TY - JOUR AU - Galliski , Miguel Ángel AU - Márquez-Zavalía, María Florencia AU - Roquet, María Belén PY - 2021/08/02 Y2 - 2024/03/29 TI - The Nb-Ta-U minerals of the María Elena pegmatite, San Luis range, Argentina JF - Revista de la Asociación Geológica Argentina JA - RAGA VL - 78 IS - 3 SE - DO - UR - https://revista.geologica.org.ar/raga/article/view/211 SP - 355-367 AB - <p>The Nb-Ta-U mineral association of the María Elena pegmatite, San Luis range, Argentina is described. The assemblage of columbite-(Mn), kenopyrochlore, plumbopyrochlore and minor plumbomicrolite and kenomicrolite occurs in a rare-element pegmatite of beryl type. Primary, magmatic columbite-(Mn) forms up to 10 cm dark gray crystals covered by thin yellow films in the core-margin association of the pegmatite. Crystals show #Ta variable from 0.12 to 0.14, with TiO<sub>2</sub> contents between 0.54 and 2.18 wt.% and of UO<sub>2 </sub>from 0.01 to 0.89 wt.%. The columbite-(Mn) crystals show minor local replacement by irregular millimetric veinlets and patches of pyrochlore supergroup minerals. Kenopyrochlore, associated with plumbopyrochlore and minor amounts of U-Ca-rich pyrochlore, contains irregular domains, fine cracks and tabular crystals mainly of plumbomicrolite and kenomicrolite. Besides, a second generation of secondary minerals contain yellow uranium-rich kenopyrochlore in fine veinlets that cut across columbite-(Mn). The hydrothermal overprint that reworked the primary phase mobilizing its Nb, Ta and U contents, contained a Pb input from a possibly exogenous source.</p> ER -