ASSESSING THE PRESERVATION POTENTIAL OF BIOGENIC FEATURES IN PRE-NEOGENE TUFAS AND TRAVERTINES- APPLICATIONS TO EXOBIOLOGY Justin Richardson A Thesis Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 2005 Committee: James Evans, Co-Advisor Margaret Yacobucci, Co-Advisor © 2005 Justin Richardson All Rights Reserved iii ABSTRACT James Evans and Margaret Yacobucci, Advisors If evidence for life on Mars is found, it may come from Martian paleo- groundwater deposits (tufas and travertines). Tufas and travertines uniquely preserve evidence of life from both surface and subsurface environments. What is known about tufa and travertine is biased towards Holocene examples. Most geologically older examples remain poorly studied, possibly due to poor preservation potential, or from being overlooked or misclassified. This study examines preservation potential of lithologic and biogenic features in pre-Neogene paleo-groundwater deposits, focusing on biogenic microstructures detected using SEM, EDS, and petrography. This study compares pre-Neogene deposits from the Eocene Chadron Formation (Badlands of South Dakota), the Jurassic Shuttle Meadow Formation (Hartford Basin of Connecticut), and Triassic Mercia Mudstone Group (south Wales, United Kingdom) to Neogene tufa and travertine (San Ysidro Quadrangle, central New Mexico). The goal is to discern trends in biogenic microstructure preservation potential through geologic time. Dominant microstructures observed of probable biogenic origin include clotted micrite, pseudo- stromatolitic features (e.g., shrub-and-ray dendrites), microcolonial fungal sacs, coccoliths, and extracellular polymeric substances (EPS). Neogene samples include pisolites, coated grains, lithoclasts, encapsulated algae, shrub-and-ray dendrites, EPS, and calcite ice. Eocene samples include pisolites, coated grains, lithoclasts, shrub-and-ray dendrites, macrofossils (molluscs, ostracodes, and vertebrate bones), charophyte stems iv and gyrogonites, microcolonial fungal sacs, coccoliths. Jurassic samples include pisolites, shrub-and-ray dendrites, EPS, calcite ice, calcite microspherules associated with algal and/or bacterial growth, and Fe-Mn oxide star structures. Triassic samples are dolomitized, but show "ghosts" of pisoids and Fe oxide star structures. In summary, paleo-groundwater deposits on Earth contain distinctive features observable through the Late Triassic. Some features are inorganic or biologically mediated, such as pisolites, lithoclasts, and dendrites. Others are clearly biogenic. Eocene paleogroundwater deposits contain oncoids, coated grains, EPS, macrofossils (molluscs, ostracods, and vertebrates), and microfossils (coccoliths and microcolonial fungal sacs). Deposits as old as the Jurassic contain Fe- oxide star structures and spherules. Triassic deposits contain Fe- oxide star structures. The quality of preservation of these features does not substantially decline in samples as old as the Late Triassic, suggesting that tufas and travertines uniquely preserve evidence of life from surface, subsurface, and potentially ancient environments. v To my family and friends. vi ACKNOWLEDGMENTS I would like to thank Dr. Evans for suggesting paleo-groundwater deposits as a possible avenue of research. I would like to thank both Dr. Evans and Dr. Yacobucci for guidance and review of the thesis, in addition to providing additional contacts to researchers. I am grateful for the valuable suggestions from Dr. Jeremy Young of the Natural History Museum of London, Dr. David Watkins of the University of Nebraska, Dr. Don Steinker of Bowling Green State University, Dr. Charles Kahle (emeritus) of Bowling Green State University, Dr. Penelope Boston of New Mexico Tech, and Dr. Jack Farmer of Arizona State University regarding data collection and interpretation of samples. I wish to thank Dr. R. P. Steinen for providing Jurassic samples from Coe’s Quarry, Connecticut. The samples were collected by Dr. R. P. Steinen, John Jansky, Jon Byrnes, and John Mooney at the University of Connecticut. I wish to thank Dr. Evans for providing both the Eocene samples from the Badlands, South Dakota, and the Triassic samples from Wales, U.K. Karen Waggoner and Lori Manship assisted in the collection of field data at San Ysidro Quadrangle, New Mexico. Scanning Electron Microscope work was conducted through the Biology Department at Bowling Green State University with the assistance of Marilyn Cayer. The assistance of these people is gratefully acknowledged. This project received funding support from the Geological Society of America, the Paleontological Society, and Bowling Green State University. vii TABLE OF CONTENTS Page ABSTRACT............................................................................................................... iii ACKNOWLEDGEMENTS....................................................................................... vi TABLE OF CONTENTS........................................................................................... vii LIST OF FIGURES ................................................................................................... x LIST OF TABLES..................................................................................................... xiv CHAPTER I. INTRODUCTION.............................................................................. 1 Carbonate Geology ........................................................................................ 1 Tufa and Travertine........................................................................................ 2 Economic Significance.................................................................................. 4 Depositional Environments and Basin Analysis............................................ 5 Life in Extreme Environments and Exobiology ............................................ 10 Purpose of Study............................................................................................ 14 CHAPTER II. TUFAS AND TRAVERTINES........................................................ 15 Mode of Formation ........................................................................................ 15 Classification and Description of Features .................................................... 17 Macroscopic Features.................................................................................... 21 Microscopic Features..................................................................................... 25 Neogene Tufas and Travertines ..................................................................... 30 Ancient Tufas and Travertines....................................................................... 30 CHAPTER III. GEOLOGIC BACKGROUND OF FIELD SITES.......................... 31 Regional Geology of New Mexico Research Site ......................................... 31 viii Regional Geology of South Dakota Research Site ........................................ 32 Regional Geology of Connecticut Research Site........................................... 37 Regional Geology of South Wales (UK) Research Site ................................ 39 CHAPTER IV. METHODOLOGY.......................................................................... 42 Sample Collection.......................................................................................... 42 Sample Treatment .......................................................................................... 42 Contamination ............................................................................................... 43 Scanning Electron Microscope Analysis ....................................................... 44 CHAPTER V. RESULTS ......................................................................................... 46 Neogene travertine from San Ysidro, New Mexico....................................... 46 General Description .................................................................................. 46 Macroscopic Features ............................................................................... 47 Microscopic Features................................................................................ 48 Paleogene tufa and travertine from the Badlands of South Dakota............... 61 General Description .................................................................................. 61 Macroscopic Features ............................................................................... 62 Microscopic Features................................................................................ 62 Early Jurassic tufa and travertine of the Hartford Basin, Connecticut .................................................................................................... 74 General Description .................................................................................. 74 Macroscopic Features ............................................................................... 75 Microscopic Features................................................................................ 75 Late Triassic travertine from south Wales (UK)............................................ 87 ix General Description .................................................................................. 87 Macroscopic Features ............................................................................... 88 Microscopic Features...............................................................................