DYNAMIC SYSTEMS ANALYSIS OF FOSSIL DINOFLAGELLATES FROM THE ATLANTIC COASTAL PLAIN, USA. by Jon Clayton Cawley Thesis submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE GEOLOGICAL SCIENCES APPROVED: RAOK BAL Richard K. Bambach, Chairman SpunIH. Yuedim —— LBs A fh Dewey M. McLean Bruce C. Parker July, 1996 Blacksburg, Virginia Keywords: Dinoflagellate, Eocene, Virginia, Systems dynamics, Community, Modeling. ™ Cooes oea AAG CANS eC = ee § og DYNAMIC SYSTEMS ANALYSIS OF FOSSIL DINOFLAGELLATES FROM THE ATLANTIC COASTAL PLAIN, USA. by Jon Clayton Cawley R.K. Bambach, Chairman Geological Sciences ABSTRACT Dynamic Systems modeling suggests that complex coastal dinoflagellate bio- systems can be modeled using environmental parameters such as temperature, salinity, and bulk nutrient levels. The former Salisbury Embayment of northern Virginia and Maryland is modeled here, using STELLA I and FORTRAN models based on physical oceanography and temperature, salinity, and nutrient conditions of the modern Yellow Sea. In these models, dinoflagellate assemblages are predicted based on environmental conditions associated with depth. Cluster analyses of fossil dinoflagellate frequency data from Tertiary Pamunky Group (Aquia and Nanjemoy Formations) of the Salisbury Embayment produce 17 discrete groupings. Samples within the Salisbury fossil cluster groups are statistically similar (via ANOVA analysis), but not the same. Therefore they represent paleocommunity types rather than paleocommunities. Although individual sinofiagellate species reccur in similar environmental settings, the paleocommunity types do not appear to repeat. In the past, such associations have been used as depth indicators. It is suggested here that they relate to estuarine, nearshore, and offshore coastal regions because of the temperature, salinity, and nutrient conditions of each. In the modern Yellow Sea, nearshore and offshore regions are separated by discrete lateral fronts in some areas, and by gradational regions of mixing in others. Both types of watermass boundaries are modeled in this study. Results suggest that evidences that discrete watermass boundaries might have occurred between some fossil dinoflagellate associations. Circulation patterns of the Salisbury Embayment may have been roughly similar to those of the modern Yellow Sea. ACKNOWLEDGEMENTS I would like to thank Dr. Dewey M. McLean, Dr. Richard K. Bambach, and Dr. Bruce Parker for their guidance (and their patience) during this study. I thank Dr. Cahit Coruh, Karen Hunt, and Dr J. Fred Read for their input at critical times. I would like to thank my friends Ross Irwin, Jerry Dorsey, Steve Ruzila, Bill Weitzel, and Steve and Carole McNall for their help, insight, and occasional sanity. And I thank my parents and family for their moral support. iif for chris of course. iv TABLE OF CONTENTS INTRODUCTION. ..0. 0... ce cence eee nc ence nc eeeea eee eeceeeeeceneeeeeesenseestesentenseeees 1 General COMMENIS............. ccc cc ececececececeneceneecececeneeecenseseceseaeeeesenens 1 Objectives Of this Study... ecceeeecccceeecceesscccseeeeeeecereneeeeseneceses 1 Method ology.........ccccccccccccenccence nc ee ee ene eens eee eeeseeseeeeeeeeeeeeeseeeseeaneeees 1 PART I. GEOGRAPHICAL AND GEOLOGICAL SETTING.........0000000000.. 3 The Salisbury Embayment......................ccccccssccceeceeeeceeeeees 3 The Pamunkey Group.............ccccccceeccecceeeeceeeceeceeeeeeeeeeas 6 The Aquia Formation.............cccccceccceeecesecceeeeeneeees 8 The Marlboro Formation................c.cccccccccesseeeeeeeeees 8 The Nanjemoy — Formation....................ccccceeeeceeseeeeees 9 Wl. THE DINOFLAGELLATES oon. cccccccessseececeseeceseneees 10 Dinoflagellate Lifecycle: Theca Versus Cyst Forme................. 10 I. FACTORS CONTROLLING DINOFLAGELLATE ABUNDANCE, DIVERSITY, AND PRESERVATION ................... 15 General Statement................cccc cccceececeeceececnececeeoeees 15 Physical Factors Controlling Abundance and Diversity............. 15 TE MPerature...... ccc cece cee eccencenceeceeereetencencteeeees 15 SALIMILY 0... ccc ce cece cee ee ence eceenseeseeneestenaeessenees 15 Eddies, Fronts, and Upwelling........0.. eee 16 NUtrientS......... cece ccc ce eee ecceceeceeceeeeteceeneeaeteeeees 17 LIQht... 0... cece cece ecc eee e nc eeceeceeaseeseseeeaeecseseeeueens 18 Biological Responses to Physical Factors..............cccccseeee 18 SUCCESSION.......... ccc ccc ccccecceceeceececeeceeseeeseeseneenees 18 TNOCULATION. ...... 0. cece cence cee ncecencenceneenceeeeeeeees 19 Dinoflagellate BIOOMS.................ccccsecceseccneeneeeeeees 19 Factors Controlling Preservation.................cccccsseececeeseeeeees 20 IV. THE YELLOW SEA AS A MODERN PHYSICAL ANALOG FOR THE SALISBURY EMBAYMENT.......0.00......cccccccccccccseseeseeeeees 22 V. METHOODG......0... ccc cccccceccccceenececeuseeccecncececeaceesceeaeccecaueesecseneees 26 Sources Of Data Sets... ccsceeeececccceenecessssseeeeees 26 Corellation of Samples (Cluster Analysis)................c:ccccesee 26 Q-mode Cluster AmalySis..............c.cccccccesesecceeeeeeees 28 Fossil Community Definitions....................ccccccssssseceeeeeeees 29 ANOVA = AnalSIS..............ccccccccceceneneeceeeceeececsceceeaeeeas 30 Dynamic Systems Modeling...................ccccessesecessseeceeeees 30 Phase Plane Interactions..................ccece ceceeceneceeeeseneesenes 32 VI. RESULTS AND DISCUSSION... cccccececcsseccneeseeeeeees 34 STELLA II Dynamic Systems Model... eeeeeeeeees 34 FORTRAN Dynamic Systems Models..................ccccccceeeees 36 Discussion of the FORTRAN Models......0....... ccc ceeeees 39 V Results of Q-mode Cluster AnnalySis...0.........ccs eeeeeeeeecees 40 Total Data Seto. ecccccsscesceeeeeceeeceeeseeees 40 Common Species Cluster Associations (>10%)............. 42 IntermediateSpecies Cluster Associations (10-1%)......... 42 Rare Species Cluster Associations (<1%)...........00 42 Discussion of Paleocommunity Makeup.................c:cccce08 46 Results of Chosen Phase Plane Plots... eeeeeeeees 52 VI. CONCLUSIONS ...... 0... c eee eee ene eee e eee eee seen neeenes 54 REFERENCE... ccc ccc cece ccc cnc cence nee e nee e eee e ee eea eee eeeeeeneeeeseeseseaeegseeseeeeees 55 APPENDICES Appendix A: Transformed Dinoflagellate Data Sets... 64 Appendix B: Modern Analog FORTRAN Model X, Z.................... 130 Appendix C: Plants 77 FORTRAN Cluster Analysis Program............ 146 VITA Lecce cece ence ene ee ne enna eee ee ee eeseea cece nese nesses eeneeeenseteeteeeteensennseeeas 159 vi LIST OF FIGURES Page 1. Map of East Coast of US. showing Embayments and Arches..................... 4 2. Basin Maps of Areal Extent Salisbury Embayment...........0....ccecesseee 5 3. General Geologic Column of the Pamunkey Group............0....ccccseeeee 7 4. Modern Dinoflagellate Lifecycle... cesesccesseceesencessseecesteceeeseneeees 11 5. Dinoflagellate Morphology..............ccccceeecccceeccseccceeecceeececeseeeeeeoeees 13 6. Basin Map of the Yellow Sea, Showing Fronts and Currents.................... 23 7. Sample Site Locatioms............. cece ceccceecccnecenecceccuseceeeseeceenseaeesans 27 8. Flow Chart for FORTRAN Models....0....0.0cece eecccessseseseteeeeseeeees 31 9. Phase Plane Archtypes............c ec ceccceeecccsesccececeescnsseccenceseeesenseees 33 10. STELLA JI Model Time Series... eeereeeetersenereseeteneeees 35 11. Fortran Model Output, X,Y... cceeeessseesssessseteeeerenseees 37 12. Fortran Model Output, Zo... ce ccccccccecccceeesssseeeceeecenaeess 38 13. Total Data Set Cluster Dendrogram........... ec ccccseeeeseeeeseees 41 15. Chosen Phase Plane = PlOts........ ee ee eeeeneeeeeceeseneeeceeeseneeeensoees 53 LIST OF TABLES Table 1: Comparison of Cluster GroupingS........ i. eee eeceesecceeeeeeteeeeees 43 Table 2: Dinoflagellate Master List 0... cecsscessessrecceesseeeeeeeeeees 47 Vil INTRODUCTION General Comments Fossil marine dinoflagellates (microscopic phytoplankton belonging to the Division Pyrrhophyta) are used extensively for age dating, correlation, and paleoenvironmental analysis. However, they have never been studied via system dynamics analyses of their community structure. System dynamics are used routinely in many fields of science to study complex multivariate systems (Roberts, 1983: Rose, 1987). Analyses of living systems and their environment involve complex interactions (May, 1981; May, 1993). This study is the first to use system dynamics to study fossil marine dinoflagellate assemblages. The Virginia Tech Palynology Program produced numerous dissertations and theses on the taxonomy, morphology, and biostratigraphy of Cretaceous and Tertiary dinoflagellates from the Atlantic Coastal Plain. This current study uses data from previous studies of the Aquia (Paleocene) and Nanjemoy (Eocene) Formations of the Virginia Coastal Plain (McLean, 1969; McLean, 1972; Witmer, 1975; Goodman, 1975; and Witmer, 1987). The Aquia and Nanjemoy Formations were deposited in an ancient embayment known as the Salisbury Embayment located geographically in the region of the present Chesapeake Bay and Atlantic Coastal Plain in the states of Virginia, Maryland, and Delaware (Figure 1). The localities studied herein are from Virginia, in the central and southern parts of the Salisbury Embayment. Objectives of this Study The primary objective of this study is to examine fossil dinoflagellate frequency data from the Salisbury Embayment for paleocommunity structure and environmental