The Umm Irna Formation is a geological formation in Jordan. It is found in several outcrops in Jordan in the area around the eastern shore of the Dead Sea. It is Late Permian (likely Changhsingian) in age, and is the oldest unit in the succession, overlying the Cambrian aged Umm Ishrin Sandstone Formation. The formation predominantly consists of sandstones, claystones and mudstones deposited in fluvial and lacustrine conditions.[1] The formation is of considerable paleobotanical interest, as it preserves the earliest known remains of plant groups that would become widespread during the Mesozoic, including corystosperm "seed ferns", represented by the widespread Triassic genus Dicroidium, cycads (cf. Ctenis), conifers (which were originally suggested to be podocarps, but this was later questioned[2]), as well as Bennettitales.[3] Other plant groups present in the formation include Noeggerathiales, gigantopterids, lyginopterids and possible ginkgophytes.[3][4]
| Umm Irna Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Geological formation |
| Underlies | Ma'in Formation |
| Overlies | Unconformity with Umm Ishrin Sandstone |
| Thickness | 60–70 m (200–230 ft) |
| Lithology | |
| Primary | Claystone, siltstone, sandstone |
| Location | |
| Coordinates | 31°18′N 35°33′E / 31.3°N 35.55°E |
| Country |  Jordan |
| Extent | Several exposures along the eastern Dead Sea coast |
| Type section | |
| Named by | Bandel & Khoury |
| Location | Wadi Himara |
| Year defined | 1981 |
| Thickness at type section | 63 m (207 ft) |
  Umm Irna Formation (Jordan) | |
References
edit- ^ Stephenson, Michael H.; Powell, John H. (2013-07-01). "Palynology and alluvial architecture in the Permian Umm Irna Formation, Dead Sea, Jordan". GeoArabia. 18 (3): 17–60. Bibcode:2013GeoAr..18...17S. doi:10.2113/geoarabia180317. ISSN 1025-6059. S2CID 140176430.
- ^ Andruchow-Colombo, Ana; Escapa, Ignacio H; Aagesen, Lone; Matsunaga, Kelly K S (2023-08-04). "In search of lost time: tracing the fossil diversity of Podocarpaceae through the ages". Botanical Journal of the Linnean Society. 203 (4): 315–336. doi:10.1093/botlinnean/boad027. hdl:11336/227952. ISSN 0024-4074.
- ^ a b Blomenkemper, Patrick; Kerp, Hans; Hamad, Abdalla Abu; DiMichele, William A.; Bomfleur, Benjamin (2018-12-21). "A hidden cradle of plant evolution in Permian tropical lowlands". Science. 362 (6421): 1414–1416. Bibcode:2018Sci...362.1414B. doi:10.1126/science.aau4061. ISSN 0036-8075. PMID 30573628.
- ^ Zavialova, Natalia; Blomenkemper, Patrick; Kerp, Hans; Hamad, Abdalla Abu; Bomfleur, Benjamin (2021-03-04). "A lyginopterid pollen organ from the upper Permian of the Dead Sea region". Grana. 60 (2): 81–96. Bibcode:2021Grana..60...81Z. doi:10.1080/00173134.2020.1772360. ISSN 0017-3134. S2CID 224931916.