Influence of climate change and uplift on Colorado Plateau paleotemperatures from carbonate clumped isotope thermometry

Abstract

The elevation history of Earth's surface is key to understanding the geodynamic processes responsible for the rise of plateaus. We investigate the timing of Colorado Plateau uplift by estimating depositional temperatures of Tertiary lake sediments that blanket the plateau interior and adjacent lowlands using carbonate clumped isotope paleothermometry (a measure of the temperature‐dependent enrichment of 13C‐18O bonds in carbonates). Comparison of modern and ancient samples deposited near sea level provides an opportunity to quantify the influence of climate and therefore assess the contribution of changes in elevation to the variations of surface temperature on the plateau. Analysis of modern lake calcite from 350 to 3300 m elevation in the southwestern United States reveals a lake water carbonate temperature (LCT) lapse rate of 4.2 ± 0.6°C/km. Analysis of Miocene deposits from 88 to 1900 m elevation in the Colorado River drainage suggests that the ancient LCT lapse rate was 4.1 ± 0.7°C/km, and temperatures were 7.7 ± 2.0°C warmer at any one elevation than predicted by the modern trend. The inferred cooling is plausible in light of Pliocene temperature estimates off the coast of California, and the consistency of lapse rates through time supports the interpretation that there has been little or no elevation change for any of the samples since 6 Ma. Together with previous paleorelief estimates from apatite (U‐Th)/He data from the Grand Canyon, our results suggest most or all of the plateau's lithospheric buoyancy was acquired ∼80–60 Ma and do not support explanations that ascribe most plateau uplift to Oligocene or younger disposal of either the Farallon or North American mantle lithosphere.

Evolution of Neoproterozoic Wonoka–Shuram Anomaly-aged carbonates: Evidence from clumped isotope paleothermometry

“…The non-temperature dependent phenomena exhibited by Porites corals likely results from vital effects that do not occur in abiogenic carbonates, similar to those examined here. Whereas a biotic origin for the micrites analyzed here is feasible, published data for micrites (Huntington et al, 2010) agree well with equilibrium clumped isotope signatures. Furthermore, we find no evidence for biogenicity in the examined Neoproterozoic micrites, and the ages of these units preclude the possible incorporation of Porites-sourced carbonates.…”

Use of Clumped-Isotope Thermometry To Constrain the Crystallization Temperature of Diagenetic Calcite

“…The data indicated temperatures in excess of typical Earth-surface conditions; however, details of the sample context and textures were not presented and no interpretation of the results was offered except the speculation that the samples may have experienced reheating due to emplacement of the nearby basalt flow (Huntington et al 2010).…”

“…Previously, D 47 data were reported for three samples from the same locality that included sparry calcite cement (DB4-1), microspar matrix calcite (DB4-2), and calcified gastropod shell (DB4-3) (Huntington et al 2010). The data indicated temperatures in excess of typical Earth-surface conditions; however, details of the sample context and textures were not presented and no interpretation of the results was offered except the speculation that the samples may have experienced reheating due to emplacement of the nearby basalt flow (Huntington et al 2010).…”

“…A thermodynamic driving force that increases with decreasing temperature makes it more favorable for 13 C and 18 O to ''clump'' into bonds with each other instead of being distributed randomly throughout the crystal lattice (Wang et al 2004;Schauble et al 2006). The 13 C-18 O-bond enrichment can be determined by measuring the d 18 O, d 13 C, and abundance of mass-47 species in CO 2 produced by phosphoric acid digestion of carbonate using gas-source isotope ratio mass spectrometry Affek and Eiler 2006;Huntington et al 2009 18 O of water data for ancient Earth-surface deposits to constrain paleoclimate and landscape evolution (e.g., Ghosh et al 2006b;Affek et al 2008;Huntington et al 2010;Passey et al 2010), but recent studies of altered fossil shells, carbonatites, and marbles suggest that the thermometer might also be applied to quantify temperatures of diagenesis. Came et al (2007) applied the clumped-isotope thermometer to Silurian and Middle Pennsylvanian fossil brachiopod and mollusk shells that appeared to be altered by postdepositional processes.…”

History of upwelling in the Tropical Eastern Pacific and the paleogeography of the Isthmus of Panama

“…Quade et al, 2011), or the clumped-isotopes in the carbonates of ancient lake sediments (e.g. Huntington et al, 2010), and use the tight correlations between temperature and elevation and precipitation and elevation to estimate paleoaltitude corrected for latitude, but these approaches require paleosols or lake sediments to be preserved from a variety of different elevations and ages; a rare occurrence in a highly volcanic zone like the Isthmus of Panama. Alternatively one may observe the types and amount of sediments reaching coastal basins which is highly dependent upon several factors including rainfall and the amount of rock exposed to weathering, both of which are possible proxies for elevation, but depositional basins around the Isthmus of Panama are perhaps too heterogeneous to permit great success with such an approach.…”