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Article: Late Cryogenian magmatic activity in the North Lhasa terrane, Tibet: Implication of slab break-off process

TitleLate Cryogenian magmatic activity in the North Lhasa terrane, Tibet: Implication of slab break-off process
Authors
KeywordsEast African Orogen
Geochemistry and isotope
North Lhasa terrane
Tibet
Zircon U–Pb dating
Issue Date2019
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcr
Citation
Gondwana Research, 2019, v. 71, p. 129-149 How to Cite?
AbstractThe North Lhasa terrane in Tibet is generally interpreted to be paleotectonically unrelated to the East African Orogen (EAO) and is instead thought to have derived from northeastern India or northwestern Australia. In this study, we present petrogenetic and geochronological results pertaining to the analysis of gabbros (ca. 652 Ma), diorites (ca. 658 and 646 Ma), and tonalites (ca. 652 Ma) from the North Lhasa terrane. The gabbros are calc-alkaline and exhibit arc-like geochemical features. Low positive zircon ε Hf (t) values (+1.0 to +3.8), high zircon δ 18 O (6.25‰ to 7.94‰), and low negative whole-rock ε Nd (t) values (−3.5 to −1.4) indicate that the gabbros were derived from the lithospheric mantle, with geochemical modification by a subduction component. The diorite suite is characterized by a wide range of whole-rock chemistries (e.g., SiO 2 = 51.33–61.98 wt%) and Hf–O–Sr isotopic compositions (ε Hf (t) = −10.8 to −0.1; δ 18 O = 5.17‰ to 7.11‰; I Sr = 0.706 to 0.710), and negative whole-rock ε Nd (t) values (−7.0 to −4.7). These diorites are geochemically similar to OIB and are interpreted to be products of the partial melting of a relatively deep mantle source (>85 km) prior to extensive modification by continental crustal material. The tonalites are adakitic and have moderate Mg # values (47–54), low compatible element abundances, positive zircon ε Hf (t) values (+3.4 to +6.2), high I Sr values (0.714 to 0.715), and small negative whole-rock ε Nd (t) values (−1.6 to −0.4). These tonalites most likely formed by the melting of thickened Mesoproterozoic continental crust. The generation of these ca. 650 Ma magmatic rocks was related to slab break-off in a collision zone. By integrating the findings of previous studies with the data of the present study, we suggest that the North Lhasa terrane was most likely located in the northern segment of the EAO in paleotectonic reconstructions of the Gondwana supercontinent. © 2019 International Association for Gondwana Research
Persistent Identifierhttp://hdl.handle.net/10722/274961
ISSN
2017 Impact Factor: 5.657
2015 SCImago Journal Rankings: 4.949

 

DC FieldValueLanguage
dc.contributor.authorHu, P.Y.-
dc.contributor.authorZhai, G-
dc.contributor.authorZhao, G-
dc.contributor.authorWang, J-
dc.contributor.authorTang, Y-
dc.contributor.authorWang, H-
dc.contributor.authorZhu, Z-
dc.contributor.authorWu, H-
dc.contributor.authorWang, W-
dc.contributor.authorHuang, Z-
dc.date.accessioned2019-09-10T02:32:29Z-
dc.date.available2019-09-10T02:32:29Z-
dc.date.issued2019-
dc.identifier.citationGondwana Research, 2019, v. 71, p. 129-149-
dc.identifier.issn1342-937X-
dc.identifier.urihttp://hdl.handle.net/10722/274961-
dc.description.abstractThe North Lhasa terrane in Tibet is generally interpreted to be paleotectonically unrelated to the East African Orogen (EAO) and is instead thought to have derived from northeastern India or northwestern Australia. In this study, we present petrogenetic and geochronological results pertaining to the analysis of gabbros (ca. 652 Ma), diorites (ca. 658 and 646 Ma), and tonalites (ca. 652 Ma) from the North Lhasa terrane. The gabbros are calc-alkaline and exhibit arc-like geochemical features. Low positive zircon ε Hf (t) values (+1.0 to +3.8), high zircon δ 18 O (6.25‰ to 7.94‰), and low negative whole-rock ε Nd (t) values (−3.5 to −1.4) indicate that the gabbros were derived from the lithospheric mantle, with geochemical modification by a subduction component. The diorite suite is characterized by a wide range of whole-rock chemistries (e.g., SiO 2 = 51.33–61.98 wt%) and Hf–O–Sr isotopic compositions (ε Hf (t) = −10.8 to −0.1; δ 18 O = 5.17‰ to 7.11‰; I Sr = 0.706 to 0.710), and negative whole-rock ε Nd (t) values (−7.0 to −4.7). These diorites are geochemically similar to OIB and are interpreted to be products of the partial melting of a relatively deep mantle source (>85 km) prior to extensive modification by continental crustal material. The tonalites are adakitic and have moderate Mg # values (47–54), low compatible element abundances, positive zircon ε Hf (t) values (+3.4 to +6.2), high I Sr values (0.714 to 0.715), and small negative whole-rock ε Nd (t) values (−1.6 to −0.4). These tonalites most likely formed by the melting of thickened Mesoproterozoic continental crust. The generation of these ca. 650 Ma magmatic rocks was related to slab break-off in a collision zone. By integrating the findings of previous studies with the data of the present study, we suggest that the North Lhasa terrane was most likely located in the northern segment of the EAO in paleotectonic reconstructions of the Gondwana supercontinent. © 2019 International Association for Gondwana Research-
dc.languageeng-
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/jcr-
dc.relation.ispartofGondwana Research-
dc.subjectEast African Orogen-
dc.subjectGeochemistry and isotope-
dc.subjectNorth Lhasa terrane-
dc.subjectTibet-
dc.subjectZircon U–Pb dating-
dc.titleLate Cryogenian magmatic activity in the North Lhasa terrane, Tibet: Implication of slab break-off process-
dc.typeArticle-
dc.identifier.emailZhao, G: gzhao@hku.hk-
dc.identifier.authorityZhao, G=rp00842-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.gr.2019.02.005-
dc.identifier.scopuseid_2-s2.0-85063099665-
dc.identifier.hkuros302987-
dc.identifier.volume71-
dc.identifier.spage129-
dc.identifier.epage149-
dc.publisher.placeNetherlands-

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