Mesozoic Stratigraphy of Honduras

Abstract

Honduras, from the geological viewpoint, has long been a poorly understood region of northern Central America. This paper is an attempt to describe the Mesozoic stratigraphy and to sketch the geological history of the country. With the aid of micropaleontological age determinations, the writers introduce a new sedimentary rock group name with four facies having formation status. Most of the San Juancito Mountains terminology defined by Carpenter (1954) is extended throughout Honduras. The history of the country is described according to geotectonic cycles after Dengo and Bohnenberger (in press). After the late Paleozoic orogeny, the taphrogenic phase of the Jaliscoan cycle involved block faulting that created a shallow trough which extended from the Caribbean into southern Morazan and El Paraiso Departments. Shallow-marine and flood-plain black shale and sandstone comprise the El Plan Formation which was deposited during Jurassic time. Folding and block faulting occurred during Late Jurassic and Neocomian times and post-orogenic Todos Santos molasse clastic sediments were deposited. The Mexican cycle started with orthogeosynclinal subsidence during Aptian time. By Albian time, the Honduras Intracontinental basin was formed, including at least three local basins, the Jocotan, Ulua, and Mosquitia. The Honduras Intracontinental basin was the southern counterpart of the Mexican miogeosyncline in Guatemala, but was separated partly from it by the Nuclear foreland which occupied a large part of the Caribbean Sea. The Honduras Intracontinental basin was bordered on the south by a hinterland that extended from southeast Guatemala, across southern Honduras, and along the Honduras-Nicaragua border to the Nicaragua Rise The Yojoa Group was deposited during Aptian-Turonian time. It includes a backreef facies, the Cantarranas a patch-reef facies, the Atima a forereef facies, the Guare and a mid-Albian limestone-conglomerate facies, the Ilama Formation. Intense Laramide orogenesis began at the end of Turonian time, and the older sediments were strongly folded and faulted into a series of east-west-striking anticlines. The taphrogenic phase of the Mexican cycle began in Late Cretaceous time, and was accompanied by post-orogenic molasse deposition, the Valle de Angeles redbed group. Block faulting outlined the grabens of the Honduras depression, and during the Late Cretaceous-Eocene transition period, a shallow sea invaded the Ulua basin through Sula Valley; marly limestone and shale, called the Esquias Formation, were deposited in this sea During middle Tertiary time, there was extensive uplift and widespread magmatic activity. The Nuclear foreland foundered, leaving only a ridge between the present-day Bay Islands and the Northern Cordillera. Block faulting during this time determined the final form of the Honduras depression. Transcurrent faulting occurred in the western Mosquitia region. The final magmatic stage of the taphrogenic phase was late Cenozoic volcanism which formed the volcanic chain along the Pacific Coast of Central America. The Nuclear foreland continued to subside; all that remains today of this foreland are the Bay Island ridge and the Northern Cordillera. End_Page 1711------------------------------