Early Cambrian Ichnofossils from the Mussoorie Syncline and revision of Trace Fossil Biozonation of the Lesser Himalaya, India

Abstract

A new locality bearing ichnofossils of the Cruziana Assemblage Zone‐III from the Mussoorie syncline, Lesser Himalaya, is located in rocks of Member‐B of the Dhaulagiri Formation, Tal Group, exposed along the Maldewta‐Chhimoli fresh road cut section. The site yielded ichnofossils Bergaueria perata, Cochlichnus anguineus, ?Diplocraterion isp., Dimorphichnus obliquus, diplichnitiform Cruziana bonariensis, Diplichnites gouldi, Glockeria isp., Helminthopsis isp., Monomorphichnus lineatus, Phycodes palmatum, Palaeophycus striatus, Planolites beverleyensis, Planolites montanus, Treptichnus cf. T. pedum, scratch marks and an undetermined worm impression. An Early Cambrian age (Cambrian Series 2) is assigned to the ichnofossil‐bearing strata based on the stratigraphic position between the Drepanuroides and Palaeoolenus trilobite zones. A revised Cambrian ichnofossil zonation is presented for the Tal Group of the Mussoorie syncline. Together with their occurrence on rippled surfaces, and the lateral displacement of some trackways (due to current action), a sub‐aqueous shallow‐marine depositional setting is proposed for the rocks of Member‐B.

New detrital zircon U–Pb insights on the palaeogeographic origin of the central Sanandaj–Sirjan zone, Iran

“…These authors argued that ichnozone 1 in the Alborz Mountains is evidenced by the Treptichnus pedum zone, which is the index fossil for the lowermost Cambrian. This reveals a similar situation for the Ediacaran-Cambrian succession of the Alborz Mountains and eastern Yunnan Province, South China (Zhu, 1997), western Mongolia (Smith et al 2015), Lesser Himalaya, India (Singh et al 2014) and southern Kazakhstan (Weber et al 2013), where the first appearance of the trace fossil T. pedum post-dates the Ediacaran-Cambrian transition. Similarly, Hamdi et al (1989) found evidence of an assemblage of phosphatic layers in the Lower Shale Member in the Alborz Mountains and pointed out the similarities with successions containing a major Tommotian phosphorite horizon nearly contemporaneous across the 'Proto-/Palaeotethyan' belt in South China, India, Pakistan, Kazakhstan and Mongolia.…”

Ichnostratigraphy of the Ediacaran-Cambrian boundary: new insights on lower Cambrian biozonations from the Soltanieh Formation of northern Iran

“…Therefore, ichnozone 1 in the Alborz Mountains may be understood as a distal expression of the Treptichnus pedum Zone, which is commonly recognized in settings above storm wave base (Buatois et al, 2013). A similar situation has been noted in the Ediacaran-Cambrian succession of eastern Yunnan Province, South China (Zhu, 1997), western Mongolia (Smith et al, 2015), Lesser Himalaya, India (Singh et al, 2014), and southeastern Kazakhstan (Weber et al, 2013), where the first appearance of the trace-fossil T. pedum postdates the Ediacaran-Cambrian transition.…”

Ichnology, palaeoenvironment, and ecosystem dynamics of the Early Cambrian (Stage 4, Series 2) Guanshan Biota, South China

“…The individual ridges are not well preserved, so a precise identification at the ichnospecies level is not possible. Monomorphichnus is interpreted as a swimming‐grazing trail made by endopodite claws of trilobites (Crimes, ; Singh, Lokho, Kishore, & Virmani, ). However, according to Keighley and Pickerill (), Monomorphichnus type trails are also found in Carboniferous terrestrial sediments from eastern Canada; therefore, Monomorphichnus may also be produced by non‐marine arthropods.…”