Slab-derived fluid evolution induced from oxygen and hydrogen isotopes compositions of blueschist-facies phengites

2020 ◽  
Author(s):  
Tatsuki Tsujimori ◽  
Daniel Pastor-Galán ◽  
Antonio Álvarez-Valero
Keyword(s):  
Subduction Zone ◽  
Hydrogen Isotope ◽  
Hot Spring ◽  
Far East ◽  
Isotopic Fractionation ◽  
Metasedimentary Rocks ◽  
East Russia ◽  
Japan Subduction Zone ◽  
D Values ◽  
Sw Japan

<p>Phengite is the most common metamorphic mineral in H<em>P</em>-UH<em>P</em> metasedimentary rocks, which can convey H<sub>2</sub>O, LILEs (especially K, Ba, Cs and Rb), Li, B and N in their structure formed at depths up to 300 km. The breakdown of phengite in a downgoing oceanic slab would cause fluid-induced element transport into the overlying mantle wedge. We have investigated the <sup>2</sup>H/<sup>1</sup>H (D/H) and <sup>18</sup>O/<sup>16</sup>O ratios of twenty-four phengite separates from pelitic schists of the Devonian–Carboniferous Renge Belt (SW Japan), Permian Shaiginsky Complex (Far East Russia) and Cretaceous Sambagawa Belt (SW Japan).</p><p>We found the presence of the very light hydrogen isotope (δD < –95‰) in blueschist-facies phengites in the three different metamorphic belts. For example, phengite from the lawsonite- and epidote-grade metasedimentary schists of the Osayama Serpentinite Mélange (OSM) of the Renge Belt are characterized by negative hydrogen isotope compositions (δD values relative to VSMOW) ranging from –113 to –93.9‰ and oxygen isotope compositions (δ18O values relative to VSMOW) ranging from +12.9 to +14.6‰.</p><p>High-Si features and K–Ar ages of the investigated phengites deny the possibility of meteoric-hydrothermal alteration to have caused the low δD values. The light values might be attributed to isotopic fractionation during progressive metamorphic dehydration.Assuming a meamorphic temperatures range of 250–350°C for the OSM schists, the inferred metamorphic fluid compositions in blueschist-facies depth for that fossil slab had a range of δD = ~–40 to –75‰ and δ18O = ~+13 to +15‰. These values are significantly lighter than the slab-fluid induced from the Arima hot spring water in a forearc region of modern SW Japan subduction zone. Our study suggests that slab-derived fluids in ancient Pacific-type subduction zone are characterized by light hydrogen isotope and that the phengite breakdown can affect hydrogen isotope of nominally anhydrous minerals (NAMs) in the deep mantle.</p>

scholarly journals Anelastic strain recovery reveals extension across SW Japan subduction zone

2009 ◽  
Vol 36 (23) ◽  
Author(s):  
Timothy B. Byrne ◽  
Weiren Lin ◽  
Akito Tsutsumi ◽  
Yuhji Yamamoto ◽  
Jonathan C. Lewis ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Strain Recovery ◽  
Anelastic Strain ◽  
Anelastic Strain Recovery ◽  
Japan Subduction Zone ◽  
Sw Japan

PERMIAN RADIOLARIAN FAUNAS FROM CHERT IN THE KHABAROVSK COMPLEX, FAR EAST RUSSIA, AND THE AGE OF EACH LITHOLOGIC UNIT OF THE KHABAROVSK COMPLEX

2005 ◽  
Vol 79 (4) ◽  
pp. 687-701 ◽  
Author(s):  
NORITOSHI SUZUKI ◽  
SATORU KOJIMA ◽  
HARUMASA KANO ◽  
SATOSHI YAMAKITA ◽  
AKIHIRO MISAKI ◽  
...  
Keyword(s):  
Far East ◽  
East Russia ◽  
Lithologic Unit

Bipolaris sacchari. [Distribution map].

2012 ◽  
Author(s):  
Keyword(s):  
Tamil Nadu ◽  
Solomon Islands ◽  
Far East ◽  
Uttar Pradesh ◽  
French Polynesia ◽  
Virgin Islands ◽  
Peninsular Malaysia ◽  
Pennisetum Purpureum ◽  
Distribution Map ◽  
East Russia

Abstract A new distribution map is provided for Bipolaris sacchari (E.J. Butler) Shoemaker. Ascomycota: Pleosporales. Hosts: sugarcane, citronella grass (Cymbopogon citratus) and elephant grass (Pennisetum purpureum). Information is given on the geographical distribution in Europe (Italy; Madeira, Portugal; and Far East, Russia), Asia (Bangladesh; Bhutan; Cambodia; Fujian, Guangdong, Guangxi, Hong Kong, Hunan, Jiangxi, Nei Menggu, Sichuan and Yunnan, China; Andaman and Nicobar Islands, Andhra Pradesh, Assam, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan, Tamil Nadu, Uttar Pradesh and West Bengal, India; Irian Jaya, Indonesia; Iran; Israel; Japan; Peninsular Malaysia, Sabah and Sarawak, Malaysia; Myanmar; Pakistan; Philippines; Sri Lanka; Taiwan; Thailand; and Vietnam), Africa (Cameroon, Congo Democratic Republic, Egypt, Ghana, Kenya, Madagascar, Malawi, Mauritius, Mozambique, Nigeria, Reunion, Senegal, Sierra Leone, South Africa, Tanzania, Uganda, Zambia and Zimbabwe), North America (Mexico, and Alabama, Florida, Georgia, Hawaii, Louisiana and Maryland, USA), Central America and Caribbean (Antigua and Barbuda, Belize, Costa Rica, Cuba, Dominican Republic, El Salvador, Grenada, Guadeloupe, Guatemala, Haiti, Honduras, Jamaica, Martinique, Nicaragua, Panama, Puerto Rico, Saint Kitts and Nevis, Saint Lucia, Trinidad and Tobago, United States Virgin Islands and Windward Islands), South America (Argentina; Bolivia; Acre, Minas Gerais, Pernambuco and Rio Grande do Sul, Brazil; Colombia; French Guiana; Guyana; Peru; Suriname; and Venezuela) and Oceania (New South Wales and Queensland, Australia; Cook Islands; Federated States of Micronesia; Fiji; French Polynesia; New Zealand; Palau; Papua New Guinea; Samoa; Solomon Islands; and Vanuatu).

Holopogon pekinensis (Orchidaceae), a new heteromycotrophic species from Northern China

Phytotaxa ◽  
2017 ◽  
Vol 326 (2) ◽  
pp. 151
Author(s):  
XIAN-YUN MU ◽  
BING LIU ◽  
YI-XUAN ZHU ◽  
LING TONG ◽  
QIN-WEN LIN ◽  
...  
Keyword(s):  
New Species ◽  
Endangered Species ◽  
Conservation Status ◽  
Far East ◽  
Northern China ◽  
Identification Key ◽  
Beijing City ◽  
East Russia ◽  
Light Green

Holopogon pekinensis, a new heteromycotrophic orchid from Beijing City, China, is described and illustrated. This new species is morphologically similar to an endangered species endemic to Far East Russia, Holopogon ussuriensis Komarov & Nevski, but differs in having green flowers (vs white) and light green pubescence (vs red). Its conservation status and an identification key to Holopogon are provided.

scholarly journals Adakites, High-Nb Basalts and Copper–Gold Deposits in Magmatic Arcs and Collisional Orogens: An Overview

Geosciences ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 29
Author(s):  
Pavel Kepezhinskas ◽  
Nikolai Berdnikov ◽  
Nikita Kepezhinskas ◽  
Natalia Konovalova
Keyword(s):  
Subduction Zones ◽  
Far East ◽  
Gold Deposits ◽  
Type I ◽  
Isotopic Signatures ◽  
Epithermal Mineralization ◽  
Depleted Mantle ◽  
Mantle Sources ◽  
East Russia ◽  
Collisional Orogens

Adakites are Y- and Yb-depleted, SiO2- and Sr-enriched rocks with elevated Sr/Y and La/Yb ratios originally thought to represent partial melts of subducted metabasalt, based on their association with the subduction of young (<25 Ma) and hot oceanic crust. Later, adakites were found in arc segments associated with oblique, slow and flat subduction, arc–transform intersections, collision zones and post-collisional extensional environments. New models of adakite petrogenesis include the melting of thickened and delaminated mafic lower crust, basalt underplating of the continental crust and high-pressure fractionation (amphibole ± garnet) of mantle-derived, hydrous mafic melts. In some cases, adakites are associated with Nb-enriched (10 ppm < Nb < 20 ppm) and high-Nb (Nb > 20 ppm) arc basalts in ancient and modern subduction zones (HNBs). Two types of HNBs are recognized on the basis of their geochemistry. Type I HNBs (Kamchatka, Honduras) share N-MORB-like isotopic and OIB-like trace element characteristics and most probably originate from adakite-contaminated mantle sources. Type II HNBs (Sulu arc, Jamaica) display high-field strength element enrichments in respect to island-arc basalts coupled with enriched, OIB-like isotopic signatures, suggesting derivation from asthenospheric mantle sources in arcs. Adakites and, to a lesser extent, HNBs are associated with Cu–Au porphyry and epithermal deposits in Cenozoic magmatic arcs (Kamchatka, Phlippines, Indonesia, Andean margin) and Paleozoic-Mesozoic (Central Asian and Tethyan) collisional orogens. This association is believed to be not just temporal and structural but also genetic due to the hydrous (common presence of amphibole and biotite), highly oxidized (>ΔFMQ > +2) and S-rich (anhydrite in modern Pinatubo and El Chichon adakite eruptions) nature of adakite magmas. Cretaceous adakites from the Stanovoy Suture Zone in Far East Russia contain Cu–Ag–Au and Cu–Zn–Mo–Ag alloys, native Au and Pt, cupriferous Ag in association witn barite and Ag-chloride. Stanovoy adakites also have systematically higher Au contents in comparison with volcanic arc magmas, suggesting that ore-forming hydrothermal fluids responsible for Cu–Au(Mo–Ag) porphyry and epithermal mineralization in upper crustal environments could have been exsolved from metal-saturated, H2O–S–Cl-rich adakite magmas. The interaction between depleted mantle peridotites and metal-rich adakites appears to be capable of producing (under a certain set of conditions) fertile sources for HNB melts connected with some epithermal Au (Porgera) and porphyry Cu–Au–Mo (Tibet, Iran) mineralized systems in modern and ancient subduction zones.

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