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Mineralogy and geochemistry of altered rocks associated with Lemitar carbonatites, central New Mexico, U.S.A.

LITHOS

By:
,
DOI: 10.1016/0024-4937(90)90042-Y

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Abstract

The intrusion of more than 100 Cambrian-Ordovician carbonatite dikes caused minor alteration of Proterozoic granitic and mafic rocks in the Lemitar Mountains, although hematization, carbonatization and fenitization caused extensive alteration locally. Ampibolites within 15-20 m of the carbonatite dike contacts were highly altered by carbonatization. Locally the Lemitar diorite/gabbro adjacent to some carbonatites were altered in a thin, discontinuous zone by sodic-potassic fenitization. The granite at Polvadera Peak was locally altered by potassic fenitization. Most of the altered rocks have been further altered by hematization and carbonatization. The altered rocks show increases in loss on ignition and in one or more the elements Ca, K, Na and Al. Only granitic fenites in the Lemitar Mountains lost silica and some diorite/gabbro fenites gained silica. Petrologic and geochemical studies clearly indicate that the types and degree of alteration differ notably in different rock types. The fenitizing fluids were oxidizing, slightly acidic, high in volatiles (especially CO2) and possibly fairly low in alkali elements. ?? 1990.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Mineralogy and geochemistry of altered rocks associated with Lemitar carbonatites, central New Mexico, U.S.A.
Series title:
LITHOS
DOI:
10.1016/0024-4937(90)90042-Y
Volume
26
Issue:
1-2
Year Published:
1990
Language:
English
Publisher:
Elsevier
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
LITHOS
First page:
99
Last page:
113
Number of Pages:
15