Structures and Kinematics of the Huanghua Depression in Bohai Bay Basin, East China: Implications for the Formation Mechanism of a Transtensional Basin

Abstract The Bohai Bay Basin in East Asia is a rift basin created by Cenozoic subduction of the oceanic Pacific plate beneath continent. Many prior studies suggest that was initially formed Paleocene with development several NNE-trending extensional grabens, but subsequently impacted right-lateral shear along these existing structures middle Eocene, transforming into transtensional and producing EW-trending grabens Bozhong northeastern Huanghua depressions. However, how this transformation occurred remains to be fully understood. Based on seismic drilling data, we herein investigated fault structures, architecture, evolutionary stages Depression central-west examine strain partitioning evolution mechanism during Paleogene syn-rifting stage. results reveal composed three structurally distinctive zones, namely, dextral transtensional, NW-SE extensional, N-S zones from southwest northeast, which are separated each other two transfer zones. zone interpreted as horsetail structure northern termination zone. This Tan-Lu Fault east served strike-slip boundaries within depressions such Eocene.