Cretaceous to Paleocene Tectono-Sedimentary Evolution of the Jiaolai Basin and the Contiguous Areas of the Shandong Peninsula(North China) and Its Geodynamic Implications
Cretaceous to Paleocene Tectono-Sedimentary Evolution of the Jiaolai Basin and the Contiguous Areas of the Shandong Peninsula(North China) and Its Geodynamic Implications
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发表时间：
2008
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通讯作者：
Zhang Yueqiao
中科院分区：
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作者：
Zhang Yueqiao
This paper deals with tectono-sedimentary evolution of the Jiaolai basin (North China) from Cretaceous to Paleocene, based on field observation, logging and lithostratigraphic, isotopic (40Ar-39Ar and SHRIMP U-Pb) data of the volcanic rocks, and structural interpretation of seismic profiles. Lithostratigraphic analysis shows that the Jiaolai basin is a faulted basin filled with three distinct rock units: the Early Cretaceous Laiyang and Qinshan groups and the Late Cretaceous to Paleocene Wangshi Group. Isotopic dating of the volcanic rocks of the Qingshan Group yields ages of 120 ～100 Ma. Structural interpretation of seismic profiles reveals that the extensional structure of the Jiaolai basin is confined by two deep seated detachment systems: one developed to the south basin and its detached plane is about 8～10 km beneath the surface, gently dipping southwards underneath the Sulu orogenic basement; the other consists of a series of N-dipping faults, which are developed around the northern area of the Jiaolai basin, with the major fault plane N-dipping. The both WERE formed during depositional stages of the Early Cretaceous Laiyang Group and Late Cretaceous Wangshi Group. Fault slip vector data measured from different rock units of the basin, combined with stress regimes, stratigraphic epochs and isotopic dating, helps US to establish the chronology of the Cretaceous to Paleocene tectonic regimes. The results show that the Jiaolai basin underwent alternation of extension and compression during the Cretaceous and Paleocene. The Early Cretaceous extension experienced two phases: the early NW-SE extension and the late W-E extension. This was followed by a NW-SE compression occurring at the end of Early Cretaceous to the early Late Cretaceous (about 90±5 Ma). This compression resulted in shorting of the Jiaolai basin and sinistral slip of the Tan-Lu fault zone. Tectonic regime transformed to N-S extensional one during Late Cretaceous to Paleocene, and ended by a NE-SW compression at the end of Paleocene. This Cretaceous to Paleocene tectono-sedimentary evolution of the Jiaolai basin and the Yi-Shu rift zone provides constraint on geodynamic settings of the lithosphere thinning processes underneath North China. From above-mentioned it is concluded that the two extensional phases in Early Cretaceous were dynamically associated with either gravity collapse or lithospheric delamination of the thickened crust or lithosphere in North China and the NW-SE compression records the long-distance effect by the subduction of paleo Pacific plate towards the bottom of the Asian continent. Different from above-mentioned one, the Late Cretaceous to Paleocene extension was a dextral strike slip along the NNE-striking Tan-Lu fault system and its pull-apart, which were geodynamically controlled by joint stress fields resulted from far-distance continental collision of the Qinghai-Tibet blocks and the subduction of the paleo pacific plate towards the Asian continent.
