79-7 Holocene climate changes induce millennial-scale changes in dust cycle dynamics in Arizona, USA

Session: Soil, Dust, and Everything in Between: Current, Quaternary and Earlier Geological Processes and Records

Presenting Author:

Onn Crouvi

Authors:

Tau, Guy¹, Crouvi, Onn², Enzel, Yehouda³, Teutsch, Nadya⁴, Ginoux, Paul⁵, Rasmussen, Craig⁶

(1) Geological Survey of Israel, Jerusalem, Israel; Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel, (2) Geological survey of Israel, Jerusalem, Israel, (3) Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel, (4) Geological Survey of Israel, Jerusalem, Israel, (5) National Ocean and Atmospheric Administration, Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA, (6) Department of Environmental Science, University of Arizona, Tucson, AZ, USA,

Abstract:

The long-term relationships between climate and dust emission remain unclear, with two opposite hypotheses: 1) The common hypothesis stresses that dust emission will increase with increased aridity, which will lead to a reduction in vegetation coverage. 2) The second hypothesis claims that dust emission will decrease under a drier, less stormy climate as less sediments replenish dust sources or emits dust. Here, these two contradicting hypotheses have been tested by analyzing an ~11 m long core retrieved from a natural sinkhole in the carbonates of central Arizona, Montezuma Well. The fluvial addition to the well is minimal, thus marking it as an ideal natural dust trap. The core was dated to the last 12 ka, a time interval where the climate changed from relatively humid during the Younger Dryas and the early Holocene (12.9 – 8.2 ka), to a drought during the middle Holocene (8.2 – 4.2 ka). The current relatively humid climate was established in the late Holocene (after 4.2 ka). Major elements indicate that the core sediments originated from two end-members: the local carbonate bedrock and external silicate-rich dust. The particle-size distributions of the dust fraction of the core reveal fine (<20 μm) and coarse (20 – 60 μm) dust that fit measured particle-size distributions of current and active dust sources in the region. The fine dust fraction is transported during winter from western Arizona and the Mojave Desert in eastern California. The coarse dust is transported during summer from the Sonoran Desert in southern and southwestern Arizona. These dust pathways fit Arizona’s current climate systems. Moreover, surveys of potential dust sources indicate that current summer and winter dust sources are in a supply-limited state, as they are connected to fluvial systems. Dust fluxes were higher during wetter phases of the Holocene when winter sources dominated. During the middle Holocene drought, dust fluxes were minimal and dominated by summer sources until dust input ceased as drought conditions did not produce enough floods to refill sources with sediments. We propose that in the Sonoran Desert, dust emission is strongly connected with climate, increasing during humid intervals and enhanced by fluvial sediment replenishment at dust sources.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9145

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