The base level during the deposition of Jurassic in the Qiangtang Basin shows a complete cycle from rising to falling.The base level change is closely connected with tectonic evolution of the basin,especially connecte...The base level during the deposition of Jurassic in the Qiangtang Basin shows a complete cycle from rising to falling.The base level change is closely connected with tectonic evolution of the basin,especially connected with Bangonghu-Nujiang ocean evolution process in the formation and evolution of the basin.It is also affected by climate.The Jurassic strata correspond to a long-term base level cycle sequence.The sequence is in fact a non-complete symmetrical cycle,consisting of rising hemicycle and falling hemicycle.It can be divided into 6 intermediate-term base level cycle sequences,including 2 carbonate sequences,3 mixture sedimentary sequences of carbonate and clastic rocks and one clastic sedimentary sequence.Depositional filling characteristics during base level change show that Bangonghu-Nujiang ocean spreads in Toarcian-Bajocian ages,and is at the height of spreading of Bangonghu-Nujiang ocean in Bathonian-Oxfordian ages.In that process,sea area became smaller because of the dry climate.Eventually,marine depositional filling is ended with the subduction and collision of Bangonghu-Nujiang ocean.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.40602013,40572078)Doctoral Foundation of Ministry of Education of China(Grant No.20060489002)
文摘The base level during the deposition of Jurassic in the Qiangtang Basin shows a complete cycle from rising to falling.The base level change is closely connected with tectonic evolution of the basin,especially connected with Bangonghu-Nujiang ocean evolution process in the formation and evolution of the basin.It is also affected by climate.The Jurassic strata correspond to a long-term base level cycle sequence.The sequence is in fact a non-complete symmetrical cycle,consisting of rising hemicycle and falling hemicycle.It can be divided into 6 intermediate-term base level cycle sequences,including 2 carbonate sequences,3 mixture sedimentary sequences of carbonate and clastic rocks and one clastic sedimentary sequence.Depositional filling characteristics during base level change show that Bangonghu-Nujiang ocean spreads in Toarcian-Bajocian ages,and is at the height of spreading of Bangonghu-Nujiang ocean in Bathonian-Oxfordian ages.In that process,sea area became smaller because of the dry climate.Eventually,marine depositional filling is ended with the subduction and collision of Bangonghu-Nujiang ocean.
