<p>Three stratigraphic sections of the Upper Jurassic Antalo Limestone successions in the Mekelle Outlier (Hagere-Selam, Messobo, and Wukro sections) have been investigated using detailed fieldwork, section logging, mapping, and microscopic examination to document their microfacies signature and their equivalent depositional environments. According to petrographical studies of 100 thin sections and field investigations, 14 microfacies types are recognized. These microfacies are grouped into 4 microfacies associations: tidal flat (MFT1-2 (Microfacies Tidal Flat)), lagoon (MFL1-2 (Microfacies Lagoon)), shoal (MFS1-4 (Microfacies Shoal)), and open marine (MFO1-6 (Microfacies Open Marine)) environments. Hence, the Antalo limestone successions are deposited in shallow carbonate ramps with a wide lateral and vertical distribution of facies. The rock unit is deposited in a homoclinal carbonate ramp environment characterized by four depositional sequences (A1, A2, A3, A4) from bottom to top. These sequences are situated in a mid-ramp setting with high-energy shoal and shallow marine facies, a storm-controlled estuarine environment, and a shallow tidal environment. The vertical and lateral variations in the facies suggest sea-level fluctuations within the basin during the Upper Jurassic period, associated with the Tethys Ocean. The Antalo Limestone correlates with Ethiopian sedimentary basins, such as the Ogaden Basin and the Blue Nile, and with the Upper Jurassic Hanifa Formation of Saudi Arabia and Yemen, having similar sedimentological, biostratigraphical, and paleontological characteristics.</p>