University of New Mexico UNM Digital Repository Earth and Planetary Sciences ETDs Electronic Theses and Dissertations Spring 3-2-2017 THE DYNAMIC GEOMORPHIC SETTING OF THE LATE PLEISTOCENE HARTLEY MAMMOTH SITE: BURIAL AND SKELETAL PRESERVATION IN A SLUMP-BLOCK DEPRESSION NEAR ABIQUIU, NEW MEXICO Jennifer K. Muus University of New Mexico Follow this and additional works at: https://digitalrepository.unm.edu/eps_etds Part of the Geology Commons, and the Geomorphology Commons Recommended Citation Muus, Jennifer K.. "THE DYNAMIC GEOMORPHIC SETTING OF THE LATE PLEISTOCENE HARTLEY MAMMOTH SITE: BURIAL AND SKELETAL PRESERVATION IN A SLUMP-BLOCK DEPRESSION NEAR ABIQUIU, NEW MEXICO." (2017). https://digitalrepository.unm.edu/eps_etds/189 This Thesis is brought to you for free and open access by the Electronic Theses and Dissertations at UNM Digital Repository. It has been accepted for inclusion in Earth and Planetary Sciences ETDs by an authorized administrator of UNM Digital Repository. For more information, please contact [email protected]. i Jennifer Muus ______________________________ Candidate Earth and Planetary Sciences __________________ Department This thesis is approved, and it is acceptable in quality and form for publication: Approved by the Thesis Committee: Dr. Grant Meyer, Chairperson ___________________________________ Dr. Leslie McFadden Dr. Bruce Huckell _____________________________________________ ii THE DYNAMIC GEOMORPHIC SETTING OF THE LATE PLEISTOCENE HARTLEY MAMMOTH SITE: BURIAL AND SKELETAL PRESERVATION IN A SLUMP-BLOCK DEPRESSION NEAR ABIQUIU, NEW MEXICO BY JENNIFER KRISTINE MUUS B.A. GEOLOGY, WESTERN WASHINGTON UNIVERSITY, 2010 B.SC. HONOURS PHYSICAL GEOGRAPHY, VICTORIA UNIVERSITY OF WELLINGTON, 2012 THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science Earth and Planetary Sciences The University of New Mexico Albuquerque, New Mexico May, 2017 iii ACKNOWLEDGEMENTS I would like to thank my advisor and committee chair, Dr. Grant Meyer, and my committee members, Dr. Leslie McFadden and Dr. Bruce Huckell for their valuable help pertaining to this research, as well as their guidance throughout my years of graduate study. I also thank the Geological Society of America, New Mexico Geological Society, UNM Geology Alumni Association, Dr. Anna Mary Backer (Jean-Luc Miossec Memorial Scholarship), and the National Science Foundation (summer 2015 fieldwork support, partial LIDAR costs) for their generous funding for this project. Thanks to Jedediah Frechette for his LiDAR scanning, DEM construction and point-cloud editing instruction, Shawn Penman for GIS advice and Dr. Mehdi Ali for his XRF and LOI lab work. iv THE DYNAMIC GEOMORPHIC SETTING OF THE LATE PLEISTOCENE HARTLEY MAMMOTH SITE: BURIAL AND SKELETAL PRESERVATION IN A SLUMP-BLOCK DEPRESSION NEAR ABIQUIU, NEW MEXICO By Jennifer Muus B.A., Geology, Western Washington University, 2010 B.Sc. Honours, Physical Geography, Victoria University of Wellington, 2012 M.S., Earth and Planetary Sciences, University of New Mexico, 2017 ABSTRACT Near Abiquiu in northern New Mexico, the skeletal remains of two mammoths were discovered in the summer of 2014 in the near-surface deposits of a very small alluvial channel. The channel occupies a depression on the back- tilted top of a Toreva slump block, a highly unusual setting for a mammoth burial. Geomorphological investigation of the site has provided insight into processes leading to burial and preservation of the remains, as well as local environmental change. Field mapping of sediment sources and LiDAR scans of the contributing slope basin and slump bench provided a map of geomorphic features and surficial geologic deposits. To better understand the geomorphic context of the v mammoth remains, termed the ‘Hartley Mammoth,’ six soil pits from the mapped surficial geologic deposits were described in the field. Bedrock and soil samples were analyzed using x-ray fluorescence (XRF), loss on ignition (LOI), x-ray diffraction (XRD) and particle size analysis. Bone collagen from a limb fragment returned a calibrated 14C age for one mammoth of about 33 ka. On the mammoth site slump bench, discontinuous bouldery footslope colluvial deposits show clay films and stage l to l+ carbonate, and were likely deposited shortly following slumping due to failure of oversteepened slump scarps. The deposit surrounding the mammoth remains consists of cobbles and small boulders of sandstone supported by a muddy matrix; this texture strongly suggests that the remains were buried by a debris flow. The debris-flow deposit created a high point in the channel, so that subsequent flow was diverted off the downslope edge of the slump block, protecting the mammoth remains from later erosion. Ped-face carbonate coatings (stage I+) in the debris-flow deposit indicate a greater age than the relatively well-sorted and stratified alluvial deposits in the channel above the debris flow. Following mammoth burial, incremental deposition of finer footslope colluvium continued to the present. Overall, field observations, XRF and XRD analyses indicate that despite the ~33 ka age of the mammoth, very little chemical weathering and limited soil development has occurred in the debris flow and other surficial deposits of apparent late Pleistocene age in this dynamic environment. vi TABLE OF CONTENTS LIST OF FIGURES……………………………………………………………………..ix LIST OF TABLES………………………………………………………………………xi CHAPTER 1 INTRODUCTION………………………………………………………..1 CHAPTER 2 REGIONAL SETTING…………………………………………………..3 Bedrock geology and evidence for slumping episodes……………………..3 Local climate and vegetation…………………………………………………..5 Late Pleistocene paleoenvironment…………………………………………..7 Mammoths in New Mexico……………………………………………………..9 CHAPTER 3. METHODS……………………………………………………………..11 Surficial geologic and geomorphic mapping………………………………..11 Sediment analysis……………………………………………………………..12 Selecting soil pit samples for particle size analysis………………..13 Soil auger tests………………………………………………………...13 Excavation of mammoth skeletal remains…………………………..13 Soil and bedrock analyses: XRF, XRD, LOI………………………..14 vii CHAPTER 4. RESULTS……………………………………………………………...16 Geomorphology of the broader site location………………………………..16 Surficial geologic and geomorphic map……………………………………..16 Soil samples: field analysis…………………………………………………...17 Mammoth excavation………………………………………………………….22 Soil samples: particle size distribution………………………………………24 X-Ray fluorescence of soil samples…………………………………………31 X-Ray diffraction of bedrock and sediment samples………………………32 CHAPTER 5. DISCUSSION………………………………………………………….34 Bouldery midslope colluvium…………………………………………………34 Bouldery footslope colluvium (with younger fine colluvium inset)………..34 Fine footslope colluvium………………………………………………………35 Channel alluvium………………………………………………………………36 Fine distal toeslope deposits…………………………………………………37 Debris flow deposit…………………………………………………………….37 Summary: geomorphic position and degree of pedogenesis……………..39 Interpretation of geomorphic processes…………………………………….40 viii The Hartley Mammoth depositional setting…………………………………42 Possible human interaction with mammoth carcass……………………….43 Summary of geomorphic history……………………………………………..44 In summary: a rare geomorphic setting……………………………………..45 CHAPTER 6. CONCLUSIONS………………………………………………………47 REFERENCES…………………………………………………………………………49 ix LIST OF FIGURES Figure 1. Site location maps .............................................................................. 1 Figure 2. (A) Site of mammoth burial (B) Sediment source area for mammoth- burying alluvium ................................................................................................ 4 Figure 3. Mammoth site location ........................................................................ 6 Figure 4. Mammuthus localities throughout New Mexico .................................. 10 Figure 5. Broader geomorphology of the site location ...................................... 17 Figure 6. (A) Surficial geologic and geomorphic map of contributing basin on DEM base (B) Close-up of mammoth excavation and adjacent soil auger sites ................................................................................................................... 18 Figure 7. Three-dimensional map of Hartley Mammoth site and the contributing hillslope basin .................................................................................................... .19 Figure 8. Soil pit E soil profile ............................................................................ 20 Figure 9. (A) Recent alluvial channel stratigraphy (B) Soil pit F, located within older channel alluvium ...................................................................................... 22 Figure 10. Debris flow deposit and enclosed mammoth skeletal remains ......... 24 Figure 11. Soil depth profiles for soil pits A, B, C, D, E and F ........................... 25 Figure 12. Soil texture for surficial deposits ..................................................... 27 x Figure 13. Cumulative frequency curves indicating the particle size distribution for the < 2 mm fraction of soil pits and surficial deposits ....................................... 29 Figure 14. Cumulative frequency curves for the recent channel deposits, indicat- ing particle size distribution for both the < 2 mm and > 2 mm fraction………….30 Figure 15. Normalized mass % composition of oxides from XRF analyses…….32 xi LIST OF TABLES Table 1. Particle size analysis results…………………………………………........26 Table 2. XRF Results for local bedrock and selected soil