Ontong Java Plateau

{{Infobox rockunit

| name = Ontong Java Plateau

| image =

| caption =

| type = Igneous

| age = Cretaceous {{fossil range|125|90}}

| period = Cretaceous

| prilithology = Basalt

| otherlithology =

| namedfor = Ontong Java Atoll

| namedby =

| region = South Pacific Ocean

| country =

| coordinates = {{Coord|3|03|S|160|23|E|source:kolossus-ruwiki|display=ti}}

| unitof =

| subunits =

| underlies =

| overlies =

| thickness =

| extent =

| area ={{Convert|1.5|e6km2|sqmi|abbr=unit}}

| map ={{Location map

|Pacific Ocean

|relief=1

|label=Ontong Java Plateau

|lon_dir=E

|lat_dir=S

|lat_deg=3

|lat_min=3

|lon_deg=160

|lon_min=23

|position=right

|width=300

|float=right

|mark=Cercle rouge 100%.svg

|marksize=20

|caption=Location of the Ontong Java Plateau in the Pacific Ocean

}}

| map_caption =

}}

The Ontong Java Plateau (OJP) is a massive oceanic plateau located in the southwestern Pacific Ocean, north of the Solomon Islands.

The OJP was formed around {{mya|116}} (Ma),{{Harvnb|Davidson|Koppers|Sano|Hanyu|2023|loc=Sections:Editor's summary, Abstract}} with a much smaller volcanic event around 90 Ma. Two other southwestern Pacific plateaus, Manihiki and Hikurangi, now separated from the OJP by Cretaceous oceanic basins, are of similar age and composition and probably formed as a single plateau and a contiguous large igneous province together with the OJP.{{Cite journal | last = Taylor | first = B.| title = The single largest oceanic plateau: Ontong Java–Manihiki–Hikurangi| year = 2006 | journal = Earth and Planetary Science Letters | volume = 241 | issue = 3–4 | pages = 372–380 | url = http://www.largeigneousprovinces.org/sites/default/files/06TaylorOJMHP.pdf | access-date = 28 July 2019| doi = 10.1016/j.epsl.2005.11.049 | bibcode = 2006E&PSL.241..372T }}

When eruption of lava had finished, the Ontong Java–Manihiki–Hikurangi plateau covered 1% of Earth's surface and represented a volume of {{Convert|80|e6km3|e6cumi|abbr=unit}} of basaltic magma.{{Harvnb|Rizo|2016}}

This "Ontong Java event", first proposed in 1991, represents the largest volcanic event of the past 200 million years, with a magma eruption rate estimated at up to {{Convert|22|km3|abbr=on}} per year over 3 million years, for a total several times larger than the Deccan Traps.{{Harvnb|Tarduno|Mayer|Winterer|Sliter|1991|p=401}}

The smooth surface of the OJP is punctuated by seamounts such as the Ontong Java Atoll, one of the largest atolls in the world.{{Harvnb|Neal|Mahoney|Kroenke|Duncan|1997|loc=Physical features and gross structure of the OJP, pp. 184–187}}{{Citation|last1=Neal|first1=Clive R.|title=The Ontong Java Plateau|date=2013-03-18|work=Large Igneous Provinces: Continental, Oceanic, and Planetary Flood Volcanism|pages=183–216|publisher=American Geophysical Union|isbn=978-1-118-66434-6|last2=Mahoney|first2=John J.|last3=Kroenke|first3=Loren W.|last4=Duncan|first4=Robert A.|last5=Petterson|first5=Michael G.|doi=10.1029/gm100p0183}}

Geological setting

The OJP covers {{Convert|1.5|e6km2|sqmi|abbr=unit}}, roughly the size of Alaska. It reaches up to {{Convert|1700|m|abbr=on}} below sea level but has an average depth closer to {{Convert|2000|-|3000|m|abbr=on}}. It is bounded by Lyra Basin to the northwest, East Mariana Basin to the north, Nauru Basin to the northeast, and the Ellice Basin to the southeast. The OJP has collided with the Solomon Islands island arc and now lies on the inactive Vitiaz Trench and the Pacific–Australian plate boundary.

The high plateau, with a crustal thickness estimated to at least {{Convert|25|km|abbr=on}} but probably closer to {{Convert|36|km|abbr=on}},{{Harvnb|Davidson|Koppers|Sano|Hanyu|2023|loc=Sections:Supplementary Text:Sampled stratigraphy}} has a volume of more than {{Convert|5|e6km3|e6cumi|abbr=unit}}. The maximum extent of the event can, however, be much larger since lavas in several surrounding basins are closely related to the OJP event and probably represent dike swarms associated with the formation of the OJP. These swarms or eruptions involved the Ontong Java-Manihiki-Hikurangi plateaus.

File:Map showing the location of oceanic plateaus (in green) in the Australia-New Zealand region of the South Pacific.svg and Hikurangi plateaus.]]

The OJP basaltic basement is four tholeiitic magma series called the Kwaimbaita, Kroenke, Singgalo, and Wairahito.{{Harvnb|Davidson|Koppers|Sano|Hanyu|2023|loc=Sections:Supplementary Text:Geochemistry of dredge samples}} All except the Singgalo are isotopically identical so they are likely from the same mantle source. It can be assumed that the Singgalo basalts have a different mantle source to the rest. The Kwaimbaita basalts are dominant and in stratigraphic series the oldest.{{Harvnb|Davidson|Koppers|Sano|Hanyu|2023|loc=Sections:Supplementary Material:Figure S5}}

Tectonic evolution

OJP formed quickly over a mantle plume head, most likely the then newly formed Louisville hotspot, followed by limited volcanism for at least 30 million years. The extant seamounts of the Louisville Ridge started to form 70 Ma and have a different isotopic composition, and therefore a shift in intensity and magma supply in the plume must have occurred before that.{{Harvnb|Mahoney|Storey|Duncan|Spencer|1993|loc=Abstract}}

The early, short-duration eruptions of OJP were thought to coincide with the global Early Aptian oceanic anoxic event (known as OAE1a or the Selli Event, 125.0–124.6 Ma) that led to the deposition of black shales during the interval 124–122 Ma. However, dating of the basalts to between 117 and 108 Ma makes this unlikely. There are still unresolved dates by two other research groups that are 4 Ma older so the potential association is not totally eliminated,{{Harvnb|Davidson|Koppers|Sano|Hanyu|2023|loc=Sections:Supplementary Text:Non-groundmass OJP literature ages}} but all OJP lavas are normally magnetized so are presumably dated after the Cretaceous Normal Superchron (C34, CNS) began at 120.964 Ma{{Cite journal

|title=Geomagnetic Polarity Time Scale

|doi=10.1016/B978-0-12-824360-2.00005-X

|url=https://www.researchgate.net/publication/347655685

|last1=Ogg

|first1=J. G.

|journal=Geologic Time Scale 2020

|year=2020

|volume=1

|pages=159–192

|isbn=9780128243602

}} Additionally, isotopic records of seawater in sediments have been associated with the 90 Ma OJP submarine eruptions.{{Harvnb|Tejada|Suzuki|Kuroda|Coccioni|2009|loc=Abstract; Introduction, pp. 855–856}}

About 80% of the OJP is being subducted beneath the Solomon Islands. Only the uppermost {{cvt|7|km}} of the crust is preserved on the Australian Plate.{{Harvnb|Mann|Taira|2004|loc=Abstract}}

This collision has lifted some of the OJP between {{Convert|200|and(-)|2000|m|abbr=on}} above sea level. The construction of Pliocene stratovolcanoes in the western end of the convergence zone has resulted in the New Georgia Islands ({{Convert|1768|m|abbr=on|disp=comma}}) and Bougainville Island ({{Convert|2743|m|abbr=on|disp=comma}}). Shortening, uplift, and erosion of the northern Melanesian arc and the Malaita accretionary prism at deep levels has produced Guadalcanal ({{Convert|2447|m|abbr=on|disp=comma}}), Makira ({{Convert|1250|m|abbr=on|disp=comma}}), and Malaita ({{Convert|1251|m|abbr=on|disp=comma}}).{{Harvnb|Mann|Taira|2004|loc=Erosional levels of rocks in the Solomon Islands, p. 166}}

References

=Notes=

=Sources=

{{Cite book

| last1 = Mahoney | first1 = J. J.

| last2 = Storey | first2 = M.

| last3 = Duncan | first3 = R. A.

| last4 = Spencer | first4 = K. J.

| last5 = Pringle | first5 = M.

| chapter = Geochemistry and age of the Ontong Java Plateau | pages = 233–261

| title = The Mesozoic Pacific: geology, tectonics, and volcanism

| publisher = Washington DC American Geophysical Union Geophysical Monograph Series

| year = 1993 | series = Geophys. Monogr. Ser. | volume = 77 | location = Washington, D. C.

| chapter-url = http://www.mantleplumes.org/WebDocuments/Mahoney93_GeoMon77.pdf | access-date = 17 December 2016

| doi = 10.1029/GM077p0233 | bibcode = 1993GMS....77..233M | isbn = 978-0-87590-036-0

}}

{{Cite journal

| last1 = Mann | first1 = P.

| last2 = Taira | first2 = A.

| title = Global tectonic significance of the Solomon Islands and Ontong Java Plateau convergent zone

| url = https://www.researchgate.net/publication/223180444 | access-date = 18 December 2016

| doi = 10.1016/j.tecto.2003.10.024 | bibcode = 2004Tectp.389..137M}}

{{Cite book | last1 = Neal | first1 = C. R. | last2 = Mahoney | first2 = J. J. | last3 = Kroenke | first3 = L. W. | last4 = Duncan | first4 = R. A. | last5 = Petterson | first5 = M. G. | chapter = The Ontong Java Plateau | pages = 183–216 | title = Large Igneous Provinces: Continental, Oceanic, and Planetary Flood Volcanism | publisher = Washington DC American Geophysical Union Geophysical Monograph Series | editor1-last = Mahoney | editor1-first = J. J. | editor2-last = Coffin | editor2-first = F. | year = 1997 | location = Washington D.C. | series = Geophys. Monogr. Ser. | volume = 100 | chapter-url = http://www3.nd.edu/~icpmslab/pdfs/OJP_Paper.pdf | access-date = 17 December 2016 | doi = 10.1029/GM100p0183 | bibcode = 1997GMS...100..183N | url-status = dead | archive-url = https://web.archive.org/web/20170101204714/http://www3.nd.edu/~icpmslab/pdfs/OJP_Paper.pdf | archive-date = 1 January 2017 | isbn = 9781118664346 }}
{{Cite web

| last = Rizo | first = H.

| title = September 2016 LIP of the Month: Phanerozoic Large Igneous Provinces sample remnants of early differentiation events on Earth

| date = September 2016 | publisher = Large Igneous Provinces Commission

| url = http://www.largeigneousprovinces.org/16sep | access-date = 14 April 2017

}}

{{Cite journal

| last1 = Tarduno | first1 = J. A.

| last2 = Mayer | first2 = H.

| last3 = Winterer | first3 = E. L.

| last4 = Sliter | first4 = W. V.

| last5 = Kroenke | first5 = L.

| last6 = Mahoney | first6 = J. J.

| last7 = Leckie | first7 = M.

| last8 = Musgrave | first8 = R.

| last9 = Storey | first9 = M.

| title = Rapid formation of Ontong Java Plateau by Aptian mantle plume volcanism

| url = http://www.mantleplumes.org/WebDocuments/Tarduno91_Science.pdf | access-date = 17 December 2016

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}}

{{Cite journal

| last = Taylor | first = Brian

| title = The single largest oceanic plateau: Ontong Java-Manihiki-Hikurangi

| doi = 10.1016/j.epsl.2005.11.049 | bibcode=2006E&PSL.241..372T }}

{{cite web |date=6 February 2006 |title=February 2006 LIP of the Month |website=Large Igneous Provinces Commission |url=http://www.largeigneousprovinces.org/06feb}}
{{Cite journal

| last1 = Tejada | first1 = M. L. G.

| last2 = Suzuki | first2 = K.

| last3 = Kuroda | first3 = J.

| last4 = Coccioni | first4 = R.

| last5 = Mahoney | first5 = J. J.

| last6 = Ohkouchi | first6 = N.

| last7 = Sakamoto | first7 = T.

| last8 = Tatsumi | first8 = Y.

| title = Ontong Java Plateau eruption as a trigger for the early Aptian oceanic anoxic event

| url = https://www.researchgate.net/publication/240669852 | access-date = 17 December 2016

| doi = 10.1130/G25763A.1 | bibcode = 2009Geo....37..855T}}

{{Cite journal|last1=Davidson|first1=P. C.|last2=Koppers|first2= A. A. P.|last3= Sano|first3= T. |last4= Hanyu |first4= T. |title=A younger and protracted emplacement of the Ontong Java Plateau. |journal=Science |volume=380|pages= 1185–1188 |year=2023|issue=6650 |doi=10.1126/science.ade8666|pmid=37319200 |bibcode=2023Sci...380.1185D |s2cid=259166067 }}