Progradating deposits

a result of the progressive accumulation and superimposition of sediments transported from provenance to unloading areas

is a normal sedimentary configuration in petro-exploration

dipping to the unloading areas.The interior MKT Formation mudstone of the middle block at the southeast margin of Pre-Caspian Basin is composed of a series of “reverse prograding deposits” dipping west (i.e.towards the early uplifted provenances).As the origin of the sedimentary configuration has triggered many controversies

there is no consensus as to the sedimentation and evolution of the Carboniferous

which has constrained follow-up exploration.Through the analysis of regional setting

dril-ling and seismic data

we made a comparative analysis of such elements as depositional mode

lithology

paleo-geographic location

geometry and scale

discussed the genetic mechanism of the “reverse prograding deposits”

and proposed that the MKT Formation is deep water tractive current deposits

instead of a retrogradation wedge of transgression origin.Therefore

the “reverse prograding deposits” is a peculiar sedimentary configuration resulted from landward migration of sediments along with the deep water tractive current.In the end

we analyzed the evolution of the MKT Formation and divided it into four stages

namely initiation

peak

recession and late adjustment.The discovery of deep water tractive current deposits not only improves our understanding of the sedimentary evolution rules at the southeast margin of the Carboniferous Pre-Caspian Basin

paves the way for further exploration

and enriches the category of basin sedimentation

but also provides a precious case for global research on the Paleozoic deep water tractive current.