Records of late Quaternary environmental change from high-elevation lakes in the Ruby Mountains and East Humboldt Range, Nevada

Abstract

Sedimentary records were analyzed from three lakes in the Ruby Mountains and East Humboldt Range of northeastern Nevada. Lakes are rare in the arid Great Basin, and these represent the highest-elevation lacustrine records from this region. The three cores cover overlapping time intervals: One, from a lake located just beyond a moraine, is interpreted to represent the Last Glacial Maximum, extending back to 26 cal ka; another extends to deglaciation ca. 14 cal ka; and the third extends to deposition of the Mazama ash, ca. 7.7 cal ka. Multiproxy analysis focused on measurements of bulk density, organic matter content, C:N ratio, biogenic silica abundance, and grain-size distribution. Depth-age models were developed using optically stimulated luminescence (OSL) dating, along with accelerator mass spectrometry (AMS) 14C dating of terrestrial macrofossils (wood and conifer needles), charcoal, and pollen concentrates (for deep sediment in one lake). Collectively, the three lakes record a series of discrete intervals spanning an unusually long stretch of time. These include the local Last Glacial Maximum (26.0–18.5 cal ka), local deglaciation (18.5–13.8 cal ka), the onset of biologic productivity (13.8–11.3 cal ka), early Holocene aridity (11.3–7.8 cal ka), deposition and reworking of the Mazama ash (7.8–5.5 cal ka), a neopluvial interval (5.5–3.8 cal ka), a variable late Holocene climate (3.8–0.25 cal ka), and a latest Holocene productivity spike (250 yr B.P. to the present) that may be anthropogenic. Data from all three lakes are presented, and the collective record of climate and environmental change for the Ruby Mountains and East Humboldt Range is compared with other paleorecords from the Great Basin.

A Top-to-Bottom Luminescence-Based Chronology for the Post-LGM Regression of a Great Basin Pluvial Lake

“…13.1 ± 1.1 ka, when the glacier length was just 30% of its maximum extent. A calibrated basal 14 C date of 13.5 ka from Overland Lake in the East Humboldt Mountains also indicates that the glacier in this valley had retreated to <25% its maximum length by this time [16]. Overall, this pattern is consistent with the idea that the local glacier maximum was driven by cold, relative dry conditions that favored ice advance but not tremendous increases in effective moisture.…”

“…This setting provides, therefore, an unusual opportunity to simultaneously consider co-located, high-resolution pluvial and glacial records spanning the last deglaciation. Third, high-resolution records of post-glacial environmental change have been developed from lakes in the mountains immediately west of Lake Clover, providing a useful point of reference for paleoclimate changes during the last glacial-interglacial transition [16]. Finally, recent work has inferred the existence of a prominent dipole pattern in winter precipitation in this area during the late Pleistocene, with pluvial lakes in the latitude band~39-41 • N reaching their highstands~2 ka earlier and out of phase with Lake Chewaucan farther north in Oregon [9].…”

“…A summary of lake highstands, including Lake Clover, is shown in pink [14]. Dated moraines at the Angel Lake type locality (red recalculated from [33]), and the calibrated basal 14 C age for Overland Lake (star [16]) are also shown for reference. Comparison of the hydrograph for Lake Clover (dashed black line) with other pluvial lake hydrographs for the Great Basin including Lake Franklin [13], Lake Lahonton [32], Lake Bonneville [6], Lake Surprise [31], and Lake Chewaucan [9].…”

“…A summary of lake highstands, including Lake Clover, is shown in pink [14]. Dated moraines at the Angel Lake type locality (red recalculated from [33]), and the calibrated basal 14 C age for Overland Lake (star [16]) are also shown for reference.…”

Holocene records of eolian dust deposition from high‐elevation lakes in the Uinta Mountains, Utah, USA

“…In addition, the measurements made with the core scanner are in units of X‐ray intensity, not elemental abundance, precluding the possibility of converting the masses of sediment to masses of dust‐related elements. Future work could involve direct measurement of bulk density for remaining samples from these cores using a pycnometer, or estimation of bulk density from water content (Munroe et al ., 2018; Munroe and Brencher, 2019). XRF scanning coupled with ICP‐MS analysis could also yield calibration factors to convert X‐ray intensities to elemental concentrations.…”