40Ar/39Ar and K-Ar geochronological age constraints for the inception and early evolution of the Izu-Bonin-Mariana Arc system

Online Access: Get full text
doi: 10.1111/j.1440-1738.1998.00211.x
Author(s): Cosca, Michael A.; Arculus, Richard J.; Pearce, Julian A.; Mitchell, John G.
Author Affiliation(s): Primary:
Universite de Lausanne, Institut de Mineralogie et Petrographie, Lausanne, Switzerland
University of Texas at Dallas, United States
Australian National University, Australia
University of Durham, United Kingdom
University of Newcastle-upon-Tyne, United Kingdom
Volume Title: Izu-Bonin-Mariana Arc system
Volume Author(s): Stern, Robert J., prefacer; Arima, Makoto
Source: Izu-Bonin-Mariana Arc system, prefaced by Robert J. Stern and Makoto Arima. Island Arc, 7(3), p.579-595. Publisher: Wiley Blackwell on behalf of Geological Society of Japan, Tsukuba, Japan. ISSN: 1038-4871
Note: In English. Australian National University, Department of Geology, GEMOC Publ. No. 130. 47 refs.; illus., incl. 3 tables, sketch map
Summary: K-Ar and 40Ar/39Ar dates are presented for locations in the Izu-Bonin-Mariana (IBM) forearc (Ocean Drilling Program (ODP) sites 786 & 782, Chichijima, Deep Sea Drilling Program (DSDP) sites 458 & 459, Saipan), and Palau on the remnant arc of the Kyushu-Palau Ridge. For a number of these locations, the 40Ar/39Ar plateau and 36Ar/40Ar versus 39Ar/40Ar isochrons give older ages than the K-Ar results. The most important results are: (i) at site 786, initial construction of the proto-IBM (now forearc) basement occurred at least by ca 47-45 Ma, consistent with the age of the immediately overlying sediments (middle Eocene nannofossil Zone CP13c); the younger pulse of construction dated at ca 35 Ma by K-Ar could not be confirmed by 40Ar/39Ar analysis; (ii) 40Ar/39Ar ages for the initial construction of the Mariana portion of the IBM system are as old as those of the Izu-Bonin portion, for example at site 458, initial construction commenced at least by ca 49 Ma and at ca 47 Ma at Saipan (Sankakayuma Formation); and (iii) a combination of K-Ar and 40Ar/39Ar ages indicate continued boninite magmatism in the Izu-Bonin forearc (and remnant arc at Palau) until ca 35 Ma. Subduction inception including boninite series rocks along most of the exposed length of the IBM system, clearly preceded by some 5 million years the Middle Eocene (ca 43.5 Ma) change in Pacific plate motion. Boninitic series magmatism persisted at locations now exposed in the forearc for ∼15 million years after arc inception concurrently with low-K tholeiitic series eruptions from a subaerial arc system, established at ≥40 Ma, on the Kyushu-Palau Ridge. For the Mariana portion of the IBM system, reconstruction of the proto-arc places this activity adjacent to the concurrent but orthogonally spreading Central Basin Ridge of the West Philippine Basin. It is possible that a combination of subduction of a young North New Guinea Plate beneath newly created back-arc basin crust may account for some of the features of the Mariana system. It is clear, however, that the understanding of the processes of subduction initiation and early IBM arc development is incomplete.
Year of Publication: 1998
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 03 Geochronology; 18 Geophysics, Solid-Earth; Absolute age; Aimeliik Formation; Algae; Alutom Formation; Andesites; Ar/Ar; Arakabesan Formation; Babelduap Formation; Basins; Biostratigraphy; Boninite; Caroline Islands; Cenozoic; Chichijima; DSDP Site 458; DSDP Site 459; Dates; Deep Sea Drilling Project; Eocene; Facpi Formation; Fore-arc basins; Geochronology; Guam; Hagman Formation; Hypabyssal rocks; IPOD; Igneous rocks; Island arcs; Izu-Bonin Arc; Izu-Bonin-Mariana Arc; K/Ar; Kyushu-Palau Ridge; Leg 125; Leg 60; Lower Oligocene; Magmatism; Mariana Islands; Microfossils; Micronesia; Middle Eocene; Nannofossils; North Pacific; Northern Mariana Islands; Northwest Pacific; ODP Site 782; ODP Site 786; Ocean Drilling Program; Oceania; Oligocene; Pacific Ocean; Palau; Paleogene; Philippine Sea; Plantae; Plate tectonics; Relative age; Saipan; Sankakayuma Formation; Sea-floor spreading; Spreading centers; Subduction; Tertiary; Volcanic rocks; West Pacific; West Philippine Basin
Coordinates: N060000 N320000 E1470000 E1340000
Record ID: 2012050273
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.