Metallogenic evolution of central and southwestern Honduras, Central America.

We studied the geology of 50 deposits out of 103 metal ore deposits distributed in central and southwestern Honduras of Central America. Based on geological characteristics, these 50 deposits were classified into the following five types: 1) orogenic gold, 2) sedex, 3) hydrothermal (low-sulfidation epithermal, high-sulfidation epithermal, mesothermal, hypothermal), 4) porphyry copper, and 5) skarn.<BR>K-Ar dating of K-bearing hydrothermal-alteration minerals from 18 deposits out of the 50 deposits yielded 206 Ma for one orogenic gold deposit, 86-67 Ma for four hydrothermal deposits, 40-2.5 Ma for 12 hydrothermal deposits and 13 Ma for one porphyry copper deposit. Moreover, formation ages of sedex and skarn deposits, which yielded no mineral proper for K-Ar dating, were inferred from related geological data. Taking the K-Ar ages and the inferred formation ages into consideration, we concluded that metallogenic evolution of central and southwestern Honduras were as follows: 1) "in Early Jurassic" orogenic gold deposits were formed, 2) "from the latter half of Jurassic to the middle of Early Cretaceous (?)" sedex deposits were formed, 3) "from the middle of Late Cretaceous to Oligocene" hydrothermal and skam deposits were formed, 4) "in Miocene" hydrothermal, porphyry copper, and skam deposits were formed, 5) "in Pliocene" hydrothermal deposits were formed.<BR>Comparison of the above-mentioned metallogenic evolution to the plate-tectonic evolution revealed by an existing study reached an interpretation that each type of mineralization might have taken place under the control of plate-tectonic setting of the Chortis block, in which Honduras is located, as follow: 1) orogenic gold deposits were formed under the condition that a part of the Honduras Group accreted to the Chortis block in Early Jurassic, 2) sedex deposits were formed under tension stress condition of the Chortis block, which moved eastward due to seafloor spreading from the latter half of Jurassic to the middle of Late Cretaceous, 3) hydrothermal, porphyry copper, and skarn deposits were formed under active igneous condition caused by subduction of oceanic plates after the middle of Late Cretaceous.