Base Triassic Jordan

The Permian-Triassic boundary sections in Jordan are some of the less well known in the world. Here we investigated Upper  Permian  to  Lower  Triassic  successions  exposed  in  the  Al  Mamalih  area,  east  of   the  Dead  Sea, which record the transition between the alluvial Umm Irna Formation (Upper Permian) and the overlying shallow marine Ma’in Formation (Lower Triassic). The Permian-Triassic boundary is constrained either within a hiatus represented  by  a  sequence  boundary  between  these  formations  or  within  ca  15  m  of   shallow  marine  beds  overlying the boundary. Above the sequence boundary reddened, shallow-marine beds (Himara Member) mark the initial Triassic (presumed early Induan) marine transgression (Himara Member). Absence of both body fossils and vertical infaunal burrows  indicates  low-diversity  ecosystems  following  the  Permian-Triassic  extinction  event.  A  gradational  upward increase in grey, green and yellow siltstones beds (Nimra Member), accompanied by a concomitant increase in bioturbation (surface traces and infaunal vertical burrows), bivalves and brachiopods, stromatolites, conchostracans and lingulids in the lower part of  the Nimra Member indicates colonisation of  the substrate under shallow marine conditions  during  the  recovery  phase.  Shallow-water carbonates  in  the  Nimra  Member  yielded  an  abundant,  low  diversity assemblage of  conodonts (e.g. Hd. aequabilis and H. agordina) and a foraminifera assemblage (Postcladella gr. Kalhori - Earlandia spp.-Ammodiscus jordanensis n. sp.) that are interpreted as euryhaline recovery taxa that characterise the mid-late Induan. Abundant new material has allowed revision of the conodont apparatus and the foraminifera include a new species Ammodiscus jordanensis n. sp. of  Induan age. The discovery of the bivalves Claraia bittneri (C. aurita group) and Eumorphotis multiformis is worthy of note. Upper Permian alluvial lithofacies (Jordan) pass basinwards, about 50 km to the northwest, to coeval shallow marine siliciclastic and carbonates in the Negev and Mediterranean coast of Israel. Read more Powell, J H, Nicora, A, Perri, M C, Rettori, R, Posenato, R, Stephenson, M H, Masri, A, Borlenghi, L M, and Gennari, V. 2019. Lower Triassic (Induan to Olenekian) conodonts, foraminifera and bivalves from the Al Mamalih area, Dead Sea, Jordan: constraints on the P-T boundary. Rivista Italiana di Paleontologia e Stratigrafia, 125(1): 147-181.