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Section 2, Cycle 2, Unit 5 (Karoo Sequence) (Permian of Namibia)

Also known as Damaraland; Karroo; Huab Basin

Where: Erongo, Namibia (21.2° S, 14.1° E: paleocoordinates 51.0° S, 30.5° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Huab Formation ("Ecca" Group), Artinskian (290.1 - 279.5 Ma)

• Cycle 2 is at the top of Unit 5 in Sections 2, 3, 4, and interfingers with the sandstones of Unit 6 in section 5. underlies the Gai-as Formation (=depositional unit 7). Unit 5/6 is correlated with the Irati Shale Fm in the Parana Basin, Rio Grande do Sul, Brazil, and with the upper Prince Albert Fm and overlying Whitehill Fm in the Karoo Basin, Eastern Cape Province, South Africa (Horsthemke et al., 1990).

•The description above along with absolute datings of ash beds in the Gai-as Fm. (272-263 Ma; see Warren et al., 2001, J. Vert. Paleont.), a bentonite bed in the Irati Fm. (278.5 Ma; see Santos et al., 2006, Gondwana Res. 9) and a tuff bed in the Whitehill Fm. of southern Namibia (280.5 Ma; Werner, 2006, PhD thesis, http://www.opus-bayern.de/uni-wuerzburg/volltexte/2007/2175/pdf/00-Complete_thesis-STD.pdf) implies an Artinskian age (cf. time scales in Gradstein et al. (2004) and Ogg et al. (2008)) for the beds in question (referred to as Huab Formation in Warren et al., 2001) (TL).

•According to the facts given above the original maximum time interval entry >>Rotliegendes<< is replaced by >>Artinskian<<, the group name >>Karoo<< is replaced by >>"Ecca"<< (due to the fact that "Karoo" refers to a superordinate unit and the Huab Fm. is part of a series equivalent to the Ecca Group of the Main Karoo), and formation name >>Huab<< is added (TL).

• group of beds-level stratigraphic resolution

Environment/lithology: lacustrine; concretionary, stromatolitic mixed carbonate-siliciclastic sediments and calcareous shale

• Shallow lake with increased salinity.
• Cycle 2: Section 2 in the west is composed of carbonates (domal stromatolites with east west orientation and thin laminae <1 mm); eastward sections 3 and 4 are oolitic conglomeritic horizon up to 50 cm thick. Carbonates are overlain by silty, partly calcareous shales (containing abundant syneresis cracks in section 4). "Cycle 2 is of special regional importance in that it ubiquitously and, in virtually all lithological units, contains bones of the amphibious reptile Mesosaurus tenuidens." Mesosaurus fossils are found in concretions.

Size class: macrofossils

Preservation: concretion

Collection methods: not clear whether any fossils were collected

Primary reference: E. Horsthemke, S. Ledendecker, and H. Porada. 1990. Depositional environments and stratigraphic correlation of the Karoo Sequence in northwestern Damaraland. Communications of the Geological Survey of South West Africa/Namibia 6:63-73 [J. Alroy/R. Whatley/M. Uhen] more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 28468: authorized by John Alroy, entered by Robin Whatley on 15.02.2003

Creative Commons license: CC BY (attribution)