PATTERNS IN THE STRATA: INSIGHTS FROM THE BELLY OF A CONTINENT, COLORADO (Invited Presentation)

Perched on the belly of a continent at low latitudes for most of the Phanerozoic, Colorado may not seem an intuitive candidate to be a sensitive recorder of global glacial, marine, or lithospheric evolution. Yet its sedimentary record, including its conspicuous gaps and imperfections, chronicles such events with remarkable fidelity, amplified by a new temporal and spatial framework that improves correlation of strata across many Rocky Mountain basins. This new framework, built as a community effort as The Colorado Stratigraphic Chart, is freely available at coloradostratigraphy.org. In a break with tradition, this chart employs a linear timescale, which facilitates comparison of its strata to larger-scale forcing factors.

Although the majority of geologic time is represented by gaps in deposition and preservation, Colorado’s surviving strata accumulated in logical and predictable patterns. Accumulation of this stratigraphy is controlled by: i) eustasy dominated by mid-ocean ridge (M.O.R.) volume, ii) eustasy dominated by glaciation (glacioeustasy), and iii) tectonics, all of which are modulated by local climate regimes. Often these elements combine to dictate the spatiotemporal distribution of local resources. For example, much of the deep karsting that mars the tropical shallow marine strata of the White River Plateau may have been caused by glacial events half-way round the world and amplified by onset of Ancestral Rockies uplift. Nearly 400 million years later, this karsting facilitated deposition of substantial gold and mineral deposits linked to intrusives along the Colorado Mineral Belt, and still localizes hot springs that are tourist attractions in and near Glenwood Springs. Likewise, deposition of ductile Cretaceous Interior Seaway strata fostered glide-plane movement of Laramide compressional faults tens of millions of years later, modifying patterns of Colorado’s mountain fronts.