Sedimentary Sequence Feature of the Half Graben Rift-lake Basin: A Case Study of the East Sag, Liaohe Basin

Abstract

The Paleogene of the east sag is in the rift period of the lake basin, which is subjected to the effect of the bedrock burial hill and the east branch of the Tan-Lu faulted zone, with the layers present the half graben rift, which is break in east and overlap in west. According to the distribution of the main synsedimentary faulting in the plane and profile, the half graben rift can be further divided into abrupt slope fault zone and gentle slope fault zone. In the corrective background, the LST of the brupt slope fault zone have developed the alleviation system (alluvial fan, braided river and flood plain deposition) and the vertical accretion of the macrofragment deposition; in the TST, the alluvial fan has evolved to the fan delta and turbidite fan; the deep lake fades faded, the water body shoaled and the shoremeare and flood plain environment is coming in HST, with the development of the large scale prograde fan delta. The LST of the gentle slope fault zone have developed the alleviation system in the corrective background; TST changed from the alluvial fan to the retrograde fan delta, with the onshore fan delta plain above the faulting fold belt, the fan delta front between the upper and underlying and the slumping turbidite fan under the underlying fold belt; HST developed the prograde alluvial fan deposit, which are from the upper to the low-lying successively: alluvial fan, braided river, braided river delta plain, braided river delta front and the deep slump turbidite fan.