Analogue Modeling of Releasing Stepovers in Strike-slip Faults and Its Application in the Calculation of Strike-slip Displacement

Abstract

exploration can provide key parameters for the study of favorable reserves distribution, structural traps analysis and fault sealing ability. Analogue modeling of releasing stepovers in strike-slip faults can be used to calculate the displacement. This research utilizes the dual-layer model composed of brittle overburden and ductile layer which can represent a detachment level at crustal scale or a weak sedimentary layer at basin scale and has a higher similarity with the natural world to simulate the stepovers. Two types of secondary faults could be observed in the stepovers part including the transverse faults striking at 80°-90°(T fractures) to the imposed shear direction and the oblique faults striking at nearly 45°clockwise (R shears) with respect to the shear direction. In the experiment, by changing the overlapping length and offset distance of two main faults and the imposed strike-slip displacement, we can calculate the continuous change of the ratio between transverse faults and oblique faults and identify the relationship among the variables above by means of data fitting. The results show that(1)the increase of overlapping length or strike-slip displacement or the decrease of offset distance will all result in higher ratio of transverse faults to oblique faults; (2)Four measured variables in every experiment are found to have specific logarithmic relationship; (3) Proportional reduced analogue modeling experiment relative to the natural world could be conducted to acquire the function relationship among overlapping length, offset distance, ratio between two types of faults and strike-slip displacement so that the first three measured data, conversely, can be used to calculate the strike-slip displacement in the nature world. The method of analogue modeling is applied to the calculation of strike-slip displacement of Tan-Lu fault zone in Liaodong Bay, Bohai sea and this research concludes that its dextral strike-slip displacement science neotectonics is about 2.1 km.

AAPG Datapages/Search and Discovery Article #90350 © 2019 AAPG Annual Convention and Exhibition, San Antonio, Texas, May 19-22, 2019