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Diamond sources of the Juína region, Amazonian craton: textural and mineral chemical characteristics of Kimberley-type pyroclastic kimberlites 亚马逊克拉通胡伊纳地区的钻石来源:金伯利型火成岩金伯利岩的纹理和矿物化学特征
IF 1.4 4区 地球科学
Mineralogy and Petrology Pub Date : 2023-12-22 DOI: 10.1007/s00710-023-00849-8
Izaac Cabral-Neto, Excelso Ruberti, David Graham Pearson, Yan Luo, Rogério G. Azzone, Francisco V. Silveira, Vidyã V. Almeida
{"title":"Diamond sources of the Juína region, Amazonian craton: textural and mineral chemical characteristics of Kimberley-type pyroclastic kimberlites","authors":"Izaac Cabral-Neto,&nbsp;Excelso Ruberti,&nbsp;David Graham Pearson,&nbsp;Yan Luo,&nbsp;Rogério G. Azzone,&nbsp;Francisco V. Silveira,&nbsp;Vidyã V. Almeida","doi":"10.1007/s00710-023-00849-8","DOIUrl":"10.1007/s00710-023-00849-8","url":null,"abstract":"<div><p>Juína is the second-largest diamond-producing municipality in Brazil and is globally known for its outstanding sublithospheric diamond occurrences in both placer and kimberlite-hosted deposits. However, the scarcity of petrological data for Juína kimberlite pipes hampers understanding the nature and mantle source of these primary diamond sources in this region. Here, we present a textural and mineralogical study of ten kimberlite pipes from the Juína area. Based on petrographic features and mineral compositions, we interpret the studied Juína pipes as archetypal kimberlites with pyroclastic emplacement styles filled with resedimented volcaniclastic kimberlite and Kimberley-type pyroclastic kimberlite variants. The composition and texture of the magmatic phases, particularly spinel and phlogopite, suggest crystallisation from kimberlite sensu stricto magmas. The presence of high-Na eclogitic garnets and the absence of high-Cr low-Ca G10 garnets within the mantle xenocryst suite suggest the likelihood of eclogitic diamonds among Juína's lithospheric diamond populations. The Zr and Y contents, Ti/Eu and Zr/Hf ratios in the peridotite garnets, and Zr contents, Ca/Al, La<sub>N</sub>/Yb<sub>N</sub> (primitive-mantle normalised), Ti/Eu, and Zr/Hf ratios in the clinopyroxenes suggest a solid connection to kimberlite melt-related mantle metasomatism. Thermobarometry calculations indicate a relatively narrow stability window (825–936 ºC and 32–36 kbar) for lithospheric diamonds in the Juína region. Our findings have important implications for regional diamond exploration programs, shedding light on the primary sources of Juína's diamonds and contributing to understanding the deep geological processes in the underlying lithospheric mantle beneath the Amazonian craton.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"118 1","pages":"1 - 22"},"PeriodicalIF":1.4,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138943910","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}
引用次数: 0
"I've Spent My Whole Life Striving to Be Normal": Internalized Stigma and Perceived Impact of Diagnosis in Autistic Adults. “我一生都在努力变得正常”:自闭症成年人的内在耻辱和诊断的感知影响
IF 1.4 4区 地球科学
Mineralogy and Petrology Pub Date : 2023-12-01 Epub Date: 2023-12-12 DOI: 10.1089/aut.2022.0066
Yunhe Huang, Julian N Trollor, Kitty-Rose Foley, Samuel R C Arnold
{"title":"\"I've Spent My Whole Life Striving to Be Normal\": Internalized Stigma and Perceived Impact of Diagnosis in Autistic Adults.","authors":"Yunhe Huang, Julian N Trollor, Kitty-Rose Foley, Samuel R C Arnold","doi":"10.1089/aut.2022.0066","DOIUrl":"10.1089/aut.2022.0066","url":null,"abstract":"<p><strong>Background: </strong>Receiving an autism diagnosis in adulthood often leads to improved self-understanding and deeper self-reflection, which can have major impacts on people's well-being and sense of identity. However, autism diagnosis also exposes individuals to societal stigma, which may become internalized over time. This study aimed to explore relationships between psychological and service-related impacts of diagnosis and internalized stigma using mixed methods.</p><p><strong>Methods: </strong>One hundred forty-three autistic adults completed an online survey involving impact of diagnosis domains of Self-Understanding, Well-being, Clinician Support, and Service Access, internalized stigma, and open-ended questions on beliefs about autism diagnosis.</p><p><strong>Results: </strong>On average, participants reported mild levels of internalized stigma and positive impact of diagnosis in all domains except Service Access. Older age at diagnosis was positively associated with Clinician Support only. The path analysis model showed positive relationships between impact of diagnosis domains, with Self-Understanding having a positive effect on Well-being via lowered internalized stigma. We developed four themes of <i>Continuity and Acceptance</i>, <i>Late Diagnosis as Regret and Freedom</i>, <i>Coming to Terms with Being Autistic</i>, and <i>Stigma Resistance</i> from qualitative data.</p><p><strong>Conclusions: </strong>Self-understanding protects against the development of internalized autism stigma. Diagnosticians and service providers play an important role in improving self-understanding and well-being in autistic adults. More research is needed to understand the role of age at diagnosis and mechanisms behind positive identity development after autism diagnosis.</p>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"23 4","pages":"423-436"},"PeriodicalIF":1.4,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10726184/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41301477","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}
引用次数: 0
The auriferous quartz lode of the Veloso deposit, Quadrilátero Ferrífero of Minas Gerais, Brazil: geological characterisation and constraints from tourmaline boron isotopes 巴西米纳斯吉拉斯州Quadrilátero Ferrífero Veloso矿床含金石英矿脉:电气石硼同位素的地质特征和限制
IF 1.4 4区 地球科学
Mineralogy and Petrology Pub Date : 2023-11-28 DOI: 10.1007/s00710-023-00848-9
Júlia S. Pimenta, Alexandre R. Cabral, Glaucia Queiroga, Cristiano Lana, Miguel Tupinambá, Armin Zeh, Rogerio Kwitko-Ribeiro
{"title":"The auriferous quartz lode of the Veloso deposit, Quadrilátero Ferrífero of Minas Gerais, Brazil: geological characterisation and constraints from tourmaline boron isotopes","authors":"Júlia S. Pimenta,&nbsp;Alexandre R. Cabral,&nbsp;Glaucia Queiroga,&nbsp;Cristiano Lana,&nbsp;Miguel Tupinambá,&nbsp;Armin Zeh,&nbsp;Rogerio Kwitko-Ribeiro","doi":"10.1007/s00710-023-00848-9","DOIUrl":"10.1007/s00710-023-00848-9","url":null,"abstract":"<div><p>Veloso is one of numerous and poorly documented auriferous deposits of Ouro Preto, the town that symbolises the gold rush in Brazil at the turn of the seventeenth century. We present the results of underground geological mapping, combined with a boron (B) isotopic study of tourmaline, an elusive mineral in the auriferous quartz lode of the historical Veloso deposit. Its lode is characteristically brecciated in a host rock that shows no cataclastic fabric. The host rock is itabirite, a metamorphosed banded iron formation. Tourmaline is essentially dravite and locally occurs as abundant crystals in breccia-cementing pockets of goethite, formed from the oxidation of sulfide minerals. Gold is spatially associated with tourmaline in the goethite-rich pockets. In situ measurements for B isotopes yielded δ<sup>11</sup>B values in the range of −21 to −9‰. This range is similar to that reported for tourmaline of the Passagem de Mariana deposit, the best documented auriferous lode deposit at the south-eastern edge of the Quadrilátero Ferrífero. The tourmaline B isotopic data reflect auriferous fluids of crustal origin that sourced B from metasedimentary rocks, which may include a non-marine evaporitic component.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"118 1","pages":"89 - 103"},"PeriodicalIF":1.4,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138494547","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}
引用次数: 0
Crystal chemistry and origin of epidote-(Sr) in alkaline rocks of the teschenite association (Silesian Unit, Outer Western Carpathians, Czech Republic) 铁燧岩联合体碱性岩(捷克共和国,外西喀尔巴阡山脉,西里西亚单元)中的表铁矿(Sr)的晶体化学和起源
IF 1.4 4区 地球科学
Mineralogy and Petrology Pub Date : 2023-11-13 DOI: 10.1007/s00710-023-00847-w
Kamil Kropáč, Zdeněk Dolníček, Pavel Uher, David Buriánek, Tomáš Urubek
{"title":"Crystal chemistry and origin of epidote-(Sr) in alkaline rocks of the teschenite association (Silesian Unit, Outer Western Carpathians, Czech Republic)","authors":"Kamil Kropáč,&nbsp;Zdeněk Dolníček,&nbsp;Pavel Uher,&nbsp;David Buriánek,&nbsp;Tomáš Urubek","doi":"10.1007/s00710-023-00847-w","DOIUrl":"10.1007/s00710-023-00847-w","url":null,"abstract":"<div><p>A new occurrence of epidote-(Sr) CaSr(Al<sub>2</sub>Fe<sup>3+</sup>)[Si<sub>2</sub>O<sub>7</sub>][SiO<sub>4</sub>]O(OH), Sr-REE-rich epidote and Sr-rich allanite-(Ce) is located in Lower Cretaceous, Sr-rich hydrothermally altered leucocratic dykes penetrating alkaline igneous rocks (teschenites) near the Nový Jičín town (the Silesian Unit, Outer Western Carpathians). The dykes contain phenocrysts of pyroxene, amphibole, biotite, fluorapatite and dominant felsic groundmass consisting mostly of alkali feldspars and zeolites (analcime, natrolite and thomsonite-Ca). Accessory minerals include Ti-rich magnetite, prehnite, chamosite, pyrite, calcite, (OH, F)-rich grossular, epidote-group minerals, HFSE-, REE-rich minerals, Sr-rich baryte and slawsonite. The Sr-rich epidote forms columnar crystals or irregular aggregates, which are mostly spatially related to chamosite-titanite pseudomorphs; it contains 0.15–0.81 apfu Sr, ≤ 0.55 apfu REE; Fe<sup>3+</sup>/(Fe<sup>3+</sup> + Al) = 0.16–0.48. The Sr<sup>2+</sup> substitutes Ca<sup>2+</sup> in the <i>A2</i> site by a coupled substitution involving other <i>A2</i> (REE<sup>3+</sup>, Th<sup>4+</sup>) or <i>M</i> (Al<sup>3+</sup>, Fe<sup>3+</sup>, Fe<sup>2+</sup>) cations. The Sr-rich epidote crystallized from hydrothermal solutions, probably at temperatures between ~ 250–430 °C, during cooling of the host rock. The dykes show higher Sr contents (5680–7830 ppm) and <sup>87</sup>Sr/<sup>86</sup>Sr<sub>i(120 Ma)</sub> ratios (~ 0.7046–0.7047) compared to host mesocratic teschenites (1310–1470 ppm Sr and ~ 0.7038–0.7045, respectively). The Sr isotopes indicate origin of most Sr from primary magmatic plagioclase in parent teschenite. Nevertheless, there also participated external fluids, derived from the Lower Cretaceous seawater or diagenetic waters related to associated siliciclastic sediments with <sup>87</sup>Sr/<sup>86</sup>Sr<sub>i(120 Ma)</sub> = ~ 0.7073–0.7083. These more radiogenic sources contributed at least 6–21% of the bulk Sr budget of the studied Sr-rich epidote-bearing leucocratic dykes.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"118 1","pages":"55 - 70"},"PeriodicalIF":1.4,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136281898","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}
引用次数: 0
Correction to: Reply to the comment by S. Bouhlel 更正为对 S. Bouhlel 评论的答复
IF 1.4 4区 地球科学
Mineralogy and Petrology Pub Date : 2023-09-14 DOI: 10.1007/s00710-023-00846-x
Nejib Jemmali, Larbi Rddad, Marta Sośnicka, Emna Rahali, Fouad Souissi, Emmanuel John Carranza
{"title":"Correction to: Reply to the comment by S. Bouhlel","authors":"Nejib Jemmali,&nbsp;Larbi Rddad,&nbsp;Marta Sośnicka,&nbsp;Emna Rahali,&nbsp;Fouad Souissi,&nbsp;Emmanuel John Carranza","doi":"10.1007/s00710-023-00846-x","DOIUrl":"10.1007/s00710-023-00846-x","url":null,"abstract":"","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 4","pages":"801 - 801"},"PeriodicalIF":1.4,"publicationDate":"2023-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134911865","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}
引用次数: 0
Mallestigite, Pb3Sb(SO4)(AsO4)(OH)6·3H2O, from the type locality – new data, crystal structure, and structural relationships 产自典型矿区的Mallestigite,Pb3Sb(SO4)(AsO4)(OH)6-3H2O--新数据、晶体结构和结构关系
IF 1.4 4区 地球科学
Mineralogy and Petrology Pub Date : 2023-09-11 DOI: 10.1007/s00710-023-00837-y
Kurt Mereiter, Franz Walter, Hans-Peter Bojar
{"title":"Mallestigite, Pb3Sb(SO4)(AsO4)(OH)6·3H2O, from the type locality – new data, crystal structure, and structural relationships","authors":"Kurt Mereiter,&nbsp;Franz Walter,&nbsp;Hans-Peter Bojar","doi":"10.1007/s00710-023-00837-y","DOIUrl":"10.1007/s00710-023-00837-y","url":null,"abstract":"<div><p>A report of the supergene mineral mallestigite, Pb<sub>3</sub>Sb<sup>5+</sup>(SO<sub>4</sub>)(AsO<sub>4</sub>)(OH)<sub>6</sub>·3H<sub>2</sub>O, from the type locality Neufinkenstein-Grabanz district, Mallestiger Mittagskogel, Carinthia, Austria, is given in order to close gaps that have been left open since its first description. At the type locality, the dump of an abandoned small copper-lead-zinc mine, the mineral occurs frequently in up to ⁓2 mm long clear colourless idiomorphic hexagonal prisms {100} terminated by the bipyramid {101}. Details of the occurrence, paragenesis, physical properties, a FTIR spectrum and X-ray powder diffraction data are reported. Chemical analysis in a scanning electron microscope in conjunction with a crystal structure analysis gave the empirical formula Pb<sub>3.02</sub>Sb<sub>1.06</sub>(SO<sub>4</sub>)<sub>0.96</sub>(AsO<sub>4</sub>)<sub>0.97</sub>(OH)<sub>6</sub>·3H<sub>2</sub>O. An ab-initio crystal structure determination with CCD diffractometer data, Mo<i>K</i>α radiation, and a nearly untwinned crystal proved that mallestigite is hexagonal, space group <i>P</i>6<sub>3</sub>, <i>a</i> = 8.9326(4), <i>c</i> = 11.1044(5) Å, <i>V</i> = 767.33(8) Å<sup>3</sup>, <i>Z</i> = 2, and gave a final <i>R</i>1 = 0.0184 for 1632 independent reflections with <i>I</i> &gt; 2σ(<i>I</i>). Mallestigite belongs to the fleischerite group. The structure is built up from [Sb<sup>5+</sup>(OH)<sub>6</sub>]<sup>1–</sup> octahedra which are linked by triplets of edge-sharing Pb<sup>2+</sup> into chains [Pb<sub>3</sub>Sb(OH)<sub>6</sub>]<sup>5+</sup> extending along a 6<sub>3</sub> axis. Each three of such chains are bridged by triplets of H<sub>2</sub>O and by rows of SO<sub>4</sub><sup>2–</sup> and AsO<sub>4</sub><sup>3–</sup> tetrahedra alternating along a 3-fold axis and showing very different links to the Pb atom. Pb<sup>2+</sup> is in a strongly distorted one-sided [9]-coordination by O atoms that makes the structure clearly hemimorphic. Structural relationships to the fleischerite group minerals schaurteite, genplesite, despujolsite and fleischerite as well as to synthetic Ba<sub>3</sub>Sn<sup>4+</sup>(SeO<sub>4</sub>)<sub>2</sub>(OH)<sub>6</sub>·3H<sub>2</sub>O are outlined and changes in the space group symmetry of despujolsite (<i>P</i><span>(overline6)</span>2c → <i>P</i>6<sub>3</sub>/<i>mmc</i>) and fleischerite (<i>P</i><span>(overline6)</span>2c → <i>P</i>6<sub>3</sub>) are proposed.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"117 4","pages":"761 - 774"},"PeriodicalIF":1.4,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-023-00837-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135980599","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}
引用次数: 0
Noble and base metal geochemistry of late- to post-orogenic mafic dykes from central Spain 西班牙中部晚造山后镁铁质岩脉的贵金属和贱金属地球化学
IF 1.4 4区 地球科学
Mineralogy and Petrology Pub Date : 2023-09-08 DOI: 10.1007/s00710-023-00844-z
David Orejana, María García-Rodríguez, Cristina de Ignacio, Sergio Ruiz-Molina
{"title":"Noble and base metal geochemistry of late- to post-orogenic mafic dykes from central Spain","authors":"David Orejana,&nbsp;María García-Rodríguez,&nbsp;Cristina de Ignacio,&nbsp;Sergio Ruiz-Molina","doi":"10.1007/s00710-023-00844-z","DOIUrl":"10.1007/s00710-023-00844-z","url":null,"abstract":"<div><p>The post-tectonic and post-orogenic mafic rocks from the Spanish Central System (SCS) (Iberian Massif) include dyke swarms of shoshonitic (microgabbros) and alkaline (lamprophyres and diabases) geochemical affinity, which register the nature of the metasomatic lithospheric mantle under central Spain. Such magmas sometimes show a direct (or indirect) relationship with the formation of orogenic and intrusion-related gold deposits, which are relatively abundant in the Iberian Massif. The noble and base metal composition of these intrusions shows Primitive Mantle-normalized patterns characterized by positive Au and Co anomalies and fractionated platinum group elements (PGE): from lower Ir-group PGE (IPGE; Ir–Ru) to higher Pd-group PGE (PPGE; Rh–Pt–Pd). The low contents of PGE, together with the base metal contents of pyrite (which is the dominant sulphide phase in the alkaline dykes), is in accordance with low degrees of mantle partial melting and the early segregation of sulphides during magma differentiation. The scarcity of PGE mineral deposits in the Iberian Massif could be explained in part by the apparent lack of PGE enrichment in the Iberian lithospheric mantle. On the contrary, the positive Au anomaly of the SCS mafic dykes represents relatively high Au contents, similar to (and higher than) those of mafic rocks derived from metasomatized subcontinental lithospheric mantle underlying Au-endowed cratons. Several geochemical features point to subduction-related metasomatism of either oceanic or continental nature as the main source of Au enrichment. The Au re-fertilization of the lithospheric mantle under central Spain makes it a potential source in the formation of gold mineralizations.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"118 1","pages":"71 - 88"},"PeriodicalIF":1.4,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-023-00844-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41462481","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}
引用次数: 0
A tribute to Lanchand (Lalou) Govindram Gwalani 向Lanchand Govindram Gwalani致敬
4区 地球科学
Mineralogy and Petrology Pub Date : 2023-09-01 DOI: 10.1007/s00710-023-00845-y
Kirtikumar Randive, Anton Chakhmouradian, Peter Downes
{"title":"A tribute to Lanchand (Lalou) Govindram Gwalani","authors":"Kirtikumar Randive, Anton Chakhmouradian, Peter Downes","doi":"10.1007/s00710-023-00845-y","DOIUrl":"https://doi.org/10.1007/s00710-023-00845-y","url":null,"abstract":"","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"367 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135304558","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}
引用次数: 0
Geochemistry and formation of agate-bearing lithophysae in Lower Permian volcanics of the NW-Saxonian Basin (Germany) 德国西北-撒克逊盆地下二叠统火山岩含玛瑙岩系地球化学及形成
IF 1.4 4区 地球科学
Mineralogy and Petrology Pub Date : 2023-08-22 DOI: 10.1007/s00710-023-00841-2
Jens Götze, Robert Möckel, Yuanming Pan, Axel Müller
{"title":"Geochemistry and formation of agate-bearing lithophysae in Lower Permian volcanics of the NW-Saxonian Basin (Germany)","authors":"Jens Götze,&nbsp;Robert Möckel,&nbsp;Yuanming Pan,&nbsp;Axel Müller","doi":"10.1007/s00710-023-00841-2","DOIUrl":"10.1007/s00710-023-00841-2","url":null,"abstract":"<div><p>Geochemical and mineralogical investigations of the Lower Permian Kemmlitz rhyolite within the NW-Saxonian Basin (Germany) and associated lithophysae (high-temperature crystallization domains) as well as agates were carried out to constrain the genesis and characteristics of these volcanic rocks and the origin of the agate-bearing lithophysae. The volcanic rocks of rhyolitic composition are dominated by quartz, sanidine, and orthoclase and most likely derive from lava flows. Agate-bearing lithophysae were exclusively formed in a glassy facies (pitchstone) of the rhyolites, which was afterwards altered to illite-smectite mixed-layer clays. The results of this study show that agate formation can be related to the alteration of the volcanic rocks accompanied by the infill of mobilized silica into cavities of lithophysae. Fluid inclusion studies point to temperatures of agate formation above 150 °C, indicating that the mobilization and accumulation of silica started already during a late phase of or soon after the volcanic activities. Remarkable high concentrations of B (29 ppm), Ge (&gt; 18 ppm), and U (&gt; 19 ppm) as well as chondrite-normalized rare earth element (REE) distribution patterns of the agates with pronounced negative Eu-anomalies, slightly positive Ce-anomalies and enriched heavy rare earth elements (HREE) indicate interactions of the host rocks and transport of SiO<sub>2</sub> with magmatic volatiles (F/Cl, CO<sub>2</sub>) and heated meteoric water. Characteristic yellow cathodoluminescence (CL), heterogeneous internal textures as well as high defect density of micro- and macrocrystalline quartz detected by electron paramagnetic resonance (EPR) spectroscopy point to crystallization processes via an amorphous silica precursor under non-equilibrium conditions.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"118 1","pages":"23 - 40"},"PeriodicalIF":1.4,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-023-00841-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43484812","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}
引用次数: 0
Mineralogy of Pakkanadu carbonatites and associated rocks, South India: constraints on evolution and evidences for REE enrichment 南印度Pakkanadu碳酸盐岩和伴生岩石的矿物学:演化的制约因素和REE富集的证据
IF 1.8 4区 地球科学
Mineralogy and Petrology Pub Date : 2023-08-17 DOI: 10.1007/s00710-023-00843-0
S. Mahapatro, T. Meshram, Mahesh Korakappa
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引用次数: 1
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