Jurassic-recent tectonic and stratigraphic history of the Chortis block of Honduras and Nicaragua (northern Central America)

I document four post-Jurassic tectonic events recorded in the geology of the Chortis block of northern Central America within the context of the regional evolution of the Caribbean plate and the southernmost North American Cordillera. The earliest event is Aptian-early Cenomanian, intra-arc rifting followed by late Cretaceous inversion of the rift basin in the Frey Pedro range of east-central Honduras. A 3.5-km-thick stratigraphic section of clastic, carbonate, volcaniclastic and volcanic rocks were deposited in the intra-arc rift and on its rift shoulders. The geochemistry of rift-related volcanic rocks shows magmatic arc affinity. The northwest-directed Colon fold-thrust belt of eastern Honduras and the Nicaragua Rise and adjacent island arc Siuna belt of northern Nicaragua, record the late Cretaceous collision between the south-facing margin of the Chortis block and the northeastward-moving Caribbean arc system. This previously unrecognized arc-continent collision can be traced for a distance of 350 km across Honduras and the Nicaragua Rise. North trending rifting of the western Chortis block and NNW-SSE transtensional extension of northern Honduras and the offshore Honduran borderlands reveal Miocene to Recent divergence between the Caribbean and North America plates. Observed boundary-normal extension occurs where the angle between the plate boundary fault and the Caribbean motion vector is greater than 10º and boundary-parallel transtension where the angle is between 5 and 10º. P-wave tomographic images of the mantle beneath northern Central America reveal a detached slab of the subducted Cocos plate. Landscape features of the region above the detached slab are consistent with epeirogenic uplift produced by mantle upwelling following slab breakoff between 10 and 4 Ma. Correlation of regional aeromagnetic data with outcrop exposures allows subdivision of the Chortis block into five terranes: 1) Central Chortis with continental Paleozoic basement; 2) Eastern Chortis with Jurassic metasedimentary basement; 3) Southern Chortis of low magnetic intensity and covered by Miocene volcanic strata; 4) Siuna with oceanic island arc basement; and 5) Northern Chortis where early Tertiary magmatism overprints the Central and Eastern Chortis terranes. Common geologic and geophysical characteristics of the Chortis terranes and Mexico terranes allow improved reconstructions of the region prior to its Tertiary fragmentation.Geological Science