Tazareh Section, Alburz Mts, Deltaic facies 1 (Jurassic of Iran)

Where: Iran (36.4° N, 54.5° E: paleocoordinates 14.0° S, 47.6° E)

• coordinate stated in text

• outcrop-level geographic resolution

When: Shemshak Formation, Early/Lower Bajocian (171.6 - 168.4 Ma)

• group of beds-level stratigraphic resolution

Environment/lithology: deltaic; lithified, medium-grained, coarse sandstone and lithified, fine-grained, carbonaceous siltstone

• ...represent various subenvironments of the delta plain with small distributaries, swamps, freshwater lakes, and marine embayments with a moderately diverse molluscan fauna. The latter may be evidence of a delta abandonment phase, which was either due to switching of delta lobes or eustatic sea-level rise. Tidal influence and sedimentation on mud flats is indicated by thinly interlayered clay-silt beds and lenticular bedding (e.g. at 3,565 m), but appears to have been of minor importance.
• One facies association is composed of finely interlayered silty clay and fine-grained ripple-laminated sandstone, coal, highly carbonaceous silt, in some cases associated with ferruginous concretions, root horizons, channeled, immature (arkosic), large-scale cross-bedded, medium- to coarse-grained, fining-upward sandstone sequences. In addition, 1–3-m thick coarsening upward sequences of silty clay to fine sand occur... Plant debris is ubiquitous, whereas larger wood fragments are restricted to the sandstone bodies.

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 141259: authorized by Martin Aberhan, entered by Thomas Schossleitner on 23.03.2013

Creative Commons license: CC BY (attribution)

Taxonomic list

Bivalvia
 Ostreida - Bakevelliidae
Bakevellia sp. King 1848 oyster
 Pholadida - Ceratomyidae
Ceratomya sp. Sandberger 1864 clam
 Pholadomyida - Pholadomyidae
Gastropoda
 Neogastropoda - Turridae
Pseudomelania sp. Pictet and Campiche 1862 turrid
 Ichnofossils -