Paleogene accretion of Upper Cretaceous oceanic limestone in northern California ( USA).

Blocks of pelagic limestone, tectonically incorporated into coastal terrane melange, contain planktonic foraminifers of early Campanian to middle Maestrichtian age (82-69Ma) typical of low latitudes between 20oN and 20oS. Carbonate concretions from the sheared terrigenous matrix of the melange yield temperate, middle-latitude planktonic foraminifers and dinoflagellates of middle to late Eocene age (49-41Ma). The pelagic limestone and the basaltic substrate presumably formed on the E flank of the Pacific-Farallon spreading ridge in a low-latitude zone of high productivity and migrated N on the Farallon plate until approx 40Ma when they initially encountered terrigenous turbidites N of lat. 30oN. N translation and final accretion were completed by approx 25Ma.-Authors