Compiler: Jan Ehrenberg
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One color sheet, 44.5" x 38". From text: This map presents a new stratigraphy for the tertiary volcanic rocks in the Nicaraguan Highland, going from a layer-cake interpretation to a facies interpretation. Semiregional geologic mapping of Tertiary volcanic rocks in the Nicaraguan Highland was carried out east and northeast of Managua from 1986 to 1991 as part of the SAREC (Swedish Agency for Research Cooperation with Developing Countries)/INMINE (Instituto Nicaragüense de la Minería)/SGAB (Swedish Geological Company) geoscience project. The general results of this study have been published in Ehrenborg, 1996. This map is a companion to that article. Tertiary volcanic rocks of the Coyol and Matagalpa Groups dominate the geology in the map area. Physiographically the area is part of the Nicaraguan Highland. The map area in the southwest is dominated by the Nicaraguan Depression, with its interstratified sedimentary and volcanic rocks. Crossing the eastern side of the Nicaraguan Depression toward the northeast, the relief changes into a flat upland dominated by rhyolitic to dacitic pyroclastic flows and basaltic to andesitic lavas and breccias, both part of the Coyol Group. The central and eastern parts of the area are dominated by rolling hills made up of basalt and andesite of the Coyol Group. This region is dissected by northeast-trending valleys where underlying pyroclastic deposits of the Matagalpa Group are exposed. The Matagalpa Group dominates the northeastern part of the area where it constitutes a flat and low-lying terrain. It is underlain by sedimentary and volcanic rocks of the Sub-Matagalpa Group exposed in the northeasternmost part of the area.
Published: 3/01/1999
Pages: 1 sheet
Product Category: Maps and Charts