Abstract:

Temporal-spatial differences of syndepositional tectonics have profound impact on accommodation space,sedimentation rate,types and distributional characteristics of provenance systems of a basin.Episodic tectonic movement of the Nanpu Sag is a major contributor to accommodation space.Several NE-SW-trending contemporaneous faults that were developed in the period of Es in the southern provenance enhanced the compartmentalization of lake basin.A series of echelon growth faults extending toward the basin controlled the distribution of the Shahejie Formation.The linear subsags with the same strike as the growth faults formed in the downthrown blocks are the main unloading areas for sediments.The main depositional system is the combination of braided river delta,infralittoral subaqueous fans,beach bar and lake system in the southern provenance.On this basis,a model of contemporaneous fault controlling sandstone distribution is established in southern Nanpu Sag.The contemporaneous faults stretching into the lake basin controlled the sandstone distribution of braid river delta,with lobate deposits occurring laterally along strikes on the downthrown blocks of faults and superimposing vertically in the shape of wedges.The favorable objectives for future exploration are braided river delta,infralittoral subaqueous fans at the distal end of these deltas,and the beach bars developed on the tilted blocks.

Key words: contemporaneous fault, depositional model, sedimentary facies, Shahejie Formation, Nanpu Sag