200 k.y. paleoclimate record from Death Valley salt core

Abstract

A 186-m-long core (DV93-1) from Death Valley, California, composed of interbedded salts and muds contains a 200 k.y. record of closed-basin environments and paleoclimates, interpreted on the basis of sedimentology, ostracodes, homogenization temperatures of fluid inclusions in halite, and correlation with shoreline tufa. The 200 k.y. paleoclimate record is dominated by two dry and/or warm and wet and cold cycles that occurred on a 100 k.y. time scale. These cycles begin with mud-flat deposits (192 ka to bottom of core, and 60 ka to 120 ka). Wetter and/or colder conditions produced greater effective moisture; saline pan and shallow saline lake evaporites overlie mud-flat sediments (186 ka to 192 ka and 35 ka to 60 ka). Eventually, enough water entered Death Valley to sustain perennial lakes that had fluctuating water levels and salinities (120 ka to 186 ka and 10 ka to 35 ka). When more arid conditions returned, mud-flat deposits accumulated on top of the perennial lake sediments, completing the cycle (120 ka and 10 ka). Of particular significance are the major lacustrine phases, 10 ka to 35 ka and 120 ka to 186 ka (oxygen isotope stages 2 and 5e-6), which represent markedly colder and wetter conditions than those of modern Death Valley. Of the two major lake periods, the penultimate glacial lakes were deeper and far longer lasting than those of the last glacial.

Diabolical survival in Death Valley: recent pupfish colonization, gene flow and genetic assimilation in the smallest species range on earth

“…Although overland dispersal across kilometres of desert by an aquatic organism is difficult to fathom, this view is much more consistent with established theories of population persistence and known hydrological connectivity over historical and geological timescales. For example, our time-calibrated phylogeny reasonably indicates that Death Valley pupfishes were isolated from other desert basins after the drying of the most recent pluvial lake in the region 10 kyr ago [20]. Our demographic analysis of the most recent mixing between two desert spring populations is coincident with the largest recorded rainfall in the area in 1862 [67] which would have flooded the dry riverbed connecting these two habitats (figure 1a).…”

“…This interval is centered directly on the most recent flooding of the Death Valley basin from 10 to 35 kyr ago observed in core samples [20]. figure 2d).…”

Highest Pluvial-Lake Shorelines and Pleistocene Climate of the Western Great Basin

“…Limited evidence suggests that temperatures may have been colder during earlier glaciations. Interpretations based on fluid inclusions in halite in the Death Valley core suggest that average temperatures could have been a few degrees colder during part of isotope stage 6 than during isotope stage 2 (Lowenstein et al, 1999). Relict colluvial deposits in southern Nevada suggest that winter temperatures in the southern Great Basin were at least 1°-3°C colder in the early and middle Pleistocene than in the late Pleistocene (Whitney and Harrington, 1993).…”

The paleoclimatic and geochronologic utility of coring red beds and evaporites: a case study from the RKB core (Permian, Kansas, USA)

“…Drilling marine sediments has been long exploited to clarify climate dynamics and atmospheric-oceanic linkages, especially for the Neogene, but extending even to the Cretaceous (e.g., IODP 2008). Continental climate reconstructions also benefit greatly from drill core data, and core from modern, long-lived lacustrine systems in particular have facilitated major advances in understanding climate dynamics of Earth's recent record, from the tropics to the poles (e.g., Lowenstein et al 1999;Scholz et al 2007;Cohen 2011;Melles et al 2012).…”

“…Moreover, in red bedevaporite successions, the evaporites-if protected from dissolution and alteration caused by post-depositional infiltration of dilute waters-can yield a variety of high-resolution quantitative and qualitative paleoclimate data (e.g., Benison and Goldstein 1999;Sánchez Botero et al 2013;Zambito and Benison 2013). In addition, sedimentary structures and primary fluid inclusions in Cenozoic and Permian bedded halite can represent arid climate floodingevaporation-desiccation cycles and air temperature proxies, respectively (Benison and Goldstein 1999;Lowenstein et al 1999;Zambito and Benison 2013). Paleoclimate reconstructions from such strata, however, are dependent upon obtaining cores drilled using methods suitable for extracting intact evaporites and (commonly friable) finegrained red beds.…”