USGS MR 4343, Marin Headlands (M-20) (Jurassic to of the United States)

Where: Marin County, California (37.9° N, 122.5° W: paleocoordinates 30.4° N, 58.0° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Toarcian to Toarcian (182.7 - 170.3 Ma)

• Assemblage MH-2?: Middle Jurassic, probably Bajocian (U.S. Geological Survey does not recognize Aalenian, but considers such strata early Bajocian). Toarcian-Aalenian 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 185338: authorized by Matthew Clapham, entered by Matthew Clapham on 18.04.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

Radiolaria
 Nassellaria - Hsuidae
Hsuum "sp. B" Pessagno 1977 radiolarian
 Nassellaria - Parvicingulidae
Parvicingula "sp. A" Pessagno 1977 radiolarian