Stratigraphic implications of palaeomagnetic data from Honduras

SUMMARY Palaeomagnetic results from mainly Cretaceous rocks in Honduras delineate a distinctive apparent polar wander path (APWP) which is well suited for magnetostratigraphy. The APWP is based on palaeomagnetic data from palaeontologically dated units in the established stratigraphic column and three radiometrically dated intrusions. The ages and stratigraphic positions of sedimentary units whose stratigraphic assignments have been debated, can be inferred by comparing their palaeornagnetic pole postion with the known APWP. The results demonstrate the usefulness of magnetostratigraphy for resolving stratigraphic problems in the absence of fossils or marker beds, and for areas of discontinuous exposures. For regional interpretations, the most important conclusion is that strata in Honduras that have been assigned to the Todos Santos Formation were not deposited on the same tectonic plate as the Todos Santos Formation of Guatemala and southern Mexico. There is no evidence that the Honduran ‘Todos Santos’ strata are depositionally related to the true Todos Santos Formation. The name ‘Todos Santos Formation’ should be abandoned in Honduras and for the entire Chortis Block.