Rotated oceanic blocks in western Ecuador

Resumen

A paleomagnetic study of over 250 cores from 21 sites sampled over a distance exceeding 250 Km in the early Cretaceous Pinon formation in the Costa of Western Ecuador indicates that the sampled lithologies (essentially MORB‐type basalts and dolerites) carry a stable remanent magnetization, whose direction significantly deviates from that of coeval formations of stable South America. Although both normal and reverse directions have been recorded, the two polarities cannot easily be distinguished because of the low latitude of the ocean floor at the time of formation. The most likely interpretation is that the entire area has undergone 70° clockwise rotation since its genesis. These results thus yield new evidence for an allochtonous origin of this suspect terrane.