中生代から新生代にかけてのプレート沈み込みに起因するマグマの特徴

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Mesozoic through Cenozoic magmatic evolution of East Asia was governed by oceanic plate subduction responsible for generation of a high-velocity anomaly, known as "the stagnated slab", at the mantle transition zone and the low-velocity Transbaikal mantle domain at depth of 200-350km. Based on spatial-temporal distribution of magmatic activity, the anomalous mantle region is suggested to be a time-integrated expression of subduction processes. High- and low-velocity material could be stored firstly during closing of the Mongolia-Okhotsk Ocean finalized at ca. 140Ma. After terrane accretion and structural reorganization at 113-107Ma, subduction of the Kula-Izanagi plate defined the northern margin of the anomalous mantle region. Low-velocity anomalies extended from a continental margin landward over 1000km beneath Aldan shield of the Siberian craton. The structural reorganization between 65 and 50Ma took place contemporaneously with accretion of the Okhotsk Sea plate to Eurasia. Block rotation and extension at the continental margin were accompanied by formation of the oblique Sikhote-Alin slab flexure of the Pacific plate. Afterwards, the slab flexure was widening to the south due to landward growing of the directly subducted Honshu-Khingan slab fragment. The latter resulted in development of the southern margin of the anomalous mantle region. The structural reorganization between 21 and 15Ma was coeval to accretion of the Philippine Sea plate to Eurasia with formation of the Japan-Korea oblique slab flexure, trench rolling-back effect, block rotations, and extension at the continental margin. The present-day subduction activity of the Pacific slab is focused at the oblique Japan-Korea and direct Hokkaido-Amur flexures.論文Article
東北大学の論文
2005-03-28

中生代から新生代にかけてのプレート沈み込みに起因するマグマの特徴

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