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Rotated oceanic blocks in western Ecuador
Author(s) -
Roperch P.,
Mégard F.,
Laj C.,
Mourier T.,
Clube T. M.,
Noblet C.
Publication year - 1987
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl014i005p00558
Subject(s) - terrane , paleomagnetism , geology , clockwise , cretaceous , paleontology , low latitude , basalt , lithology , latitude , remanence , mid ocean ridge , rotation (mathematics) , geophysics , magnetization , tectonics , geodesy , geometry , physics , mathematics , quantum mechanics , magnetic field
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.