Fe-smectite-glauconite transition in hydrothermal green clays from the Galapagos spreading center

Author(s): Buatier, Martine; Honnorez, Jose; Ehret, Gabrielle
Author Affiliation(s): Primary:
CNRS, Cent. Sédimentol. et Géochim. Surf., Strasbourg, France
Volume Title: Clays and Clay Minerals
Source: Clays and Clay Minerals, 37(6), p.532-541. Publisher: Clay Minerals Society, Clarkson, NY, United States. ISSN: 0009-8604 CODEN: CLCMAB
Note: In English. 34 refs.; illus. incl. 2 tables
Summary: X-ray powder diffraction (XRD) and energy-dispersive X-ray analyses (EDX) of individual clay particles from hydrothermal mounds in the Galapagos spreading center (GSC) (Deep Sea Drilling Project, hole 509B) and high-resolution transmission electron microscopy (HRTEM) of the <2-µm size fraction of these sediments were carried out to document the mineralogy, geochemistry, and evolution of their clay horizons. The hydrothermal clay minerals of the GSC mounds were found to be intercalated with pelagic sediments and occurred as irregular interstratified illite/smectite according to X-ray powder diffraction analyses. On the basis of TEM, HRTEM, and EDX data, two types of clays appeared to coexist; these types differed in morphology, potassium content, and mode of stacking sequence. Lath-shaped particles having regular 10-Å, spacings were identified as glauconite, and filmy or veil-like particles, having curly edges and variable 10-13-Å spacings were identified as Fe-smectite (nontronite and Fe-montmorillonite). The absence of lattice fringes between Fe-smectite and glauconite crystallites was observed by HRTEM in clay aggregates. This structural discontinuity between Fe-smectite and glauconite layers suggests that a dissolution-recrystallization mechanism was responsible for the textural and chemical transition from the filmy Fe-smectite to the lath-like glauconite.
Year of Publication: 1989
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 06 Petrology, Sedimentary; Age; Areal studies; Clay mineralogy; Clay minerals; DSDP Site 509; Deep Sea Drilling Project; EDX data; East Pacific; Equatorial Pacific; Fe-smectite; Galapagos Rift; Glauconite; High-resolution methods; Hydrothermal alteration; IPOD; Illite; Iron minerals; Leg 70; Metasomatism; Mica group; Mixed-layer minerals; Montmorillonite; Nontronite; Pacific Ocean; Sea-floor spreading; Sedimentary petrology; Sheet silicates; Silicates; Smectite; TEM data; X-ray diffraction data
Coordinates: N003521 N003521 W0860753 W0860753
Record ID: 1990024583
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland