A diverse ichnofauna from Eocene‐Miocene rocks of the Makran Range (S.E. Iran)

Abstract

A diverse assemblage of trace fossils has been collected from Lower Eocene to Upper Miocene strata during regional geological mapping of 75,000 km 2 of the Makran Range of southeastern Iran. Almost all are excellently preserved and this allows detailed descriptions, which in some cases can be used as a basis for taxonomic revisions of much used but inadequately analysed ichnogenera. 27 ichnogenera have been identified and 25 ichnospecies described. These ichnotaxa include forms which are: straight, unbranched (Planolites), straight, unbranched but twisted around a horizontal axis (Helicorhaphe), straight, branched (Chondrites, Palaeophycus, Thalassinoides), winding unbranched (Scolicia, Subphyllochorda, Taphrhelminthopsis), meandering or winding branched (Acanthorphaphe), spirals (Spirorhaphe, Spirophycus), networks (Desmograpton, Megagrapton, Paleodictyon, Urohelminthoida), rosettes (Glockerichnus, Lorenzinia) and spreite (Phycosiphon). There are also pellet lined burrows (Ophiomorpha) and rare unbranched vertical burrows (Skolithos).Descriptions are given of some 25 ichnospecies but three ichnogenera (Nereites, Paleodictyon, Urohelminthoida), are subjected to more detailed treatment, with taxonomic revision. All examples of Nereites with a sinuous or winding habit are placed in N. jacksoni Emmons 1844, to separate them from those with tight meanders and spirals for which N. cambrensis Murchison 1839 and N. macleayii Murchison 1839 are available. 6 ichnospecies of Paleodictyon are described and it is recognised that there is considerable gradation in mesh and string size, with significant overlap in the dimensions of these parameters between some ichnospecies where they are used as the main or sole diagnostic criteria. Consequently, the diagnosis of P. carpathicum (Matyasovsky, 1878) is emended to include all regular equidimensional to elongate hexagonal meshes with maximum length 3-10 mm and string diameter 0.1-2.5 mm. As a result, some examples of the following are placed in synonomy with it: P. majus Meneghini 1879, P. miocenicum Sacco 1886, P. regulare Sacco 1886, Glenodictyon caucasicum Papp 1910, P. chattoni Pugin 1955 and P. carpaticum Vialov and Golev 1964. A detailed analysis shows no consistent difference between Urohelminthoida appendiculata (Heer 1877) and U. dertonensis Sacco 1888, so they are united under the former, which has priority, and an emended diagnosis is given.The sequences containing the trace fossils occur in a series of tectonic slices bounded by reverse faults. Stratigraphic position and correlation between these slices is based on detailed paleontological and, more particularly, micropaleontological determinations.The oldest sequence, comprising the Zaboli Unit is Eocene in age and shows a transition from trace fossil barren shelf carbonates to deep water turbidite sandstones and shales containing: Acanthorhaphe, Desmograpton, Helminthoida, Lorenzinia, Paleodictyon, Spirophycus, Spirorhaphe, Taphrhelminthopsis and Urohelminthoida. The Darban, Mosri, Shirinzad, Ruk, Angohran and Shahr...

The unusual record of Nereites, wrinkle marks and undermat mining trace fossils from the late Silurian–earliest Devonian of central-western margin of Gondwana (Argentina)

“…jacksoni has been recorded in Upper Ordovician successions of Portugal (Delgado, 1910), in the Upper Ordovician-lower Silurian of North America (Pickerill et al, 1987), in the Silurian of North America and Europe (Emmons, 1844;Benton, 1982a,b;Orr and Pickerill, 1995), in the Upper Carboniferous of Portugal (Delgado, 1910), and in the Miocene of Iran, Crimes and McCall (1995). The latter is the youngest record of this ichnospecies.…”

“…Therefore, N. pugnus is not comparable with this specimen. Rounded lobes (ovate in the sense of Crimes and McCall, 1995;Orr and Pickerill, 1995) preclude any comparison with Nereites macleayii and with Nereites jacksoni (two ichnospecies that may overlap due to toponymic reasons; Orr and Pickerill, 1995, fig. 8).…”

“…Additional Palaeozoic successions bearing Nereites have been documented in several papers from the Northern Hemisphere (e.g., McCann, 1990McCann, , 1993Crimes, 1992;Crimes and Fedonkin, 1994;Crimes and McCall, 1995;Orr, 1995).…”

Ichnology of deep‐sea fan overbank deposits of the Ganei slates (Eocene, Switzerland)— a classical flysch trace fossil locality studied first by Oswald Heer

“…Furthermore, among the studies dealing with post-Jurassic trace-fossil associations only a few are suitable for detailed comparisons; most studies only briefly summarize the occurrence of trace fossils without differentiating between the various subenvironments that exist within submarine fans. Even more detailed variations of trace-fossil associations within such environments are not explicitly discussed (e.g., Miller, 1993;Crimes and McCall, 1995). Therefore, only a few flysch deposits are appropriate for comparison with the Ganei Slates, in terms of ichnology and sedimentology.…”

The Mesozoic amber of Schliersee (southern Germany) is Cretaceous in age

“…This is in contrast to the shallow marine to fluvial depositional environment of the Late Triassic Raibler sandstone (Jerz, 1966;Pflaumann & Stephan, 1968). In addition, P. minimum has so far only been reported from Cretaceous-Neogene (Miocene) strata and is most common in the Late Cretaceous and early Tertiary (Crimes & McCall, 1995). It is reported in the Northern Alps from Albian-Turonian strata (Gaupp, 1980).…”