Mineralogy and Petrology最新文献

{"title":"Geochronology and geochemistry of the felsic-intermediate dikes from Xiangshan uranium ore field, South China: Implications for petrogenesis, tectonic setting and uranium mineralization","authors":"Yong-Jian Wang,&nbsp;Jiang-Tao Nie,&nbsp;Jin-Rong Lin,&nbsp;Hong-Zuo Wang","doi":"10.1007/s00710-022-00780-4","DOIUrl":"10.1007/s00710-022-00780-4","url":null,"abstract":"<div><p>Xiangshan volcanic-related uranium ore field, as the historic largest uranium producer in China, is characterized by a large volcanic-intrusive complex and a number of uranium deposits. In most of the deposits, various types of dikes are spatially associated with the uranium ore bodies, although there have been no systematic attempts to integrate the geochronology and petrogenesis of these dykes and their link with uranium mineralization. In this study, whole-rock major and trace elements, zircon U–Pb dating and zircon Hf–O isotopic analysis were carried out on the Xiagnshan felsic-intermediate dikes, including granitic porphyry, quartz monzonitic porphyry and dioritic porphyry. These felsic-intermediate dikes have the similar geochemical characteristics with the major ore-hosting volcanic rocks, such as enrichment in large lithophile elements (i.e., Rb and Th) and some high-field strength elements (i.e., Zr, Y), but relative depletion in Sr, Ba, P and Ti. These dikes also exhibit zircon ε_Hf(t) values concentrating from -9 to -4 and zircon δ¹⁸O values ranging from 7.6 to 10.0 ‰. Geochemical and isotopic data suggest that these dikes were predominantly derived from partial melting of crustal materials and possibly mingled with different proportions of mantle-derived materials during the formation of melts. SIMS and SHRIMP U–Pb dating of zircon grains from these felsic-intermediate dikes yield high-precision ages ranging from 136 to 131 Ma. Combined with previously reported age data indicates a rapid and concentrated dike emplacement event, although a few mafic-felsic dikes were sporadically emplaced at 126 -122 Ma. Such a relatively concentrated dike emplacement in the Early Cretaceous were most likely caused by the back-arc extension or intra-arc rift due to progressive rollback of the Paleo-Pacific Plate. Previous metallogenetic studies supported that the late-stage dikes at Xiangshan were temporally and spatially closely related to uranium mineralization. However, our new geochronological data and field observations indicate that the two episodes of uranium mineralization were not synchronous with the majority of dikes intrusions, indicating that they probably have no direct relationship in origin and that spatial coexistence were more likely due to multistage activities of faults. Rather, these dikes might act as a relatively reduced environment, and thus could facilitate the precipitation of uranium. In addition, all of these dikes can be considered favorable prospecting indicators in the Xiangshan ore field.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4979866","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":"Orthopyroxene megacrysts from the Chilka Lake anorthosite massif, Eastern Ghats, India: a clue to magmatic evolution","authors":"Sandip Choudhuri,&nbsp;Rajib Kar,&nbsp;Samarendra Bhattacharya,&nbsp;Sanchari Chatterjee,&nbsp;Anwesha Ghosh,&nbsp;Biswajit Ghosh,&nbsp;Tomoaki Morishita","doi":"10.1007/s00710-022-00779-x","DOIUrl":"10.1007/s00710-022-00779-x","url":null,"abstract":"<div><p>The present study reports the occurrence of orthopyroxene megacrysts from the Chilka Lake anorthosite massif, Eastern Ghats, India. An insight into the mineral chemistry of different phases, coupled with detailed field and petrographic evidences from this study, shed light on a long debate on the origin of orthopyroxene megacrysts in anorthosite massifs. The megacrysts contain exsolved lamellae of plagioclase and opaque oxides (ilmenite, rutile) oriented along orthopyroxene cleavage planes. The trace element distribution patterns of the megacryst and matrix plagioclase are mirror reflections of each other and mutually complementary. The calculated compositions of melts in equilibrium with these two phases show comparable patterns for LREE (light rare earth elements, La–Sm), but differ markedly in terms of HREE (heavy rare earth elements, Eu–Lu), suggesting that the megacrysts and matrix plagioclases did not crystallize simultaneously. We infer that the orthopyroxene megacrysts have a longer crystallization history, initially as a low-Ca non-quad member of the pyroxene group at pressure ≥ 10 kbar, incorporating some amount of Ca, Al and Ti in their structure. Subsequently, they have been carried by a plagioclase crystal mush to mid-crustal levels at pressure ~ 4–6 kbar following a near-isothermal decompression that may be linked to the emplacement of the anorthosite massif, giving rise to the exsolution lamellae of plagioclase and opaque oxides.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00779-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4902745","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":"Geochemistry of granitoids from the Austroalpine Seckau Complex: a key for revealing the pre-Alpine evolution of the Eastern Alps","authors":"Magdalena Mandl,&nbsp;Walter Kurz,&nbsp;Christoph Hauzenberger,&nbsp;Harald Fritz,&nbsp;Stefan Pfingstl","doi":"10.1007/s00710-022-00781-3","DOIUrl":"10.1007/s00710-022-00781-3","url":null,"abstract":"<div><p>Recent studies revealed that the calc-alkaline metagranitoids of the Seckau Complex comprise both (1) a Late Cambrian to Early Ordovician and (2) a Late Devonian to Early Carboniferous (early Variscan) intrusive complex. The older rocks of the Hochreichart Plutonic Suite reflect I to S-type affinity and are peraluminous and characterized by a general decrease in TiO₂, Al₂O₃, MgO, CaO, P₂O₅, FeOt and MnO with increasing SiO₂. Chondrite-normalized rare earth element (REE) plots display a slight enrichment in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) as well as negative Eu anomalies ((Eu/Eu*)_N = 0.15- 0.77). The whole-rock initial ⁸⁷Sr/⁸⁶Sr ratios calculated back to the time of emplacement (~ 496 Ma) vary between 0.7056 to 0.7061. The early Variscan rocks of the Hintertal Plutonic Suite can be subdivided into (a) the meta- to peraluminous granodioritic suite of the Pletzen Pluton and (b) the peraluminous granitic suite of the Griessstein Pluton. The Pletzen Pluton shows typical magmatic fractionation trends for most of the major oxides and trace elements plotted against SiO₂. On a chondrite-normalized diagram, metagranitoids are strongly enriched in LREE and show no significant negative Eu anomaly. Metagranitoids of the Griessstein Pluton have a more peraluminous character and similar major and trace element fractionation trends compared to the Pletzen Pluton. However, the contents in SiO₂, major and trace elements clearly point towards a more evolved melt with generally lower TiO₂, Al₂O₃, MgO and CaO values and higher K₂O content. Metagranitoids of the Griessstein Pluton are additionally characterized by a slight negative Eu anomaly of about 0.81 on a chondrite-normalized REE plot. Initial ⁸⁷Sr/⁸⁶Sr values calculated back to the time of emplacement (~ 353 Ma) of the Pletzen Pluton and the Griessstein Pluton vary between 0.7051—0.7061 and 0.7054—0.7063, respectively, and suggest the same magmatic source for both units. Application of rhyolite-MELTS modelling to the Hintertal Plutonic Suite revealed that the Griessstein Pluton formed by fractional crystallization (~ 30%) from the more primitive Pletzen Pluton. Our geochemical data from the Hochreichart Suite granitoids suggest the existence of a Late Cambrian to Early Ordovician active margin with its remnants now exposed in the Seckau Complex. The early Variscan grainitoids of the Seckau Complex are inferred as part of a magmatic arc along the southern Bohemian active continental margin that was related to the subduction of differently termed oceanic domains (Galicia-Moldanubian Ocean or Paleotethys), prior to the final collision of Gondwana and Laurussia. The general paleogeographic position of the Seckau Complex during the Variscan orogeny is considered to be south to so","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00781-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4767818","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":"Early Cretaceous ultramafic-alkaline-carbonatite magmatism in the Shillong Plateau-Mikir Hills, northeastern India – a synthesis","authors":"R. Srivastava, V. Guarino, L. Melluso","doi":"10.1007/s00710-022-00777-z","DOIUrl":"https://doi.org/10.1007/s00710-022-00777-z","url":null,"abstract":"","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45226665","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":"Estimation of Li and OH contents in (Li,Al)-bearing tourmalines from Raman spectra","authors":"Adam Pieczka,&nbsp;Bożena Gołębiowska,&nbsp;Marcin Stachowicz,&nbsp;Krzysztof Nejbert,&nbsp;Jakub Kotowski,&nbsp;Piotr Jeleń,&nbsp;Andreas Ertl,&nbsp;Krzysztof Woźniak","doi":"10.1007/s00710-022-00774-2","DOIUrl":"10.1007/s00710-022-00774-2","url":null,"abstract":"<div><p>Six Al- and Li-bearing tourmaline crystals from pegmatites were structurally and chemically characterized. These samples can be assigned to elbaite, fluor-elbaite and rossmanite. Quantitative analyses of light elements such as Li, B and H are not always easily accessible. Therefore a method for the calculation of Li and OH would be of a general interest for the Geosciences. In the present work we test whether relatively accurate Li and OH estimations are possible based on the deconvolution of the O–H stretching vibration modes in a Raman spectrum on common (Al, Li)-rich tourmalines. We use the short-range arrangement model in our band interpretation as this model, in contrast to other models, provides the ability to evaluate an additional parameter by analyzing the OH stretching modes that can be used in the formula calculation process, which ultimately leads to the estimation of Li and OH with high accuracy. We also compare microprobe and Raman spectroscopy results, which we combine, with optimized data derived from microprobe and single-crystal structure refinement by using the same crystals. Based on our investigations, where the Raman spectra were recorded on non-oriented crystal sections, we conclude that we produce more accurate estimations, when the effects of the section orientation are considered. Therefore, we also propose a new method to correct the influence of the orientation of the crystal section.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4148064","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":"Impact diamonds from meteorite craters and Neogene placers in Ukraine","authors":"Victor M. Kvasnytsya,&nbsp;Richard Wirth","doi":"10.1007/s00710-022-00778-y","DOIUrl":"10.1007/s00710-022-00778-y","url":null,"abstract":"<div><p>There are seven meteorite craters and several Neogene placers in the Ukrainian Shield containing impact apographitic diamond. In this work impact diamonds from the Bilylivka meteorite crater and from the Samotkan’ Neogene titanium-zirconium placer were studied in detail. The results of a comprehensive study of impact diamond crystals — morphology, microtopography, microstructure, carbon isotope composition, photoluminescence, optical, infrared, and Raman spectroscopy — are presented. The size of the impact diamonds is up to 0.5 mm. Impact diamond crystals are mostly two- or three-phase polycrystalline aggregates (diamond, lonsdaleite, graphite). They show external morphological and internal microstructural features of solid-state phase transition of graphite to diamond during impact shock metamorphism – they are paramorphoses on graphite crystals. Microstructural features of the graphite-diamond transition in the studied crystals of impact diamonds are their polysynthetic (11 <span>(overline{2})</span> 1) twinning and the polycrystalline structure of the twins themselves. The carbon isotopic composition of impact diamonds ranges: for Bilylivka diamonds – from –14.80 to –21.84 ‰ δ¹³C VPDB, with an average value of –17.21 ‰ δ¹³C and for Samotkan’ diamonds – from –10.35 to –23.06 ‰ δ¹³C VPDB, with an average value of –17.64 ‰ δ¹³C. The photo luminescent and spectroscopic features of the studied diamonds indicate the absence of nitrogen defects in crystals that are characteristic for mantle diamond. The location of the source rocks and potential routes how diamond have been incorporated into the Samotkan’ placer are discussed.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00778-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5127752","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":"Magma hybridization and crystallization in coexisting gabbroic and granitic bodies in the mid-crust, Akechi district, central Japan","authors":"Toru Yamasaki","doi":"10.1007/s00710-022-00775-1","DOIUrl":"10.1007/s00710-022-00775-1","url":null,"abstract":"<div><p>Petrological and geochemical features of gabbros and fine-grained mafic rocks (mafic microgranular enclaves; MMEs) in the Inagawa Granite of the Ryoke Plutonic Complex were investigated to assess the interactions between coexisting mafic and silicic magmas, and the petrogenetic relationships between the MMEs and surrounding gabbros. The MMEs exhibit mingling textures that imply the coexistence of mafic and silicic magmas that did not undergo complete mixing, but the geochemical compositions of the MMEs require substantial hybridization and homogenization. The gabbroic rocks exhibit disequilibrium textures and mineral compositions, such as quartz–hornblende ocellar textures and patchy plagioclase crystals with bimodal anorthite contents. These textures and compositions record an abrupt decrease in crystallization temperature and mechanical mixing between crystallizing gabbroic mush and silicic (granitic) melt. Geochemical variations of the gabbroic rocks can be explained by hybridization and fractional crystallization (HFC) processes between crystallizing gabbroic mush and granitic melt. Extrapolation of the mixing trend to a basaltic composition suggests that the primitive mafic end-member was a low-K basaltic magma. Given that HFC yields magnesian andesite by the addition of a small amount of silicic melt to a primitive mafic end-member, the compositional modification of mafic magmas by magma mixing might be an essential process in the formation of andesitic magma in arc crust.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00775-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4904427","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":"Geochemistry of rhodonite in the Luziyuan Pb − Zn skarn deposit, Southwestern China","authors":"Yulong Yang,&nbsp;Lin Ye,&nbsp;Wei Gao,&nbsp;Tan Bao,&nbsp;Zhenli Li,&nbsp;Yusi Hu,&nbsp;Chen Wei","doi":"10.1007/s00710-022-00776-0","DOIUrl":"10.1007/s00710-022-00776-0","url":null,"abstract":"<div><p>The Luziyuan skarn deposit is the second largest Pb − Zn deposit in the Baoshan block, Yunnan Province, Southwestern China. Rhodonite is a widespread skarn mineral in the host rock, occurring as coarse-grained crystals and veins, and is closely associated with Pb − Zn mineralization. In-situ elemental analysis of rhodonite from three levels (1220 m, 1265 m and 1495 m above sea level) by laser ablation-inductively coupled plasma-mass spectrometry and Sm − Nd isotopic dating of the rhodonite − calcite pair were conducted to constrain the compositions and the timing of Pb − Zn mineralization. The new Sm − Nd isotopic data reveal that the Luziyuan deposit formed during the Early Jurassic (183 ± 2.3 Ma; MSWD = 0.72). These chronological constraints, combined with regional tectonic evolution, suggest that the Luziyuan Pb − Zn mineralization is genetically linked to eastward subduction of the Shan Boundary Ocean beneath the Baoshan block during the Meso-Tethys period. Furthermore, all examined rhodonite samples contain relatively high concentrations of MnO (34.7 − 43.0 wt%) and Zn (536 − 2117 ppm), but generally low contents of FeO (1.07 − 6.08 wt%), Cu, Co, Ni, Ga, Mo, Sn, W and Pb. A positive correlation between Zn and MnO contents among different skarn deposits and nearly chondritic Y/Ho ratio (~ 28) in the Luziyuan rhodonite suggests that this mineral formed from magmatic fluids and its Zn enrichment was controlled by the fluid chemistry. The same data also suggest that Zn-rich rhodonite in skarns may be used as an indicator mineral for Zn exploration when combined with other geological, geophysical, and geochemical criteria.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4393285","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":"Orthopyroxene rim growth during reaction of (Co, Ni, Mn, Zn)-doped forsterite and quartz: Experimental constraints on element distribution and grain boundary diffusion","authors":"Sarah Incel,&nbsp;Ralf Milke,&nbsp;Bernd Wunder","doi":"10.1007/s00710-022-00773-3","DOIUrl":"10.1007/s00710-022-00773-3","url":null,"abstract":"<div><p>Mantle metasomatism is an important process in subduction zones in which fluids from the dehydrating oceanic slab interact with the overlying upper mantle resulting in a chemical alteration of the mantle. Consequently, this fluid-rock interaction may influence the mantle rock's physical properties such as the deformation behavior. In order to study element redistribution during mantle metasomatism in the laboratory, we used the simplified model reaction olivine + quartz = orthopyroxene, where olivine acts as representative for the upper mantle and quartz as proxy for the metasomatizing agent. We conducted piston-cylinder experiments at 1.5 GPa and 950 to 1400 °C, lasting between 48 and 288 h, on samples containing a mixture of quartz and one set of synthesized forsterite samples doped with either Co, Ni, Mn, or Zn. Additionally, we tested the influence of either nominally anhydrous or hydrous experimental conditions on the chemical distribution of the respective dopant element by using either crushable alumina or natural CaF₂ as pressure medium. Results of the chemical analyses of the recovered samples show dopant specific partitioning between doped forsterite and orthopyroxene independent of the confining pressure medium; except for the runs in which Ni-doped forsterite samples were used. The observed Ni- and Co-enrichment in forsterite samples may be used to identify mantle rocks that underwent mantle metasomatism in nature.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00773-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4967560","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":"Chevkinite-group minerals in selected intrusions of the Mazury Complex, North-Eastern Poland: insights into the formation of a titanite-like phase by hydrothermal alteration","authors":"Justyna Domańska-Siuda,&nbsp;Krzysztof Nejbert,&nbsp;Bogusław Bagiński,&nbsp;Ray Macdonald,&nbsp;Jakub Kotowski,&nbsp;Marcin Stachowicz","doi":"10.1007/s00710-022-00772-4","DOIUrl":"10.1007/s00710-022-00772-4","url":null,"abstract":"<div><p>Chevkinite-group minerals forming large and common (up to 0.03 vol%) accessory phases in monzodiorites and granodiorites from the Mesoproterozoic anorthosite-mangerite-charnockite-granite (AMCG) suite intrusions, Mazury Complex, north-eastern Poland, range from pristine magmatic types to hydrothermally altered varieties. The unaltered phase is perrierite-(Ce), with the uncommon feature of having Al dominant in the C site. Hydrothermal alteration of the perrierite-(Ce) followed two main trends: one shows depletion in Ca, Fe, Si, Al and Mg, and increasing Ti contents; the other shows increases in Si, Ti and Ca and decreases in light rare-earth elements (LREE), Y and Mg, at about constant Fe content. The second trend resulted in the formation of a phase compositionally similar to titanite. Result of chemical analyses show that the transition from perrierite-(Ce) to the titanite-like phase is sharp; an electron back-scatter diffraction (EBSD) study shows the titanite- like material to be amorphous. The hydrothermal alteration of a chevkinite-group mineral to titanite has commonly been reported in natural sequences but this is the first record of the identification of a titanite-like phase made on the basis of a structural analysis.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-022-00772-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4788852","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}