Actinide-series disequilibrium as a tool to establish the chronology of deep-sea hydrothermal activity

Conference · Sun Feb 28 23:00:00 EST 1993 · Geochimica et Cosmochimica Acta; (United States)

OSTI ID:6487442

Lalou, C; Reyss, J L; Brichet, E ^[1]

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1. CNRS/CEA, Gif-sur-Yvette (France)

This paper describes the different radiochronological methods used to date geologically recent (i.e., <400,000 years) deep-sea hydrothermal deposits as well as the basic conditions necessary to obtain reliable dates. The limitations of the different techniques also are described. Using measurements of [sup 210]Pb/Pb, [sup 228]Th/[sup 228]Ra, [sup 230]Th/[sup 234]U, [sup 231]Pa/[sup 235]U, and [sup 228]Ra/[sup 226]Ra, the authors have undertaken an exhaustive chronological study of the hydrothermal deposits along the East Pacific Rise, the Mid-Atlantic Ridge, and in some back-arc basins. The objectives of this study were to obtain regional chronologies and to establish a general synthesis on the evolution of the hydrothermal processes at the scale of the mid-oceanic ridge system. Some results obtained by other authors are included in this synthesis. The dependence of the general trends of temporal development of the hydrothermal chimneys, edifices, and fields on their tectonic settings is discussed. This study demonstrates that hydrothermal activity does not represent a regular input of matter to the ocean, and that its pulsed character must be taken into account in all modeling attempts (chemical, biological, and tectonic) affected by hydrothermal processes. In areas of rapid spreading, like the East Pacific Rise, recent and fossil deposits are spatially separated. By contrast, at the slow spreading Mid-Atlantic Ridge, fossil and present activity are found in the same location. 54 refs., 5 figs., 4 tabs.

• OSTI ID: 6487442
• Report Number(s): CONF-911017--
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 57:6; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical &amp; Spectral Procedures
54 ENVIRONMENTAL SCIENCES
540330 -- Environment
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540340 -- Environment
Aquatic-- Thermal Effluents Monitoring &amp; Transport-- (1990-)
ACTINIDE ISO
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ACTINIDES
AGE ESTIMATION
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
ALPHA SPECTROSCOPY
BARITE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MODELS
CARBON 14 DECAY RADIOISOTOPES
CHALCOGENIDES
ELEMENTS
EQUILIBRIUM
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GAMMA SPECTROSCOPY
GEOLOGIC DEPOSITS
HEAVY ION DECAY RADIOISOTOPES
HEAVY NUCLEI
HYDROTHERMAL ALTERATION
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LEAD
LEAD 210
LEAD ISOTOPES
MAGNESIUM 28 DECAY RADIOISOTOPES
MASS SPECTROSCOPY
METALS
MID-ATLANTIC RIDGE
MINERALS
MINUTES LIVING RADIOISOTOPES
NEON 24 DECAY RADIOISOTOPES
NUCLEI
ODD-EVEN NUCLEI
PACIFIC OCEAN
PLATE TECTONICS
PROTACTINIUM 231
PROTACTINIUM ISOTOPES
RADIOISOTOPES
RADIUM 226
RADIUM 228
RADIUM ISOTOPES
SEAS
SPECTROSCOPY
SPONTANEOUS FISSION RADIOISOTOPES
SULFATE MINERALS
SULFIDES
SULFUR COMPOUNDS
SURFACE WATERS
TECTONICS
THORIUM 228
THORIUM 230
THORIUM ISOTOPES
URANIUM 234
URANIUM 235
URANIUM ISOTOPES
YEARS LIVING RADIOISOTOPES