Academic Journal
Na-Bearing white micas from Triassic rocks of the transition between the Maláguide and alpujárride complexes (Betic Cordiellera, Spain)
| العنوان: | Na-Bearing white micas from Triassic rocks of the transition between the Maláguide and alpujárride complexes (Betic Cordiellera, Spain) |
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| المؤلفون: | Ruiz Cruz, Maria Dolores |
| سنة النشر: | 2008 |
| المجموعة: | Universitat Autònoma de Barcelona: Dipòsit Digital de Documents de la UAB |
| مصطلحات موضوعية: | Intermediate Na-Ca mica, Intermediate Na-K mica, Low-grade Metamorphism, Muscovite, Paragonite |
| الوصف: | The structural significance of micas with Na-K intermediate composition, and their chemical and structural evolution at increasing metamorphic grade have been investigated in Triassic rocks from the transition between the Maláguide and Alpujárride complexes (Internal zones of the Betic Cordillera, Spain). Micas were studied by X-ray diffraction (XRD) and by scanning and transmission electron microscopy (SEM/TEM). Three samples, belonging to the late diagenesis and to the low and medium anchizone, were selected for this study. Na-bearing mica appears as submicroscopic packets intergrown in parallel with K-mica, becoming more compositionally uniform with increasing grade. The diagenetic sample contains illite, minor paragonite, and two main populations of intermediate Na-K micas, with average compositions MsPrg and MsPrg, respectively, where Ms represents muscovite and Prg, paragonite. The lattice-fringe images of mica packets with intermediate compositions suggest the presence of random mixed-layered paragonite-muscovite. Under low anchizonal conditions the amount of discrete paragonite increases and the Na-K intermediate mica has a mean composition of MsPrg. The TEM images suggest that the packets with intermediate composition are solid solutions of paragonite and illite. Micas with Na-K intermediate composition are lacking in the sample with the highest metamorphic grade. In this sample, paragonite and muscovite coexist with mica, with composition intermediate between paragonite and margarite. The lattice-fringe images of these Na-Ca-bearing packets suggest that they consist of irregularly shaped domains enriched either in Na or in Ca. Our data indicate that NaK-bearing micas have several origins: detrital stacks of K- and Na-bearing micas coexist with authigenic phases, formed from dickite in the diagenetic, coarse-grained samples, and perhaps from smectite-bearing mixed-layers or detrital illite, in the fine-grained rocks. The changes observed at increasing metamorphic grade can be related to the influence ... |
| نوع الوثيقة: | article in journal/newspaper |
| وصف الملف: | application/pdf |
| اللغة: | English |
| ردمك: | 978-4-9549106-8-4 4-9549106-8-4 |
| تدمد: | 15528367 |
| Relation: | Ministerio de Educación y Ciencia CGL2006-02481; Clays and Clay Minerals; Vol. 56, Núm. 3 (2008), p. 344-358; https://ddd.uab.cat/record/224533; urn:10.1346/CCMN.2008.0560305; urn:oai:ddd.uab.cat:224533; urn:scopus_id:49549106845; urn:articleid:15528367v56n3p344; urn:wos_id:000258023600005 |
| الاتاحة: | https://ddd.uab.cat/record/224533 |
| Rights: | restricted access ; Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permÃs del(s) titular(s) de drets. ; https://rightsstatements.org/vocab/InC/1.0/ |
| رقم الانضمام: | edsbas.81F9DD5C |
| قاعدة البيانات: | BASE |
| ردمك: | 9784954910684 4954910684 |
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| تدمد: | 15528367 |