FOSSIL EARTHQUAKES: THE FORMATION AND PRESERVATION OF PSEUDOTACHYLITES

By W. GARIA

CONTENTS INTRODUCTION TERMINOLOGY AND ORIGIN OF PSEUDOTACHYLYTE TERMINOLOGY CONTROVERSY REGARDING THE PHYSICAL ORIGIN OF PSEUDOTACHYLYTE PSEUDOTACHYLYTE-RELATED FAULT ROCKS AND CONCEPTUAL FAULT MODELS FAULT ROCKS CLASSI?CATION OF FAULT ROCKS MYLONITIC ROCKS CATACLASTIC ROCKS FORMATION OF S-C FABRICS FAULT ZONE STRENGTH AND FAULT MODEL SEISMOGENIC FAULT ZONE STRENGTH CONCEPTUAL FAULT ZONE MODEL TECTONIC ENVIRONMENT AND STRUCTURE OF PSEUDOTACHYLYTE VEINS TECTONIC ENVIRONMENT AND FIELD OCCURRENCE OF PSEUDOTACHYLYTE TECTONIC ENVIRONMENT FIELD OCCURRENCE CHILLING-MARGIN AND CRACK TEXTURES CLASSI?CATION OF PSEUDOTACHYLYTE VEINS FAULT VEINS AND INJECTION VEINS PSEUDOTACHYLYTE GENERATION ZONES RELATION BETWEEN FAULT VEIN THICKNESS AND SLIP AMOUNT PSEUDOTACHYLYTE MATRIX MICROSTRUCTURAL CHARACTERISTICS TEXTURAL CLASSI?CATION OF PSEUDOTACHYLYTE MATRIX FLOW STRUCTURES VESICLES AND AMYGDULES POWDER X-RAY DI?RACTION ANALYSIS X-RAY DI?RACTION PATTERNS FOR PSEUDOTACHYLYTE QUANTITATIVE ANALYSIS OF GLASS AND THE CRYSTALLINE FRACTION QUANTITATIVE ANALYSIS OF CRYSTALLINE MATERIAL DISCUSSION PROPERTIES OF GLASS AND GLASSY MATRIX E?ECT OF FRICTIONAL MELT ON FAULT STRENGTH ESTIMATION OF THE FORMATION DEPTH OF PSEUDOTACHYLYTE MICROLITES TEXTURE AND MORPHOLOGY OF MICROLITE TEXTURE MORPHOLOGY MICROLITE CHEMISTRY AND MAGNETIC PROPERTIES MICROLITE CHEMISTRY MAGNETIC PROPERTIES DISCUSSION OF THE MECHANISM OF MICROLITE FORMATION FRAGMENTS WITHIN PSEUDOTACHYLYTE VEINS FRAGMENTS THAT RESEMBLE CONGLOMERATE CLASTS GRAIN-SIZE ANALYSIS GRAIN-SIZE DISTRIBUTION WITHIN MELT-ORIGIN PSEUDOTACHYLYTE GRAIN-SIZE DISTRIBUTION: A DISCUSSION FABRICS OF FRAGMENTS AND DEGREE OF ROUNDING FABRICS DEGREE OF ROUNDING OF FRAGMENTS FORMATION OF ROUNDED FRAGMENTS: A DISCUSSION CHEMICAL COMPOSITION AND MELTING PROCESSES OF PSEUDOTACHYLYTE BULK-VEIN AND MATRIX COMPOSITIONS BULK COMPOSITION OF PSEUDOTACHYLYTE VEINS CHEMICAL COMPOSITION OF PSEUDOTACHYLYTE MATRIX WATER CONTENTS OF PSEUDOTACHYLYTE VEINS MELTING PROCESSES MELT TEMPERATURE ROLE OF WATER DURING FRICTIONAL MELTING FORMATION OF PSEUDOTACHYLYTE IN THE BRITTLE AND PLASTIC REGIMES WOODRO?E PSEUDOTACHYLYTES TECTONIC SETTING OF THE WOODRO?E THRUST FIELD OCCURRENCES OF THE WOODRO?E PSEUDOTACHYLYTES MICROSTRUCTURES DAHEZHEN PSEUDOTACHYLYTES TECTONIC SETTING OF THE DAHEZHEN SHEAR ZONE FIELD OCCURRENCE OF THE DAHEZHEN PSEUDOTACHYLYTES MICROSCOPY AND CHEMICAL COMPOSITION FORMATION MECHANISMS OF LARGE VOLUMES OF PSEUDOTACHYLYTES CONDITIONS OF FORMATION OF THE DAHEZHEN AND WOODRO?E M-PT VEINS CRUSHING-ORIGIN PSEUDOTACHYLYTE AND VEINLET CATACLASTIC ROCKS 10 1 INTRODUCTION 10 2 OCCURRENCE OF CRUSHING-ORIGIN PSEUDOTACHYLYTE AND CATACLASTIC VEINS 10 2 1 CRUSHING-ORIGIN PSEUDOTACHYLYTE 10 2 2 FAULT-GOUGE INJECTION VEINS 10 2 3 LAYERED FAULT GOUGE AND PSEUDOTACHYLYTE VEINS 10 2 4 CRACK-FILL VEINS 10 3 PETROLOGIC CHARACTERISTICS OF VEINLET CATACLASTIC ROCKS 10 3 1 MICROSTRUCTURES OF VEINLET CATACLASTIC ROCKS 10 3 2 POWDER X-RAY DI?RACTION ANALYSIS OF VEINLET MATERIAL 10 3 3 CHEMICAL COMPOSITION DATA AND ISOTOPE ANALYSES 10 3 4 AGE DATA FOR CRACK-?LL VEINS 10 4 DISCUSSION ON THE FORMATION MECHANISMS OF VEINLET CATACLASTIC ROCKS 10 4 1 FORMATION MECHANISM OF AMORPHOUS MATERIAL WITHIN VEINLET CATACLASTIC ROCKS 10 4 2 COSEISMIC FLUIDIZATION OF FINE-GRAINED MATERIAL WITHIN FAULT ZONES 10 4 3 REPEATED EVENTS OF SEISMIC SLIP 10 4 4 REPEATED COSEISMIC IN?LTRATION OF SURFACE WATER INTO DEEP FAULT ZONES LANDSLIDE-RELATED PSEUDOTACHYLYTE 11 1 INTRODUCTION 11 2 OCCURRENCES OF LANDSLIDES AND RELATED PSEUDOTACHYLYTES 11 2 1 LANGTANG HIMALAYA LANDSLIDE AND RELATED PSEUDOTACHYLYTE 11 2 2 CHIUFENER-SHAN LANDSLIDE AND RELATED PSEUDOTACHYLYTE 11 3 PETROGRAPHIC CHARACTERISTICS OF LANDSLIDE-RELATED PSEUDOTACHYLYTES 11 3 1 PETROGRAPHY OF THE LANGTANG HIMALAYA PSEUDOTACHYLYTE 11 3 2 PETROGRAPHY OF THE CHIUFENER-SHAN PSEUDOTACHYLYTE 11 3 3 GLASS CONTENTS OF THE OBSERVED PSEUDOTACHYLYTES 11 4 DISCUSSION OF THE P-T CONDITIONS DURING THE FORMATION OF LANDSLIDE-RELATED PSEUDOTACHYLYTE EXPERIMENTALLY GENERATED PSEUDOTACHYLYTE 12 1 INTRODUCTION 12 2 HIGH-VELOCITY FRICTIONAL EXPERIMENTS 12 2 1 TEST EQUIPMENT AND EXPERIMENTAL CONDITIONS 12 2 2 EXPERIMENT SAMPLES AND PROCEDURES 12 2 3 HIGH-VELOCITY FRICTIONAL PROPERTIES 12 3 MICROSTRUCTURES OF EXPERIMENTALLY GENERATED PSEUDOTACHYLYTE 12 3 1 TEXTURES OF THE FAULT SHEAR PLANE 12 3 2 VEIN GEOMETRY AND TEXTURE OF MOLTEN MATERIAL 12 4 POWDER X-RAY DI?RACTION ANALYSIS OF RUN PRODUCTS 12 4 1 DI?RACTION PATTERNS OF RUN PRODUCTS 12 4 2 QUANTITATIVE ANALYSIS 12 5 CHEMICAL COMPOSITION DATA 12 5 1 GABBRO SAMPLES 12 5 2 GRANITE SAMPLES 12 5 3 ALBITITE–QUARTZ AND ANORTHOSITE–ANORTHOSITE PAIRS 12 6 DISCUSSION 12 6 1 VEIN GEOMETRY 12 6 2 MELTING TEXTURES 12 6 3 NON-EQUILIBRIUM MELTING PROCESSES 12 6 4 MELTING TEMPERATURE 12 6 5 HIGH-VELOCITY SLIP WEAKENING REFERENCES