Tazareh Section, Alburz Mts, Deltaic facies 2 (Jurassic of Iran)

Where: Iran (36.4° N, 54.5° E: paleocoordinates 13.8° S, 47.7° E)

• coordinate stated in text

• outcrop-level geographic resolution

When: Shemshak Formation, Late/Upper Aalenian (175.6 - 171.6 Ma)

• group of beds-level stratigraphic resolution

Environment/lithology: deltaic; lithified, bioturbated, fine-grained, coarse, silty sandstone and lithified, fine-grained sandstone

• The sharp-based, parallel-laminated, graded sandstones intercalated between highly bioturbated fine-sandy silt and the rare hummock cross-stratified sandstone beds have been deposited by density currents. In contrast to the tempestites discussed below, which exhibit more or less identical features, they are interpreted as sediments of the lower delta front and prodelta, because up-section they grade into upper delta front sandstones and distributary channel deposits....There is no clear and distinct boundary between prodelta sediments and outer shelf sediments.
• A widespread facies association are bioturbated silty fine-grained sandstones, rich in comminuted plant debris, with intercalations of 2–20 cm thick, fine-grained sandstones. The latter exhibit a sharp, planar base, are graded, parallel-laminated, and occasionally topped by oscillation ripples. Rarely, their internal structure is made up of hummocky cross-stratification, followed by wave ripple lamination. Wood fragments are common.

Size class: macrofossils

Primary reference: F. T. Fürsich, M. Wilemsen, K. Seyed-Emami, F. Cecca, and M. R. Majidifard. 2005. The upper Shemshak Formation (Toarcian–Aalenian) of the Eastern Alborz (Iran): Biota and palaeoenvironments during a transgressive–regressive cycle. Fazies 51:365-384 [M. Aberhan/T. Schossleitner/T. Schossleitner]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 141260: authorized by Martin Aberhan, entered by Thomas Schossleitner on 23.03.2013

Creative Commons license: CC BY (attribution)

Taxonomic list

Bivalvia
 Pectinida -
Entolium sp. Meek 1865 scallop
 Pholadomyida - Pholadomyidae
Pholadomya sp. Sowerby 1823 clam
 Ichnofossils -