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Article: Triassic depleted lithospheric mantle underneath the Paleozoic Chinese Altai orogen: Evidence from MORB-like basalts

TitleTriassic depleted lithospheric mantle underneath the Paleozoic Chinese Altai orogen: Evidence from MORB-like basalts
Authors
KeywordsAltai orogen
Triassic MORB-like basalt
Intraplate magmatism
Depleted lithospheric mantle
Issue Date2019
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/jseaes
Citation
Journal of Asian Earth Sciences, 2019, v. 185, p. article no. 104021 How to Cite?
AbstractWhole-rock geochemical and Sr–Nd–Pb–Hf isotopic analyses were conducted on the Triassic Ashele post-orogenic basalts from the Chinese Altai. The tholeiitic Ashele basalts possess moderate Na2O (2.46–4.52 wt%) but extremely low K2O (≤0.06 wt%) contents, and are depleted in light rare earth elements (LREE). Their (La/Sm)N and (La/Yb)N ratios range from 0.78 to 0.88 and from 0.72 to 0.84, respectively, which, together with their low initial 87Sr/86Sr (0.7048–0.7052), high εNd(t) (+4.9 to +5.6) and εHf(t) (+14.3 to +16.3) values, indicate that the magmas were derived from a depleted mantle source. Their 206Pb/204Pb and 207Pb/204Pb ratios (17.919–18.125 and 15.507–15.522, respectively) also support this interpretation. On the other hand, the Ashele basalts are enriched in Cs, Th and U, but depleted in Rb, Ba, Nb and Ta, possibly due to slight mantle metasomatism by subduction-related fluids. Because there was no record for large-scale thermal activity in the deep mantle during the Triassic, and geological evidence demonstrates reactivation of the Erqis fault, we propose that such a tectonic reactivation affected the lithospheric mantle and resulted in its partial melting and subsequent generation of the Ashele basalts. This study shows that a depleted lithospheric mantle, not an ancient continental lithosphere, was underneath the Chinese Altai in the Triassic, which was possibly accreted during the Paleozoic orogeny. Therefore, the lithospheric mantle in this area today was possibly evolved from such a depleted mantle modified by consecutive partial melting after the Paleozoic orogeny.
Persistent Identifierhttp://hdl.handle.net/10722/289685
ISSN
2020 Impact Factor: 3.449
2015 SCImago Journal Rankings: 1.393
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorLin, Z-
dc.contributor.authorYuan, C-
dc.contributor.authorZhang, Y-
dc.contributor.authorSun, M-
dc.contributor.authorLong, X-
dc.contributor.authorWang, X-
dc.contributor.authorHuang, Z-
dc.date.accessioned2020-10-22T08:16:00Z-
dc.date.available2020-10-22T08:16:00Z-
dc.date.issued2019-
dc.identifier.citationJournal of Asian Earth Sciences, 2019, v. 185, p. article no. 104021-
dc.identifier.issn1367-9120-
dc.identifier.urihttp://hdl.handle.net/10722/289685-
dc.description.abstractWhole-rock geochemical and Sr–Nd–Pb–Hf isotopic analyses were conducted on the Triassic Ashele post-orogenic basalts from the Chinese Altai. The tholeiitic Ashele basalts possess moderate Na2O (2.46–4.52 wt%) but extremely low K2O (≤0.06 wt%) contents, and are depleted in light rare earth elements (LREE). Their (La/Sm)N and (La/Yb)N ratios range from 0.78 to 0.88 and from 0.72 to 0.84, respectively, which, together with their low initial 87Sr/86Sr (0.7048–0.7052), high εNd(t) (+4.9 to +5.6) and εHf(t) (+14.3 to +16.3) values, indicate that the magmas were derived from a depleted mantle source. Their 206Pb/204Pb and 207Pb/204Pb ratios (17.919–18.125 and 15.507–15.522, respectively) also support this interpretation. On the other hand, the Ashele basalts are enriched in Cs, Th and U, but depleted in Rb, Ba, Nb and Ta, possibly due to slight mantle metasomatism by subduction-related fluids. Because there was no record for large-scale thermal activity in the deep mantle during the Triassic, and geological evidence demonstrates reactivation of the Erqis fault, we propose that such a tectonic reactivation affected the lithospheric mantle and resulted in its partial melting and subsequent generation of the Ashele basalts. This study shows that a depleted lithospheric mantle, not an ancient continental lithosphere, was underneath the Chinese Altai in the Triassic, which was possibly accreted during the Paleozoic orogeny. Therefore, the lithospheric mantle in this area today was possibly evolved from such a depleted mantle modified by consecutive partial melting after the Paleozoic orogeny.-
dc.languageeng-
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/jseaes-
dc.relation.ispartofJournal of Asian Earth Sciences-
dc.subjectAltai orogen-
dc.subjectTriassic MORB-like basalt-
dc.subjectIntraplate magmatism-
dc.subjectDepleted lithospheric mantle-
dc.titleTriassic depleted lithospheric mantle underneath the Paleozoic Chinese Altai orogen: Evidence from MORB-like basalts-
dc.typeArticle-
dc.identifier.emailZhang, Y: zyy518@hku.hk-
dc.identifier.emailSun, M: minsun@hku.hk-
dc.identifier.authoritySun, M=rp00780-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.jseaes.2019.104021-
dc.identifier.scopuseid_2-s2.0-85072213018-
dc.identifier.hkuros317256-
dc.identifier.volume185-
dc.identifier.spagearticle no. 104021-
dc.identifier.epagearticle no. 104021-
dc.identifier.isiWOS:000496840600001-
dc.publisher.placeUnited Kingdom-
dc.identifier.issnl1367-9120-

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