U-Series Chronology of Lacustrine Deposits in Death Valley, California

Abstract

Uranium-series dating on a 186-m core (DV93-1) drilled from Badwater Basin in Death Valley, California, and on calcareous tufas from nearby strandlines shows that Lake Manly, the lake that periodically flooded Death Valley during the late Pleistocene, experienced large fluctuations in depth and chemistry over the last 200,000 yr. Death Valley has been occupied by a long-standing deep lake, perennial shallow saline lakes, and a desiccated salt pan similar to the modern valley floor. The average sedimentation rate of about 1 mm/yr for core DV93-1 was punctuated by episodes of more-rapid accumulation of halite. Arid conditions similar to the modern conditions prevailed during the entire Holocene and between 120,000 and 60,000 yr B.P. From 35,000 yr B.P. to the beginning of the Holocene, a perennial saline lake existed, over 70 m at its deepest. A much deeper and longer lasting perennial Lake Manly existed from about 185,000 to 128,000 yr B.P., with water depths reaching about 175 m, if not 330 m. This lake had two significant “dry” excursions of 102–103yr duration about 166,000 and 146,000 yr B.P., and it began to shrink to the point of halite precipitation between 128,000 and 120,000 yr B.P. The two perennial lake periods correspond to marine oxygen isotopic stages (OIS) 2 and 6. Based on the shoreline tufa ages, we do not rule out the possible existence ∼200,000 yr ago of yet a third perennial lake comparable in size to the OIS 6 lake. The234U/238U data suggest that U in tufa owes its origin mainly to Ca-rich springs fed by groundwater that emanated along lake shorelines in southern Death Valley, and that an increase of this spring-water input relative to the river-water input apparently occurred during OIS 6.

An Assessment of Late Pleistocene to Middle Holocene Lake Level Fluctuations in Surprise Valley, California

“…(a) NGRIP Greenland ice core δ 18 O on extended GICC05 timescale (Rasmussen et al, 2006), red line is smoothed at 1 %; (b) δ 18 O from Cave of the Bells (Wagner et al, 2010); (c) vein calcite δ 18 O from Devils Hole, Nevada (Winograd et al, 2006); (d) Alkenone SST proxy from Ocean Drilling Program sites 1012 (Liu et al, 2005) and 2020 (Liu, 2004); (e) reconstructed relative ΔP-ET (%) from Maher et al, (in prep) pink, Newark Valley; dark blue, Diamond Valley; light blue, Fish Lake Valley; purple, Yucca Mountain. (f) January and July insolation for 40˚N calculated using the program of (Laskar et al, 2004); (g) SPECMAP δ 18 O record (Martinson et al, 1987); (h) Chewaucan Basin relative lake level curve from sediment cores (Licciardi, 2001) and 230 Th-U dated tufa samples (this study); (i) Lake Surprise lake level fluctuations from 230 Th-U dated tufa samples (this study), BSE detrital corrected ages only; (j) and (k) Lake Lahontan, NV and Lake Bonneville, UT relative lake levels (Compiled by Brook et al, 2006, from McCoy, 1987Oviatt et al, 1987;Benson et al, 1990;Oviatt et al, 1992); (e) Lake Manly, CA lake level (m) (Ku et al, 1998); (f) Searles Lake, CA relative lake level (Smith, 1984); (i) Babicora Basin, Mexico relative lake level (Metcalfe et al, 2002). The radiocarbon dated lake level curves ((h), (j), (k), (i), (m) and (n)) have substantial error and uncertainty due to the necessary 14 C dead carbon correction and the radiocarbon to calendar age conversion uncertainty, particularly after the LGM due to plateaus in the calibration curve.…”

“…Therefore, the timing of fluctuations during past lake cycles can be determined by dating beach deposits such as tufa (Ku et al, 1998;Garnet et al, 2004) and studying lake sediment cores (e.g. Licciardi et al, 2000;Zic et al, 2002).…”

“…The additional paleoclimate records, used for comparison are found denoted by the black stars and circles. Data from previous studies includes a ΔP-ET proxy using ( 234 U/ 238 U) 0 for pedogenic carbonates from Wind River, Wyoming (WR) (Sharp et al, 2003), deep vadose zone opal from Yucca Mountain (YM) (Paces et al, 2010) and pedogenic opal from Diamond Valley, Nevada (DV), Newark Valley, Nevada (NV), Fish Lake Valley, Nevada (FLV) and Barstow, California (BA) (Maher et al, in prep); vein calcite from Devils Hole, Nevada (DH) (Winograd et al, 2006); speleothem from Cave of the Bells, Arizona (COB) (Wagner et al, 2010); and the timing of lake highstands at Lake Bonneville, Utah (Oviatt et al, 1992); Lake Lahontan, Nevada (Adams and Wesnousky, 1998); Lake Newark, Nevada (Kurth et al, 2011); Lake Diamond, Nevada (Tackman, 1993); Lake Jakes Lake, Nevada (Garcia and Stokes, 2006); Lake Manly, California (Ku et al, 1998) and Searles Lake, California (Lin et al, 1998).…”

“…Typically samples with ( 230 Th/ 232 Th) < 20 require a detrital Th correction to be applied to the age. The Total Sample Dissolution (TSD hereafter) approach (Bischoff and Fitzpatrick, 1991;Luo and Ku, 1991;Ku et al, 1998;Ku, 2000) has previously been applied to samples with (Lin et al, 1996;Garnet et al, 2003) and evaporites (Ku et al, 1998) …”

“…The number (#) is the sample number and the subsamples are the coeval samples taken to apply the TSD detrital correction calculation. (Table continued Ku (1991) and Ku et al (1998), the least squares fit does not consider error-weighting and correlation of the measured activity ratios. The least square regressions and error calculations were carried out in Isoplot (Ludwig, 2003a;.…”