Prolific Carboniferous-Permian source rocks in the Junggar Basin and adjacent regions record critical information on the final closure of the Paleo-Asian Ocean.This succession reflects a transitional marine-to-contine...Prolific Carboniferous-Permian source rocks in the Junggar Basin and adjacent regions record critical information on the final closure of the Paleo-Asian Ocean.This succession reflects a transitional marine-to-continental setting and is characterized by a scarcity of marine index fossils,causing significant uncertainty in chronostratigraphic correlation.The lack of precise temporal control has long challenged the correlation of hydrocarbon-bearing strata and the reconstruction of the basin's tectonostratigraphic evolution.In this study,we conducted comprehensive zircon U-Pb geochronological analyses of volcanic ash layers from key Carboniferous-Permian sections and drill cores across the northwestern,southern,and eastern margins of the Junggar Basin and the adjacent Turpan-Hami,Santanghu,and Yili basins.Using high-precision CA-ID-TIMS,SIMS,and LA-ICPMS dating techniques,we successfully obtained 53 U-Pb ages from ash beds,providing the first robust chronostratigraphic constraints for multiple key source rock intervals.The results show that:(1) The principal source rocks in the Junggar Basin's Mahu Sag(Fengcheng Formation) were deposited from the late Carboniferous(Kasimovian) to the earliest Permian(Asselian);(2) The main source rocks in the southern Junggar,Turpan-Hami,and Santanghu basins(Lucaogou/Tarlong Formation) were deposited during the Sakmarian to Artinskian(Cisuralian,early Permian);(3) The key source rocks in the Yili Basin's Yining Sag(Tamuqisayi Formation) were deposited during the early Kungurian(late Cisuralian);and(4) The Pingdiquan Formation in the eastern Junggar Basin is most likely Wuchiapingian(Lopingian,late Permian) in age.These data define three major source rock development intervals:Kasimovian-Asselian,Sakmarian-Kungurian,and Wuchiapingian.This refined chronostratigraphic framework reveals a pronounced diachroneity in the marine-terrestrial transition,which becomes progressively younger from the northwest(Kasimovian) to the east(Gzhelian).This temporal pattern provides new evidence supporting the “scissor-like” closure model for the Paleo-Asian Ocean.This new,robust Carboniferous-Permian chronostratigraphic framework for the Junggar Basin and its surrounding regions provides a solid foundation for hydrocarbon exploration and basin evolution studies in northwest China.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2024YFF0808100)the Major Program of the National Natural Science Foundation of China(Grant No.42293280)the Key Prograsm of the National Natural Science Foundation of China(Grant No.42230808)。
文摘Prolific Carboniferous-Permian source rocks in the Junggar Basin and adjacent regions record critical information on the final closure of the Paleo-Asian Ocean.This succession reflects a transitional marine-to-continental setting and is characterized by a scarcity of marine index fossils,causing significant uncertainty in chronostratigraphic correlation.The lack of precise temporal control has long challenged the correlation of hydrocarbon-bearing strata and the reconstruction of the basin's tectonostratigraphic evolution.In this study,we conducted comprehensive zircon U-Pb geochronological analyses of volcanic ash layers from key Carboniferous-Permian sections and drill cores across the northwestern,southern,and eastern margins of the Junggar Basin and the adjacent Turpan-Hami,Santanghu,and Yili basins.Using high-precision CA-ID-TIMS,SIMS,and LA-ICPMS dating techniques,we successfully obtained 53 U-Pb ages from ash beds,providing the first robust chronostratigraphic constraints for multiple key source rock intervals.The results show that:(1) The principal source rocks in the Junggar Basin's Mahu Sag(Fengcheng Formation) were deposited from the late Carboniferous(Kasimovian) to the earliest Permian(Asselian);(2) The main source rocks in the southern Junggar,Turpan-Hami,and Santanghu basins(Lucaogou/Tarlong Formation) were deposited during the Sakmarian to Artinskian(Cisuralian,early Permian);(3) The key source rocks in the Yili Basin's Yining Sag(Tamuqisayi Formation) were deposited during the early Kungurian(late Cisuralian);and(4) The Pingdiquan Formation in the eastern Junggar Basin is most likely Wuchiapingian(Lopingian,late Permian) in age.These data define three major source rock development intervals:Kasimovian-Asselian,Sakmarian-Kungurian,and Wuchiapingian.This refined chronostratigraphic framework reveals a pronounced diachroneity in the marine-terrestrial transition,which becomes progressively younger from the northwest(Kasimovian) to the east(Gzhelian).This temporal pattern provides new evidence supporting the “scissor-like” closure model for the Paleo-Asian Ocean.This new,robust Carboniferous-Permian chronostratigraphic framework for the Junggar Basin and its surrounding regions provides a solid foundation for hydrocarbon exploration and basin evolution studies in northwest China.
