East Mariana Basin tholeiites; Cretaceous intraplate basalts or rift basalts related to the Ontong Java plume?

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doi: 10.1016/0012-821X(94)90263-1
Author(s): Castillo, P. R.; Pringle, M. S.; Carlson, R. W.
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, La Jolla, CA, United States
Other:
U. S. Geological Survey, Menlo Park, CA, United States
Carnegie Institution of Washington, Washington, D.C., United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 123(1-4), p.139-154. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 49 refs.; illus. incl. 2 tables, sketch map
Summary: Studies of seafloor magnetic anomaly patterns suggest the presence of Jurassic oceanic crust in a large area in the western Pacific that includes the East Mariana, Nauru and Pigafetta Basins. Sampling of the igneous crust in this area by the Deep Sea Drilling Program (DSDP) and the Ocean Drilling Program (ODP) allows direct evaluation of the age and petrogenesis of this crust. ODP Leg 129 drilled a 51 m sequence of basalt pillows and massive flows in the central East Mariana Basin. 40Ar/39Ar ages determined in this study for two Leg 129 basalts average 114.6±3.2 Ma. This age is in agreement with the Albian-late Aptian paleontologic age of the overlying sediments, but is distinctively younger than the Jurassic age predicted by magnetic anomaly patterns in the basin. Compositionally, the East Mariana Basin basalts are uniformly low-K tholeiites that are depleted in highly incompatible elements compared to moderately incompatible ones, which is typical of mid-ocean ridge basalts (MORB) erupted near hotspots. The Sr, Nd and Pb isotopic compositions of the tholeiites (87Sr/86Srinit=0.70360-0.70374; 143Nd/144Ndinit=0.512769-0.512790; 206Pb/204Pbmeas=18.355-18.386) also overlap with some Indian Ocean Ridge MORB, although they are distinct from the isotopic compositions of Jurassic basalts drilled in the Pigafetta Basin, the oldest Pacific MORB. The isotopic compositions of the East Mariana Basin tholeiites are also similar to those of intraplate basalts, and in particular, to the isotopic signature of basalts from the nearby Ontong Java and Manihiki Plateaus. The East Mariana Basin tholeiites also share many petrologic and isotopic characteristics with the oceanic basement drilled in the Nauru Basin at DSDP Site 462. In addition, the new 110.8±1.0 Ma 40Ar/39Ar age for two flows from the bottom of Site 462 in the Nauru Basin is indistinguishable from the age of the East Mariana Basin flows. Thus, while magnetic anomaly patterns predict that the igneous basement in the Nauru and East Mariana Basins is Jurassic in age, the geochemical and chronological results discussed here suggest that the basement formed during a Cretaceous rifting event within the Jurassic crust. This magmatic and tectonic event was created by the widespread volcanism responsible for the genesis of the large oceanic plateaus of the western Pacific.
Year of Publication: 1994
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 03 Geochronology; 05 Petrology, Igneous and Metamorphic; Absolute age; Alkaline earth metals; Ar/Ar; Basalts; Cretaceous; Crust; DSDP Site 462; Dates; Deep Sea Drilling Project; Equatorial Pacific; Geochemistry; IPOD; Igneous rocks; Intraplate processes; Isotope ratios; Isotopes; Lava; Lead; Leg 129; Leg 61; Leg 89; Lithogeochemistry; Magnetic anomalies; Major elements; Mantle; Mantle plumes; Mariana Trough; Mesozoic; Metals; Nauru Basin; Nd-144/Nd-143; Neodymium; North Pacific; Northwest Pacific; ODP Site 802; Ocean Drilling Program; Oceanic crust; Ontong Java Plateau; Pacific Ocean; Pb-206/Pb-204; Pillow lava; Plate tectonics; Radioactive isotopes; Rare earths; Rifting; Sr-87/Sr-86; Stable isotopes; Strontium; Tholeiite; Trace elements; Volcanic rocks; West Pacific
Coordinates: N120546 N120547 E1531238 E1531237
N071415 N071415 E1650150 E1650150
Record ID: 1994037718
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands