to + 0.24 ‰, with two overlapping populations of + 0.03 ± 0.07 ‰ (n = 4) in granite, and slightly heavier of + 0.11 ± 0.10 ‰ (n = 5) in pegmatite. By contrast, molybdenite from a quartz– muscovite vein has an isotopically heavy δ 98 Mo value of + 1.61 ‰. We interpret this trend from granite through pegmatite to vein system towards isotopically heavy Mo to reflect the fractionation of an evolving magmatic–hydrothermal system. Furthermore, the LREE-enriched bulk-rock patterns with largely negative Eu anomalies and the overall enrichment of HREE in zircon indicate plagioclase fractionation as the dominant petrogenetic process during melt evolution. Furthermore, the presence of accessory ilmenite indicates relatively reducing conditions of the melt system, unfavorable for significant Mo accumulation. Therefore, the Ekomédion granite system seems to have limited economic potential for molybdenum despite the advanced degree of magmatic evolution.
{"title":"Molybdenum isotopic composition of molybdenite and the fertility potential of the Ekomédion U–Mo prospect, SW Cameroon","authors":"V. F. Embui, Cheo Emmanuel, Suh, Bernd Lehmann, Lukáš Ackerman","doi":"10.3190/jgeosci.363","DOIUrl":"https://doi.org/10.3190/jgeosci.363","url":null,"abstract":"We present Mo isotope data for molybdenite from the Ekomédion U–Mo prospect, SW Cameroon, a Late Neoproterozoic granite–pegmatite–quartz vein system. Disseminated and veinlet-controlled molybdenite in granite and pegmatitic pods yields a narrow range of δ 98 Mo values from – 0.06 to + 0.24 ‰, with two overlapping populations of + 0.03 ± 0.07 ‰ (n = 4) in granite, and slightly heavier of + 0.11 ± 0.10 ‰ (n = 5) in pegmatite. By contrast, molybdenite from a quartz– muscovite vein has an isotopically heavy δ 98 Mo value of + 1.61 ‰. We interpret this trend from granite through pegmatite to vein system towards isotopically heavy Mo to reflect the fractionation of an evolving magmatic–hydrothermal system. Furthermore, the LREE-enriched bulk-rock patterns with largely negative Eu anomalies and the overall enrichment of HREE in zircon indicate plagioclase fractionation as the dominant petrogenetic process during melt evolution. Furthermore, the presence of accessory ilmenite indicates relatively reducing conditions of the melt system, unfavorable for significant Mo accumulation. Therefore, the Ekomédion granite system seems to have limited economic potential for molybdenum despite the advanced degree of magmatic evolution.","PeriodicalId":15957,"journal":{"name":"Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49349274","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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