scholarly journals Light hydrocarbons in volcanic gases from the Japanese island arc.

1995 ◽  
Vol 29 (4) ◽  
pp. 231-242 ◽  
Author(s):  
Yasuhiro Kiyosu ◽  
Noriko Asada
1995 ◽  
Vol 59 (394) ◽  
pp. 1-14 ◽  
Author(s):  
Mitsuyoshi Kimata ◽  
Norimasa Nishida ◽  
Masahiro Shimizu ◽  
Shizuo Saito ◽  
Tomoaki Matsui ◽  
...  

AbstractAnorthite megacrysts are common in basalts from the Japanese Island Arc, and signally rare in other global fields. These anorthites are 1 to 3 cm in size and often contain several corroded Mg-olivine inclusions. The megacrysts generally range from An94Ab4Ot2 to An89Ab6Ot5 (Ot: other minor end-members, including CaFeSi3O8, CaMgSi3O8, AlAl3SiO8, □Si4O8) and show no chemical zoning. They often show parting. Redclouded megacrysts contain microcrystals of native copper with a distribution reminiscent of the shape of a planetary nebula. Hydrocarbons are also present, both in the anorthite megacrysts and in the olivines included within them. Implications of lateral variations in the Fe/Mg ratio of the included olivines, in Sr-content and in Sr-isotope ratio of the anorthite megacrysts with respect to the Japanese island arc, relate to mixing of crustal components and subducted slab-sediments into the basaltic magmas.


Episodes ◽  
1991 ◽  
Vol 14 (3) ◽  
pp. 236-241 ◽  
Author(s):  
Yoshiro Kikuchi ◽  
Satoshi Tono ◽  
Masaaki Funayama

2004 ◽  
Vol 206 (1-2) ◽  
pp. 81-96 ◽  
Author(s):  
Bruno Capaccioni ◽  
Yuri Taran ◽  
Franco Tassi ◽  
Orlando Vaselli ◽  
Giuliana Mangani ◽  
...  

2018 ◽  
Vol 9 (3) ◽  
pp. 947-965
Author(s):  
A. N. Didenko ◽  
M. I. Kuzmin

The spatial analysis was conducted to analyze the positions of earthquakes hypocenters in the transit zone of the upper mantle and the focal mechanisms of the strongest earthquakes in the subduction slabs of theOkhotskSeasegment of the Kuril-Kamchatka island arc and theJapanSeasegment of the Japanese island arc. It revealed a significant difference in the morphology of these slabs, as well as in the positions of the earthquake hypocenters relative to the active and stagnating parts of the slabs and the forces that caused the earthquakes. Based on the seismic data presented in the article, it is confirmed that there are two types of subduction of the oceanic lithospheric plates in the mantle. The article discusses relationships between the subduction and various geological processes at the upper–lower mantle boundary. It considers possible causes (including those related to phase transitions) of deep-focus earthquakes, in case of which splitting of the oceanic lithospheric plates takes place at depths near the upper–lower mantle boundary. Subduction of the oceanic lithospheric plates and their splitting predetermine a possibility for the crustal elements to penetrate into the lower mantle and deeper into the D″ layer, wherein new plumes arise and transport the deep magma together with the recycled substance into the crust. Deep-focus earthquakes are a necessary link in the mechanism providing for the recycling of chemical elements in the crust – mantle – D″ layer system and thus leading to the formation of a wide range of mineral deposits.


2019 ◽  
Vol 41 (4) ◽  
Author(s):  
Le Doan Dung ◽  
Akira Tsukagoshi

One survey was done with SCUBA diving in Ha Long Bay and Cat Ba Island, Northern Vietnam (December 2013) and another one at Nha Trang Bay Marine Protected Area, Nha Trang city, Central Vietnam and Phu Quoc Marine Protected Area, Kien Giang Province, Southern Vietnam (November 2014). Sixteen species of the genus Loxoconcha and fourteen species of the genus Xestoleberis were found and identified. Eight species of the genus Loxoconcha were identified in group A, three species in group B, two in group C and three unidentified. Meanwhile, twelve species of the genus Xestoleberis were classified in group A and two in group B according to phylogenetic groups. From geographical distribution of the pore groups of the species in two genera Loxoconcha and Xestoleberis showed that the fauna of these genera in Vietnam is close to those of southern part of Japanese Island Arc, i.e., from Amami Island to the Philippines and Australia rather than Japanese Island Arc faunas.  


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