Deciphering the dynamic evolution of the South Caspian Basin: Insights from channel patterns of the Amu Darya Delta

Abstract

This research investigates the South Caspian Basin's (SCB) tectono-sedimentary evolution by analyzing submarine channel geometry and azimuth, seismic stratigraphy, and data from a recent exploration well in the basin center. The SCB is a unique basin due to its significant tectonic activity, large sediment supply from surrounding mountain ranges, and complex geological history. It is also a critical region for hydrocarbon exploration, with substantial petroleum resources concentrated in its Pliocene strata. Understanding the SCB is crucial as it provides insights into how similar basins fill and evolve over time. Using enhanced 3D seismic data, multiple horizons are mapped to reveal channels. Thickness maps and reflector patterns help identify the Amu Darya Delta paleo-shelf breaks at the basin's eastern margin. Basin disconnections and reconnections are marked by an angular unconformity (∼3.4 Ma) and two maximum flooding surfaces (∼2.75 and ∼1.76 Ma). Subsidence curves of one well indicate significant tectonic subsidence and high sediment supply from the nearby mountains, resulting in a deep isolated present-day basin. The Amu Darya shelf break has been prograding southwestward with a northward shift of the Amu Darya River as its main channel since the mid-Pleistocene considering the channels and Gross Depositional Environment (GDE) maps. The channel patterns reveal different stages of delta development.