Geology of the Zambrano Quadrangle, Honduras, Central America

Front Cover
University of Texas at Austin, 1970 - Geology - 256 pages
0 Reviews
The Matagalpa Formation, the oldest unit exposed (Oligocene? - Early Miocene?), consists of over 300 meters of hydrothermally altered mafic flows and some interbedded sedimentary rocks. Up to 1400 meters of siliceous volcanic and sedimentary rocks (Mid-Miocene-Pliocene?), correlative with the Padre Miguel Group in Guatemala, nonconformably overlie the Matagalpa Formation. The lower 1000 meters of this group consists mainly of rhyolitic to andesitic ignimbrites that were probably erupted from a vertically zoned magma. Faulting accompanied the extrusion of these ignimbrites. These are overlain by up to 400 meters of airfall tuffs, fluvial, lacustrine, and laharic deposits, and a series of structurally-controlled rhyolitic domes. The uppermost unit consists of several thin ignimbrites. Most of the faulting occurred after the deposition of the Padre Miguel Group, probably from Middle Pliocene to Early Pleistocene times. Normal faults trend N50-80°W, N10-25°E, N35°E, and N70°E. They are probably surficial features caused by left-lateral shear in the basement related to movement between the Caribbean and Americas plates. Minor northwest-trending folds formed contemporaneous with and perhaps prior to faulting. Olivine basalt was extruded from structurally-controlled vents after most of the faulting had ceased. Cut terraces and pediments formed adjacent to the ancestral Rio del Hombre, Subsequent downcutting may have been the result of regional uplift, stream capture along the Rio Choluteca, or both.

From inside the book

What people are saying - Write a review

We haven't found any reviews in the usual places.

Contents

Geologic history
4
Purpose and methods of investigation
14
Terminology
18

10 other sections not shown

Common terms and phrases

Bibliographic information