Cambrian–Ordovician magmatism of the Ikh-Mongol Arc System exemplified by the Khantaishir Magmatic Complex (Lake Zone, south-central Mongolia)

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F18%3A00000011" target="_blank" >RIV/00025798:_____/18:00000011 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11310/18:10377880

Výsledek na webu

<a href="http://dx.doi.org/10.1016/j.gr.2017.10.003" target="_blank" >http://dx.doi.org/10.1016/j.gr.2017.10.003</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.gr.2017.10.003" target="_blank" >10.1016/j.gr.2017.10.003</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Cambrian–Ordovician magmatism of the Ikh-Mongol Arc System exemplified by the Khantaishir Magmatic Complex (Lake Zone, south-central Mongolia)

Popis výsledku v původním jazyce

The Khantaishir Magmatic Complex (KMC) (south–central Mongolia) exposes a section of a magmatic system consisting of deep crustal, ultramafic cumulates (Amp gabbros and hornblendites; c. 0.35–0.5 GPa) to shallower crustal levels dominated by Amp–Bt tonalites (c. 0.1–0.2 GPa). The magmatic rocks were emplaced during most of the Cambrian (c. 538–495 Ma) and are mostly geochemically primitive (Mg# ~50), Na-rich and metaluminous. The (normal-) calc-alkaline signature and characteristic trace-element enrichment in hydrous-fluid mobile large-ion lithophile elements (LILE) relative to high-field strength elements (HFSE) suggest an origin within a magmatic arc. Multiple intrusions of basic magma derived from a subduction-modified depleted mantle developed by fractional crystallization and/or accumulation of (Ol, Cpx) Amp + Bt, later joined by Pl. Magma mixing with, or without, exchange of xenocrysts between compositionally dissimilar melt batches was also important. Over time, partial melting of older, lower crustal metabasic rocks became increasingly significant, again with a strong subduction signature. The lack of zircon inheritance in the magmatic products and rather high zircon EpsHf(t) values (all >+3, but for most samples > +8) as well as whole-rock Sr–Nd isotopic compositions imply that the arc was not founded on mature continental crust. It was probably located at the margin of the Baydrag microcontinent, dominated by accreted metabasic rocks of an older (early Tonian?) island arc covered by a thin layer of subordinate metasediments containing detrital zircons with Tonian and ill-defined Palaeoproterozoic ages. The KMC represents a vestige of an extensive Cambrian–Ordovician subduction system (termed here the Ikh-Mongol Arc System), bordering the western margin of a chain of Precambrian microcontinents (Tuva-Mongolia, Zabkhan and Baydrag) that, together with accreted Neoproterozoic marginal basins (the Lake Zone), defines the external part of the Mongolian orocline.

Název v anglickém jazyce

Cambrian–Ordovician magmatism of the Ikh-Mongol Arc System exemplified by the Khantaishir Magmatic Complex (Lake Zone, south-central Mongolia)

Popis výsledku anglicky

The Khantaishir Magmatic Complex (KMC) (south–central Mongolia) exposes a section of a magmatic system consisting of deep crustal, ultramafic cumulates (Amp gabbros and hornblendites; c. 0.35–0.5 GPa) to shallower crustal levels dominated by Amp–Bt tonalites (c. 0.1–0.2 GPa). The magmatic rocks were emplaced during most of the Cambrian (c. 538–495 Ma) and are mostly geochemically primitive (Mg# ~50), Na-rich and metaluminous. The (normal-) calc-alkaline signature and characteristic trace-element enrichment in hydrous-fluid mobile large-ion lithophile elements (LILE) relative to high-field strength elements (HFSE) suggest an origin within a magmatic arc. Multiple intrusions of basic magma derived from a subduction-modified depleted mantle developed by fractional crystallization and/or accumulation of (Ol, Cpx) Amp + Bt, later joined by Pl. Magma mixing with, or without, exchange of xenocrysts between compositionally dissimilar melt batches was also important. Over time, partial melting of older, lower crustal metabasic rocks became increasingly significant, again with a strong subduction signature. The lack of zircon inheritance in the magmatic products and rather high zircon EpsHf(t) values (all >+3, but for most samples > +8) as well as whole-rock Sr–Nd isotopic compositions imply that the arc was not founded on mature continental crust. It was probably located at the margin of the Baydrag microcontinent, dominated by accreted metabasic rocks of an older (early Tonian?) island arc covered by a thin layer of subordinate metasediments containing detrital zircons with Tonian and ill-defined Palaeoproterozoic ages. The KMC represents a vestige of an extensive Cambrian–Ordovician subduction system (termed here the Ikh-Mongol Arc System), bordering the western margin of a chain of Precambrian microcontinents (Tuva-Mongolia, Zabkhan and Baydrag) that, together with accreted Neoproterozoic marginal basins (the Lake Zone), defines the external part of the Mongolian orocline.

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

Gondwana research

ISSN

1342-937X

e-ISSN

—

Svazek periodika

54

Číslo periodika v rámci svazku

February

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

28

Strana od-do

122-149

Kód UT WoS článku

000428481300008

EID výsledku v databázi Scopus

2-s2.0-85033607608