Large scale isotopic Sr, Nd and O isotopic anatomy of altered oceanic crust; DSDP/ODP sites 417/418

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doi: 10.1016/0012-821X(94)00263-X
Author(s): Staudigel, Hubert; Davies, G. R.; Hart, Stanley R.; Marchant, K. M.; Smith, Brian M.
Author Affiliation(s): Primary:
Vrije Universiteit Amsterdam, Centre for Isotope Geology, Amsterdam, Netherlands
Woods Hole Oceanographic Institution, Woods Hole, MA, United States
Scripps Institution of Oceanography, La Jolla, CA, United States
Lawrence Berkeley Laboratory, Berkeley CA, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 130(1-4), p.169-185. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 58 refs.; illus., incl. 2 tables
Summary: Large-scale compositional domains at DSDP/ODP drill sites 417A, 417D and 418A were analyzed for O, Sr and Nd isotope ratios, and REE, U, K, Rb and Sr abundances, to constrain the bulk chemical composition of the oceanic crust that is recycled at subduction zones. The combination of the three sites gives the composition of the upper oceanic crust in this region over a distance of about 8 km. The δ18OSMOW and 87Sr/86Srmeas of compositional domains 10-100 m in size correlate well, with a range of 7.7-19.2 and 0.70364-0.70744, and mean of 9.96 and 0.70475, respectively. The Rb inventory of the upper crust increases by about an order of magnitude, while Sr contents remain constant. U abundances increase moderately under oxidizing alteration conditions and nearly triple in the commonly reducing alteration environments of the upper oceanic crust. REEs are influenced by alteration only to a small extent, and recycled oceanic crust is similar to MORB with respect to 143Nd/144Nd. Even though the average composition of the upper oceanic crust is well defined, the large scale composition varies widely. Highly altered compositional domains may not have a large impact on the average composition of the oceanic crust, but they may preferentially contribute to fluids or partial melts derived from the crust by prograde metamorphic reactions.
Year of Publication: 1995
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; 07 Marine Geology and Oceanography; Actinides; Alkaline earth metals; Alteration; Atlantic Ocean; C-13/C-12; Carbon; Chemical composition; Composite samples; Crust; DSDP Site 417; DSDP Site 418; Deep Sea Drilling Project; Geochemistry; IPOD; Igneous rocks; Isotope ratios; Isotopes; Lava; Leg 102; Leg 51; Leg 52; Leg 53; Metals; Nd-144/Nd-143; Neodymium; North Atlantic; Northwest Atlantic; O-18/O-16; Ocean Drilling Program; Oceanic crust; Oxygen; Rare earths; Sr-87/Sr-86; Stable isotopes; Strontium; Subduction zones; Thorium; Trace elements; Uranium; Volcanic rocks; Volcaniclastics
Coordinates: N250000 N250000 W0680000 W0680000
N250205 N250207 W0680326 W0680327
Record ID: 1995029196
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands