EVIDENCES OF DIASTROPHISM AND UNCONFORMITY BETWEEN JURASSIC AND CRETACEOUS FLAT CONTINENTAL AND MARINE LAYERS IN COLOMBIA: FAR FROM RHETORIC, CLOSER TO REALITY
The methodology of this research has been field trips in Colombia and the eastern region of the United States. Also, literature review of comparable volcanic-sedimentary sequences in others regions in South and North America.
Sequences of volcano-sedimentary Jurassic rocks exhibit noticeable evidences of diastrophism, which caused identifiable strata with highest dip in contrast to flat cretaceous layers. These sequences have different stratigraphic names in Colombia, as Payande, Saldaña, Girón, Montebel, Morrocoyal, Payande, Guatapurí, and La Quinta Formations, among others.
In the same manner, authors through the time had described unconformity for that age in different places in America as Goyllarisquizga Group in Peru, La Quinta Formation in Venezuela, Nazas Formation in Durango region, Also, Dakota, Morrison, Summerville, Cape Fear, and Newark Supergroup in USA and TJ Mic Mac Fm in Canada.
However, Girón Formation as Jura-Triassic in Colombia shows low dip, especially in a short distance along the Chicamocha Canyon, which is morphologically similar to the Grand Canyon.
Different analysis based on stratigraphy, structural, tectonics during field trips for several years showed a volcanic-sedimentary sequence with andesitic intrusions, vertical faults, and presence of cooper. There are in the Upper Mesozoic regions of Colombia such as La Quinta Formation and Saldaña Formation. These andesitic intrusions mentioned are not present clearly in the Giron Formation, and others.
Over top of volcanic-sedimentary sequences in some different places showing a presence of clear unconformity underlying coastal sandstone and calcareous layers very slight dip deposited in would-be horizontal basins. For example, in Colombia, Cerro Pintao Formation unconformity over La Quinta Formation. Also, Tambor, Rosa Blanca, and Tibasosa Formations unconformity over Girón Formation. In addition, Yaví Formation unconformity over Saldaña Formation.