TH Pit: Dyeran, Nevada
collected by J. S. Hollingsworth

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Trilobita - Corynexochida - Edelsteinaspididae
Polliaxis hanseni n. sp. Hollingsworth 2005
Trilobita - Redlichiida - Olenellidae
Teresellus goldfieldensis n. gen., n. sp. Hollingsworth 2005
Trilobita - Redlichiida - Wanneriidae
Elliptocephala praenuntius (Cowie 1968)
Trilobita - Ptychopariida - Solenopleuridae
? Keeleaspis terhaari n. sp. Hollingsworth 2005
see common names

Geography
Country:United States State/province:Nevada County:Esmeralda
Coordinates: 37.7° North, 117.3° West (view map)
Paleocoordinates:1.3° South, 95.0° West
Basis of coordinate:stated in text
Time
Period: Cambrian Epoch: Series 2
10 m.y. bin: Cambrian 2-3
Key time interval: Dyeran Trilobite zone:  Bonnia-Olenellus
Age range of interval: 514.8 - 511 m.y. ago
Stratigraphy
Formation:Poleta Member:Middle
Stratigraphy comments: "The base of the Dyeran Stage is drawn at the abrupt faunal change from “Nevadella” Zone trilobites to those of the Bonnia- Olenellus Zone (Fritz, 1972). This distinct transition occurs 97 m above the base of the middle member of the Poleta at the stratotype section. In turn, the TH Pit is 64 m above this stage boundary."
Lithology and environment
Primary lithology: calcareous siltstone
Secondary lithology:lenticular,fine sandstone
Lithology description: "At the TH Pit, the fossiliferous interval ranges from 26 to 48 cm in thickness averaging about 30 cm. The calcareous siltstone is commonly laminated but portions up to two cm thick have obscure, swirled bedding (Fig. 2b). This bed has been traced laterally for at least 250 m where it sometimes contains numerous lenses and clasts of carbonate. The tri- lobite content is variable but they are never as common as at the TH Pit. Above and below this bed, there are numer- ous fine sandstone beds about a meter thick (Fig. 1c). These beds are lenticular along strike, with laminated bedding sometimes swirled into ball-and-pillow structures (Fig. 2d).
Environment:open shallow subtidal Tectonic setting:passive margin
Glacial or sequence phase:regressive
Geology comments: The middle member is mostly siliciclastics, 198 m thick, beginning with deep subtidal siltstones, shallowing upward through an interval of sandstones and siltstones with inter- bedded carbonate beds.
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils
Articulated whole bodies:some
Disassociated major elements:many
Collection methods and comments
Collection methods:bulk,selective quarrying,mechanical,field collection
Collection size:657 specimens
Rock censused:1000 kg
Reason for describing collection:general faunal/floral analysis
Museum repositories:USNM
Collectors:J. S. Hollingsworth
Collection method comments: "Nearly a tonne of material has been removed and split. The hand-dug pits are located at 37°43.48'N and 117°19.00'W."
"Illustrated materials are reposited in the collections of the Department of Paleobiology, National Museum of National History (USNM), Smithsonian Institution, Washington, DC. and the Institute for Cambrian Studies reference and replica collection (ICS). The remainder of the TH Pit collection is housed in my personal biostratigraphic collections."
Metadata
Database number:204959
Authorizer:J. Marcot Enterer:J. Marcot
Research group:marine invertebrate
Created:2019-10-01 10:54:08 Last modified:2019-10-01 10:54:08
Access level:the public Released:2019-10-01 10:54:08
Creative Commons license:CC BY
Reference information

Primary reference:
70351. J. S. Hollingsworth. 2005. A trilobite fauna in a storm bed in the Poleta Formation (Dyeran, Lower Cambrian), western Nevada, U.S.A. Geosciences Journal 9(2):129-143 [J. Marcot/J. Marcot]