Upper Cretaceous Al Hisa Phosphorite (AHP) and Muwaqqar Chalk Marl (MCM) formations located in western Jordan are characterized by a particular facies association including phosphate deposits, oyster mounds, and organic-rich lithofacies, all of which have economic importance in the region. The present work investigates their sedimentological, geochemical, and stratigraphic evolution. This study combines well-exposed outcrop observations with shallow-cored wells (up to 70 m deep) and a regional set of gamma-ray logs. A total of 191 samples have been analysed for mineralogical content, carbon (δ13Corg and δ13Ccarb) and oxygen (δ18O) isotopes, TOC content, natural gamma-ray spectrometry, palynology, nannofossils and dinoflagellates for age dating, and microfacies types. The preliminary results show that: (1) the marine decimeter to meter thick phosphate-rich intervals were deposited coevally with the oyster mounds. The oysters are exceptionally large (up to 20cm in length), and locally preserved in situ forming a topographic relief of up to 20m; (2) the overlying, carbonate mudstone, deposited in deeper water conditions, is locally rich in planktonic foraminifera and organic matter showing up to 22 wt%. (3) nanofossils and dinoflagellates are used for age dating and place the facies transition at or around the Campanian-Maastrichtian boundary, (4) the regional stratigraphic and well log correlations show that this rapid facies transition can be traced across Jordan from N to S, and (5) in this overall nutrient-rich environment, the coupling/decoupling of the δ13Corg and δ13Ccarb with quantitative analysis of the dinoflagellate cyst species can be used to discuss the palaeoproductivity and its impact on the transition from the AHP to the MCM. The ongoing data integration analysis will further address the environmental and geochemical conditions, and timing of this drastic facies transition, with the aim to place it in the broader context of similar sedimentation patterns observed along the southern Neo-Tethys Ocean.