About this Earth and Planetary Sciences article

Burial metamorphism of a Cretaceous volcanic sequence west from Santiago, Chile by B. Levi is a Earth and Planetary Sciences article available to read on EtoBox.

This report is a petrographic study of alteration phenomena in an area of 100 km-~ in the Coastal Range west of Santiago. The stratified sequence of the area is of Cretaceous age and belongs to the western monoclinal limb of the Andean Geosyncline. Two structural units are present, separated by an angular unconformity. The older is about 9,000 m thick, and the younger 300 m thick. The rock types are mostly altered andesitic flows and flow breccias, and keratophyric ignimbrites and lavas, with alternating marine, brackish-water and terrestrial interbeds. Stratified rocks are cut locally by acid and basic apophyses and dikes, probably feeders of their volcanic host rocks. Discordant Cretaceous granitic plutons intrude the older unit. Throughout the whole stratigraphic section there are alteration minerals, which selectively replace the primary minerals, or fill amygdules and open fractures, or form a cement in flows, dikes and sedimentary interbeds. Patterns of alteration are regular and persistent; they correlate on a large scale with stratigraphic level and on a smaller scale with position within each individual flow and situation within amygdules. The stratigraphically controlled

Author

B. Levi

Publisher

Springer; Springer-Verlag; Springer Verlag; Springer Science and Business Media LLC; Society for Mining, Metallurgy and Exploration Inc. (ISSN 0010-7999)

Published

1969

Language

EN

Field

Earth and Planetary Sciences (Physical Sciences)