Journal article Open Access

Franciscan Complex Calera limestones: accreted remnants of Farallon Plate oceanic plateaus

Tarduno, John A.; McWilliams, Michael; Debiche, Michel G.; Sliter, William V.; Blake, M. C.

The Calera Limestone, part of the Franciscan Complex of northern California, may have formed in a palaeoenvironment similar to Hess and Shatsky Rises of the present north-west Pacific1. We report here new palaeomagnetic results, palaeontological data and recent plate-motion models that reinforce this assertion. The Calera Limestone may have formed on Farallon Plate plateaus, north of the Pacific–Farallon spreading centre as a counterpart to Hess or Shatsky Rises. In one model2, the plateaus were formed by hotspots close to the Farallon–Pacific ridge axis. On accretion to North America, plateau dissection in the late Cretaceous to Eocene (50–70 Myr) could explain the occurrence of large volumes of pillow basalt and exotic blocks of limestone in the Franciscan Complex. Partial subduction of the plateaus could have contributed to Laramide (70–40 Myr) compressional events3.

Files (462.3 kB)
Name Size
article.pdf
md5:66048dd8b8fd6429f700636f0d5d8614
462.3 kB Download
42
28
views
downloads
Views 42
Downloads 28
Data volume 12.9 MB
Unique views 42
Unique downloads 27

Share

Cite as