Chemical composition of basement fluids within an oceanic ridge flank: Implications for along-strike and across-strike hydrothermal circulation

Autor: Michael J. Mottl, C. Geoffrey Wheat, Henry Elderfield, Christophe Monnin
Přispěvatelé: Global Undersea Research Unit, University of Alaska [Anchorage], Department of Earth Sciences [Cambridge, UK], University of Cambridge [UK] (CAM), department of oceanography, University of Hawai‘i [Mānoa] (UHM), Laboratoire des Mécanismes et Transfert en Géologie (LMTG), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2000
Předmět:
Atmospheric Science
010504 meteorology & atmospheric sciences
Outcrop
[SDE.MCG]Environmental Sciences/Global Changes
Geochemistry
Soil Science
Aquatic Science
010502 geochemistry & geophysics
Oceanography
01 natural sciences
Socle
Geochemistry and Petrology
Oceanic crust
Marine Geology and Geophysics: Midocean ridge processes
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry
Earth and Planetary Sciences (miscellaneous)
Transect
Marine Geology and Geophysics: Heat flow (benthic) and hydrothermal processes
Geomorphology
0105 earth and related environmental sciences
Earth-Surface Processes
Water Science and Technology
Basalt
geography
geography.geographical_feature_category
Ecology
Oceanography: Biological and Chemical: Geochemistry
Paleontology
Drilling
Forestry
Mid-ocean ridge
Seafloor spreading
Geophysics
Space and Planetary Science
Geochemistry: Low-temperature geochemistry
Geology
Zdroj: Journal of Geophysical Research
Journal of Geophysical Research, American Geophysical Union, 2000, 105, pp.13437-13448. ⟨10.1029/2000JB900070⟩
Journal of Geophysical Research, 2000, 105, pp.13437-13448. ⟨10.1029/2000JB900070⟩
ISSN: 0148-0227
2156-2202
DOI: 10.1029/2000JB900070⟩
Popis: International audience; Compositions of basement fluids are presented for four sites along a 3.5-m.y.-old, partly buried basement ridge on the eastern flank of the Juan de Fuca Ridge. This ridge is roughly parallel to the active ridge axis of the Endeavor Segment ~100 km to the west. From south to north these sites are Baby Bare Outcrop, Ocean Drilling Program (ODP) Site 1026, and the southern and northern sides of Mama Bare Outcrop. The composition of basement fluids is determined or estimated from analyses of pore water samples that were extracted from sediments at each of these sites, spring waters from Baby Bare, and basement fluids that vented from the open ODP Hole 1026B. Chemical trends in basement fluids along this transect show increasing alteration from south to north. A similar trend was observed along an ODP transect perpendicular to the ridge axis with increasing fluid alteration from west to east. Much of the increase in fluid alteration along the ODP transect is explained by greater water-rock exchange with increasing basement temperature to the east. In contrast, the trend along the 3.5-m.y.-old ridge is best explained by diffusive exchange with the overlying sediment. The rate of this exchange is used to constrain hydrologic properties within basaltic basement. Flow within the 3.5-m.y.-old ridge is inferred to occur from south to north and lacks significant exchange with basement fluids from the active ridge crest to the west. Thus the two flow systems are hydrologically distinct, and flow paths are likely influenced by the complex distribution of permeability in basement, the pattern of seafloor morphology, and the type and rate of sedimentation.
Databáze: OpenAIRE
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