The first finding of explosive alkaline picrites at Nadan’hada-Alin’ (China)

Shcheka, S. A.; Volokhin, Yu. G.; Карабцов, А. А.

doi:10.1134/s1028334x0909013x

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“…See Figure 8 for symbols F I G U R E 1 6 TiO 2 versus Cr/ (Cr + Al) and Al 2 O 3 diagrams by Arai (1992) and Lenaz and Princivalle (2005), respectively, for the analyzed Cr-spinel crystals for the investigated rocks from Primorye. Crystals from mafic rocks from the Kalinovka Ophiolite (Khanchuk & Vysotskiy, 2016), Yakuno Ophiolite (Ishiwatari, 1985), and meimechite-picrite complex (Shcheka, 1983;Shcheka et al, 2003Shcheka et al, , 2009Simonov et al, 2014) from the Sikhote-Alin accretionary prism are shown for comparison 2. During the Jurassic-earliest Cretaceous, the plume activity culminated, as recorded by the meimechite-picrite complex and related basalts and picrites from the accretionary complexes of Central Asia, Russian Far East, and Japan (Ishiwatari et al, 2013;Safonova et al, 2009;and references therein).…”

Section: Major Change In Magma Sourcesmentioning

confidence: 99%

A major change in magma sources in late Mesozoic active margin of the circum‐Sea of Japan domain: Geochemical constraints from late Paleozoic to Paleogene mafic dykes in the Sergeevka belt, southern Primorye, Russia

et al. 2021

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More than 30 mafic dykes crop out in the Sergeevka belt in the coastal South Primorye, Far East Russia, of which geologic settings have been unclear for years. This study conducted major-and trace elements characterization, Sr-Nd isotope analyses, and Ar-Ar amphibole and U-Pb zircon datings for these rocks in order to identify their origin. The results demonstrated that all dykes are characterized by high Ba/Yb and low Nb/Y, Zr/Y, and Th/Yb ratios, which suggest their origin from arc melts derived from thin wedge mantle and shallow-dipping slab. These dykes are clearly separated into two distinct age/geochemistry suites; that is, the Paleogene and Early Cretaceous one with dolerites/basalts and adakitic rocks, and the Permian-Triassic one with high-Mg and high-Al gabbro-dolerite varieties. Their geochemistry suggests that the older suite was sourced from a primitive depleted MORB mantle (DMM)-type mantle, whereas the younger suite from an enriched mantle II (EM2)-type mantle domain. The transition in source type from DMM to EM2 occurred during the Jurassic-earliest Cretaceous time, probably by a strong influence of a mantle plume onto the long-continuing subductionrelated magmatism. The plume influence reached the maximum when the unique meimechite-picrite complex formed in the region.

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