EXPLORATION OF MICROBIAL DEPOSITS KNOWN AS GIANT HAMS FROM THE LOWER PERMIAN LABORCITA FORMATION, SACRAMENTO MOUNTAINS, NEW MEXICO By Kevin Martin Moore A Thesis Submitted to the Faculty of Mississippi State University in Partial Fulfillment of the Requirements for the Degree of Masters of Science in Geosciences in the Department of Geosciences Mississippi State, Mississippi December 2010 Copyright 2010 By Kevin Martin Moore EXPLORATION OF MICROBIAL DEPOSITS KNOWN AS GIANT HAMS FROM THE LOWER PERMIAN LABORCITA FORMATION, SACRAMENTO MOUNTAINS, NEW MEXICO By Kevin Martin Moore Approved: _________________________________ _________________________________ Brenda L. Kirkland Darrel W. Schmitz Associate Professor of Geology Professor of Geology (Director of Thesis) (Head of Department of Geosciences and Committee Member) _________________________________ _________________________________ Christopher P. Dewey Gary Myers Associate Professor of Geology Dean of College of Arts and Sciences (Graduate Coordinator and Committee Member) Name: Kevin Martin Moore Date of Degree: December 10, 2010 Institution: Mississippi State University Major Field: Geosciences Major Professor: Dr. Brenda L. Kirkland Title of Study: EXPLORATION OF MICROBIAL DEPOSITS KNOWN AS GIANT HAMS FROM THE LOWER PERMIAN LABORCITA FORMATION, SACRAMENTO MOUNTAINS, NEW MEXICO Pages in Study: 45 Candidate for Master of Science The Lower Permian Laborcita Formation, Sacramento Mountains, New Mexico crops out along a narrow, 27 km strip, and is 240 m at its thickest. The objective of this study was to document ham-shaped microbial deposits through petrography and scanning electron microscopy. The study concluded that the hams began as microbial oncoids, and only the third growth zone exhibited in situ growth giving the deposit its shank-like shape. They are believed to have originated as oncoids on the presence of irregular, concentric, biogenic micritic laminae surrounding a nucleus. A microbial origin is based upon the presence of irregular laminations, fenestral fabrics, peloids, and fossil bacteria seen in SEM. The results are significant because they document enigmatic carbonate precipitation in a dominantly siliciclastic, ecologically stressful setting. By improving the understanding of organic matter in calcium carbonate precipitation, the results of this study will potentially benefit applications in medical, industrial, and academic fields. DEDICATION To my grandfather, who inadvertently set me on this road so many years ago. ii ACKNOWLEDGEMENTS I would like to thank the Mississippi State University Electronic Microscope Center, especially Richard Kuklinski for all of his help in my SEM workings. Thin sections were funded by The Geology Foundation and Department of Energy Grant DOE NT15458. I would also like to thank Greg Thompson and the staff of the University of Texas at Austin thin section lab for creating the exceptional polished slabs used for this project. I’d also like to thank Ian Thornkild Gordon for his work on the hams and bringing a sample from the field. I would also like to thank Dr. Kirkland for keeping me from straying away from my thesis while all of the other kids were outside playing. I’d also like to thank Dr. Schmitz and Dr. Dewey, for their help in wrangling this beast. Lastly I’d like to thank Cale, Josh, and Will for keeping me entertained over the past couple of years. I’d also like to thank Brittany for giving me all sorts of insight into writing a thesis. To all the cast of characters who have played their parts during my time here: Thank you. I couldn’t have done it without you all. iii TABLE OF CONTENTS Page DEDICATION .................................................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................... iii LIST OF FIGURES ........................................................................................................... vi CHAPTER I. INTRODUCTION: ............................................................................................1 Setting 1 Significance........................................................................................................5 II. METHODS ........................................................................................................6 Sample Collection ..............................................................................................6 Cutting slabs.......................................................................................................6 Thin Sections .....................................................................................................6 Scanning Electron Microscope ..........................................................................7 III. RESULTS ..........................................................................................................8 1st Growth Zone ..............................................................................................13 Ham Slabs ..................................................................................................13 Thin sections ..............................................................................................14 2nd Growth zone ...............................................................................................18 Ham slabs ...................................................................................................18 Thin Sections .............................................................................................20 3rd Growth zone................................................................................................26 Ham slices ..................................................................................................26 Thin sections ..............................................................................................27 SEM Pictures ...................................................................................................28 FESEM .......................................................................................................38 IV. DISCUSSION ..................................................................................................39 V. CONCLUSIONS..............................................................................................42 iv REFERENCES ..................................................................................................................43 v LIST OF FIGURES FIGURE Page 1 Stratigraphic column of the Sacramento Mountains (Gordon, 1997) ..................2 2 Map of Laborcita with the hams originating in the area of the red box (Modified from Fly, 1986) .......................................................................3 3 Growth Zone Map – B .........................................................................................9 4 Growth Zone Map - A ..........................................................................................9 5 Growth Zone Map – 2 ........................................................................................10 6 Growth Zone Map - 1 .........................................................................................10 7 Used for area description of ham. ......................................................................11 8 Ham slabs ...........................................................................................................11 9 Ham diagram ......................................................................................................12 10 Ham in outcrop. ..................................................................................................12 11 Ham slab 2 ..........................................................................................................13 12 Laminae taken from Ham slab 2 ........................................................................14 13 Scanned image of thin section Ham 2b “stringers” ............................................16 14 Peloidal micrite forming a shotgun pattern ........................................................17 15 Chain pattern formed by micrite rims around calcite spar and clusters of peloids ....................................................................................................17 16 Scanned image of thin section Ham E ...............................................................18 17 Ham slab 1 upside down ....................................................................................19 18 Large calcite filled opening ................................................................................20 vi 19 Scanned image of Ham 2d thin section ..............................................................21 20 Scanned image of thin section Ham A ...............................................................23 21 Micritic peloids surrounded by needle like crystals (previously aragonite), which are surrounded by blocky spar. .................................24 22 Radial aragonite fans with peloidal micrite at the base or center of the fans. Peloidal micrite forms the core for splays of needle like crystals interpreted as being originally aragonitic. .................................24 23 Scanned image of thin section Ham 2c ..............................................................25 24 Ham slab 1. .........................................................................................................26 25 3rd growth zones texture. ....................................................................................27