Hydrothermal alumina-rich clays and boehmite on the Gorda Ridge

Journal Article · Thu Sep 01 04:00:00 EDT 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90129-9· OSTI ID:5327414

Howard, K J; Fisk, M R ^[1]

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1. Oregon State Univ., Corvallis (USA)

Hydrothermal alteration of basalt on the northern Gorda Ridge produced an alteration crust up to 1mm thick that can be divided into two layers based on mineralogy. An inner layer next to the basalt surface is an Al-rich interlayered smectite/chlorite similar to high temperature Al-rich clays recovered from the East Pacific Rise, 21{degree}N with minor quartz, zeolite (phillipsite ) and relict plagioclase. An exterior layer of boehmite, AlO(OH) and minor anatase results from severe leaching of the underlying clays. The alteration crust is progressively enriched in Al, Ti, V, and Cr from interior to exterior by residual weathering. The presence of boehmite and absence of a silica-rich phase in the exterior of the crust indicates the hydrothermal fluids were silica undersaturated or silica was maintained in solution by extremely acidic fluids. This constitutes the first reporting of boehmite as a major alteration mineral in a mid-ocean ridge hydrothermal environment.

• OSTI ID: 5327414
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:9; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
152003* -- Geothermal Data & Theory-- Rock-Water-Gas Interactions
58 GEOSCIENCES
580000 -- Geosciences
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
BASALT
CHALCOGENIDES
CHEMISTRY
CHLORITE MINERALS
CLAYS
ENERGY SYSTEMS
FELDSPARS
FLUIDS
GEOCHEMISTRY
GEOTHERMAL FLUIDS
GEOTHERMAL SYSTEMS
HYDROTHERMAL ALTERATION
HYDROTHERMAL SYSTEMS
IGNEOUS ROCKS
MINERALOGY
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PACIFIC OCEAN
QUARTZ
ROCK-FLUID INTERACTIONS
ROCKS
SEAS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
SMECTITE
SURFACE WATERS
VOLCANIC ROCKS