The geology of aluminium phosphates and sulphates of the alunite group minerals: a review

Dill, Harald G.

doi:10.1016/s0012-8252(00)00035-0

Cited by 213 publications

(173 citation statements)

References 81 publications

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“…The association of the crandallite-bearing horizons with three of four prominent K/Al minima could favour the latter explanation, because crandallite was reported to be formed by an interaction of volcanic fallouts with other sediment components (Dill 2001). We cannot clearly distinguish between these two explanations, but both changes in watershed weathering and volcanic fallout could have produced whole-basin key markers.…”

Section: Interpretation Of Key Correlation Horizons In Z3 Unitmentioning

confidence: 90%

“…Actually the knowledge on the position of K/Al minima helped us to focus on proper stratigraphic levels of the sediments in fields or drill cores and identify them. The crandallite-bearing horizons have substantially increased Al, Ca, Sr, Ba and P signals in EDXRF measurement, which corresponds to the formula of Sr-rich crandallite (Dill 2001); it is Ca-Al phosphate with increased Sr and Ba contents. …”

Section: K and Ti Element Signatures And Crandallite-bearing Horizonsmentioning

confidence: 94%

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Regional chemostratigraphic key horizons in the macrofossil-barren siliciclastic lower Miocene lacustrine sediments (Most Basin, Eger Graben, Czech Republic)

Grygar¹,

Mach²

2013

Bull. Geosci.

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Six sediment cores from two of four depocentres in the Most Basin, mostly consisting of macrofossil barren fluviodeltaic and lacustrine sediments of Holešice and Libkovice members of the Most Formation (lower Miocene, Burdigalian) were subjected to chemostratigraphic correlation, based on CEC and EDXRF proxy element analyses. CEC-step, prominent K/Al minima and crandallite-bearing horizons in monotonous lacustrine mudstones of the Libkovice Member provide several local isochronous or nearly isochronous key horizons, which we propose for a basin-scale correlation of the upper Most Basin sediment fill. These key horizons prove a spatially uniform sedimentary environment in a single lake (original area~1,000 km 2 ) during deposition of a considerable part of the siliciclastics overlying the main coal seam that tops the lower basin fill. We propose the CEC-step horizon as a novel boundary between Holešice and Libkovice members, i.e. the conversion of previously formal lithostratigraphic units to members with an isochronous boundary. That boundary together with recent sedimentological studies would assign Břešťany clay to the top of the Holešice Member. The upper boundary of the Libkovice Member could be the sediment coarsening related to a lake level decrease before deposition of Lom coal seam. The study will allow progress in palaeogeographic and palaeoenviromental reconstruction of the lower Miocene in the Most Basin. The proxy analyses (CEC vs Al/Si ratios) allow reliable numeric differentiation between kaolinite-rich, smectite-poor and smectite-rich clay assemblages in Holešice and Libkovice members. The plots of CEC vs Al/Si ratios should be applicable for fingerprinting any other monotonous lacustrine clastics with variable mineralogy of the clay assemblage.•

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Section: Interpretation Of Key Correlation Horizons In Z3 Unitmentioning

confidence: 90%

Section: K and Ti Element Signatures And Crandallite-bearing Horizonsmentioning

confidence: 94%

Regional chemostratigraphic key horizons in the macrofossil-barren siliciclastic lower Miocene lacustrine sediments (Most Basin, Eger Graben, Czech Republic)

Grygar¹,

Mach²

2013

Bull. Geosci.

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“…Samples from pure supergene kaolin deposits contain high Cr and Nb, whereas these elements are very low in hypogene deposits (Dill 2005). Cr only forms soluble species below pH 4-5 depending on the activity of Cr (10 -4 to 10 -6 ) and above pH 13.5 (Dill 2005). Hydrothermal kaolin deposits in which alunite coexists with kaolinite probably 94 B.…”

Section: Geochemical Studiesmentioning

confidence: 99%

Geology and mineralogy of advanced argillic alteration in the Keshe area (Mt. Karkas), Central Iran

Taghipour¹,

Mackizadeh²,

Pourmoghani³

et al. 2008

Central European Geology

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The Keshe area is a part of Cenozoic magmatic belt of Central Iran. Some volcanics in this area underwent hydrothermal alteration including kaolinitization and alunitization. The altered rocks are characterized by an assemblage of alunite, kaolinite and quartz, which is typical in advanced argillic alteration. The mineralogical study suggests that the hydrothermal alteration in this area occurred in a magmatic hydrothermal environment.

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“…The model proposed for their origin suggests the precipitation of APS minerals as a consequence of the dissolution of detrital apatite in low pH environment. In an extensive review, Dill (2001) remarked that the precipitation of these minerals indicates extreme acid and oxidising conditions at shallow depths, and describes that these are common occurrences in different geological settings. This origin was also proposed by Benito et al, (2005) and Galán Abellán et al, (2008) who studied the APS minerals group in palaeosols from the southeastern continental Late Permian of the Iberian Range.…”

Section: Introductionmentioning

confidence: 99%

“…Aluminium phosphate-sulphate (APS) minerals occur in a wide range of geological environments, ranging from superficial weathering through sedimentary, diagenetic, hydrothermal and metamorphic environments, to post-magmatic systems (Dill, 2001). But, APS minerals have been neglected by geologists and geochemists due to their extremely small sizes (< 0.1-10 µm) and their low concentrations, generally less than 0.05 wt % (Gaboreau et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Origen y naturaleza de los minerales fosfato-sulfato alumínicos (APS) asociados a la mineralización de uranio en los red-beds triásicos (Cordillera Ibérica, España)

Marfil

Iglesia

Estupiñán³

2013

Estud. geol.

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Origin and nature of the aluminium phosphate-sulfate minerals (APS) associated with uranium mineralization in triassic red-beds (Iberian Range, Spain) Origen y naturaleza de los minerales fosfato-sulfato alumínicos (APS) asociados a la mineralización de uranio en los red-beds triásicos (Cordillera Ibérica, España) R. Marfil 1 , A. La Iglesia 2 , J. Estupiñan 3 ABSTRACT This study focuses on the mineralogical and chemical study of an Aluminium-phosphate-sulphate (APS) mineralization that occurs in a clastic sequence from the Triassic (Buntsandstein) of the Iberian Range. The deposit is constituted by sandstones, mudstones, and conglomerates with arenaceous matrix, which were deposited in fluvial to shallow-marine environments. In addition to APS minerals, the following diagenetic minerals are present in the clastic sequence: quartz, K-feldspar, kaolinite group minerals, illite, Fe-oxides-hidroxides, carbonate-sulphate cement-replacements and secondary uraniferous minerals. APS minerals were identified and characterized by optical microscopy, X-ray diffraction, scanning electron microscopy, and electron microprobe. Microcrystalline APS crystals occur replacing uraniferous minerals, associated with kaolinite, mica and filling pores, in distal fluvial-to-tidal arkoses-subarkoses. Given their Ca, Sr, and Ba contents, the APS minerals can be defined as a solid solution of crandallite-goyacite-gorceixite (0.53 Ca, 0.46 Sr and 0.01 Ba). The chemical composition, low LREE concentration and Sr > S suggest that the APS mineral were originated during the supergene alteration of the Buntsandstein sandstones due to the presence of the mineralizing fluids which causes the development of Ubearing sandstones in a distal alteration area precipitating from partially dissolved and altered detrital minerals. Besides, the occurrence of dickite associated with APS minerals indicates they were precipitated at diagenetic temperatures (higher than 80ºC), related to the uplifting occurred during the late Cretaceous post-rift thermal stage.Keywords: APS minerals, U-bearing sandstones, Diagenesis, Triassic Buntsandstein, Iberian Range, Spain. RESUMENEste estudio se centra en el estudio mineralógico y químico de una mineralización de fosfato de aluminio y sulfato (APS) que se produce en una secuencia clástica del Triásico (Buntsandstein) de la Cordillera Ibérica. El depósito está constituido por areniscas, lutitas y conglomerados con matriz arenosa, que fueron depositados en ambientes de fluvial a marino somero. Además de los minerals APS, los minerales diagenéticos siguientes están presentes en la secuencia clástica: cuarzo, feldespato potásico, minerales del grupo de la caolinita, illita, óxidos-hidróxidos de Fe, cemento sulfatado-carbonatado de sustitución y minerales secundarios uraníferos. Los minerales APS fueron identificados y caracterizados por microscopía óptica, difracción de rayos X, microscopía electrónica de barrido, y microsonda electrónica. Los microcristales APS reemplazan a minerales uraníferos, asociados con caolinita, ...

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The geology of aluminium phosphates and sulphates of the alunite group minerals: a review

Cited by 213 publications

References 81 publications

Regional chemostratigraphic key horizons in the macrofossil-barren siliciclastic lower Miocene lacustrine sediments (Most Basin, Eger Graben, Czech Republic)

Regional chemostratigraphic key horizons in the macrofossil-barren siliciclastic lower Miocene lacustrine sediments (Most Basin, Eger Graben, Czech Republic)

Geology and mineralogy of advanced argillic alteration in the Keshe area (Mt. Karkas), Central Iran

Origen y naturaleza de los minerales fosfato-sulfato alumínicos (APS) asociados a la mineralización de uranio en los red-beds triásicos (Cordillera Ibérica, España)

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