Geochemistry of the oldest Atlantic oceanic crust suggests mantle plume involvement in the early history of the central Atlantic Ocean

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doi: 10.1016/S0012-821X(01)00452-6
Author(s): Janney, Philip E.; Castillo, Paterno R.
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, La Jolla, CA, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 192(3), p.291-302. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 39 refs.; illus., incl. 3 tables, sketch map
Summary: Controversy has surrounded the issue of whether mantle plume activity was responsible for Pangaean continental rifting and massive flood volcanism (resulting in the Central Atlantic Magmatic Province or CAMP, emplaced around 200 Ma) preceding the opening of the central Atlantic Ocean in the Early Mesozoic. Our new Sr-Nd-Pb isotopic and trace element data for the oldest basalts sampled from central Atlantic oceanic crust by deep-sea drilling show that oceanic crust generated from about 160 to 120 Ma displays clear isotopic and chemical signals of plume contamination (e.g., 87Sr/86Sri=0.7032-0.7036, εNd(t)=+6.2 to +8.2, incompatible element patterns with positive Nb anomalies), but these signals are muted or absent in crust generated between 120 and 80 Ma, which resembles young Atlantic normal mid-ocean ridge basalt. The plume-affected pre-120 Ma Atlantic crustal basalts are isotopically similar to lavas from the Ontong Java Plateau, and may represent one isotopic end-member for CAMP basalts. The strongest plume signature is displayed near the center of CAMP magmatism but the hotspots presently located nearest this location in the mantle reference frame do not appear to be older than latest Cretaceous and are isotopically distinct from the oldest Atlantic crust. The evidence for widespread plume contamination of the nascent Atlantic upper mantle, combined with a lack of evidence for a long-lived volcanic chain associated with this plume, leads us to propose that the enriched signature of early Atlantic crust and possibly the eruption of the CAMP were caused by a relatively short-lived, but large volume plume feature that was not rooted at a mantle boundary layer. Such a phenomenon has been predicted by recent numerical models of mantle circulation. Abstract Copyright (2001) Elsevier, B.V.
Year of Publication: 2001
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; Alkaline earth metals; Atlantic Ocean; Basalts; CAMP; Central Atlantic magmatic province; Crust; DSDP Site 100; DSDP Site 105; DSDP Site 367; DSDP Site 384; DSDP Site 386; DSDP Site 387; DSDP Site 417; DSDP Site 418; DSDP Site 534; DSDP Site 543; Deep Sea Drilling Project; Deep drilling; Drilling; Flood basalts; Geochemistry; IPOD; Igneous rocks; Isotope ratios; Isotopes; Lead; Leg 102; Leg 11; Leg 41; Leg 43; Leg 51; Leg 52; Leg 53; Leg 76; Leg 78A; Lithogeochemistry; Magma contamination; Mantle; Mantle plumes; Metals; Mid-ocean ridge basalts; Nd-144/Nd-143; Neodymium; Ocean Drilling Program; Oceanic crust; Pangaea; Pb-206/Pb-204; Pb-207/Pb-204; Pb-208/Pb-204; Radioactive isotopes; Rare earths; Sr-87/Sr-86; Stable isotopes; Strontium; Trace elements; Volcanic rocks
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Record ID: 2002000929
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands