BASIN ANALYSIS OF LUANPING BASIN, HEBEI PROVINCE, NORTHEAST CHINA: EARLY CRETACEOUS TRANSTENSION IN THE YANSHAN AREA
Sediment dispersal patterns, facies trends, and the presence of basin bounding normal faults associated with thick, coarse grained alluvial fan and fan delta deposits favor a modified half graben model for Luanping basin. In this model, the northern and western margins of the basin are bounded by normal faults which were active during deposition and controlled sedimentation into the basin. The southeastern margin of the basin is a gently dipping ramp. Interfingering fan delta and profundal lacustrine deposits occupy the region nearest the juncture of these two faults, while predominantly fine grained shallow lacustrine, perilacustrine, and fluvial deposits dominate the ramp.
This structural configuration, odd for a simple rift basin, coupled with the presence of a number of NE-trending sinistral strike-slip faults in the area, may indicate a transtensional mode of origin for Luanping basin. Provenance of conglomerates adjacent to the northern basin-bounding fault support the existence of at least 10 km of left slip on this fault.