F86 - Silverado Formation, Santa Ana Mountains (Paleocene of the United States)

Also known as USGS #18983; Field #S25

Where: Orange County, California (33.9° N, 117.7° W: paleocoordinates 37.5° N, 98.2° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Silverado Formation, Thanetian (59.2 - 56.0 Ma)

• The type section suggests a thickness of around 350 m for the Silverado Formation, which lies unconformably upon the Late Cretaceous Williams Formation and Ladd Formation, and is overlain unconformably by the Santiago Formaton. The Silverado Formation is given a Paleocene age on the basis of macrofauna (sparse index taxa), but more finely assigned by McCulloh et al. (2000) to the Martinez stage = Thanetian. Calcareous nannoplankton zone CP7-CP; Planktonic foraminifera zone P4-P5; Ynezian foram zone. The Silverado Formation is correlative to the lower-middle Santa Susana Formation. From uppermost marine fossiliferous part of formation.

• bed-level stratigraphic resolution

Environment/lithology: marine; fine-grained, medium sandstone

• The contact below the Silverado Formation represents an episode of deformation and extensive erosion and deep weathering between the deposition of the late Cretaceous rocks and the Paleocene strata.
• Fine-medium grained sandstone

Size class: macrofossils

Reposited in the USGS

Collection methods: quarrying,

• Collected by J.E. Schoelhamer. Material likely to be reposited in USGS Menlo Park collections or USNM.

Primary reference: J. E. Schoellhamer, J. G. Vedder, R. F. Yerkes and D. M. Kinney. 1981. Geology of the Northern Santa Ana Mountains, California. United States Geological Survey Professional Paper 420(D):1-109 [J. Alroy/J. Alroy/R. McClees-Funinan]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 52596: authorized by Austin Hendy, entered by Austin Hendy on 11.08.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

• Fossils identified by Stewart (1954, 1955) and Moore (1959). Relatively good nomenclature
Bivalvia
 Arcida - Glycymerididae
"Glycymeris cf. veatchii" = Axinaea veatchii
"Glycymeris cf. veatchii" = Axinaea veatchii Gabb 1864 clam
Subspecies: Glycymeris veatchii major
 Arcida - Cucullaeidae
 Mytilida - Mytilidae
Brachidontes cf. lawsoni Nelson 1925 mussel
 Pholadida - Corbulidae
 Cardiida - Veneridae
? Macrocallista sp., "? Pitar cf. uvasana" = Meretrix uvasana
? Macrocallista sp. Meek 1876 venus clam
"? Pitar cf. uvasana" = Meretrix uvasana Conrad 1855 venus clam
 Cardiida - Cardiidae
Cardiidae indet. Lamarck 1809 cockle
 Lucinida - Lucinidae
Miltha (? Plastomiltha) sp. Adams and Adams 1857 clam
 Protobranchia - Nuculanidae
Nuculana cf. gabbi pointed nut clam
Gastropoda
 Cephalaspidea - Cylichnidae
"Cylichnina cf. tantilla" = Cylichnella tantilla Anderson and Hanna 1925 snail
 Neogastropoda - Olividae
Ancilla sp. Lamarck 1799 olive snail
 Neogastropoda - Buccinidae
? Pseudoliva sp. Swainson 1840 true whelk
 Neogastropoda - Tudiclidae
 Neogastropoda - Conidae
Conus sp. Linnaeus 1758 cone shell
 Stromboidea - Strombidae
"Ectinochilus (Cowlitzia) sp." = Rimella
"Ectinochilus (Cowlitzia) sp." = Rimella Agasiz 1841 true conch
 Ficoidea - Ficidae
Ficopsis sp. Conrad 1866 fig shell
 Naticoidea - Naticidae
Amaurellina sp. Fischer 1885 moon snail
 Calyptraeoidea - Calyptraeidae
Calyptraea diegoana Conrad 1857 slipper shell
 Sorbeoconcha - Turritellidae
Turritella pachecoensis Stanton 1896 turret shell
 Turbinoidea - Turbinidae
? Homalopoma cf. wattsi Dickerson 1916 snail