File Download

There are no files associated with this item.

  Links for fulltext
     (May Require Subscription)
  • Find via Find It@HKUL
Supplementary

Conference Paper: Geochronology and geochemistry of Paleozoic plutons in the Alxa Terrane: petrogenesis and tectonic implications

TitleGeochronology and geochemistry of Paleozoic plutons in the Alxa Terrane: petrogenesis and tectonic implications
Authors
Issue Date2016
PublisherCopernicus GmbH. The Journal's web site is located at http://www.geophysical-research-abstracts.net
Citation
European Geosciences Union (EGU) General Assembly, Vienna, Austria, 17-22 April 2016. In Geophysical Research Abstracts, 2016, v. 18, EGU2016, no. 1927 How to Cite?
AbstractSituated between the Tarim Craton and the North China Craton (NCC), the Paleozoic magmatic record in the Alxa Terrane places important constraints on the accretionary orogenesis of the southern Paleo-Asian Ocean (PAO) forming the southern section of the Central Asian Orogenic Belt. New results of LA-ICPMS zircon U-Pb ages and whole-rock major- and trace-element compositions reveal two groups of diorites and granitoids in the Alxa Terrane. One group consists of diorites and granitoids that were emplaced at 458-440 Ma, characterized by lower Al2O3/TiO2 ratios and higher TiO2 contents, implying high temperature - low pressure crystallization conditions and a shallow source region. In contrast, the second group consists of granitoids that were formed at 417-407 Ma, displaying low high rare earth elements, very high Sr/Y ratios and mostly positive Eu anomalies, suggesting low temperature - high pressure crystallization conditions and source regions at deep crustal levels where garnet is stable in the residual phase. Both of two groups are mostly calc-alkaline to high-K calc-alkaline, and depleted in Nb, Ta and Ti and enriched in Ba, K and Sr, suggesting an arc affinity related to a PAO oceanic subduction regime since the Late Ordovician. Both zircon ɛHf(t) and whole-rock ɛNd(t) values decrease from 458 Ma to 440 Ma but increase from 417 Ma to 407 Ma, whereas whole-rock initial 87Sr/86Sr ratios display an opposite trend. Such an isotopic change suggests a tectonic switch from an advancing to a retreating subduction setting in the Early Devonian. Compiled with previous studies, we suggest that the early Paleozoic magmatic arc existing in the Alxa Terrane represented the western extension of the super-large early Paleozoic active continental margin on the northern margin of the NCC.
DescriptionPoster Session: TS6.5 Tectonics of the Central Asian Orogenic Belt and the geodynamics of arc systems along convergent plate boundaries : no. X2.85
Persistent Identifierhttp://hdl.handle.net/10722/246268
ISSN

 

DC FieldValueLanguage
dc.contributor.authorLiu, Q-
dc.contributor.authorZhao, G-
dc.date.accessioned2017-09-18T02:25:29Z-
dc.date.available2017-09-18T02:25:29Z-
dc.date.issued2016-
dc.identifier.citationEuropean Geosciences Union (EGU) General Assembly, Vienna, Austria, 17-22 April 2016. In Geophysical Research Abstracts, 2016, v. 18, EGU2016, no. 1927-
dc.identifier.issn1607-7962-
dc.identifier.urihttp://hdl.handle.net/10722/246268-
dc.descriptionPoster Session: TS6.5 Tectonics of the Central Asian Orogenic Belt and the geodynamics of arc systems along convergent plate boundaries : no. X2.85-
dc.description.abstractSituated between the Tarim Craton and the North China Craton (NCC), the Paleozoic magmatic record in the Alxa Terrane places important constraints on the accretionary orogenesis of the southern Paleo-Asian Ocean (PAO) forming the southern section of the Central Asian Orogenic Belt. New results of LA-ICPMS zircon U-Pb ages and whole-rock major- and trace-element compositions reveal two groups of diorites and granitoids in the Alxa Terrane. One group consists of diorites and granitoids that were emplaced at 458-440 Ma, characterized by lower Al2O3/TiO2 ratios and higher TiO2 contents, implying high temperature - low pressure crystallization conditions and a shallow source region. In contrast, the second group consists of granitoids that were formed at 417-407 Ma, displaying low high rare earth elements, very high Sr/Y ratios and mostly positive Eu anomalies, suggesting low temperature - high pressure crystallization conditions and source regions at deep crustal levels where garnet is stable in the residual phase. Both of two groups are mostly calc-alkaline to high-K calc-alkaline, and depleted in Nb, Ta and Ti and enriched in Ba, K and Sr, suggesting an arc affinity related to a PAO oceanic subduction regime since the Late Ordovician. Both zircon ɛHf(t) and whole-rock ɛNd(t) values decrease from 458 Ma to 440 Ma but increase from 417 Ma to 407 Ma, whereas whole-rock initial 87Sr/86Sr ratios display an opposite trend. Such an isotopic change suggests a tectonic switch from an advancing to a retreating subduction setting in the Early Devonian. Compiled with previous studies, we suggest that the early Paleozoic magmatic arc existing in the Alxa Terrane represented the western extension of the super-large early Paleozoic active continental margin on the northern margin of the NCC.-
dc.languageeng-
dc.publisherCopernicus GmbH. The Journal's web site is located at http://www.geophysical-research-abstracts.net-
dc.relation.ispartofGeophysical Research Abstracts-
dc.titleGeochronology and geochemistry of Paleozoic plutons in the Alxa Terrane: petrogenesis and tectonic implications-
dc.typeConference_Paper-
dc.identifier.emailZhao, G: gzhao@hku.hk-
dc.identifier.authorityZhao, G=rp00842-
dc.identifier.hkuros278543-
dc.identifier.volume18, EGU2016-
dc.identifier.spageno. 1927-
dc.identifier.epageno. 1927-
dc.publisher.placeGermany-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats