The regional northwest trending, symmetrical anticlines and synclines that form ranges and valleys were created by the compressive Laramide Orogeny
during the Eocene which was followed by a relaxation period resulting in the basin and range morphology evident today.
Given that the Laramide Orogeny
occurred from roughly 70 to 40 Ma ago (e.g., ) throughout western North America and that pre-70 Ma strata include numerous formations associated with the Western Interior Seaway, much of the present day topographic relief was developed during the part of the Montana carbonate record that exhibits substantial disequilibrium.
In the Late Cretaceous, the Laramide orogeny
altered the sedimentary regime in the region and caused deformation in all sedimentary sequences (Eguiluz de Antunano, 2001).
These rock formations illustrates the geological processes that have marked the south-western border of Rodnei mountains after the rising from hercynian and laramide orogeny
, respectively the deposition of postaustrian sedimentary couverture, and intrusion of pannonian magmas (Figure 5).
But many geologists think it may have been at least partially related to the same event (known as the Laramide orogeny
) that raised the Rocky Mountains between about 70 million and 40 million years ago.--Alexandra Witze
Later, one of the tectonic plates under North America's crust shifted position, building another mountain range-the Laramide Orogeny
, or the infant stage of the modern-day Rocky Mountains-furthereast.
There was compression in the Grand Canyon region during the Laramide orogeny
(~60-40 million years ago), and this was the time when the Colorado Plateau was uplifted almost to its present elevation and when most folding occurred.
Like the neighboring Bluefish and Bell-Driftwood basins, the Old Crow Basin was formed by the Laramide orogeny
during the early Tertiary, with subsequent infilling of late Tertiary and Quaternary clastic sediments originating from the neighboring Old Crow and Keele ranges.
Plutonic and volcanic rocks of the Mesa Formation were emplaced during the Laramide Orogeny
in Late Cretaceous-Pal eocene times.
English, J., Johnston, S.T., and Wang, K., 2003, Thermal modeling of the Laramide orogeny
: Testing the flat slab subduction hypothesis: Earth and Planetary Science Letters, v.
The Late Cretaceous to Early Eocene Laramide Orogeny
changed the depositional environment from marine to continental with the advent of clastic deposition which included fine volcanoclastic beds, precursors of extensive Tertiary volcanism.