The origin of low-Ca olivine from ultramafic xenoliths and host basaltic lavas in a back-arc setting, James Ross Island, Antarctic Peninsula

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F19%3A00000078" target="_blank" >RIV/00025798:_____/19:00000078 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216224:14310/19:00111176

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0024493719302294" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0024493719302294</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.lithos.2019.05.039" target="_blank" >10.1016/j.lithos.2019.05.039</a>

Jazyk výsledku

angličtina

Název v původním jazyce

The origin of low-Ca olivine from ultramafic xenoliths and host basaltic lavas in a back-arc setting, James Ross Island, Antarctic Peninsula

Popis výsledku v původním jazyce

The James Ross Island Volcanic Group (JRIVG) at the northern tip of the Antarctic Peninsula is composed of various types of volcanic rocks erupted during the Late Miocene to Late Pleistocene. The sub-aerial lavas are themost abundant erupted products within the suite and are represented by alkali olivine basalts that contain significant amounts of ultramafic xenoliths. Precise determination of chemical compositions of olivine by electron microprobe and LA-ICP-MS reveals more than one compositionally distinct olivine population in the xenoliths and the host lavas. The majority of the olivine grains fromthe xenolith suite are remarkable for their high Mg/Fe ratios (NFo88) and low-Ca contents (b500 ppm) and are similar in composition to themantle olivine, while some others, despite their similarly low-Ca abundances, are characterized by significantly lower Mg/Fe (bFo85) reflecting some degree of differentiation. We interpret the co-existence of both olivine types with low-Ca contents as reflecting a magmatic cumulate origin of the xenoliths through olivine-dominated fractional crystallization from a H2O-rich parent magma, during which the presence of water affects the partitioning behavior of elements and reduces the DCaO olivine/melt significantly. The cores of the most primitive olivine macrocrysts (NFo88) from the basaltic lavas also have low Ca contents compared to MORB olivine at similar Fo, indicating an arc-melt like volatile content of the primary magma. Evaluation of minor and trace element relative abundances in olivine further indicate that the alkaline basalts in the JRIVG are the products of peridotite-dominated partial melting of a volatile-rich mantle sourcewith signatures of mantle hydration most probably promoted by preceding subduction events. The results from olivine chemistry, when combined with the evaluation of primary melt compositions, appear to be consistent with the viewthat the primary magmas from which the JRIVG basalts were derived are the results of partial melting of a mantle domain that has experienced hydrous silicate melt metasomatism through interaction of peridotitic upper mantle rocks with melts of a slab-derived component, most probably generated by dehydration melting of subducted oceanic crust.

Název v anglickém jazyce

The origin of low-Ca olivine from ultramafic xenoliths and host basaltic lavas in a back-arc setting, James Ross Island, Antarctic Peninsula

Popis výsledku anglicky

The James Ross Island Volcanic Group (JRIVG) at the northern tip of the Antarctic Peninsula is composed of various types of volcanic rocks erupted during the Late Miocene to Late Pleistocene. The sub-aerial lavas are themost abundant erupted products within the suite and are represented by alkali olivine basalts that contain significant amounts of ultramafic xenoliths. Precise determination of chemical compositions of olivine by electron microprobe and LA-ICP-MS reveals more than one compositionally distinct olivine population in the xenoliths and the host lavas. The majority of the olivine grains fromthe xenolith suite are remarkable for their high Mg/Fe ratios (NFo88) and low-Ca contents (b500 ppm) and are similar in composition to themantle olivine, while some others, despite their similarly low-Ca abundances, are characterized by significantly lower Mg/Fe (bFo85) reflecting some degree of differentiation. We interpret the co-existence of both olivine types with low-Ca contents as reflecting a magmatic cumulate origin of the xenoliths through olivine-dominated fractional crystallization from a H2O-rich parent magma, during which the presence of water affects the partitioning behavior of elements and reduces the DCaO olivine/melt significantly. The cores of the most primitive olivine macrocrysts (NFo88) from the basaltic lavas also have low Ca contents compared to MORB olivine at similar Fo, indicating an arc-melt like volatile content of the primary magma. Evaluation of minor and trace element relative abundances in olivine further indicate that the alkaline basalts in the JRIVG are the products of peridotite-dominated partial melting of a volatile-rich mantle sourcewith signatures of mantle hydration most probably promoted by preceding subduction events. The results from olivine chemistry, when combined with the evaluation of primary melt compositions, appear to be consistent with the viewthat the primary magmas from which the JRIVG basalts were derived are the results of partial melting of a mantle domain that has experienced hydrous silicate melt metasomatism through interaction of peridotitic upper mantle rocks with melts of a slab-derived component, most probably generated by dehydration melting of subducted oceanic crust.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

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

Název periodika

Lithos

ISSN

0024-4937

e-ISSN

—

Svazek periodika

342-343

Číslo periodika v rámci svazku

October

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

12

Strana od-do

276-287

Kód UT WoS článku

000477091500017

EID výsledku v databázi Scopus

2-s2.0-85067172228