Mineralogy and Petrology最新文献

{"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}

{"title":"Serpierite polytypoids from Zvezdel, Bulgaria, and Lavrion, Greece","authors":"Rositsa P. Nikolova,&nbsp;Nadia L. Petrova,&nbsp;Zlatka G. Delcheva,&nbsp;Liliya V. Tsvetanova,&nbsp;Tsveta Stanimirova,&nbsp;Iskra Piroeva","doi":"10.1007/s00710-022-00797-9","DOIUrl":"10.1007/s00710-022-00797-9","url":null,"abstract":"<div><p>Structural characteristics of serpierite samples from Zvezdel, Bulgaria, and Lavrion, Greece, are reported. The thermal behaviour of serpierite from Lavrion is discussed. The chemical composition of the studied samples is analysed by energy-dispersive spectroscopy (EDS) and confirmed by single-crystal structure refinements. The obtained chemical formulas correspond well to that of serpierite with Cu:Zn ratio varying between 2.9 and 5.6. The sample from Zvezdel, with composition Ca[Cu_3.3Zn_0.7(OH)₆(SO₄)₂•3H₂O, crystallizes in the monoclinic crystal system, with space group <i>I</i>2 and unit-cell parameters <i>a</i> = 18.418(3), <i>b</i> = 6.220(1), <i>c</i> = 12.091(2) Å, <i>β</i> = 90.78(1)˚, whereas the one from Lavrion Ca[Cu_2.8Zn_1.2(OH)₆(SO₄)₂]•3H₂O, shows similar unit-cell parameters <i>a</i> = 18.394(1), <i>b</i> = 6.256(1), <i>c</i> = 12.097(1) Å, <i>β</i> = 90.92(1)˚, but higher <i>I</i>2<i>/m</i> space-group symmetry. Both studied crystals exhibit serpierite structure topology, but different stacking sequence of the octahedral layers. While in previously studied serpierite of Sabelli and Zanazzi (Acta\u0000Cryst B24:1214-1221, 1968) there are two layers per unit cell, in currently studied samples there is only one. As a consequence, their unit-cell volumes are half than that of the first structurally characterized serpierite specimen with SG <i>C</i>2/<i>c</i> and unit-cell parameters <i>a</i> = 22.186(2), <i>b</i> = 6.250(2), <i>c</i> = 21.853(2) Å, <i>β</i> = 113.36(1)˚. Taking into account the structural peculiarities of the studied samples they are considered as serpierite polytypoids.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 1","pages":"27 - 38"},"PeriodicalIF":1.8,"publicationDate":"2022-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00797-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4320172","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":"Petrology of ultramafic and mafic rocks from the South Andaman Ophiolite, Bay of Bengal: Evidence for an arc-related high-pressure origin","authors":"Tavheed Khan,&nbsp;Luc Achille Ziem A Bidias,&nbsp;Syed H. Jafri,&nbsp;Rohit Pandey,&nbsp;Nittala V. Chalapathi Rao,&nbsp;Manavalan Satyanarayanan,&nbsp;Drona Srinivasa Sarma","doi":"10.1007/s00710-022-00796-w","DOIUrl":"10.1007/s00710-022-00796-w","url":null,"abstract":"<div><p>Minor ultramafic (dunite) and mafic (gabbroic) rock occurrences are exposed in South Andaman Island, Bay of Bengal. Dunite is in contact with serpentinite, while gabbroic rocks are in contact with the pyroxenite. Petrographic analysis using a petrographic microscope, major and trace element [including rare earth elements (REE)] analysis using an X-ray Fluorescence (XRF) spectrometer and the High Resolution Inductively Coupled Plasma Mass Spectrometer (HR-ICPMS), and mineral chemistry using an Electron Probe Micro-Analyzer (EPMA) were performed on selected ultramafic and mafic rocks. Petrographically, dunite is composed of olivine, clinopyroxene, and orthopyroxene, while olivine, clinopyroxene, orthopyroxene, and calcic plagioclase are present in olivine–gabbronorite. The bulk rock elemental relationship (Zr versus P₂O₅ and TiO₂ versus Zr/P₂O₅) indicate that the dunite and olivine–gabbronorite are tholeiitic in composition. The clinopyroxene with high Mg# [Mg²⁺/(Mg²⁺ + Fe²⁺)] and lower TiO₂ content is present in dunite, whereas the clinopyroxene with high Mg# and high TiO₂ content exists in olivine–gabbronorite. Cr₂O₃ versus Mg# in the clinopyroxene relationship and negative Nb, Ta, and Ti anomalies in these rocks imply high pressure arc related peridotite mantle source. Our results suggest that the dunite and gabbroic rocks were also intruded in the Andaman Ophiolitic suite of rocks during earlier subduction setting in Late Cretaceous time. Further, it is suggested that these ophiolites have been obducted on to the leading edge of the Eurasian continent during the Mid–Eocene to Late Oligocene event, prior to the current tectonically active Andaman–Java subduction, which was initiated in the Late–Miocene.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"116 6","pages":"473 - 492"},"PeriodicalIF":1.8,"publicationDate":"2022-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00796-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4954912","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":"Multi-stage alteration history of volcanic clasts containing buddigtonite from Upper Cretaceous strata of the Subsilesian Unit, Czech part of the Outer Flysch Carpathians","authors":"Dalibor Matýsek,&nbsp;Petr Skupien,&nbsp;Miroslav Bubík,&nbsp;Jakub Jirásek,&nbsp;Radek Škoda","doi":"10.1007/s00710-022-00794-y","DOIUrl":"10.1007/s00710-022-00794-y","url":null,"abstract":"<div><p>Floods in 1997 and 2010 exposed the Frýdek and Frýdlant formations of the Subsilesian Unit in the Ostravice River bed near Frýdek-Místek. In the sedimentary sequence of upper Campanian to Maastrichtian marls and paraconglomerates, clasts of strongly altered basic volcanic rock were found, accompanied by carbonate concretions and layers. Rare apatite, biotite, and a Cr-rich spinel subgroup mineral are the only relatively well-preserved primary minerals in the clasts. The matrix contains buddingtonite, albite, sanidine, kaolinite, illite-muscovite, a mineral of the smectite group, and possibly also a mixed structure mineral of the chlorite-smectite type. Laths of buddingtonite, identified by powder X-ray diffraction and wavelength-dispersive X-ray spectrometry, are not homogenous. Their compositions range from Bd₄₁ to Bd₅₉ molar component, with Kfs ranging between 26 and 35 mol%, Nafs between 5 and 27 mol%, and Ca-feldspar between 1 and 4 mol%. The matrix is irregularly dolomitized. Carbonates are also present in pseudomorphs after idiomorphic olivine and in fill of amygdaloidal cavities. These carbonates reveal complicated alteration rock history, having cores of magnesite passing into almost pure siderite outer parts. Calcite is always the youngest and most homogenous carbonate, probably connected with a different geological event. Accompanying carbonate concretions are composed of three dolomitic phases with quartz, calcite, and muscovite. We can conclude that buddingtonite originates in alteration of primary feldspar and/or volcanic glass during the catagenetic breakdown of kerogen in the sediment, surrounded by clayey sediments rich in decomposing organic matter. Volcanic clasts have similar texture and supposed pre-alteration phase composition as the rocks of teschenite association, namely monchiquites to picrites. However, the source of volcanic clast within the sediments remains unclear.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"116 6","pages":"429 - 441"},"PeriodicalIF":1.8,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4439096","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}