Abstract. The Puerto Rico-Virgin Islands carbonate platform was deposited over an area of 18,000 km 2 from early Oligocene to Holocene on top of an inactive and subsiding Cretaceous-earliest Oligocene island arc. Regional single-channel and multichannel seismic reflection lines presented in this study provide the first information on the regional stratigraphy and structure of this platform that has previously been known mainly from onshore stratigraphic sections of a relatively small (2250 km 2) portion of the platform exposed by late Neogene tectonic uplift along the north

High-resolution single-channel seismic refl ection profi les, bathymetry and sidescan sonar imagery from the Puerto Rico trench document the present-day and postcollisional effects of the obliquely subducting southeastern extension of the Bahama Province and the Main Ridge fracture zone on the northern Puerto Rico-Virgin Islands margin. In contrast to an orthogonal system, where it is unlikely that two high-standing ridges will impact the same section of margin, along the Puerto Rico trench convergence is highly oblique and the deformational effects of the two ridges are superimposed and often diffi cult to isolate. A middle-upper Miocene margin-wide unconformity in the Oligocene-lower Pliocene shallow-water carbonate platform of the Virgin Islands, Puerto Rico, and eastern Hispaniola provides an excellent horizontal reference frame for the timing and impact of the high-standing ridges on the margin. During the past 10 m.y., trenchward tilting (4-6°) of the carbonate platform including the margin-wide erosional surface to >5000 m water depths provides evidence that the margin has experienced signifi cant subsidence. In this paper we present a model of accelerated subduction erosion and diachronous margin subsidence triggered by the ridges sweeping from east to west beneath the Puerto Rico forearc. Evidence for ongoing and past subduction erosion include zones of enhanced seismicity, oversteepening and mass wasting of the forearc slope, and landward migration of the inner trench-slope break. We document over 3 km of Neogene subsidence presumed to be the result of rapid crustal thinning associated with the tunneling of the

No abstract

No abstract

No abstract