Geochemistry of mafic-ultramafic rocks of the 3.33 Ga Kromberg type-section, Barberton greenstone belt, South Africa: Implications for early Earth geodynamic processes

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985831%3A_____%2F22%3A00558659" target="_blank" >RIV/67985831:_____/22:00558659 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11310/22:10452513

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0009254122002418?via%3Dihub" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0009254122002418?via%3Dihub</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.chemgeo.2022.120947" target="_blank" >10.1016/j.chemgeo.2022.120947</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Geochemistry of mafic-ultramafic rocks of the 3.33 Ga Kromberg type-section, Barberton greenstone belt, South Africa: Implications for early Earth geodynamic processes

Popis výsledku v původním jazyce

In conjunction with major, trace and rare earth element data, this study presents the first whole-rock Lu–Hf isotope analyses of mafic-ultramafic rocks of the c. 3.3 Ga Kromberg type-section in the Barberton greenstone belt of South Africa. Three compositionally distinct volcanic rock types are identified namely Group 1 metabasalts, Group 2 metabasalts and komatiitic metabasalts. Group 1 metabasalts are Fe–Mg tholeiitic with compositions that plot close to the Primitive Mantle composition, have isochron intercept εHf(t) value of 0.01 ± 0.4 and Eoarchean Hf model ages. Group 2 metabasalts have very high Al2O3/TiO2 ratios (c. 50), small negative Nb anomalies, LREE-depleted slightly concave up REE patterns, and negative εHf(t) values. The komatiitic basalts variably record small negative Nb anomalies in a primitive mantle normalized plot. Group 1 metabasalts and cumulate peridotites (wehrlites) yield a Lu–Hf isochron age of 3.340 ± 0.190 Ga (95% confidence level). The highly variable major and trace element geochemistry of the rocks in the sequence implies highly dynamic and variable mantle melting environments. The Group 2 metabasalts have geochemical characteristics similar to that of boninites and are interpreted to have formed from a shallow, refractory mantle source. Group 2 metabasalts are argued to have formed in a proto-plate tectonic back-arc basin involving crustal contamination, whereas Group 1 metabasalts likely formed from within a deep mantle plume.

Název v anglickém jazyce

Geochemistry of mafic-ultramafic rocks of the 3.33 Ga Kromberg type-section, Barberton greenstone belt, South Africa: Implications for early Earth geodynamic processes

Popis výsledku anglicky

In conjunction with major, trace and rare earth element data, this study presents the first whole-rock Lu–Hf isotope analyses of mafic-ultramafic rocks of the c. 3.3 Ga Kromberg type-section in the Barberton greenstone belt of South Africa. Three compositionally distinct volcanic rock types are identified namely Group 1 metabasalts, Group 2 metabasalts and komatiitic metabasalts. Group 1 metabasalts are Fe–Mg tholeiitic with compositions that plot close to the Primitive Mantle composition, have isochron intercept εHf(t) value of 0.01 ± 0.4 and Eoarchean Hf model ages. Group 2 metabasalts have very high Al2O3/TiO2 ratios (c. 50), small negative Nb anomalies, LREE-depleted slightly concave up REE patterns, and negative εHf(t) values. The komatiitic basalts variably record small negative Nb anomalies in a primitive mantle normalized plot. Group 1 metabasalts and cumulate peridotites (wehrlites) yield a Lu–Hf isochron age of 3.340 ± 0.190 Ga (95% confidence level). The highly variable major and trace element geochemistry of the rocks in the sequence implies highly dynamic and variable mantle melting environments. The Group 2 metabasalts have geochemical characteristics similar to that of boninites and are interpreted to have formed from a shallow, refractory mantle source. Group 2 metabasalts are argued to have formed in a proto-plate tectonic back-arc basin involving crustal contamination, whereas Group 1 metabasalts likely formed from within a deep mantle plume.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2022

Kód důvěrnosti údajů

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

Název periodika

Chemical Geology

ISSN

0009-2541

e-ISSN

1872-6836

Svazek periodika

605

Číslo periodika v rámci svazku

September

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

11

Strana od-do

120947

Kód UT WoS článku

000810956500002

EID výsledku v databázi Scopus

2-s2.0-85131368756