Space-time relations of hydrothermal sulfide-sulfate-silica deposits at the northern Cleft Segment, Juan de Fuca Ridge

Conference · Thu Apr 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5067396

Koski, R A; Smith, V K ^[1]; Embley, R W ^[2]; Jonasson, I R ^[3]; Kadko, D C ^[4]

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1. Geological Survey, Menlo Park, CA (United States)
2. PMEL/NOAA, Newport, OR (United States)
3. Geological Survey of Canada, Ottawa, Ontario (Canada)
4. Univ. of Miami, FL (United States). Rosenstiel School of Marine and Atmospheric Science

Submersible investigations along the northern Cleft Segment of the Juan de Fuca Ridge indicate that a newly erupted sheet flow and two recent megaplume events are spatially related to a NNE-trending fissure system that is now the locus for active hydrothermal venting and deposition of massive sulfide mounds and chimneys. Samples from active high-temperature vent sites located east and north of the sheet flow terrain include zoned Cu-sulfide-rich chimneys (Type 1), bulbous anhydrite-rich chimneys (Type 2), and columnar Zn-sulfide-rich chimneys (Type 3). Type 1 chimneys with large open channelways result from the focused discharge of fluid at temperatures between 310 and 328 C from the Monolith sulfide mound. Type 2 chimneys are constructed on the Monolith and Fountain mounds where discharge of fluid at temperatures between 293 and 315 C is diffuse and sluggish. Type 3 chimneys, characterized by twisting narrow channelways, are deposited from focused and relatively low-temperature fluid discharging directly from basalt substrate. Inactive sulfide chimneys (Type 4) located within 100 m of the fissure system have bulk compositions, mineral assemblages, colloform and bacteroidal textures, and oxygen isotope characteristics consistent with low-temperature (< 250 C ) deposition from less robust vents. Field relations and [sup 210]Pb ages (> 100 years) indicate that the Type 4 chimneys formed prior to the sheet flow eruption. The sulfide mounds and Type 1 and Type 2 chimneys at the Monolith and Fountain vents, however, are an expression of the same magmatic event that caused the sheet flow eruption and megaplume events.

• OSTI ID: 5067396
• Report Number(s): CONF-9305259-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
58 GEOSCIENCES
GEOLOGIC DEPOSITS
GEOCHEMISTRY
HYDROTHERMAL SYNTHESIS
ISOTOPE DATING
PACIFIC OCEAN
SULFIDE MINERALS
FUMAROLES
GEOLOGIC FISSURES
GEOLOGIC STRUCTURES
HYDROTHERMAL SYSTEMS
OREGON
WASHINGTON
AGE ESTIMATION
CHEMISTRY
DEVELOPED COUNTRIES
ENERGY SYSTEMS
GEOTHERMAL SYSTEMS
MINERALS
NORTH AMERICA
SEAS
SURFACE WATERS
SYNTHESIS
USA
152002* - Geothermal Data &amp; Theory- Properties of Minerals &amp; Rocks
580000 - Geosciences