TY - CHAP
T1 - Geomorphic and sedimentologic evidence for pluvial Lake Carrizo, San Luis Obispo County, California
AU - Rhodes, Dallas D.
AU - Negrini, Robert M.
AU - Arrowsmith, J. Ramon
AU - Wigand, Peter E.
AU - Forman, Steven L.
AU - Palacios-Fest, Manuel R.
AU - Davis, Owen K.
N1 - Funding Information:
Funding for this project came from a number of sources. The Faculty Research Program at Georgia Southern University provided funding for the optically stimulated luminescence dating of the clay dunes. We acknowledge funding from the National Science Foundation (grants HER-030332 and HRD-1137774) and the Chevron USA REVS-UP grant to CSUB.
Funding Information:
Over the last two decades, many colleagues and students have accompanied us and assisted in conducting field investigations. Jeffrey Kilpatrick has given freely of his time on numerous trips to the Carrizo Plain. Gabriela R. Noriega, working in the Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of California–Irvine, provided the radiocarbon dates for core SL1. Colleagues from California State University–Bakersfield (CSUB) who did yeomen’s work, particularly during coring, include: Elizabeth Powers, Tom Osborn, and Randall Stephenson. Our colleague Robert Horton provided valuable assistance with the scanning electron microscopy work. We also thank the many CSUB undergraduate students and Bakersfield-area high school students and teachers who participated in this research through the Research Experience Vitalizing Science Program (REVS-UP) program. Discussions with and shared observations from Sinan Akciz, Robert S. Anderson, Jennifer Eigenbrode, Lisa Grant Ludwig, Kate Leary, Jing Liu, Lisa M. Pratt, John Sims, Kathleen Springer, Jeff Pigati, and others have helped to focus our thinking about Soda Lake. Lisa A. Rossbacher provided valuable comments on earlier versions of the manuscript. George Brook (University of Georgia) provided the thermoluminescence date for the Big Dune sample. We also thank two anonymous reviewers and the volume’s editors, Scott Starratt and Mike Rosen, for their revisions, comments, and insights. Funding for this project came from a number of sources. The Faculty Research Program at Georgia Southern University provided funding for the optically stimulated luminescence dating of the clay dunes. We acknowledge funding from the National Science Foundation (grants HER-030332 and HRD-1137774) and the Chevron USA REVS-UP grant to CSUB. Much of this research was made possible through the cooperation of the Bureau of Land Management and the staff of the Carrizo Plain National Monument. We particularly wish to recognize Johna Cochran, Kathy Sharum, and Larry Vredenburgh.
Publisher Copyright:
© 2019 The Geological Society of America. All rights reserved.
PY - 2021/8/12
Y1 - 2021/8/12
N2 - The Carrizo Plain, the only closed basin in California’s Southern Coast Ranges, preserves landforms and deposits that record both climate change and tectonic activity. An extensive system of clay dunes documents the elevations of late Pleistocene and Holocene pans. Clay dune elevations, drowned shorelines, eroded anticlinal ridges, and zones of perturbed soil chemistry provide evidence of two lake levels higher than today’s (currently 581 m above sea level [masl]), one at ~591 masl at ca. 20 ka and another at ~585 masl that existed at ca. 10 ka, based on optically stimulated luminescence (OSL) dates on clay dune sediment. Two cores from the abandoned floor of the lake provide additional evidence of a long-lived lake in the Carrizo Plain during the late Pleistocene. The longer of the two cores (~42 m) was sampled for palynology, environmental magnetism, and scanning electron microscope–petrography. The magnetic susceptibility signal contains two notable features corresponding to sedimentary materials consistent with reducing conditions. The higher of these features occurs near the surface, and the lower occurs at ~18 m depth. A 14C date on charcoal from the upper reduced zone places the top of this zone at no older than 22.6–20.9 cal ka. This date is consistent with the OSL date on geomorphic features associated with a highstand above ~591 masl. Assuming that reducing conditions correspond to at least a few meters’ depth of relatively fresh water, the new 14C date suggests that the upper reduced zone represents a marine isotope stage (MIS) 2 pluvial maximum lake in the Carrizo Plain. Pollen and ostracodes from the reduced sediments indicate a wetter and cooler climate than today. These conditions would have been capable of sustaining a lake with water much less saline than that of the modern lake. The timing of the oldest documented highstand (no later than 20 ka) is consistent with a modified jet stream migration model and is not consistent with a tropical incursion model. Northeast-to-southwest asymmetry across the lake floor may be consistent with southwestward tilting driven by Coast Range shortening normal to the San Andreas fault, as is seen throughout the region.
AB - The Carrizo Plain, the only closed basin in California’s Southern Coast Ranges, preserves landforms and deposits that record both climate change and tectonic activity. An extensive system of clay dunes documents the elevations of late Pleistocene and Holocene pans. Clay dune elevations, drowned shorelines, eroded anticlinal ridges, and zones of perturbed soil chemistry provide evidence of two lake levels higher than today’s (currently 581 m above sea level [masl]), one at ~591 masl at ca. 20 ka and another at ~585 masl that existed at ca. 10 ka, based on optically stimulated luminescence (OSL) dates on clay dune sediment. Two cores from the abandoned floor of the lake provide additional evidence of a long-lived lake in the Carrizo Plain during the late Pleistocene. The longer of the two cores (~42 m) was sampled for palynology, environmental magnetism, and scanning electron microscope–petrography. The magnetic susceptibility signal contains two notable features corresponding to sedimentary materials consistent with reducing conditions. The higher of these features occurs near the surface, and the lower occurs at ~18 m depth. A 14C date on charcoal from the upper reduced zone places the top of this zone at no older than 22.6–20.9 cal ka. This date is consistent with the OSL date on geomorphic features associated with a highstand above ~591 masl. Assuming that reducing conditions correspond to at least a few meters’ depth of relatively fresh water, the new 14C date suggests that the upper reduced zone represents a marine isotope stage (MIS) 2 pluvial maximum lake in the Carrizo Plain. Pollen and ostracodes from the reduced sediments indicate a wetter and cooler climate than today. These conditions would have been capable of sustaining a lake with water much less saline than that of the modern lake. The timing of the oldest documented highstand (no later than 20 ka) is consistent with a modified jet stream migration model and is not consistent with a tropical incursion model. Northeast-to-southwest asymmetry across the lake floor may be consistent with southwestward tilting driven by Coast Range shortening normal to the San Andreas fault, as is seen throughout the region.
UR - http://www.scopus.com/inward/record.url?scp=85149966606&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85149966606&partnerID=8YFLogxK
U2 - 10.1130/2019.2536(16)
DO - 10.1130/2019.2536(16)
M3 - Chapter
AN - SCOPUS:85149966606
T3 - Special Paper of the Geological Society of America
SP - 289
EP - 317
BT - Special Paper of the Geological Society of America
A2 - Starratt, S.W.
A2 - Rosen, M.R.
PB - Geological Society of America
ER -