Safonova,I.Yu.(2009): Intraplate magmatism and oceanic plate stratigraphy of the Paleo-Asian and Paleo-Pacific Oceans from 600 to 140 Ma. Ore Geology Reviews, 35, 137-154.

『6〜1.4億年前の古アジアと古太平洋のプレート内マグマ作用と海洋プレート層序』


Abstract
 This paper reviews localities of intraplate basalts of the Paleo-Asian and Paleo-Pacific Oceans, which occur as fragments of former oceanic islands, seamounts and plateaus in accretionary complexes of Altao-Sayan, Russian Far East and Southwest Japan. Special emphasis is given to their relationships with associated rocks of oceanic plate stratigraphy (OPS), major and trace element chemistry and criteria for their identification in structurally complex orogenic belts. Accretionary complexes (ACs) host the Late Neoproterozoic-Early Cretaceous OPS units of the two paleo-oceans, which have a number of features in common: i) similar succession of oceanic sediments (pelagic chert - hemipelagic terrigenous slope facies - reef carbonates); ii) intraplate basalts occur at the bottom of the sedimentary sections and are usually overlain by a carbonate “cap”; iii) typical OIB-type chemistry of basalts is characterized by LREE-Nb-Ti enrichment. There is a 100 Ma time gap in the evolution of the oceanic intraplate magmatism, which is probably a result of our insufficient knowledge of other ACs of Central Asia. The study of intraplate magmatism and OPS of paleo-oceans is very important because it is an integral part of the study of orogenic belts incorporating many commercially valuable mineral deposits. Identification of intraplate OPS units should be based on a combination and mutual correlation of geological, lithological and geochemical features of basalts and their associated sediments. OPS units, both magmatic and sedimentary, provide a full geological record of the evolution of paleo-oceans from their opening, through subduction and formation of accretionary complexes, and finally to their closure accompanied by active tectonics, orogeny and ore mineralization.

Keywords: Basalt; Geochemistry; Mantle plume; Sedimentary rocks; Accretionary complex; Paleo-Asian ocean; Paleo-Pacific ocean』

1. Introduction
2. Geology and tectonics of OPS units and intraplate basalts
 2.1. Paleo-Asian Ocean (Late Neoproterozoic to Carboniferous)
 2.2. Paleo-Pacific Ocean (320-140 Ma)
3. Petrography and geochemistry of intraplate basalts
 3.1. Petrography
 3.2. Geochemistry of intraplate basalts
  3.2.1. Major element compositions
  3.2.2. Trace element compositions
4. Discussion
 4.1. Recognizing OPS units
 4.2. Criteria for identification of intraplate basalts
 4.3. Geochemical variability of intraplate basalts
 4.4. The 〜100 Ma time gap of the PAO intraplate magmatism
 4.5. OPS-hosted mineral deposits
5. Conclusions
Acknowledgments
References


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