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Franciscan complex calera limestones: Accreted remnants of farallon plate oceanic plateaus

J.A. Tarduno·M. McWilliams·M.G. Debiche·W.V. Sliter·M.C. Blake
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Abstract

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. ?? 1985 Nature Publishing Group.

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J.A. Tarduno, M. McWilliams, M.G. Debiche, W.V. Sliter, M.C. Blake. 1985. Franciscan complex calera limestones: Accreted remnants of farallon plate oceanic plateaus. https://doi.org/10.1038/317345a0

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