The genesis and tectonic setting of Late Triassic volcanic rocks in the Ganzi–Litang ophiolitic mélange belt have long been a subject of contention.To elucidate these ambiguities,comprehensive petrological,geoch...The genesis and tectonic setting of Late Triassic volcanic rocks in the Ganzi–Litang ophiolitic mélange belt have long been a subject of contention.To elucidate these ambiguities,comprehensive petrological,geochemical,zircon U-Pb geochronological,and Sr-Nd isotopic analyses were conducted on the Luexigou basalts in the Litang area.This investigation has newly delineated a typical volcano-sedimentary sequence indicative of a mid-ocean ridge,with basalts dated to 215±3 Ma.These basalts exhibit geochemical characteristics akin to E-MORB,displaying relatively flat distribution patterns for rare earth elements and trace elements.They are notably depleted in high-field-strength elements(such as Nb and Ta),similar to volcanic arc basalts.展开更多
In recent years,extensive Cretaceous volcanic activity has been discovered in the eastern Tethyan Himalaya,southern Tibet,have attracted significant attention due to their record of Kerguelen mantle plume magmatism an...In recent years,extensive Cretaceous volcanic activity has been discovered in the eastern Tethyan Himalaya,southern Tibet,have attracted significant attention due to their record of Kerguelen mantle plume magmatism and the breakup of the eastern Gondwana continent.However,this event remains poorly constrained in the central Tethyan Himalaya.This paper reports newly discovered mafic volcanic rocks of the Jiabula Formation in the Tingri area,central Tethyan Himalaya.Zircon U-Pb geochronology indicates that the basalts of the Jiabula Formation formed at 132±2 Ma during the Early Cretaceous.Geochemical and Sr-Nd isotope studies show that the Jiabula Formation volcanic rocks exhibit OIB-type intraplate basalt characteristics withε_(Nd)(t)<0,suggesting a magma source close to garnet-lherzolite facies from an enriched mantle.These rocks experienced approximately 8%–20%partial melting and significant crustal contamination.The study indicates that the mafic volcanic rocks of the Jiabula Formation in the Tingri area were generated by early magmatic upwelling of the Kerguelen mantle plume around 132 Ma,representing a rifting event associated with the breakup of the eastern Gondwana continent.This discovery provides new evidence for the western extension or widespread distribution of Kerguelen mantle plume remnants in the Tethyan Himalaya.展开更多
基金supported by the State Key Program of National Natural Science of China(Grant No.42230311)the China Geological Survey(Grant No.DD20243073).
文摘The genesis and tectonic setting of Late Triassic volcanic rocks in the Ganzi–Litang ophiolitic mélange belt have long been a subject of contention.To elucidate these ambiguities,comprehensive petrological,geochemical,zircon U-Pb geochronological,and Sr-Nd isotopic analyses were conducted on the Luexigou basalts in the Litang area.This investigation has newly delineated a typical volcano-sedimentary sequence indicative of a mid-ocean ridge,with basalts dated to 215±3 Ma.These basalts exhibit geochemical characteristics akin to E-MORB,displaying relatively flat distribution patterns for rare earth elements and trace elements.They are notably depleted in high-field-strength elements(such as Nb and Ta),similar to volcanic arc basalts.
基金supported by the China Geological Survey(Grant No.DD20243073).
文摘In recent years,extensive Cretaceous volcanic activity has been discovered in the eastern Tethyan Himalaya,southern Tibet,have attracted significant attention due to their record of Kerguelen mantle plume magmatism and the breakup of the eastern Gondwana continent.However,this event remains poorly constrained in the central Tethyan Himalaya.This paper reports newly discovered mafic volcanic rocks of the Jiabula Formation in the Tingri area,central Tethyan Himalaya.Zircon U-Pb geochronology indicates that the basalts of the Jiabula Formation formed at 132±2 Ma during the Early Cretaceous.Geochemical and Sr-Nd isotope studies show that the Jiabula Formation volcanic rocks exhibit OIB-type intraplate basalt characteristics withε_(Nd)(t)<0,suggesting a magma source close to garnet-lherzolite facies from an enriched mantle.These rocks experienced approximately 8%–20%partial melting and significant crustal contamination.The study indicates that the mafic volcanic rocks of the Jiabula Formation in the Tingri area were generated by early magmatic upwelling of the Kerguelen mantle plume around 132 Ma,representing a rifting event associated with the breakup of the eastern Gondwana continent.This discovery provides new evidence for the western extension or widespread distribution of Kerguelen mantle plume remnants in the Tethyan Himalaya.
