Mineralogy and Petrology最新文献

{"title":"A crystal structure refinement of uralolite, Ca2Be4(PO4)3(OH)3∙5H2O, from Weinebene, Austria","authors":"Kurt Mereiter,&nbsp;Franz Walter","doi":"10.1007/s00710-022-00806-x","DOIUrl":"10.1007/s00710-022-00806-x","url":null,"abstract":"<div><p>The crystal structure of uralolite, Ca₂Be₄(PO₄)₃(OH)₃·5H₂O, from the spodumene deposit of Weinebene, Carinthia, Austria, has been refined with X-ray single crystal data gathered on a CCD diffractometer. Uralolite is monoclinic, space group <i>P</i>2₁/<i>n</i>, <i>a</i> = 6.553(1), <i>b</i> = 16.005(3), <i>c</i> = 15.979(3) Å, <i>β</i> = 101.63(1)°, <i>V</i> = 1641.5(5) ų. While previously only isotropic displacement parameters and no hydrogen atom positions were reported for uralolite, now anisotropic displacement parameters were used for non-hydrogen atoms and hydrogen atoms were located and refined yielding <i>R</i>₁ = 0.038 for 3909 observed reflections. Uralolite is built up from corrugated layers [Be₄(PO₄)₃(OH)₃]^4- parallel to (010), which contain Z-shaped groups of four BeO₄ tetrahedra sharing corners via three OH groups and are further crosslinked by PO₄ tetrahedra. Two Ca atoms in Ca(O_phosphate)₅(H₂O)₂ coordination and an interstitial water molecule link these layers along [010]. The OH groups and the Ca-bonded H₂O molecules are all involved in hydrogen bonds with O···O distances of 2.780(2) − 3.063(2) Å and O-H···O angles of 150(1) − 179(1)° excluding a bifurcated bond. The interstitial water molecule displays a distorted tetrahedral environment of O atoms and accepts and donates each two hydrogen bonds. The crystal structure exhibits a <i>C</i>2/<i>c</i> pseudosymmetry for the [Be₄(PO₄)₃(OH)₃]^4- layers and the Ca atoms. However, the disposition of the water molecules and an asymmetric hydrogen bond pattern involving OH groups as well as H₂O molecules are decisive for the lowering of the symmetry of the structure to the true space group <i>P</i>2₁/<i>n.</i></p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 2","pages":"181 - 189"},"PeriodicalIF":1.8,"publicationDate":"2023-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00806-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4570829","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}

{"title":"Ba-rich phlogopite, dissakisite-(Ce), and fluorine-rich clinohumite in granulite-facies marbles from the In Ouzzal terrane, Western Hoggar, Algeria","authors":"Nadia Boureghda,&nbsp;Khadidja Ouzegane,&nbsp;Saïda Aït-Djafer,&nbsp;Abderrahmane Bendaoud,&nbsp;Basem A. Zoheir,&nbsp;Jean-Robert Kienast","doi":"10.1007/s00710-022-00802-1","DOIUrl":"10.1007/s00710-022-00802-1","url":null,"abstract":"<div><h2>Abstract\u0000</h2><div><p>Granulite-facies marbles are part of the Archaean crust of the In Ouzzal terrane (Western Hoggar). Besides calcite and dolomite, these marbles are characterized by forsterite, spinel, phlogopite, diopside, amphibole, and magnetite. High-Mn ilmenite (MnO: 19.43 wt%), pyrophanite (MnO: 25.83 wt%), dissakisite-(Ce) (containing 12.2–14.38 Ce₂O₃ wt% and 8.3–12.3 wt% La₂O₃), F-rich clinohumite and Ba-rich-phlogopite occur locally. Ilmenite-pyrophanite and Ba-rich phlogopite (BaO: 11.68 wt%) are interpreted to be resulted of the hydrothermal processes during carbonate deposition; whereas, dissakisite-(Ce) is inferred to have resulted from light rare earth element (LREE) enrichment of these marbles by fluids released from the syenite intrusions. Clinohumite with X_Mg [= Mg/(Mg + Fe)] of 0.89–0.91, generated by hydration of forsterite-bearing dolomitic marbles, has the highest fluorine contents ever reported in the literature (3.25–4.62 wt%), resulting in a F/(F + OH) ratio as high as 0.8. Clinohumite is the only phase incorporating F where phlogopite, amphibole and apatite are absent. Thus, all the F present in the rock would be concentrated in clinohumite, resulting in extreme fluorine enrichment in some grains.</p></div></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 1","pages":"99 - 111"},"PeriodicalIF":1.8,"publicationDate":"2023-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4451492","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}

{"title":"A new A-type granitoid occurrence in southernmost Fennoscandia: geochemistry, age and origin of rapakivi-type quartz monzonite from the Pietkowo IG1 borehole, NE Poland","authors":"Anna Grabarczyk,&nbsp;Janina Wiszniewska,&nbsp;Ewa Krzemińska,&nbsp;Zdzisław Petecki","doi":"10.1007/s00710-022-00799-7","DOIUrl":"10.1007/s00710-022-00799-7","url":null,"abstract":"<div><h2>Abstract\u0000</h2><div><p>Rapakivi-type quartz monzonite and the underlying dark-grey granodiorite from the Pietkowo IG1 borehole, in the Polish part of southernmost Fennoscandia have been investigated using whole-rock geochemistry, Sm–Nd isotope geochemistry and U–Pb zircon dating. The quartz monzonite was emplaced at 1495–1491 Ma, although slightly older zircon cores (antecrysts) of 1513 Ma imply a two-stage crystallization. The geochemical similarities with Mazury Complex granitoids, their metaluminous and alkali-calcic nature, elevated contents of F, Ga and high-field-strength-elements (HFSE), indicate that the Pietkowo IG1 rapakivi-type quartz monzonite is an ‘A-type’ granitoid. The presence of magnetite and titanite indicates crystallization under oxidizing conditions. The rock is classified as A₂ sub-type, and the Nb/Y ratio implies a within-plate setting. The dark-grey granodiorite, dated to 1813 Ma, has a calc-alkaline character, typical of a volcanic-arc environment. Initial whole rock ε_Nd values range between -2.9 and -3.3 for the rapakivi-type quartz monzonite and from -1.0 to + 1.1 for the dark-grey granodiorite. We suggest that the A-type Pietkowo IG1 rapakivi-type quartz monzonite was generated from the dark-grey granodiorite via partial melting at middle to lower crustal levels. The most plausible ascent route for the quartz monzonite was via lithospheric-scale weakness zones, between the eastern margin of the Mazowsze Domain and Belarus-Podlasie Granulite Belt, i.e., the Białystok fault. Therefore, the Pietkowo IG1 rapakivi-type quartz monzonite is a representative of the Mesoproterozoic A-type granitoid occurrence in southernmost Fennoscandia.</p></div></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 1","pages":"1 - 25"},"PeriodicalIF":1.8,"publicationDate":"2023-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00799-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4571737","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}

{"title":"Petrogenesis of strongly peraluminous plutonic rocks of the Eastern Sakarya Zone (Trabzon, Turkey): implications for crustal melting and evolution","authors":"Sabir Rasimgil,&nbsp;Nurdane Ilbeyli,&nbsp;Alper Gunes,&nbsp;Mehmet Demirbilek","doi":"10.1007/s00710-022-00800-3","DOIUrl":"10.1007/s00710-022-00800-3","url":null,"abstract":"<div><p>The Eastern Sakarya Zone in northeastern Turkey contributes for a natural laboratory to study subduction- to collision-related intrusive rocks. This paper presents data on a Carboniferous-aged Duzkoy pluton containing mainly peraluminous granitoids. In addition to plagioclase, K-feldspar and quartz, the rocks include biotite, zircon, apatite and opaque minerals. Sericitization, chloritization, epidotization, and carbonatization are  the main alteration types. The rocks display generally enrichment in large-ion lithophile elements (Rb, Th, U, K), and depletion in high field strength elements (Sr, Nb, Ta, P) in the primitive mantle-normalized trace element diagrams. The Duzkoy samples show mainly light rare earth elements-enriched patterns with marked negative Eu anomalies in the chondrite-normalized rare earth elements diagrams. The compositions of the Duzkoy plutonic rocks are consistent with their origin via partial melting of amphibolites or metagreywackes. Crystal fractionation is also likely an important process in the formation of these rocks. The origin of these rocks could be related to the delamination or slab breakoff processes during the Variscan orogeny.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 1","pages":"79 - 97"},"PeriodicalIF":1.8,"publicationDate":"2023-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4573842","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}

{"title":"Crystal structure and optical absorption spectra of LiCo(SO4)OH and its remarkable relationship to the Zn-Mn-silicate hodgkinsonite","authors":"Manfred Wildner,&nbsp;Gerald Giester","doi":"10.1007/s00710-022-00807-w","DOIUrl":"10.1007/s00710-022-00807-w","url":null,"abstract":"<div><p>Crystals of the compound LiCo(SO₄)OH were synthesised at low-hydrothermal conditions, and the crystal structure was determined and refined from single crystal X-ray diffraction data. LiCo(SO₄)OH crystallises monoclinic, space group <i>P</i>2₁/<i>c</i>, <i>Z</i> = 4, <i>a</i> = 9.586(2), <i>b</i> = 5.425(1), <i>c</i> = 7.317(1) Å, <i>β</i> = 109.65(1)°, <i>V</i> = 358.3 ų, <i>wR</i>2 = 0.0485 (2215 unique reflections, 78 variables). The structure is built from chains of edge-sharing, quite strongly bond-length and -angle distorted Co(OH)₃O₃ octahedra (&lt; Co–O &gt; = 2.126 Å), which are further linked by common corners, hydrogen bonds, and by properly shaped SO₄ tetrahedra (&lt; S–O &gt; = 1.476 Å) to sheets parallel (100). These sheets are connected to a three-dimensional framework by sharing corners with distorted LiO₄ polyhedra (&lt; Li–O &gt; = 1.956 Å). Apart from the isotypic sulfates of Mn²⁺ and Fe²⁺, only the molybdate LiCd(MoO₄)OH crystallises isostructural with LiCo(SO₄)OH. However, a very close structural relationship exists with the rare mineral hodgkinsonite, Zn₂Mn(SiO₄)(OH)₂, yielding crystal chemically very uncommon topological equivalents of Zn²⁺ ≡ S⁶⁺ and Si⁴⁺ ≡ Li⁺, aside from the expectable substitution Mn²⁺ ≡ Co²⁺. Polarised optical absorption spectra of LiCo(SO₄)OH reveal that the dominating spin-allowed ⁴T₁(P) band system of Co²⁺ (<i>d</i>⁷ configuration) is strongly split up and covers a prominent part (~ 15,500–24,500 cm⁻¹) of the visible spectral range, in accordance with the significant distortion of the Co(OH)₃O₃ polyhedron. The spectra are interpreted in terms of the Superposition Model of crystal fields, yielding a new set of intrinsic and interelectronic repulsion parameters for Co²⁺.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 2","pages":"317 - 324"},"PeriodicalIF":1.8,"publicationDate":"2023-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00807-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4162416","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}

{"title":"Concerning the incorporation of potassium in the crystal structure of combeite (Na2Ca2Si3O9)","authors":"Volker Kahlenberg","doi":"10.1007/s00710-022-00801-2","DOIUrl":"10.1007/s00710-022-00801-2","url":null,"abstract":"<div><p>Potassium incorporation in the structure of combeite has been studied in detail. Since natural combeites are known to contain only small amounts of potassium focus was laid on the Na-rich part of a hypothetical solid-solution series with composition Na_2-xK_xCa₂Si₃O₉. Samples were prepared from mixtures of silica and the corresponding carbonates for nominal compositions with x = 0.2, 0.3 and 0.5, heated from ambient temperature to 1350 °C and slowly cooled to 1000 °C. After disintegration of the carbonates, the platinum capsules used as sample containers were welded shut in order to avoid losses of the volatile K₂O and Na₂O components. From all three batches potassium containing combeite crystals could be retrieved. Single-crystal diffraction experiments revealed the following compositions: Na_2.10(1)K_0.11(1)Ca_1.90(1)Si₃O₉, Na_2.09(1)K_0.18(1)Ca_1.91(1)Si₃O₉ and Na_2.13(1)K_0.18(1)Ca_1.87(1)Si₃O₉. Consistently, the trigonal crystals (space group <i>P</i> 3₁ 2 1) contained (i) (K + Na):Ca ratios larger than 1:1 and (ii) potassium concentrations lower than those in the starting mixtures. Since the K-contents of the samples obtained from the runs with x = 0.3 and 0.5 were almost identical, the solid-solution seems to be rather limited with an upper boundary of about one potassium atom per unit cell. The structure of the K-containing combeites is very close to the K-free structures reported in the literature. It can be described as a mixed tetrahedral-octahedral network in which additional K, Na and Ca cations are incorporated for charge compensation. A detailed analysis of the topological features of the net is presented. From the six observed extra-framework sites only the M22 position showing a coordination environment with ten next oxygen neighbours is involved in the K-substitution. Potassium uptake is also reflected in increasing values for the lattice parameters <i>a</i> and <i>c</i> as well as the unit-cell volumes. Actually, the <i>c</i>-axis is more affected from the incorporation of the comparatively large K⁺-cations.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 2","pages":"293 - 306"},"PeriodicalIF":1.8,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00801-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5074105","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}

{"title":"Khurayyimite Ca7Zn4(Si2O7)2(OH)10·4H2O: a mineral with unusual loop-branched sechser single chains","authors":"Biljana Krüger,&nbsp;Irina O. Galuskina,&nbsp;Evgeny V. Galuskin,&nbsp;Yevgeny Vapnik,&nbsp;Mikhail N. Murashko","doi":"10.1007/s00710-022-00804-z","DOIUrl":"10.1007/s00710-022-00804-z","url":null,"abstract":"<div><p>The new mineral khurayyimite Ca₇Zn₄(Si₂O₇)₂(OH)₁₀·4H₂O occurs in colorless spherulitic aggregates in small cavities of altered spurrite marbles located in the northern part of the Siwaqa pyrometamorphic rock area, Central Jordan. It is a low-temperature, hydrothermal mineral and is formed at a temperature lower than 100 °C. Synchrotron single-crystal X-ray diffraction experiments have revealed that khurayyimite crystallizes in space group <i>P</i>2₁/<i>c</i>, with unit cell parameters <i>a</i> = 11.2171(8), <i>b</i> = 9.0897(5), <i>c</i> = 14.0451(10) Å, β = 113.297(8)º, V = 1315.28(17) ų and Z = 2. The crystal structure of khurayyimite exhibits tetrahedral chains of periodicity 6. The sequence of SiO₄ and ZnO₂(OH)₂-tetrahedra along the chain is Si–Si-Zn. The neighboring SiO₄-tetrahedra of the corrugated chains are bridged by additional ZnO₂(OH)₂-tetrahedra to form 3-connected <i>dreier</i> rings. The chains can be addressed as loop-branched <i>sechser</i> single chains {<b><i>lB</i></b>, 1¹_∞}[⁶Zn₄Si₄O₂₁]. The chains are linked by clusters of five CaO₆ and two CaO₇ polyhedra with additional OH groups and H₂O molecules in the coordination environment. Based on the connectedness and one-dimensional polymerisations of tetrahedra (TO₄)ⁿ⁻, chains of khurayyimite belong to the same group as vlasovite Na₂ZrSi₄O₁₁, since they can be described with geometrical repeat unit ^cT_r = ²T₄ ³T₄ and topological repeat unit ^cV_r = ²V₂ ³V₂.\u0000</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 2","pages":"191 - 200"},"PeriodicalIF":1.8,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00804-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5078901","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}

{"title":"The mineralogical and petrological constraints of the Cretaceous Kermanshah ophiolitic complex in Nourabad and Dinavar regions in western Iran","authors":"Abbas Asiabanha,&nbsp;Jacques-Marie Bardintzeff,&nbsp;Kobra Shayegh","doi":"10.1007/s00710-022-00805-y","DOIUrl":"10.1007/s00710-022-00805-y","url":null,"abstract":"<div><p>As a part of the Kermanshah ophiolite in western Iran, the Cretaceous Nourabad-Dinavar ophiolitic complex is a remnant of the Neo-Tethys oceanic lithosphere and represents transitional mantle-crust and upper crust units in the Nourabad and Dinavar regions, respectively. All the units were affected by the two metamorphic regimes of static metamorphism and dynamic metamorphism. The whole-rock chemical data of the basic samples (i.e. gabbros, basalts, and dykes) show that they are related to the island-arc regime. The main reasons for this conclusion are as follows: their affinity with the calc-alkaline series, LREE enrichment, and subduction-related proxies such as the negative anomalies of Nb, Ta, Zr, and Hf and the positive anomaly of Th. On the other hand, the mineral chemistry analysis confirms that the studied ophiolitic complex is a MORB-type ophiolite emplaced in the supra-subduction zone. This is supported by mineralogical evidence including the compositional dependence of olivines (fo_90-91) on the spinel peridotite mantle facies, spinel minerals (Al-chromite and Mg/Cr-bearing hercynite), and Mg-rich orthopyroxenes (enstatite) in the harzburgites. The geochemical modeling implies that this complex evolved through the following successive magmatic steps: 1) the partial melting of a mixed NMORB-EMORB (50:50) source producing spinel harzburgite residues; 2) the fractional crystallization of the basic partial melts during their ascent to the surface and the formation of gabbro bodies; 3) the assimilation and fractional crystallization process as the NMORB components re-enter the chamber and produce basic pillow lavas, lava flows, and some fine-grained gabbro bodies (i.e. dykes). Accordingly, it can be interpreted that the emplacement history of the studied ophiolite succession has two stages: 1) an obduction stage in the Campanian; 2) an exhumation stage in the post-Cretaceous.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 1","pages":"39 - 61"},"PeriodicalIF":1.8,"publicationDate":"2022-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4643918","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}

{"title":"Nishanbaevite, KAl2O(AsO4)(SO4), a new As/S-ordered arsenate-sulfate mineral of fumarolic origin","authors":"Igor V. Pekov,&nbsp;Natalia V. Zubkova,&nbsp;Vasiliy O. Yapaskurt,&nbsp;Dmitry I. Belakovskiy,&nbsp;Sergey N. Britvin,&nbsp;Atali A. Agakhanov,&nbsp;Anna G. Turchkova,&nbsp;Evgeny G. Sidorov,&nbsp;Anton V. Kutyrev,&nbsp;Vladislav A. Blatov,&nbsp;Dmitry Y. Pushcharovsky","doi":"10.1007/s00710-022-00803-0","DOIUrl":"10.1007/s00710-022-00803-0","url":null,"abstract":"<div><p>The new mineral nishanbaevite, ideally KAl₂O(AsO₄)(SO₄), was found in sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with euchlorine, alumoklyuchevskite, langbeinite, urusovite, lammerite, lammerite-β, ericlaxmanite, kozyrevskite, and hematite. Nishanbaevite occurs as long-prismatic or lamellar crystals up to 0.03 mm typically combined in brush-like aggregates and crusts up to 1.5 mm across. It is transparent, colourless, with vitreous lustre. <i>D</i>_calc = 3.012 g cm^− 3. Nishanbaevite is optically biaxial (–), α = 1.552, β ≈ γ = 1.567. The chemical composition (average of seven analyses) is: Na₂O 3.79, K₂O 8.01, CaO 0.10, CuO 0.21, Al₂O₃ 30.08, Fe₂O₃ 0.50, SiO₂ 1.62, P₂O₅ 0.66, As₂O₅ 32.23, SO₃ 22.59, total 99.79 wt%. The empirical formula calculated based on 9 O <i>apfu</i> is: (K_0.57Na_0.41Ca_0.01)_Σ0.99(Al_1.99Fe³⁺_0.02Cu_0.01)_Σ2.02(As_0.95S_0.95Si_0.09P_0.03)_Σ2.02O₉. Nishanbaevite is orthorhombic, <i>Pbcm</i>, <i>a =</i> 15.487(3), <i>b =</i> 7.2582(16), <i>c</i> = 6.6014(17) Å, <i>V</i> = 742.1(3) ų and <i>Z</i> = 4. The strongest reflections of the powder XRD pattern [<i>d</i>,Å(<i>I</i>)(<i>hkl</i>)] are: 15.49(100)(100), 6.56(30)(110), 4.653(29)(111), 3.881(54)(400), 3.298(52)(002), 3.113(29)(121), and 3.038(51)(202, 411). The crystal structure, solved from single-crystal XRD data (<i>R</i> = 7.58%), is unique. It is based on the complex heteropolyhedral sheets formed by zig-zag chains of Al-centred polyhedra (alternating trigonal bipyramids AlO₅ and octahedra AlO₆ sharing edges) and isolated tetrahedra AsO₄ and SO₄. Adjacent chains of Al polyhedra are connected <i>via</i> AsO₄ tetrahedra to form a heteropolyhedral double-layer. Its topological peculiarity is considered and compared with those in structurally related compounds. The (K,Na) site is located in the interlayer space between SO₄ tetrahedra. The position of nishanbaevite among the arsenate-sulfates and their specific structural features are discussed. The mineral is named in honour of the Russian mineralogist Tursun Prnazorovich Nishanbaev (1955–2017).</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 2","pages":"247 - 257"},"PeriodicalIF":1.8,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4376007","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}

{"title":"Neogene calc-alkaline volcanism in Bobak and Sikh Kuh, Eastern Iran: Implications for magma genesis and tectonic setting","authors":"Habib Biabangard,&nbsp;Fatemeh Sepidbar,&nbsp;Richard M. Palin,&nbsp;Mohammad Boomeri,&nbsp;Scott A. Whattam,&nbsp;Seyed Masoud Homam,&nbsp;Omol Banin Shahraki","doi":"10.1007/s00710-022-00798-8","DOIUrl":"10.1007/s00710-022-00798-8","url":null,"abstract":"<div><p>The Neogene post-collisional volcanism in eastern Iran is represented by the Sikh Kuh and Bobak high-Na rocks including trachybasalt, trachyandesite, trachydacite, and dacite. We report whole rock geochemistry and Nd–Sr isotopic data which constrain the characteristics of the mantle source. The rocks are highly enriched in incompatible trace elements, suggesting a metasomatized subcontinental lithospheric mantle (SCLM) as the magma source. Felsic rocks record abundant petrographic evidence, major and trace element data, and isotopic (⁸⁷Sr/⁸⁶Sr(i) = 0.70727–0.70902) signatures indicative of fractional crystallization, and potentially, crustal assimilation. Such processes however, have not significantly affected the isotopic signatures (⁸⁷Sr/⁸⁶Sr(i) = 0.70417–0.70428) of the mafic members, suggesting that they are derived from a mantle source. The geochemical and isotopic data for the Sikh Kuh and Bobak volcanic rocks suggest that these Neogene magmas were derived from a small degree of partial melting (~ 2–10 vol%) of a spinel-bearing subcontinental lithospheric mantle source in a post-collisional setting. The generated more unfractionated mafic magmas erupted during an episode of extensional tectonics, presumably caused by extension that followed Eocene collision between the Lut and Afghan continental blocks. These melts interacted with continental crust during ascent, experiencing crystal fractionation, and crustal assimilation, to produce more evolved felsic volcanic rocks.\u0000</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 1","pages":"63 - 77"},"PeriodicalIF":1.8,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00798-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5168241","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}