Coexisting nanoscale phases of K-illite, NH4,K-illite and NH4-illite-smectite: an organic nitrogen contribution in the hydrothermal system of Harghita Bai, East Carpathians, Romania (vol 54, pg 27, 2019)

• Tipo: Outras Publicações
• Data: 2019

Autores

Bobos, I (Autor) FCUP

Outras Informações

ID Authenticus: P-00Q-FH6

DOI: 10.1180/clm.2019.16

Abstract (EN): Nitrogen influx was identified in the Harghita Bãi area where the mechanism of NH 4 + -fixation in illitic clays is relevant for the N-input budget estimation. The nanotextural features of K-illite (K-I), NH 4, K-I, and NH 4 -ilite-smectite (NH 4 -I-S) mixed-layer found in argillic altered andesitic rocks from the hydrothermal area of Harghita Bãi (East Carpathians) were studied by X-ray diffraction, infrared spectroscopy and transmission-and analytic electron microscopy (TEM-AEM). TEM micrographs of undisturbed argillized altered andesite rocks exhibit a texture constituted of chaotic intergrowths of randomly oriented and curved illitic packets with abundant pore spaces and high porosity between packets. TEM image of K-I and NH 4 ,K-I intergrown show subparallel packets with clear contact, exhibiting a diffuse contrast across layers. The thickness of K-I and NH 4, K-I packets range from 150 to 500 Å and 1M d and 1M polytype were identified by selected area electron diffraction (SAED) patterns. Crystal chemistry of K-I, NH 4 ,K-I and NH 4 -I-S was carried out by AEM. A third interlayer cation Na + beside K + was measured in several NH 4 ,K-I packets. The NH 4, Na,K-I packets interleaved with NH 4, K-I or NH 4 -I-S (12 %S) packets were also identified by TEM. The thickness of NH 4, Na,K-I packets ranges from 300 to 1200 Å, with abundant lenses and lenticular layer separation along the boundaries between NH 4, Na,K-I packets. The 1M d polytype dominates the NH 4, Na,K-I packets. Straight and parallel packets, continuous 00l layers and collapsed swelling layers at the boundary of individual NH 4 -I (5 %S) packets with thickness ranging from 20 to 95 Å were observed. The nanotextural observations appointed for a direct crystallization of NH 4 -I crystals within a NH 4 -I-S series from a pore fluid, where NH 4 -I packets occupy void spaces previously occupied by fluids. © 2019 Informa UK Limited, trading as Taylor & Francis Group.

Idioma: Inglês

Tipo (Avaliação Docente): Científica