USGS MR 5103, Alexander Avenue, Marin Headlands (M-2aI) (Jurassic of the United States)

Where: Marin County, California (37.8° N, 122.5° W: paleocoordinates 31.4° N, 60.8° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Bajocian (170.3 - 168.3 Ma)

• Assemblage MH-3: The possible range of assemblage MH-3 is considered to be Middle Jurassic (Bajocian to Callovian) and possibly lower Upper Jurassic (Oxfordian?, Kimmeridgian?). Restricted to Bajocian in Kohnen & Murchey, 1995.

• bed-level stratigraphic resolution

Environment/lithology: basinal (siliceous); lithified chert

Size class: macrofossils

Reposited in the USGS

Primary reference: B. Murchey. 1984. Biostratigraphy and lithostratigraphy of chert in the Franciscan complex, Marin Headlands, California. Franciscan Geology of Northern California Field Trip Guidebook 43, Society of Economic Paleontologists and Mineralogists, Pacific Section 51-70 [M. Clapham/M. Clapham]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 185252: authorized by Matthew Clapham, entered by Matthew Clapham on 17.04.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

Radiolaria
 Nassellaria - Williriedellidae
"Tricolocapsa cf. plicarum" = Striatojaponocapsa plicarum
"Tricolocapsa cf. plicarum" = Striatojaponocapsa plicarum Yao 1979 radiolarian
 Nassellaria -
Tricolocapsa "sp. A" Haeckel 1881 radiolarian
Tricolocapsa "sp. B" Haeckel 1881 radiolarian
 Nassellaria - Unumidae
Unuma "sp. A" Ichikawa and Yao 1976 radiolarian
Unuma "sp. B" Ichikawa and Yao 1976 radiolarian
 Nassellaria - Hsuidae
Hsuum "sp. C" Pessagno 1977 radiolarian
 Nassellaria - Xitidae
Foremanina "sp. A" Empson-Morin 1981 radiolarian
 Nassellaria - Ultranaporidae
Napora "sp. D" Pessagno 1977 radiolarian
 Nassellaria - Parvicingulidae
Mirifusus "sp. A" Pessagno 1977 radiolarian
? Dictyomitrella kamoensis Mizutani and Kido 1983 radiolarian
Ristola "sp. A" Pessagno and Whalen 1982 radiolarian
 Entactinaria - Saturnalidae
Acanthocircus suboblongus Yao 1972 radiolarian