Magmatic Complexes of the Stalemate Ridge, Northwest Pacific, and Their Possible Origin

• Published in: Geochemistry international Vol. 60; no. 5; pp. 430 - 449
• Main Authors: Shabykova, V. V., Silantyev, S. A., Krasnova, E. A., Zhilkina, A. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.05.2022; Springer; Springer Nature B.V
• Subjects: Basalt; Cruises; Data acquisition; Dredging; Earth and Environmental Science; Earth Sciences; Fault zones; Faults; Geochemistry; Igneous rocks; Island arcs; Isotopes; Lava; Lithosphere; Oceanic trenches; Outcrops; Plates; Sediment samples; Segments; Ultramafic materials; Ultramafic rocks; Pacific Ocean; mantle magmatism; oceanic lithosphere; geodynamics; northwestern Pacific; ophiolite complexes; metamorphism; subduction zone
• ISSN: 0016-7029; 1556-1968
• DOI: 10.1134/S001670292205010X

— An important element in the reconstruction of the geodynamic evolution of the lithosphere in the northwestern Pacific Ocean is the Stalemate Ridge, which is located immediately south of the Aleutian island arc and stretches from southeast to northwest parallel to the Aleutian trench. The collection of our rock samples included rocks dredged along the entire strike of the Stalemate Ridge during cruises 201 and 249 of the German R/V Sonne . This study was focused on peridotites, gabbroids, dolerites, and basalts that fully represent the petrographic diversity of igneous rocks composing segments of the Stalemate Ridge located within a length of 500 km along its strike. The synthesis of all preexisting and newly acquired data on the structure of the Stalemate Ridge and the composition of its rocks led us to the following conclusions of principal importance for developing an adequate geodynamic models for the formation of magmatic complexes and their sources in this area of the northwestern Pacific Ocean: (1) the mafic-ultramafic rock association of the northwestern segment of the Stalemate Ridge was formed at a convergent boundary of lithospheric plates; (2) depleted and enriched sources participated in the formation of magmatic complexes of the Stalemate Ridge; (3) in the area at 170 o E within the Stalemate Ridge, a large fault zone occurs, with outcrops of ultramafic rocks found only northwest of this zone and absent southeast of it; and (4) throughout the whole strike of the Stalemate Ridge, magmatic rocks that have no genetic relations to the oceanic lithosphere are sporadically widespread.