A lot of orogenic belt and foreland basin systems are developed in the central and western part of China, among them the most distinctive one is the margin orogen and foreland basin system surrounding the Tibetan plateau, this system is known as the “Natural Geological Museum” with colorful geological phenomenon, it is also regarded as the “golden key to unlock global orogenic mechanism” “natural laboratory for continental dynamic theory” and “pacemaker of global change” by international geoscience circle, it is becoming the cradle and competitive field of new theories, new recognition and new discoveries in the geoscience circle.
The Longmenshan orogenic belt and foreland basin is the special regional unit in the eastern margin of Tibetan plateau, and also a gem of Chinese geoscientific field, it serves as the typical region for the research on dynamics (plateau-orogenic belt-basin dynamics) of Tibetan plateau and the surrounding orogenic belts and foreland basins. The landform of this area can be divided into three first-class geomorphic zones from west to east, and they are Tibetan plateau geomorphic zone, Longmenshan alpine geomorphic zone and piedmont alluvial plain geomorphic zone respectively. Speaking of regional geology, this area consists of four structural units from northwest to southeast, including Tibetan plateau (Boyan Kala block), Longmenshan orogenic belt, foreland basin, and forebulge. The frequent occurrence of active faults and earthquakes indicates Longmenshan orogenic belt-foreland basin system is currently active with significant deformation, it belongs to the typical active orogen and active foreland basin system, which makes it become the intensively interested area of international geoscience circle. The great emerging of new data and new thoughts are making us excited as well as confused, even though our team has long been engaged in the geological research on the Longmen Mountain. The exciting point is that the massive new data can help us understand more about the Longmen Mountain “Book which is hard to read, as well as the complicated geological processes conceived by her and the intensive earthquakes; the confusing point is that the currently new thoughts and models already have had intensive impact on the existing concepts and thoughts. We are always lost in our thoughts and comparisons, bearing the hope to understand more about the uplifting mechanism and its violent earthquake generating mechanism of this ancient mountain.
An international research team led by chief expert professor Yong Li have been committed to the research on the Longmenshan orogenic belt and foreland basin system for more than 30 years, from 1987 to 1999, the research on the coupling mechanism between Longmenshan orogenic belt and foreland basin was conducted, from 2000 to 2007, the active tectonics research on Longmen Mountain and western Sichuan basin was conducted, after the 2008 Wenchuan earthquake, the research on active tectonics deformation and surface response of Wenchuan Ms 8.0 earthquake, andlater the surface deformation and dynamics mechanism research on 2010 Suining Ms5.0 earthquake, 2013 Lushan Ms7.0 earthquake, 2017 Jiuzhaigou Ms7.0 earthquake was conducted, gradually the research ideas and methods of coupling mechanism between active orogen and active foreland basin and surface process were formed, which could not only provide scientific basis and representative example for the research on the coupling mechanism between marginal orogen of Tibetan plateau and foreland basin, earthquake generating mechanism, earthquake disaster prevention and postdisaster reconstruction, but also give a scientific example for national and even global research on the coupling mechanism between intercontinental orogen and foreland basin. Based on the results mentioned above, this symposium was compiled, which contains 40 English papers published by our team, and it covers the coupling mechanism between Longmenshan orogenic belt and foreland basin, active tectonics and earthquake, mega earthquake induced geo-disasters and long-term effect, denudation and provenance, and it is considered as the integration and sublimation of 30-year international cooperation research results. The main contents include four parts.
Table of Contents
Part I The Orogenic Belt and Foreland Basin
Chapter 1 Evolution of the Longmenshan Foreland Basin during the Late Triassic Indosinian Orogeny 2
1.1 Introduction 2
1.2 Geological History 3
1.3 Tectonostratigraphic Units of the Upper Triassic Longmenshan Foreland Basin Fill 8
1.4 Underfilled and Overfilled Condition of the Longmenshan Foreland Basin 16
1.5 Basal Unconformity and Convergence Rate 17
1.6 Flexural Model of the Longmenshan Foreland Basin 18
1.7 Conclusions 23
Chapter 2 Sedimentary and Tectonic Evolution of Longmenshan Foreland Basin 26
2.1 Introduction 26
2.2 Regional Structural Framework 26
2.3 Tectonic Sequences and Sequences 27
2.4 Sedimentation and Thrusting 32
2.5 Evolution 34
2.6 Conclusions 35
Chapter 3 Sedimentary Responses to Longmenshan Thrusting and Strike-slipping 36
3.1 Introduction 36
3.2 Depositional Patterns 38
3.3 Sediment Supply, Accumulation Rates and Drainage Systems 40
3.4 Evolution and Implications 43
3.5 Conclusions 49
Chapter 4 The Carbonate Ramp and Sponge Buildup in Longmenshan Foreland Basin 50
4.1 Introduction 30
4.2 The Geometry and Sedimentary Sequences of the Maantang Formation 52
4.3 Drowning of the Oolitic Shoal and Siliceous Sponge Buildup 57
4.4 Migration of Oolitic Shoal and Buildup of Siliceous Sponge 59
4.5 Drowning and Migration of the Carbonate Ramp and Sponge Buildup 68
4.6 Conclusions 70
Chapter 5 Black Shale in Longmenshan Foreland Basin 71
5.1 Introduction 71
5.2 Geological Setting 73
5.3 Samples and Methods 73
5.4 Results 75
5.5 Discussion 84
5.6 Conclusions 96
Chapter 6 Crustal Thickening or Isostatic Rebound of Orogenic Wedge 97
6.1 Introduction 97
6.2 Geometry of the Tectonostratigraphic Units 99
6.3 Transition between Wedge-shaped and Tabular Tectonostratigraphic Units 104
6.4 Unconformities
6.5 Conglomerate Layers 108
6.6 Deroofing History 110
6.7 Southeastward Onlapping Rate 111
6.8 Conclusions
Chapter 7 Episodic Orogeny and Coeval Sedimentary Sequences in the Foreland Basin 116
7.1 Introduction
7.2 The Transition between Wedge-shaped and Tabular Megasequences 118
7.3 Episodic Orogenic Loading and Erosional Unloading 121
7.4 Advance Rate of the Orogenic Wedge 125
7.5 The Reversion of the Strike-slipping Direction 125
7.6 Discussion on Uplift Process and Mechanism of Longmen Mountain 128
7.7 Conclusions 129
Chapter 8 The Coupling Relationship between the Uplift of Longmen Mountain and the Subsidence of Foreland Basin 130
8.1 Introduction 130
8.2 Geological Setting 132
8.3 Crustal Shortening of the Longmen Mountain and the Late Triassic Wide Wedge-shaped Foreland Basin 135
8.4 Crustal Isostatic Rebound of the Longmen Mountain and the Jurassic-Paleogene Tabular Foreland Basin 141
8.5 Lower Crustal Flow of the Longmen Mountain and the Neogene-Quatemary Narrow Wedge-shaped Foreland Basin 144
8.6 Conclusions 149
Chapter 9 Crustal Uplift of the Longmen Mountain 151
9.1 Introduction 151
9.2 Regional Tectonic Framework, Geophysical Field and Characters of Deep Structure 152
9.3 Research Objective 155
9.4 Research Method 155
9.5 Simulation of IGA Using Airy Isostasy Model 164
9.6 Discussion 172
9.7 Conclusions 174
Chapter 10 The Two Phases of Thickening of Longmen Mountain 176
10.1 Introduction 176
10.2 Geological Settings: the Border of the Tibetan Plateau from West to East 178
10.3 Xuelongbao Crystalline Massif: Crystallization Age of the Granitoid 180
10.4 Structures of Xuelongbao Massif and Its Cover 184
10.5 Metamorphic and Microstructural Analysis 187
10.6 Mineral Description and Composition 191
10.7 PT Estimates 197
10.8 Discussion 206
10.9 Conclusion 209
Chapter 11 Coseismic Uplift and Subsidence during the Wenchuan Earthquake 211
11.1 Introduction 211
11.2 Geological Setting 213
11.3 Coseismic Deformation Triggered by the Wenchuan Earthquake 215
11.4 Theories and Methods 216
11.5 Flexure Calculation Results 218
11.6 Discussion 221
11.7 Conclusions 222
Part II Active Tectonics and Earthquake
Part III Mega Earthquake Induced Geo-disasters and Long Term Effects
Part IV Denudation and Provenance
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ACTIVE TECTONICS AND EARTHQUAKES IN LONGMENSHAN OROGENIC BELT AND FORELAND BASIN SYSTEM
