The Upper Cretaceous (uppermost Albian–Turonian) Ajlun Group in Jordan consists of shallow-water car- bonates, marls and sandstones deposited along a passive continental margin of the Neo-Tethys Ocean. Ex- cellent outcrops along the Dead Sea Transform in Jordan allow for thorough sedimentological analysis and sequence stratigraphic correlations from microfacies- to basin-scale. The objective of this study is to establish a significantly improved regional-scale high-resolution sequence stratigraphic framework, utilizing outcrop and subsurface data, which forms the basis for further detailed paleontological and geochemical studies. Here we present preliminary results of the initial field study, covering a 150 km transect with five sections with a N–S orientation and thickness variations from 200 to 400 m, comprising the Naur, Fuheis, Hummar, Shueib, Wadi As Sir and Khureij formations (Ajlun Group). Lateral correlations, constrained by new nannofossil biostratigra- phy, confirm previous lithostratigraphic frameworks and highlight the regional-scale architecture with a dis- tinct proximal (S) to distal (N) trend, with increased carbonate accumulation towards the north and increased terrestrial input from the south. In addition, the results of a detailed >350 m outcrop section complemented by microfacies analysis of 152 thin sections are presented, spanning the entire Ajlun succession. The section records the initial transgression of the Naur deposits and the subsequent deposition of mostly sub- & supratidal carbonates. The overlying Fuheis, Hummar and Shueib formations are characterized by thick marl deposits with subordinate carbonate units, reflecting a significant reduction in shallow water carbonate production. A marked relative sea level drop exposing the platform at the top of the Shueib formation (Middle Turonian) is evident from sabkha/salina and fluvial deposits. At the top of the section, the overlying Upper Turonian Wadi As Sir/Khureij carbonates are composed of sub- to supratidal carbonates, likely deposited on a ramp setting. These initial results highlight the pronounced environmental changes which occurred during the evolution of the depositional systems of the Ajlun Group and provide the basis for future high-resolution sequence stratig- raphy on a regional scale.