Shallow-marine trace fossils from the Callovian-Oxfordian Tuwaiq Mountain limestone and Hanifa Formations, central Saudi Arabia

The Callovian-Oxfordian Tuwaiq Mountain Limestone and Hanifa formations of Central Saudi Arabia contain an assemblage o abundant trace fossils including Chondrites intricatus Brongniart, 1828; Chondrites stellaris Uchman, 1999; Curvolithus simplex Fritsch, 1908; Hillichnus agrioensis Pazos and Fernández, 2010; Palaeophycus cf. tubularis Hall, 1847; Phycodes cf. palmatus Hall, 1852; Thalassinoides horizontalis Myrow, 1995; Thalassinoides suevicus (Rierh, 1932) and Thalassinoides isp. This assemblage is considered to belong to the Cruziana ichnofacies. Traces of this assemblage have been described for the first time from this interval of the present area. Ethologically, the trace makers reflect a wide range of behaviours with Chemichnia (Chondrites), domichnia (Palaeophycus), complex mining "domichnia/fodinichnia" (Thalassinoides), Fodinichnia (Phycodes), Repichnia (Curvolithus) and pascichnion and possible chemichnion (Hillichnus). The trace fossil association is comparatively rich in the Hanifa Formation than those recorded in the Tuwaiq Mountain Limestone Formation. The ichnogenus Thalassinoides is the dominant trace fossil and well distributed in the whole section. On the other hand, Chondrites is predominant in the marly limestone bed at the base of the Hanifa Formation. In the studied area, The Cruziana ichnofacies reflects moderate to relatively low energy in infralittoral to shallow circalittoral substrates and below the fair-weather wave base, but not storm wave base environment.