Abstract Northern Honduras and its offshore area include an active transtensional margin separating 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 Honduran 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-displacement 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 continental 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 established in the HB and NR include: (1) a Late Cretaceous uplift in the north and south-dipping thrusting 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.

Abstract The offshore South Caribbean deformed belt (SCDB) is a 100-km-wide (62 mi), late Cenozoic sedimentary accretionary prism formed where the Caribbean plate is obliquely subducted beneath northern South America. Progradation of deltaic deposits of the 1500-km-long (932 mi) Magdalena River over the SCDB and tectonic deformation of the deltaic sedimentary rocks has created one of the youngest (last 10 Ma) and thickest (5–18 km [3–5 mi]) accretionary prisms in the world. We use three types of data (deep-penetration, seismic-reflection profiles, gravity modeling collinear with the seismic lines, and structural restorations) to describe the late Miocene to Recent thrust kinematics of the 10- to 18-km-thick (6.2–11.1 mi) SCDB formed above the subducting Caribbean Oceanic Plateau whose crust varies in thickness from 17 km (10.6 mi) in the southern part of the 180-km-long (111 mi) study area to 8 km (4.9 mi) in the north. In the southern area of thicker subducted plateau crust, the structural style is characterized by Neogene growth strata defining a major thrusted sequence that is backthrust in a landward direction, deformed by reactivation of preexisting faults as out-of-sequence thrust (OOST) faults, common shale diapirism, and active, margin-parallel strike-slip faults that accommodate the oblique-slip component of subduction. In the northern area of thinner oceanic crust (6–8 km [3.7–4.9 mi]), the structural style includes seaward-verging, imbricated thrust fans with less prominent backthrusting and strike-slip faulting, and more prominent shale diapirism. Proposed controls for the observed structural differences between the northern and southern areas include (1) more buoyancy of the subducted plate in the southern area due to its greater crustal thickness, and (2) the presence of more overpressured and ductile deformed shale layers with associated shale diapirs in the north.

Abstract The complex tectonic evolution of northwestern South America is recorded by a variety of deformed, onland basins ranging in age from Paleozoic to recent. We integrate the Mesozoic to recent structural geology and basinal history of the 12,000 km 2 , intermontane Cesar-Rancheria Basin (CRB) in northern Colombia to reconstruct the tectonic history of the basin and tectonic controls on its sedimentation, subsidence history, and petroleum systems. Methods and data used for this study include (1) interpretations of crustal structure using gravity and magnetic modeling; (2) subsurface mapping of key horizons using 3500 km (2175 mi) of two-dimensional (2-D) seismic reflection data tied to 16 wells; (3) construction of serial structural cross sections, which are balanced to the level of Late Cretaceous sedimentary rocks; and (4) construction of burial history graphs and development of a 2-D basin model showing predicted oil and gas windows. Basement-involved southeast-dipping reverse faults expose Jurassic to early Cretaceous rocks in the CRB and Paleozoic rocks in the Perija range (PR) east of the CRB. About 10% of shortening across the CRB is a consequence of motion along these faults driven by discrete interactions between the Caribbean and South America plates. Two major periods of NW-SE crustal, interplate shortening are identified: (1) an early–middle Eocene, west-to-east shortening event that produced east-dipping Cretaceous and Paleocene strata beneath a major unconformity that increases in erosional hiatus from east to west across the study area; this shortening and overlying unconformity is related to the collision of the Great Arc of the Caribbean with the northwestern continental margin of the South American plate; and (2) a late Miocene–Pliocene, west-to-east shortening event with major exhumation of the eastern CRB where faulting of recent sedimentary deposits are related to the collision between the Panama Arc and northwestern South America. The west-to-east migration of deformation during the Cenozoic controlled by the west-to-east, diachronous collision between the Great Arc of the Caribbean and northern South America also led the present-day distribution of preserved depocenters with a major thickness of the Paleocene-early Eocene section to the east of the study area, and a major Miocene depocenter to the west.

Abstract The Magdalena Valley fold-and-thrust belt is a tectonic province associated with inverted rift zones. This belt displays a narrow and discontinuous deformation front indicating association with inversion tectonics. We show the differences with an analogue belt on the eastern side of the Eastern Cordillera (Llanos foothills). To do that we use structural data (seismic, wells and geological maps) which characterize different structural geometries as well as palaeocurrents, provenance and thermochronology to analyse the timing of deformation. The new datasets allowed us to detect that inversion is limited whenever the stresses are more orthogonal to the rift structures, whereas the mountain front is more segmented in comparison to the Eastern Foothills because of the absence of a continuous low basal friction detachment horizon and a pronounced eastwards basement dip. These two factors favoured fault hard linkage. It is remarkable that, in spite of the distinct segmentation, all the different segments in the Magdalena belt are coeval. Supplementary material: U–Pb Zircon data are available at: http://www.geolsoc.org.uk/SUP18630 .