Paleoaltimetry estimates suggest low surface elevations for the
mid-Cretaceous Newark Canyon Formation within the Sevier hinterland
Abstract
The retroarc of the North American Cordilleran orogen in Nevada and Utah
has been divided into the frontal Sevier fold-thrust belt in Utah, which
accommodated shortening between ~145 and
~50 Ma, and a broad region of Nevada referred to as the
‘Sevier hinterland’. The hinterland is hypothesized to have developed
into a high-elevation orogenic plateau (or ‘Nevadaplano’) at some point
between the Late Jurassic and the Paleogene. Recent paleoaltimetry
utilizing clumped isotope temperature estimates suggests that at least
some basins on the Nevadaplano were at an elevation of 2.2-3.1 km by the
latest Cretaceous. However, it remains uncertain precisely when the
Nevadaplano attained these high elevations and if surface uplift
developed steadily along with protracted shortening in the Sevier
fold-thrust belt or occurred rapidly and was decoupled from the
shortening record. In order to extend the surface elevation history of
the Nevadaplano further back in time, we have investigated the
type-exposure of the mid-Cretaceous (~113-98 Ma) Newark
Canyon Formation (Knc) in central Nevada. The Knc records synorogenic
sedimentation in the Sevier hinterland during the early to middle stages
of shortening in the Sevier thrust belt. We will present terrestrial
surface temperature estimates from clumped isotope analyses derived from
palustrine, lacustrine, and pedogenic carbonate-bearing facies.
Contextualized by structural evidence and corrected for secular climate
change, these data suggest that the studied Knc basin had not developed
substantial surface elevation by the mid-Cretaceous. However, there was
likely some considerable surface relief in this region associated with
active fold-thrust structures in the upper crust. Preliminary
temperature estimates range between 22 and 70°C. These temperatures
reflect a range of facies-specific differences in primary carbonate
formation, as well as, diagenetic overprinting of some samples.
Consistently warm temperatures throughout the stratigraphic section
suggest that there was no significant cooling due to elevation gain
between ~113 and ~98 Ma. We will discuss
the implications of these results for the style and timing of
deformation and surface uplift within the Nevadaplano.