USGS MR 5115, Alexander Avenue, Marin Headlands (M-2aQ) (Cretaceous to of the United States)

Where: Marin County, California (37.8° N, 122.5° W: paleocoordinates 35.2° N, 69.7° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Valanginian to Valanginian (139.8 - 125.5 Ma)

• Assemblage MH-5: MH-5 is correlative with Valanginian to Hauterivian or early Barremian radiolarian zones in circum-Pacific onland sequences as well as with Deep Sea Drilling Project zonation schemes. The range of MH-5 is Valanginian to Hauterivian or early Barremian.

• 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 185262: authorized by Matthew Clapham, entered by Matthew Clapham on 17.04.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

Radiolaria
 Nassellaria - Archaeodictyomitridae
"Archaeodictyomitra apiaria" = Archaeodictyomitra apiarium
"Archaeodictyomitra apiaria" = Archaeodictyomitra apiarium Rüst 1885 radiolarian
 Nassellaria - Pseudodictyomitridae
Pseudodictyomitra "sp. A" Pessagno 1977 radiolarian
 Nassellaria - Parvicingulidae
Mirifusus ? mediodilatatus Rüst 1885 radiolarian
 Nassellaria - Syringocapsidae
Podobursa "sp. A" Wisniowski 1889 radiolarian
 Entactinaria - Saturnalidae