Paleomagnetic studies of Jurassic to Tertiary rocks in Jamaica and Cuba

Sammanfattning: Paleomagnetic studies have been performed on Jurassic to Tertiary rocks in Cuba and Jamaica. Samples of predominantly volcanic and sedimentary rocks were collected at 73 sites and the study included 792 samples. High unblocking temperature components were identified in most samples and the NRMs are carried mainly by magnetite/titanomagnetite and hematite. For one Eocene rock formation in Cuba (the Sabaneta Formation) a positive fold test could be demonstrated and an improved precision of the mean direction after structureal correction could also be demonstrated for Palocene rocks in Jamaica (the More Town Shale Formation), however, the increased precision was not significant at a 95% confidence level. A mean pole position for the Cretaceous of Jamaica was defined from paleomagnetic data of the Summerfield and Guinea Corn Formations. From these data a paleolatitude of 20 degrees north was estimated for Jamaica with respect to the North American reference pole. The paleolatitudinal position of Jamaica was also calculated for the Paleocene (7degrees north; the More Town Shale Formation) and Eocene. (7,4 degrees north; the Richmond Formation), For Cuba a Jurassic-Cretaceous paleolatitudinal position was estimated at 9.6 degrees south (Gabbro of the ophiolite complex) and at the Eocene a latitudinal position was estimated at 21 degrees north (the Sabaneta Formation). Cuba and Jamaica rotated in a pattern that ca be explained by the eastward movement of the Caribbean Plate during the lower Cretaceous to Eocene. The latitudinal position calculated here for Cuba and Jamaica support various technique models presented on basis of geological data.