Three-dimensional Euler deconvolution and tectonic interpretation of marine magnetic anomaly data in the Puerto Rico trench

During the summer of 1996 single-channel-seismic, magnetic, gravity, Hydros weep bathymetric and HMR1 sidescan data were collected north of the island of Puerto Rico to constrain the geologic and tectonic setting of the Puerto Rico trench. Magnetic data from this cruise are merged with other availabl e data, then processed and interpreted with the aid of the Euler deconvolut ion method. The area north of the island of Puerto Rico is divided into thr ee magnetic anomaly zones. Zone 1 is dominated by northwest to southeast tr ending magnetic anomalies. Zone 2 consists of an east-west region of relati vely low amplitude anomalies and occurs south of zone 1. Zone 3 is dominate d by the highest magnetic values in the study area and the source region is roughly centered under the island of Puerto Rico. Respectively, these zone s approximate three geologic provinces of the Puerto Rico trench composed o f Early Cretaceous ocean crust with sedimentary cover, a blueschist belt an d an Oligocene-Cretaceous island are with a limestone cap. Also mapped are the Main Ridge fracture zone and the Fourth of July fracture zone, both on the Worth American plate, which correlate with the Main Ridge and Fourth of July Ridge on the Caribbean plate. The 3-D Euler deconvolution facilitates the identification of new faults as well as the mapping of known faults al so evident in the seismic and bathymetric data. A model concerning the form ation of the Puerto Rico trench is proposed that incorporates the existence of strike-slip faults and the fracture zones associated with the subductio n of the North America Plate. Evidence from this study support a tectonic i nterpretation of subduction followed by more recent strike-slip faulting th at is accompanied by only a minimal amount of subduction.