Cosca, Michael A. et al. (1998): (super 40) Ar/ (super 39) Ar and K-Ar geochronological age constraints for the inception and early evolution of the Izu-Bonin-Mariana Arc system
Leg/Site/Hole:
Related Expeditions:
ODP 125
Identifier:
ID:
2012-050273
Type:
georefid
ID:
10.1111/j.1440-1738.1998.00211.x
Type:
doi
Creator:
Name:
Cosca, Michael A.
Affiliation:
Universite de Lausanne, Institut de Mineralogie et Petrographie, Lausanne, Switzerland
Role:
author
Name:
Arculus, Richard J.
Affiliation:
University of Texas at Dallas, United States
Role:
author
Name:
Pearce, Julian A.
Affiliation:
Australian National University, Australia
Role:
author
Name:
Mitchell, John G.
Affiliation:
University of Durham, United Kingdom
Role:
author
Identification:
Title:
(super 40) Ar/ (super 39) Ar and K-Ar geochronological age constraints for the inception and early evolution of the Izu-Bonin-Mariana Arc system
Year:
1998
Source:
In: Stern, Robert J. (prefacer), Arima, Makoto (prefacer), Izu-Bonin-Mariana Arc system
Publisher:
Wiley Blackwell on behalf of Geological Society of Japan, Tsukuba, Japan
Volume:
7
Issue:
3
Pages:
579-595
Abstract:
K-Ar and (super 40) Ar/ (super 39) Ar 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 (super 40) Ar/ (super 39) Ar plateau and (super 36) Ar/ (super 40) Ar versus (super 39) Ar/ (super 40) Ar 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 (super 40) Ar/ (super 39) Ar analysis; (ii) (super 40) Ar/ (super 39) Ar 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 (super 40) Ar/ (super 39) Ar 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 approximately 15 million years after arc inception concurrently with low-K tholeiitic series eruptions from a subaerial arc system, established at > or =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.
Language:
English
Genre:
Serial
Rights:
URL:
Coverage: Geographic coordinates: North:32.0000 West:134.0000 East:
147.0000 South:6.0000
Keywords: Geochronology; Solid-earth geophysics; absolute age; Aimeliik Formation; algae; Alutom Formation; andesites; Ar/Ar; Arakabesan Formation; Babelduap Formation; basins; biostratigraphy; boninite; Caroline Islands; Cenozoic; Chichijima; dates; Deep Sea Drilling Project; DSDP Site 458; DSDP Site 459; Eocene; Facpi Formation; fore-arc basins; geochronology; Guam; Hagman Formation; hypabyssal rocks; igneous rocks; IPOD; 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; Ocean Drilling Program; Oceania; ODP Site 782; ODP Site 786; 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;
.