Pacific-type orogenic belts: linking evolution of oceans, active margins and intra-plate magmatism

Abstract

Pacific-type orogens (fold belts) hosting accretionary complexes are places keeping records of the evolution of paleo-oceans, and formation and transformation of continental crust at their active convergent margins. Pacific-type orogeny induces destruction of crustal materials, their subduction to the deep mantle, generation of hydrouscarbonated plumes in the mantle transition zone (MTZ) and its related intra-plate magmatism. We propose a new approach for linking paleo-oceans, active margins and intra-plate magmatism in central and eastern Asia. The approach "stands" on three "whales": the model of Ocean Plate Stratigraphy (OPS), the parameters of Pacific-type convergent margins and a model of hydrous-carbonated plumes. The OPS model evolved from extensive studies of accretionary complexes in the western Pacific, in particular, in Japan; it allows differentiating oceanic plates of one paleoocean and evaluating their sizes and ages. An important issue for reconstructing the history of paleo-oceans is to estimate major parameters of the Pacific-type convergent margins: accreting vs. eroding, geometrical length, and life time. For the eroding margins we must define major periods of tectonic erosion and transportation of oceanic and continental materials to the deep mantle and evaluate a possibility of their accumulation in the MTZ. All this would allow us to develop a holistic model linking the evolution of paleooceans, the accretion and erosion of oceanic and continental crust materials at Pacific-type convergent margins, mantle metasomatism and intra-plate magmatism.

Growth of an accretionary complex in the southern Chinese Altai: Insights from the Palaeozoic Kekesentao ophiolitic mélange and surrounding turbidites

“…According to the accretionary prism‐OPS model, rocks from the ocean floor are off‐scraped and thrust into the base of the accumulating accretionary prism in the trench; this means that the upper most rocks in the accretionary prism are the oldest (Kimura & Ludden, 1995; Wakita, 2015; Wakita & Metcalfe, 2005). An analysis of the imbrication of an OPS of an accreted mélange enables the reconstruction of the accretionary history of a vanished ocean (Kusky et al, 2013; Safonova et al, 2016; Safonova et al, 2018; Safonova, Kotlyarov, Krivonogov, & Xiao, 2017; Wakabayashi, 2011, 2015; Wakita, 2012; Wakita, Nakagawa, Sakata, Tanaka, & Oyama, 2018).…”

Subduction zone processes and crustal growth mechanisms at Pacific Rim convergent margins: modern and ancient analogues

“…1;von Huene & Scholl, 1991;Hawkesworth & Kemp, 2006;Takahashi et al 2008;Tatsumi et al 2008;Collins et al 2011;. The Mesozoic-Cenozoic Pacific Rim orogenic belts developed largely along longitudinal (c. N-S-oriented) convergent margins that operated for more than 150 Ma (Monger & Francheteau, 1987;Taira, 2001;Dickinson, 2004;Safonova et al 2018), whereas the coeval Tethyan orogenic belts evolved mainly along latitudinal (c. E-W-oriented) convergent margins, which were terminated by the arrival, collision and partial subduction of continents or ribbon continents (Dercourt et al 1986, Doglioni et al 1999Stampfli, 2000;Dilek, 2006;Cawood et al 2009;Dilek & Furnes, 2019). The longitudinal Pacific Rim orogenic belts display wide and thick accretionary complexes that are continuous for hundreds of kilometres along-strike (Taira, 2001), well-preserved paired metamorphic belts (Brown, 2010), and robust magmatic arc systems with well-developed middle crust and deep lithospheric roots (i.e.…”