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Article: Origin and tectonic implications of Early Cretaceous high- and low-Mg series rocks and mafic enclaves in the Bomi–Chayu Fold Belt, SE Tibet

TitleOrigin and tectonic implications of Early Cretaceous high- and low-Mg series rocks and mafic enclaves in the Bomi–Chayu Fold Belt, SE Tibet
Authors
KeywordsBomi–Chayu Fold Belt
Early cretaceous
High-Mg series
Mafic enclave
Myitkyina Tethys Ocean
Issue Date2019
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithos
Citation
Lithos, 2019, v. 334-335, p. 102-116 How to Cite?
AbstractEarly Cretaceous granitoids are widespread on the Tibetan Plateau and record the tectonic evolution of several Tethyan oceans. We describe Early Cretaceous high-Mg (Mg # > 50) and low-Mg (Mg # < 50) granitoids, minor diorites, and mafic enclaves from the Bomi–Chayu Fold Belt, SE Tibet. Zircon U-Pb dating reveals two episodes of granitoid emplacement at ~122 and ~117 Ma. High-Mg series rocks have higher Mg # and compatible element concentrations (e.g., Cr and Ni) than low-Mg series samples. Their Mg # and compatible element abundances are also elevated relative to an experimental melt generated under the conditions of a thickened lower crustal. Enriched whole-rock Nd and zircon Hf isotopic signatures, coupled with low Y (<18 ppm) and Yb (<1.9 ppm) concentrations in some samples, indicate that the high-Mg series was derived from thickened lower crust and underwent minor mixing with cumulate pyroxenite in the lower crust. In contrast, low-Mg series rocks record a purely crustal origin, although differences are noted between Na-rich (subgroup 1) and K-rich (subgroup 2) compositions. Mafic enclaves hosted in the granitoids yield identical formation ages and isotopic compositions to their host rocks, suggesting a common origin. The spatial–temporal distribution of Early Cretaceous granitoids in the Bomi–Chayu Fold Belt indicates that magmatism occurred in an analogous tectonic regime to that of similar rocks in the Tengchong Terrane. The Bomi–Chayu granitoids are therefore distinct from those in the northern and central Lhasa subterranes and are related to the evolution of the Myitkyina Tethys Ocean in eastern Myanmar. © 2019 Elsevier B.V.
Persistent Identifierhttp://hdl.handle.net/10722/276322
ISSN
2017 Impact Factor: 3.857
2015 SCImago Journal Rankings: 2.920
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorDong, X-
dc.contributor.authorPeng, T-
dc.contributor.authorFan, W-
dc.contributor.authorZhao, G-
dc.contributor.authorZhang, J-
dc.contributor.authorLiu, B-
dc.contributor.authorGao, J-
dc.contributor.authorPeng, B-
dc.contributor.authorLiang, X-
dc.contributor.authorZeng, W-
dc.contributor.authorChen, L-
dc.date.accessioned2019-09-10T03:00:41Z-
dc.date.available2019-09-10T03:00:41Z-
dc.date.issued2019-
dc.identifier.citationLithos, 2019, v. 334-335, p. 102-116-
dc.identifier.issn0024-4937-
dc.identifier.urihttp://hdl.handle.net/10722/276322-
dc.description.abstractEarly Cretaceous granitoids are widespread on the Tibetan Plateau and record the tectonic evolution of several Tethyan oceans. We describe Early Cretaceous high-Mg (Mg # > 50) and low-Mg (Mg # < 50) granitoids, minor diorites, and mafic enclaves from the Bomi–Chayu Fold Belt, SE Tibet. Zircon U-Pb dating reveals two episodes of granitoid emplacement at ~122 and ~117 Ma. High-Mg series rocks have higher Mg # and compatible element concentrations (e.g., Cr and Ni) than low-Mg series samples. Their Mg # and compatible element abundances are also elevated relative to an experimental melt generated under the conditions of a thickened lower crustal. Enriched whole-rock Nd and zircon Hf isotopic signatures, coupled with low Y (<18 ppm) and Yb (<1.9 ppm) concentrations in some samples, indicate that the high-Mg series was derived from thickened lower crust and underwent minor mixing with cumulate pyroxenite in the lower crust. In contrast, low-Mg series rocks record a purely crustal origin, although differences are noted between Na-rich (subgroup 1) and K-rich (subgroup 2) compositions. Mafic enclaves hosted in the granitoids yield identical formation ages and isotopic compositions to their host rocks, suggesting a common origin. The spatial–temporal distribution of Early Cretaceous granitoids in the Bomi–Chayu Fold Belt indicates that magmatism occurred in an analogous tectonic regime to that of similar rocks in the Tengchong Terrane. The Bomi–Chayu granitoids are therefore distinct from those in the northern and central Lhasa subterranes and are related to the evolution of the Myitkyina Tethys Ocean in eastern Myanmar. © 2019 Elsevier B.V.-
dc.languageeng-
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/lithos-
dc.relation.ispartofLithos-
dc.subjectBomi–Chayu Fold Belt-
dc.subjectEarly cretaceous-
dc.subjectHigh-Mg series-
dc.subjectMafic enclave-
dc.subjectMyitkyina Tethys Ocean-
dc.titleOrigin and tectonic implications of Early Cretaceous high- and low-Mg series rocks and mafic enclaves in the Bomi–Chayu Fold Belt, SE Tibet-
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.lithos.2019.03.018-
dc.identifier.scopuseid_2-s2.0-85063373688-
dc.identifier.hkuros302989-
dc.identifier.volume334-335-
dc.identifier.spage102-
dc.identifier.epage116-
dc.identifier.isiWOS:000468720900008-
dc.publisher.placeNetherlands-

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