Seismic study of Bonaire structure

Bonaire is located 90 km offshore of Venezuela on the Caribbean Plate near the boundary with the South American plate. Bonaire's igneous basement dates to the Cretaceous when the plate was located in the Pacific Ocean. In the Pleistocene the island was uplifted due to the collision of the Caribbean and South American Plates, which allowed for the formation of carbonate terraces on igneous highs. The southern Caribbean plate exhibits multiple types of deformation that result from the complex tectonic relationship with the South American plate. Regionally there is a transform fault to the southeast of Bonaire, a convergent boundary to the north, and a subduction boundary to the W-NW. Locally previous work has shown nearshore marine deformation in the form of two sets of normal faults and one set of reverse faults with ages ranging from the Eocene-Holocene. Onshore, previous work defined structural deformation in northern Bonaire, including a plunging anticline that continues offshore. However, little data constrains the placement of onshore deformation as well as Bonaire's role in southern Caribbean tectonic deformation.

There is a paucity of geophysical data on Bonaire, and therefore limited information about the subsurface. We acquired 2.3 km of seismic reflection and refraction data in northern Bonaire, using a 24-channel land streamer with a sledgehammer source, 2-3 km to the southeast of Rincon. The survey was conducted on a bike trail that begins near Queens highway and runs northeast halfway across the island. The seismic data is coincident with a ground penetrating radar (GPR) survey that extends to the northeastern coastline. We plan to process the seismic reflection data to image the subsurface and use refraction data to construct a tomographic model of the subsurface.

Our goal is to use the geophysical results to map the contact between the igneous basement and overlying carbonates, and to provide constraint for the structural deformation observed in northern Bonaire. We will correlate our results to high-resolution marine seismic work offshore to help identify seismic facies and deformation in the offshore data. The results from these combined geophysical surveys on Bonaire can help us to interpret Bonaire's role in the complex tectonic interactions of the Caribbean and South American plates.