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Article: Zhaheba potassic basalt, eastern Junggar (NW China): Geochemical characteristics and tectonic implications

TitleZhaheba potassic basalt, eastern Junggar (NW China): Geochemical characteristics and tectonic implications
Authors
KeywordsBasement
Devonian
Junggar
Nb-enriched basalt
Potassic rocks
Tuorangekuduke Formation
Xinjiang
Zhaheba
Issue Date2006
PublisherZhongguo Dizhi Xuehui. The Journal's web site is located at http://dzxb-e.periodicals.net.cn/
Citation
Acta Geologica Sinica, 2006, v. 80 n. 2, p. 254-263 How to Cite?
AbstractZhaheba potassic basaltic rocks outcrop within the Early Devonian Tuorangekuduke Group, NE margin of the Junggar Basin. The rocks exhibit dual geochemical characteristics of both potassic rocks and high-Nb basalts. On one hand, the rocks contain relatively high K 2O(1.66% - 4.63%) and characterized by high K 2O/Na 2O ratios (0.36 - 1.65), high Sr (665 × 10 -6 - 906 × 10 -6), Ba (680 × 10 -6 - 1596 × 10 -6) and highly fractionated REE (La/Yb N>8), displaying characteristics of shoshonitic rocks. On the other hand, these rocks possess relatively high TiO 2 (∼1.7%), P 2O 5 (∼0.8%), Nb (21 × 10 -6 - 23 × 10 -6) and other HFSEs, which are quite analogous to those of high-Nb basalts. Although their high Nb contents, these rocks exhibit significant Nb-Ta depletion and show typical island-arc characteristics. The relatively high Nb/Yb (∼5.9), Nb/Ta (19 - 21), Zr/ Hf (46 - 51) ratios and K 2O contents suggest that these potassic basaltic rocks were derived from a metasomatized, phlogopite- and/or amphibole-bearing mantle source. Aqueous fluid from dehydration of subducting slab cannot be the metasomatic agent because of the weak ability of transporting HFSEs to the mantle wedge. These rocks possess high Ce/Th (47 - 50), Ce/Pb (13 - 19) and Ba/Th (341 - 777) ratios and do not show significant negative Ce anomaly, suggesting a negligible contribution from subducted sediments. We suggest that the metasomatic agent was probably the low-degree partial melt which, when interacted with the mantle wedge, could give rise to the relatively high K 2O and enrichment of HFSEs and LILEs. The Zhaheba potassic basalts were most likely produced in an island arc environment which, in combination with typical Nb-enriched basalts in the center area of the Junggar basin, suggests that hot-subduction scheme could frequently occur during the evolution of the Junggar plate, and that arc-originated terranes could dominate the basement of the Junggar basin.
Persistent Identifierhttp://hdl.handle.net/10722/72897
ISSN
2015 SCImago Journal Rankings: 0.552
References

 

DC FieldValueLanguage
dc.contributor.authorYuan, Cen_HK
dc.contributor.authorXiao, Wen_HK
dc.contributor.authorChen, Hen_HK
dc.contributor.authorLi, Jen_HK
dc.contributor.authorSun, Men_HK
dc.date.accessioned2010-09-06T06:46:08Z-
dc.date.available2010-09-06T06:46:08Z-
dc.date.issued2006en_HK
dc.identifier.citationActa Geologica Sinica, 2006, v. 80 n. 2, p. 254-263en_HK
dc.identifier.issn0001-5717en_HK
dc.identifier.urihttp://hdl.handle.net/10722/72897-
dc.description.abstractZhaheba potassic basaltic rocks outcrop within the Early Devonian Tuorangekuduke Group, NE margin of the Junggar Basin. The rocks exhibit dual geochemical characteristics of both potassic rocks and high-Nb basalts. On one hand, the rocks contain relatively high K 2O(1.66% - 4.63%) and characterized by high K 2O/Na 2O ratios (0.36 - 1.65), high Sr (665 × 10 -6 - 906 × 10 -6), Ba (680 × 10 -6 - 1596 × 10 -6) and highly fractionated REE (La/Yb N>8), displaying characteristics of shoshonitic rocks. On the other hand, these rocks possess relatively high TiO 2 (∼1.7%), P 2O 5 (∼0.8%), Nb (21 × 10 -6 - 23 × 10 -6) and other HFSEs, which are quite analogous to those of high-Nb basalts. Although their high Nb contents, these rocks exhibit significant Nb-Ta depletion and show typical island-arc characteristics. The relatively high Nb/Yb (∼5.9), Nb/Ta (19 - 21), Zr/ Hf (46 - 51) ratios and K 2O contents suggest that these potassic basaltic rocks were derived from a metasomatized, phlogopite- and/or amphibole-bearing mantle source. Aqueous fluid from dehydration of subducting slab cannot be the metasomatic agent because of the weak ability of transporting HFSEs to the mantle wedge. These rocks possess high Ce/Th (47 - 50), Ce/Pb (13 - 19) and Ba/Th (341 - 777) ratios and do not show significant negative Ce anomaly, suggesting a negligible contribution from subducted sediments. We suggest that the metasomatic agent was probably the low-degree partial melt which, when interacted with the mantle wedge, could give rise to the relatively high K 2O and enrichment of HFSEs and LILEs. The Zhaheba potassic basalts were most likely produced in an island arc environment which, in combination with typical Nb-enriched basalts in the center area of the Junggar basin, suggests that hot-subduction scheme could frequently occur during the evolution of the Junggar plate, and that arc-originated terranes could dominate the basement of the Junggar basin.en_HK
dc.languageengen_HK
dc.publisherZhongguo Dizhi Xuehui. The Journal's web site is located at http://dzxb-e.periodicals.net.cn/en_HK
dc.relation.ispartofActa Geologica Sinicaen_HK
dc.subjectBasementen_HK
dc.subjectDevonianen_HK
dc.subjectJunggaren_HK
dc.subjectNb-enriched basalten_HK
dc.subjectPotassic rocksen_HK
dc.subjectTuorangekuduke Formationen_HK
dc.subjectXinjiangen_HK
dc.subjectZhahebaen_HK
dc.titleZhaheba potassic basalt, eastern Junggar (NW China): Geochemical characteristics and tectonic implicationsen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1000-9515&volume=80&spage=254&epage=263&date=2006&atitle=Zhaheba+potassic+basalt,+Eastern+Junggar+(NW+China):+geochemical+characteristics+and+tectonic+implicationsen_HK
dc.identifier.emailSun, M:minsun@hku.hken_HK
dc.identifier.authoritySun, M=rp00780en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.scopuseid_2-s2.0-33745010207en_HK
dc.identifier.hkuros120012en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-33745010207&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume80en_HK
dc.identifier.issue2en_HK
dc.identifier.spage254en_HK
dc.identifier.epage263en_HK
dc.publisher.placeChinaen_HK
dc.identifier.scopusauthoridYuan, C=35241599200en_HK
dc.identifier.scopusauthoridXiao, W=7202456615en_HK
dc.identifier.scopusauthoridChen, H=8620950800en_HK
dc.identifier.scopusauthoridLi, J=26643194200en_HK
dc.identifier.scopusauthoridSun, M=25932315800en_HK

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