Late Paleozoic volcanic rocks are well exposed in the Yining Block,NW China,and are predominately composed of andesites,rhyolites and volcaniclastics as well as minor basalts.Study of the petrology,whole-rock geochemi...Late Paleozoic volcanic rocks are well exposed in the Yining Block,NW China,and are predominately composed of andesites,rhyolites and volcaniclastics as well as minor basalts.Study of the petrology,whole-rock geochemistry and zircon U-Pb dating for the Early Carboniferous alkaline basalts from Wusun Mountain,western Yining Block,constrains their petrogenesis and tectonic evolution.The alkaline basalts consist mainly of plagioclases,mostly albite and labradorite,as well as clinopyroxenes and olivines;zircon U-Pb dating indicates their formation at ca.350 Ma.Geochemically,the basaltic samples have low SiO_(2)contents,and high TiO_(2),Al_(2)O_(3)and alkaline contents,coupled with high Na_(2)O/K_(2)O ratios,displaying an alkaline basalt affinity.They show remarkable LILE enrichment and HFSE depletion.Meantime,these samples have relatively high TFe_(2)O_(3),MgO,and Mg#values as well as Ni and Cr,relatively high Sm/Yb and U/Th,suggesting origination from a mantle source metasomatized by slab fluids.They formed in a transitional tectonic setting from arc to intraplate,showing a typical affinity of back-arc basin basalts.The alkaline basalts were likely generated in a nascent back-arc extension setting resulting from slab rollback of the southern Tianshan oceanic lithosphere.A bidirectional subduction model seems more reasonable for the evolution of the southern Tianshan Ocean.These new data will provide a new tectonic model for Late Paleozoic tectonic evolution of the western Yining Block.展开更多
Nb-enriched arc basalts,an extremely special rock type,were formed in a specific tectonic setting,which have attracted much attention in recent years.Although Nbenriched basalts in the Yining Block were interpreted as...Nb-enriched arc basalts,an extremely special rock type,were formed in a specific tectonic setting,which have attracted much attention in recent years.Although Nbenriched basalts in the Yining Block were interpreted as arc-affinity basalts,some geologists suggested that they should be Nb-enriched continental basalts and not arcrelated.Recently,the Nb-enriched arc basalts have been first identified from the Dahalajunshan Formation in southern Wusunshan,Yining.展开更多
The Yining Block is located in the southwestern part of the Central Asian Orogenic Belt （CAOB）,which is characterized by widespread Carboniferous volcanic rocks.Recently,we carried out the National Nature Science Fo...The Yining Block is located in the southwestern part of the Central Asian Orogenic Belt （CAOB）,which is characterized by widespread Carboniferous volcanic rocks.Recently,we carried out the National Nature Science Foundation of China （No.41273033） and Special Fund for Basic Scientific Research of Central Colleges （No.310827153407） project,and focused on two suits volcanic rocks from the Early Carboniferous Dahalajunshan Formation and the Late Carboniferous Yishijilike Formation.Field observations,zircon U-Pb dating,and Sr-Nd isotopic dating were conducted to evaluate the petrogenesis.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities,CHD(Grant Nos.300102271403,300102261401 and 300102261403)the National Natural Science Foundation of China(Grant No.41672285)。
文摘Late Paleozoic volcanic rocks are well exposed in the Yining Block,NW China,and are predominately composed of andesites,rhyolites and volcaniclastics as well as minor basalts.Study of the petrology,whole-rock geochemistry and zircon U-Pb dating for the Early Carboniferous alkaline basalts from Wusun Mountain,western Yining Block,constrains their petrogenesis and tectonic evolution.The alkaline basalts consist mainly of plagioclases,mostly albite and labradorite,as well as clinopyroxenes and olivines;zircon U-Pb dating indicates their formation at ca.350 Ma.Geochemically,the basaltic samples have low SiO_(2)contents,and high TiO_(2),Al_(2)O_(3)and alkaline contents,coupled with high Na_(2)O/K_(2)O ratios,displaying an alkaline basalt affinity.They show remarkable LILE enrichment and HFSE depletion.Meantime,these samples have relatively high TFe_(2)O_(3),MgO,and Mg#values as well as Ni and Cr,relatively high Sm/Yb and U/Th,suggesting origination from a mantle source metasomatized by slab fluids.They formed in a transitional tectonic setting from arc to intraplate,showing a typical affinity of back-arc basin basalts.The alkaline basalts were likely generated in a nascent back-arc extension setting resulting from slab rollback of the southern Tianshan oceanic lithosphere.A bidirectional subduction model seems more reasonable for the evolution of the southern Tianshan Ocean.These new data will provide a new tectonic model for Late Paleozoic tectonic evolution of the western Yining Block.
基金supported by the National Natural Science Foundation of China(Grant No.41273033)
文摘Nb-enriched arc basalts,an extremely special rock type,were formed in a specific tectonic setting,which have attracted much attention in recent years.Although Nbenriched basalts in the Yining Block were interpreted as arc-affinity basalts,some geologists suggested that they should be Nb-enriched continental basalts and not arcrelated.Recently,the Nb-enriched arc basalts have been first identified from the Dahalajunshan Formation in southern Wusunshan,Yining.
文摘The Yining Block is located in the southwestern part of the Central Asian Orogenic Belt （CAOB）,which is characterized by widespread Carboniferous volcanic rocks.Recently,we carried out the National Nature Science Foundation of China （No.41273033） and Special Fund for Basic Scientific Research of Central Colleges （No.310827153407） project,and focused on two suits volcanic rocks from the Early Carboniferous Dahalajunshan Formation and the Late Carboniferous Yishijilike Formation.Field observations,zircon U-Pb dating,and Sr-Nd isotopic dating were conducted to evaluate the petrogenesis.
