INAUGURAL-DISSERTATION zur Erlangung der Doktorwürde der Naturwissenschaftlich-Mathematischen Gesamtfakultät der Ruprecht-Karls-Universität Heidelberg vorgelegt von AUNG MOE, B.Sc., M.Sc. aus TAUNGDWINGYI, MYANMAR Heidelberg, 2000 STRUCTURAL DEVELOPMENT OF A VOLCANIC SEQUENCE OF THE LAHN AREA DURING THE VARISCAN OROGENY IN THE RHENOHERCYNIAN BELT (GERMANY) Gutachter: Prof. Dr. Heiner Flick Prof. Dr. Reinhard O. Greiling Heidelberg, 2000 This thesis is dedicated to my beloved mother & sister and to the memory of my father & daughter. CONTENTS CHAPTER 1 Introduction..................................................................................................................................................... 1 1.1 Location.............................................................................................................................................. 1 1.2 Previous studies ................................................................................................................................ 1 1.3 The input of the Variscan orogeny on the study area ...................................................................... 3 1.4 Aim of the study ................................................................................................................................. 5 CHAPTER 2 Regional setting.............................................................................................................................................. 6 2.1 Tectonic setting.................................................................................................................................. 6 Variscan tectonic models .................................................................................................................... 8 2.2 Structural setting.............................................................................................................................. 12 Alpine tectonic effect on the Rheinische Schiefergebirge ............................................................... 13 2.3 The setting of the study area........................................................................................................... 15 CHAPTER 3 Field structural data analysis ....................................................................................................................... 16 3.1 Folding.............................................................................................................................................. 16 3.1.1 Regional structures ................................................................................................................. 16 3.1.2 Structural types of small-scale folds....................................................................................... 19 3.1.3 Discussion ............................................................................................................................... 19 3.2 Faulting............................................................................................................................................. 22 3.2.1 Regional structures ................................................................................................................. 22 3.2.2 Discussion ............................................................................................................................... 26 3.3 Jointing............................................................................................................................................. 26 3.3.1 Regional structures ................................................................................................................. 26 3.3.2 Discussion ............................................................................................................................... 26 3.4 Cleavage .......................................................................................................................................... 29 3.4.1 Regional structures ................................................................................................................. 29 3.4.2 Discussion ............................................................................................................................... 31 3.5 Lineation........................................................................................................................................... 31 3.5.1 Regional structures ................................................................................................................. 31 3.5.2 Discussion ............................................................................................................................... 33 3.6 Age relationship between the structures ........................................................................................ 33 3.7 Other structures ............................................................................................................................... 35 CHAPTER 4 Strain analysis .............................................................................................................................................. 37 4.1 Determination of 2-dimensional strain ............................................................................................ 39 4.1.1 Rf/φ strain analysis................................................................................................................. 39 4.1.2 Fry strain analysis ................................................................................................................... 41 4.1.3 Strain ellipse (Rf/φ ) in XZ-section.......................................................................................... 43 4.2 Determination of 3-dimensional strain ............................................................................................ 53 4.2.1 Results..................................................................................................................................... 53 4.2.2 Strain ratio plot ........................................................................................................................ 57 4.2.3 Plotting in Flinn-diagrams ....................................................................................................... 59 4.2.4 Strain intensity......................................................................................................................... 62 4.2.5 Strain path in Flinn-diagram.................................................................................................... 64 4.3 Correlation between strain and AMS.............................................................................................. 68 4.4 Strain-vorticity analysis.................................................................................................................... 68 4.5 Discussion........................................................................................................................................ 71 i CHAPTER 5 Re-analysis of previous investigations ........................................................................................................ 73 5.1 Rhenohercynian basin..................................................................................................................... 73 5.2 Central Lahn basin........................................................................................................................... 76 5.2.1 Basin structure......................................................................................................................... 76 5.2.2 Volcaniturbiditic facies study................................................................................................... 78 5.2.2.1 Freienfels-Ernsthausen sub-area................................................................................... 78 5.2.2.2 Guntersau-Freienfels sub-area ...................................................................................... 79 5.2.3 Extension model correlation ................................................................................................... 80 5.2.3.1 Red Sea Type continental extension basin ................................................................... 80 5.2.3.2 Japan Sea Type back-arc continental extension basin ................................................ 81 5.3 Structural features ........................................................................................................................... 82 5.3.1 Joint development model........................................................................................................ 82 5.3.2 Drag fold model ....................................................................................................................... 84 CHAPTER 6 Orogenic compression ................................................................................................................................. 86 6.1 Inversion involved tectonic history .................................................................................................. 86 6.2 Inversion in the Weilburg area ........................................................................................................ 89 6.2.1 Synthetic half-grabens ............................................................................................................ 91 6.2.2 Antithetic half-grabens ............................................................................................................ 91 6.2.3 Full-graben..............................................................................................................................