Southwest Pacific oceanic plateaus and the greater Ontong Java Plateau event; a unique magmatic episode in Earth history?

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Author(s): Neal, C. R.
Author Affiliation(s): Primary:
University of Notre Dame, Civil Engineering & Geological Sciences, Notre Dame, IN, United States
Volume Title: AGU 2011 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2011; American Geophysical Union 2011 fall meeting, San Francisco, CA, Dec. 5-9, 2011. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The Ontong Java Plateau (OJP) in the Southwest Pacific is the world's largest oceanic plateau and the most voluminous LIP on Earth. Recent data from the Hikurangi and Manihiki Plateaus and the Nauru Basin strongly suggest that basement lavas from these areas are related. The implication is that the Great OJP Volcanic Event covered ≈1% of the Earth's surface. Published 40-39 Ar age dates from basement lavas indicate the following: two volcanic LIP events have been recorded from the OJP (ca. 120 and 90 Ma); for the Manihiki Plateau, DSDP Site 317 lavas gave ages of ca. 117 Ma and dredge samples from the R/V Sonne expedition 193 gave ages of ca. 124.5 Ma; dredge samples recovered during R/V Sonne expedition 168 give ages spanning 118-96 Ma for Hikurangi Plateau basement lavas; in the Nauru Basin DSDP Legs 61 and 89 indicate that basaltic basement lavas erupted between 130-110 Ma. To form these different constructs at the same time would require a unique event in Earth's history. The current data are consistent with initiation of volcanism beneath the Manihiki Plateau/Nauru Basin with the main eruptive event focusing on the OJP, before waning and moving to the Hikurangi Plateau. However, there are a number of magmatic events recorded by samples from each location that suggest periodic rejuvenation of the LIP source region. Ages of 90 Ma and ≈60 Ma have been recorded on the OJP by drilling (Site 803) and sampling on the island of Santa Isabel, as well as on the Hikurangi Plateau. OJP-type lavas with ages of ≈90 Ma, ≈60 Ma, and ≈35 Ma have been recovered from the island of San Cristobal. Emplacement of basaltic sills occurred in the Nauru Basin 100-75 Ma. Finally, MORB- and OIB-type lavas have been recovered from the Solomon Islands and from the Hikurangi plateau that appear to be intercalated with OJP-type lavas, but (at least from San Cristobal) these appear to be associated with the ≈60 Ma and ≈35 Ma events. These observations need to be explained in modeling the Greater OJP Volcanic Event and they required tapping of both similar and different sources at discrete periods in geologic time. Both plume and non-plume models are presented to explain such observations along with recommendations for future ocean drilling. Generally, plume models require heterogeneity in the plume source, but also need periodic rejuvenation (combination of thermal and chemical plume models). Non-plume models require a pre-existing relatively fertile upper mantle and periodic stress changes (plate movements). The environmental implications for such a massive, and predominantly subaqueous event are that is was responsible for a radical change in ocean chemistry and was responsible for black shale deposition, known as Oceanic Anoxic Event (OAE) 1A.
Year of Publication: 2011
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 07 Marine Geology and Oceanography; 18 Geophysics, Solid-Earth; DSDP Site 317; Deep Sea Drilling Project; Depositional environment; East Pacific; Equatorial Pacific; Hikurangi Trough; IPOD; Lava; Leg 33; Leg 61; Manihiki Plateau; Mantle; Marine geology; Nauru Basin; North Pacific; Northwest Pacific; Ocean floors; Oceanic anoxic events; Ontong Java Plateau; Pacific Ocean; Plate tectonics; Plumes; South Pacific; Southeast Pacific; Southwest Pacific; Upper mantle; West Pacific
Coordinates: S110006 S110005 W1621546 W1621547
Record ID: 2014045329
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