Crustal Structure, Deformational History, and Tectonic Origin of the Bahamas Carbonate Platform.

The 2–10‐km‐thick, mainly carbonate cap of the 14,000 km2 Bahamas carbonate platform (BCP) has impeded imaging of its underlying crustal structure. The deeper structure of the BCP records both its Mesozoic rift and hotspot history and its later deformation related to its Paleogene collision with the Great Arc of the Caribbean (GAC). We use regional gravity data to model the crustal structure, type, and deformational processes of the BCP by: (a) integrating publicly available seismic data; (b) inverting the Moho along 2D regional gravity transects across the collisional zone; (c) modeling flexural uplift of a forebulge that reflects the attempted subduction of the BCP beneath the GAC; and (d) using downhole temperatures and radiogenic heat production in 1D basin models to differentiate crustal types related to the Mesozoic rift history. We interpret three crustal domains underlying the BCP: (a) 27–12‐km‐thick, rifted, and thinned continental crust of the northern Bahamas between the Blake Plateau and Exuma Sound; (b) 24–12‐km‐thick, volcanically‐thickened oceanic crust related to the Triassic‐Jurassic Bahamas hotspot in the central Bahamas southeast of Long Island; and (c) 20–12‐km‐thick, thickened oceanic crust north of Hispaniola. We propose that these crustal types reflect northwest‐southeastward, Triassic‐Jurassic rifting of the Bahamas region during the breakup of Pangea and accompanying magmatic activity related to the Triassic‐Jurassic Bahamas hotspot and early oceanic spreading. Growth of the BCP during the Cretaceous in this area was followed by Late Cretaceous‐Paleogene subduction‐related flexure and terminal Paleogene collision between the GAC and the BCP. Plain Language Summary: We investigate the thickly‐sedimented and difficult‐to‐image Bahamas carbonate platform (BCP) by generating different gravity‐based models of its sub‐surface crustal structure. These models help us better understand the crustal types extended and formed during Mesozoic rifting and hotspot activity and the later deformation of these crustal types during the Paleogene collision between the Cuban island arc and the BCP. Key Points: Regional, gravity‐based crustal models are generated for the Paleogene collisional zone between the Bahamas carbonate platform and the Great Arc of the CaribbeanFlexural modeling of the basement beneath the Bahamas reveals a suture‐parallel, forearc bulge produced by Paleogene underthrustingBurial plots of deep wells across the platform reveal the timing and extent of Mesozoic rift, passive margin, and collisional events [ABSTRACT FROM AUTHOR]