Details
| Originalsprache | Englisch |
|---|---|
| Aufsatznummer | Q07O09 |
| Fachzeitschrift | Geochemistry, Geophysics, Geosystems |
| Jahrgang | 9 |
| Ausgabenummer | 7 |
| Publikationsstatus | Veröffentlicht - Juli 2008 |
Abstract
The Ocean Drilling Program (ODP)/Integrated Ocean Drilling Program (IODP) three-leg campaign at Site 1256 (Leg 206, Expeditions 309 and 312) provides the first continuous in situ sampling of fast spread ocean crust from the extrusive lavas, through the sheeted dikes, and down into the uppermost gabbros (Cocos plate; East Pacific Rise; eastern equatorial Pacific). The lowest ∼60 m of the dikes above the gabbros were transformed to "granoblastic dikes" through a metamorphic overprint characterized by two-pyroxene domains formed under granulite-facies conditions. Equilibrium temperatures estimated by the two-pyroxene thermometer range between 930°C and 1050°C, implying that conditions within the granoblastic zone were appropriate for hydrous anatexis, with the potential to generate partial melts of trondhjemitic composition. The downhole evolution of the granoblastic overprint is expressed by systematic changes in texture, phase composition, and calculated equilibrium temperature, consistent with thermal metamorphism by a deeper heat source. Thermal modeling implies a long-lasting heat source located beneath the granoblastic dikes, providing thermal energy over several thousands of years. The most likely such source is a steady state, highlevel axial magma chamber (AMC) located at the base of the sheeted dike section.We interpret the interval of granoblastic dikes as part of a dynamic conductive boundary overlying the AMC.
ASJC Scopus Sachgebiete
- Erdkunde und Planetologie (insg.)
- Geophysik
- Erdkunde und Planetologie (insg.)
- Geochemie und Petrologie
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in: Geochemistry, Geophysics, Geosystems, Jahrgang 9, Nr. 7, Q07O09, 07.2008.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - Petrography of the dike-gabbro transition at IODP Site 1256 (equatorial Pacific)
T2 - The evolution of the granoblastic dikes
AU - Koepke, Jürgen
AU - Christie, D. M.
AU - Dziony, Wanja
AU - Holtz, Francois
AU - Lattard, Dominique
AU - MacLennan, J.
AU - Park, Sunah
AU - Scheibner, B.
AU - Yamasaki, T.
AU - Yamazaki, S.
N1 - Copyright: Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2008/7
Y1 - 2008/7
N2 - The Ocean Drilling Program (ODP)/Integrated Ocean Drilling Program (IODP) three-leg campaign at Site 1256 (Leg 206, Expeditions 309 and 312) provides the first continuous in situ sampling of fast spread ocean crust from the extrusive lavas, through the sheeted dikes, and down into the uppermost gabbros (Cocos plate; East Pacific Rise; eastern equatorial Pacific). The lowest ∼60 m of the dikes above the gabbros were transformed to "granoblastic dikes" through a metamorphic overprint characterized by two-pyroxene domains formed under granulite-facies conditions. Equilibrium temperatures estimated by the two-pyroxene thermometer range between 930°C and 1050°C, implying that conditions within the granoblastic zone were appropriate for hydrous anatexis, with the potential to generate partial melts of trondhjemitic composition. The downhole evolution of the granoblastic overprint is expressed by systematic changes in texture, phase composition, and calculated equilibrium temperature, consistent with thermal metamorphism by a deeper heat source. Thermal modeling implies a long-lasting heat source located beneath the granoblastic dikes, providing thermal energy over several thousands of years. The most likely such source is a steady state, highlevel axial magma chamber (AMC) located at the base of the sheeted dike section.We interpret the interval of granoblastic dikes as part of a dynamic conductive boundary overlying the AMC.
AB - The Ocean Drilling Program (ODP)/Integrated Ocean Drilling Program (IODP) three-leg campaign at Site 1256 (Leg 206, Expeditions 309 and 312) provides the first continuous in situ sampling of fast spread ocean crust from the extrusive lavas, through the sheeted dikes, and down into the uppermost gabbros (Cocos plate; East Pacific Rise; eastern equatorial Pacific). The lowest ∼60 m of the dikes above the gabbros were transformed to "granoblastic dikes" through a metamorphic overprint characterized by two-pyroxene domains formed under granulite-facies conditions. Equilibrium temperatures estimated by the two-pyroxene thermometer range between 930°C and 1050°C, implying that conditions within the granoblastic zone were appropriate for hydrous anatexis, with the potential to generate partial melts of trondhjemitic composition. The downhole evolution of the granoblastic overprint is expressed by systematic changes in texture, phase composition, and calculated equilibrium temperature, consistent with thermal metamorphism by a deeper heat source. Thermal modeling implies a long-lasting heat source located beneath the granoblastic dikes, providing thermal energy over several thousands of years. The most likely such source is a steady state, highlevel axial magma chamber (AMC) located at the base of the sheeted dike section.We interpret the interval of granoblastic dikes as part of a dynamic conductive boundary overlying the AMC.
KW - Conductive boundary layer
KW - Geothermometry
KW - IODP drilling
KW - Metamorphic reaction
KW - Mid-ocean ridge
KW - Sheeted dikes
UR - http://www.scopus.com/inward/record.url?scp=72049130480&partnerID=8YFLogxK
U2 - 10.1029/2008GC001939
DO - 10.1029/2008GC001939
M3 - Article
AN - SCOPUS:72049130480
VL - 9
JO - Geochemistry, Geophysics, Geosystems
JF - Geochemistry, Geophysics, Geosystems
SN - 1525-2027
IS - 7
M1 - Q07O09
ER -