Late Cretaceous – Cenozoic tectonic transition from collision to transtension, Honduran Borderlands and Nicaraguan Rise, NW Caribbean Plate boundary JAVIER SANCHEZ 1 *, PAUL MANN 1 & PETER A. EMMET 1,2 1 Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77204, USA 2 Brazos Valley GeoServices Inc., Cypress, TX 77429, USA *Corresponding author (e-mail: cjsanchez3@uh.edu) Abstract: Northern Honduras and its offshore area include an active transtensional margin sepa- rating the Caribbean and North American plates. We use deep-penetration seismic-reflection lines combined with gravity and magnetic data to describe two distinct structural domains in the Hon- duran offshore area: (1) an approximately 120 km-wide Honduran Borderlands (HB) adjacent to the Cayman Trough characterized by narrow rift basins controlled by basement-involving normal faults subparallel to the margin; and (2) the Nicaraguan Rise (NR), characterized by small-displa- cement normal faulting and sag-type basins influenced by Paleocene – Eocene shelf sedimentation beneath an Oligocene – Recent, approximately 1 – 2 km-thick carbonate platform. Thinning of con- tinental crust from 25–30 km beneath the NR to 6–8 km beneath the oceanic Cayman Trough is attributed to an Oligocene–Recent phase of transtension. Five tectonostratigraphic phases estab- lished in the HB and NR include: (1) a Late Cretaceous uplift in the north and south-dipping thrust- ing related to the collision in the south, between the Chortis continental block and arc and oceanic plateau rocks of the Caribbean; (2) Eocene sag basins in the NR and minor extension in the HB; two phases (3) and (4) of accelerated extension (transtension) across the subsidence mainly of the HB; and (5) Pliocene–Recent minor fault activity in the HB and a stable carbonate platform in the NR. Interplate sedimentary basins are classified accord- ing to the strike-slip, subduction or collisional envi- ronments in which they form (Dickinson 1976; Ingersoll 1988; Busby & Ingersoll 1995). Four controls on basin types include: (1) the degree of convergence or divergence of adjacent blocks that can lead to transpressional or transtensional basins, respectively; (2) the magnitude of the strike-slip displacement and offset along the interplate bound- ary; (3) the crustal type underlying the basin, such as continental, oceanic or intermediate-thickness continental crust; and (4) pre-existing basement structures that could be reactivated during the later strike-slip deformation (Christie-Blick & Biddle 1985). The Honduran Borderlands (HB) and Nicara- guan Rise (NR) include the offshore region of Honduras in the NW Caribbean that is adjacent to the Cayman Trough (Fig. 1). These two distinc- tive geomorphic and structural provinces are the result of the Late Cretaceous collision of the Great Arc of the Caribbean with continental crust of the eastern Chortis Block, followed by left-lateral displacement of the NW Caribbean Plate and Chortis Block from its original position along the SW continental margin of Mexico (Burke 1988; Pindell & Kennan 2001; Mann et al. 2006; Pindell et al. 2006; Rogers et al. 2007a, b). The HB is approximately 100 – 120 km wide and ranges from shelfal (0.2 km) to abyssal (2 km) water depths, with a basin and ridge morphology similar to other strike-slip-controlled borderlands, includ- ing that of offshore southern California (Rogers & Mann 2007) (Fig. 1). The HB is an ideal area to study the controls of strike-slip margin tectonics on the evolution of basins in an area of large strike- slip displacements and associated large-scale plate rotations. Most studies of the tectonic evolution of the Nicaraguan Rise (NR) and Honduras have focused on the onshore area of Honduras since an early period of oil exploration in the 1960s and 1970s (Arden 1975) (Fig. 2). Progress in understanding the offshore and its correlation with the geology of onshore Honduras started in the 1970s with the drilling of several exploration wells in the NR and HB (Fig. 2) (Aves & Manton 1984a, b). However, the obscuring presence of the approximately 1 – 2 km-thick NR carbonate platform resulted in poor From:Nemc ˇok, M., Ryba ´r, S., Sinha, S. T., Hermeston, S. A. & Ledve ´nyiova ´ , L. (eds) Transform Margins: Development, Controls and Petroleum Systems. Geological Society, London, Special Publications, 431, http://doi.org/10.1144/SP431.3 # 2015 The Author(s). Published by The Geological Society of London. All rights reserved. For permissions: http://www.geolsoc.org.uk/permissions. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics by guest on December 15, 2015 http://sp.lyellcollection.org/ Downloaded from