New Mexico Geological Society Annual Spring Meeting
April 13, 2018
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Driest Period of the Holocene in the Southwestern United States From Coralloidal Stalagmite Growth
Holly Olivarez1, Victor Polyak1 and Yemane Asmerom1
Evidence from multiple climate proxies worldwide reflect an arid climate in the Northern Hemisphere during parts of the Early and Middle Holocene (~9500 to 4200 yr B.P.). Stalagmite studies from the Guadalupe Mountains, New Mexico have concluded that effective moisture was greater in the southwestern United States during the Younger Dryas and into the Early Holocene, as shown by a hiatus of stalagmite growth in the Guadalupe Mountains for a period from ~9500 to 7500 yr B.P., and during the Late Holocene; thus implying the Middle Holocene was drier. Only one high-resolution stalagmite study has been published for this region that exhibited growth through the entire Holocene, and that study, based on δ13C and δ18O isotope time-series, does not provide clear indications of aridity.
Cave coralloids (also referred to as cave popcorn) are formed by evaporation of water films from condensation on cave walls, or formed by evaporation of water films on stalagmites and stalactites generated by splashing water; therefore, such growth can be considered a proxy for aridity. Cave coralloid growth on mid-sections of stalagmites from Helens Cave, Carlsbad Caverns National Park in the Guadalupe Mountains are not simply surficial deposits, but are characteristic of stalagmite growth itself, and therefore represent a period that can be interpreted as increased aridity. The period of growth represented by the coralloidal stalagmite growth from two Helens Cave samples, stalagmites Helens-1 and Helens-2, are bracketed by two uranium-series dates of ~8792 ± 127 yr B.P. to ~7215 ± 252 yr B.P., which is consistent with a hiatus of stalagmite growth previously reported. Our interpretation of this proxy is that climate conditions were more arid and likely warmer than any other time in the Holocene in this region of the southwestern United States. Cave coralloids are not often used in climate studies, and we illustrate here their possible value.
Speleothem, Middle Holocene, Southwest United States, Carlsbad Caverns, Guadalupe Mountains, Cave Corraloid
2018 New Mexico Geological Society Annual Spring Meeting
April 13, 2018, Macey Center, New Mexico Tech campus, Socorro, NM