Significance of highly siderophile element and Re–Os isotope systematics in global carbonatites

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985831%3A_____%2F24%3A00603913" target="_blank" >RIV/67985831:_____/24:00603913 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00025798:_____/24:10169421 RIV/00216208:11310/24:10496757

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0009281924000199" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0009281924000199</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.chemer.2024.126095" target="_blank" >10.1016/j.chemer.2024.126095</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Significance of highly siderophile element and Re–Os isotope systematics in global carbonatites

Popis výsledku v původním jazyce

The systematics of highly siderophile elements (HSE) in carbonatites have rarely been investigated although carbonatite melts are among key metasomatic agents in the Earth's mantle. Thus, establishing the Os isotope systematics of carbonatites is of prime importance because carbonatite metasomatism might play a determining role in driving 187Os/188Os signature of the Earth's mantle as a consequence of extreme mobility of carbonatite liquids. In this study, a suite of carbonatites from continental settings was analyzed for HSE abundances and Re–Os isotope systematics, combined with detailed petrography of sulfide phases, to provide constraints on the HSE behavior during the formation of carbonatite melts, the role of sulfides in distribution of HSE and the reliability of Re–Os isotope compositions. All investigated carbonatites display low ΣHSE <1 ppb whereby calciocarbonatites exhibit supra-chondritic OsN/IrN ratios from ∼1.4 to 15, in contrast to magnesiocarbonatites and Mg/Fe-rich carbonatites showing exclusively sub-chondritic OsN/IrN. We posit that preferential removal of Os over Ir during the segregation of calcite-normative melts from the co-existing S-rich silicate melts is the main driver of Os/Ir elemental fractionation. The present-day 187Os/188Os ratios in carbonatites range from mildly unradiogenic (∼0.124) to extremely radiogenic values (∼115–152), with 187Os/188Os(i) ratios spanning from negative to highly radiogenic (∼17) values, paralleled by highly variable 187Re/188Os ratios between 0.096 and ∼ 26,000, and without any clear relationship to the carbonatite type or emplacement age. The Re–Os systematics of carbonatites appear to be significantly modified by hydrothermal processes resulting in either removal of both Re and Os, or Re addition and, consequently, commonly negative calculated γOs values, which may indicate a rather limited potential of the Re–Os systematics to evaluate the nature of carbonatite melts. Conversely, limited Re–Os data for the samples that were likely not affected by late-stage perturbation indicate a largely radiogenic 187Os/188Os nature of carbonatite melts. Nevertheless, carbonatite melts may, in part, be responsible for the radiogenic γOs values commonly observed in mantle-derived silicate melts influenced by carbonatite-like metasomatism.

Název v anglickém jazyce

Significance of highly siderophile element and Re–Os isotope systematics in global carbonatites

Popis výsledku anglicky

The systematics of highly siderophile elements (HSE) in carbonatites have rarely been investigated although carbonatite melts are among key metasomatic agents in the Earth's mantle. Thus, establishing the Os isotope systematics of carbonatites is of prime importance because carbonatite metasomatism might play a determining role in driving 187Os/188Os signature of the Earth's mantle as a consequence of extreme mobility of carbonatite liquids. In this study, a suite of carbonatites from continental settings was analyzed for HSE abundances and Re–Os isotope systematics, combined with detailed petrography of sulfide phases, to provide constraints on the HSE behavior during the formation of carbonatite melts, the role of sulfides in distribution of HSE and the reliability of Re–Os isotope compositions. All investigated carbonatites display low ΣHSE <1 ppb whereby calciocarbonatites exhibit supra-chondritic OsN/IrN ratios from ∼1.4 to 15, in contrast to magnesiocarbonatites and Mg/Fe-rich carbonatites showing exclusively sub-chondritic OsN/IrN. We posit that preferential removal of Os over Ir during the segregation of calcite-normative melts from the co-existing S-rich silicate melts is the main driver of Os/Ir elemental fractionation. The present-day 187Os/188Os ratios in carbonatites range from mildly unradiogenic (∼0.124) to extremely radiogenic values (∼115–152), with 187Os/188Os(i) ratios spanning from negative to highly radiogenic (∼17) values, paralleled by highly variable 187Re/188Os ratios between 0.096 and ∼ 26,000, and without any clear relationship to the carbonatite type or emplacement age. The Re–Os systematics of carbonatites appear to be significantly modified by hydrothermal processes resulting in either removal of both Re and Os, or Re addition and, consequently, commonly negative calculated γOs values, which may indicate a rather limited potential of the Re–Os systematics to evaluate the nature of carbonatite melts. Conversely, limited Re–Os data for the samples that were likely not affected by late-stage perturbation indicate a largely radiogenic 187Os/188Os nature of carbonatite melts. Nevertheless, carbonatite melts may, in part, be responsible for the radiogenic γOs values commonly observed in mantle-derived silicate melts influenced by carbonatite-like metasomatism.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GX19-29124X" target="_blank" >GX19-29124X: VÝVOJ STAVEB A GEOCHEMICKÉ SIGNATURY KARBONATITŮ V ČASE: VÝZNAM MOBILITY A KONCENTRACE KRITICKÝCH KOVŮ</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2024

Kód důvěrnosti údajů

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

Název periodika

Chemie der Erde-Geochemistry

ISSN

0009-2819

e-ISSN

1611-5864

Svazek periodika

84

Číslo periodika v rámci svazku

4

Stát vydavatele periodika

DE - Spolková republika Německo

Počet stran výsledku

15

Strana od-do

126095

Kód UT WoS článku

001389089600001

EID výsledku v databázi Scopus

2-s2.0-85186352618