Geochemistry and geochronology of Mississippian volcanic rocks from SW Mongolia: Implications for terrane subdivision and magmatic arc ctivity in the Trans-Altai Zone

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F18%3A00000153" target="_blank" >RIV/00025798:_____/18:00000153 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.1016/j.jseaes.2018.06.029" target="_blank" >https://doi.org/10.1016/j.jseaes.2018.06.029</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.jseaes.2018.06.029" target="_blank" >10.1016/j.jseaes.2018.06.029</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Geochemistry and geochronology of Mississippian volcanic rocks from SW Mongolia: Implications for terrane subdivision and magmatic arc ctivity in the Trans-Altai Zone

Popis výsledku v původním jazyce

Baaran and Baytag “terranes” form important part of the Trans-Altai Zone of the Central Asian Orogenic Belt in the SW Mongolia. The Trans-Altai Zone represents an oceanic domain built by Ordovician to Devonian ophiolites covered by Devonian–Carboniferous oceanic sediments. This oceanic assemblage was intruded by a spectrum of Carboniferous volcanic rocks ranging from basalts to rhyolites (325.6 ± 1.4 Ma to 351.0 ± 5.9 Ma; LA-ICP-MS U–Pb dating on zircon) that display similar whole-rock trace-element and Sr–Nd isotopic signatures regardless their silica contents and the “terrane” they belong to. They are normal-K calc-alkaline rocks whose NMORBnormalized multielement patterns show an arc-like enrichment in LILE (Large Ion Lithophile Elements) and deep negative TNT (Ta, Nb, Ti) anomalies. Based on the relatively high Nb/Yb and Th/Yb ratios, the arc was probably formed on immature continental rather than typical oceanic crust. Low (87Sr/86Sr)i (0.7043–0.7047), high epsilonNd 350(+5.2 to= +5.8) and the observed in-situ Hf isotopic variation in dated zircons (epsilonHf t =+7.4 to +13) are all attributed to a partial melting of primitive and youthful (Neoproterozoic–Ordovician) arc-type lower continental crust (metamorphosed intermediate–acid igneous rocks and/or arc-derived greywackes), augmented with, and most likely facilitated by, contemporaneous arc-related basaltic intrusions. A distinct possibility remains the previously formulated model assuming that the Carboniferous magmatism in Gobi-Altai and Trans-Altai zones sampled the juvenile Neoproterozoic to Cambrian arc crust relaminated under the Ordovician–Devonian oceanic crust. In any case, the studied arc association, together with lithological sequence of ophiolites, can be closely correlated with the Dulate arc in eastern Junggar. It is proposed that the two arc sequences form a single belt, c. 500 km long, that represents one of the main known arc structures in the Central Asian Orogenic Belt.

Název v anglickém jazyce

Geochemistry and geochronology of Mississippian volcanic rocks from SW Mongolia: Implications for terrane subdivision and magmatic arc ctivity in the Trans-Altai Zone

Popis výsledku anglicky

Baaran and Baytag “terranes” form important part of the Trans-Altai Zone of the Central Asian Orogenic Belt in the SW Mongolia. The Trans-Altai Zone represents an oceanic domain built by Ordovician to Devonian ophiolites covered by Devonian–Carboniferous oceanic sediments. This oceanic assemblage was intruded by a spectrum of Carboniferous volcanic rocks ranging from basalts to rhyolites (325.6 ± 1.4 Ma to 351.0 ± 5.9 Ma; LA-ICP-MS U–Pb dating on zircon) that display similar whole-rock trace-element and Sr–Nd isotopic signatures regardless their silica contents and the “terrane” they belong to. They are normal-K calc-alkaline rocks whose NMORBnormalized multielement patterns show an arc-like enrichment in LILE (Large Ion Lithophile Elements) and deep negative TNT (Ta, Nb, Ti) anomalies. Based on the relatively high Nb/Yb and Th/Yb ratios, the arc was probably formed on immature continental rather than typical oceanic crust. Low (87Sr/86Sr)i (0.7043–0.7047), high epsilonNd 350(+5.2 to= +5.8) and the observed in-situ Hf isotopic variation in dated zircons (epsilonHf t =+7.4 to +13) are all attributed to a partial melting of primitive and youthful (Neoproterozoic–Ordovician) arc-type lower continental crust (metamorphosed intermediate–acid igneous rocks and/or arc-derived greywackes), augmented with, and most likely facilitated by, contemporaneous arc-related basaltic intrusions. A distinct possibility remains the previously formulated model assuming that the Carboniferous magmatism in Gobi-Altai and Trans-Altai zones sampled the juvenile Neoproterozoic to Cambrian arc crust relaminated under the Ordovician–Devonian oceanic crust. In any case, the studied arc association, together with lithological sequence of ophiolites, can be closely correlated with the Dulate arc in eastern Junggar. It is proposed that the two arc sequences form a single belt, c. 500 km long, that represents one of the main known arc structures in the Central Asian Orogenic Belt.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GA17-17540S" target="_blank" >GA17-17540S: Kontrastní mechanizmy růstu superkontinentu Pangea: nový pohled na tvorbu kontinentální kůry</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Asian Earth Sciences

ISSN

1367-9120

e-ISSN

—

Svazek periodika

164

Číslo periodika v rámci svazku

September

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

22

Strana od-do

322-343

Kód UT WoS článku

000442706000021

EID výsledku v databázi Scopus

2-s2.0-85049334518