Himalayan Thick-Skin Basement Deformation of the Ladakh Batholith, Leh-Ladakh Region, NW India

Description

This book presents the first report and interpretation of the deformation, structural style, and geo-tectonic evolution of a 600km2 area of the Ladakh batholith, NW India, centred on the city of Leh, Ladakh. The Ladakh (and westerly Kohistan ) batholith comprises a large component of the Jurassic-Oligocene Kohistan-Ladakh Arc-Terrane (KLA), with magmatism spanning island arc, continental margin, and post-Himalayan collision tectonic environments. The KLA is bounded to the north by the Shyok-Northern Suture and to the south by the Indus Suture. The batholith illustrates basement thick-skin tectonic deformation and is divided/partitioned into a series of crustal blocks separated by lateral accommodation structures which allow independent movement in horizontal and vertical space. Thin skinned deformation within the adjacent sedimentary molasse Indus Suture Rocks produced large thrust stacks that predominantly moved towards the N-NE.  Whilst deformation within cover sequences influences the basement structures, and helps break up the basement into crustal blocks, there is a clear distinction in deformation between the basement and cover sequences. Basement batholith deformation is more complex and heterogeneous, reflecting the variable transmission of tectonic stress within crystalline crust and the presence of a wide range of precursory inherited weaknesses and anisotropies.  Models of time-space deformation are presented using data derived from field and extensive photograph / photo-mosaic image interpretation. The batholith was deformed during at least Palaeocene-Pliocene times at crustal depths that correspond to the ductile-brittle transition zone and shallower. Preface Acknowledgements Introduction Contents About the Author List of Figures List of Tables 1 Geo-tectonic and, Topographic, and Geographical Setting of the Leh–Ladakh Region: Study Scope and Methodology 1.1 Broad Geo-tectonic and Geographical Contexts of This Study 1.2 Research Objectives and Methodology of This Study References 2 Overview of the Geology, Structure, and Tectonics of the Ladakh Batholith and Indus Suture Rocks 2.1 Overview of the Kohistan–Ladakh Batholith 2.2 Overview of the Indus Suture Rocks 2.3 Broad Palaeo-environments and Unroofing Evidence Recorded by the Indus Suture Rocks 2.4 Structure, Deformation, and Uplift of Ladakh, with References to Kohistan References 3 Geology and Lithological Variations of the Ladakh Batholith Within the Leh–Ladakh Region 3.1 Batholith Overview in the Leh–Ladakh Region 3.2 Meta-sedimentary Rocks 3.3 Gabbro–Diorites 3.4 Granodiorites–Granites (Granitoids) 3.5 Minor Intrusions and Assorted Minerals Veins 3.6 Larger Scale Examples from the Batholith 3.7 Summary of the Key Aspects of the Leh–Ladakh Batholith and Intrusive-Deformation Model Reference 4 Structural Geology of the High Strain Zone: Ladakh Batholith, Leh Region, NW India 4.1 The Structuctural High Strain Zone (HSZ) 4.2 Taroo High Strain Zone Structural Geology 4.3 Phyang High Strain Zone Structural Geology 4.4 Leh Valley High Strain Zone 4.5 Saboo–Shey–Thiksey–Stakna High Strain Zone 4.6 Whole-High Strain Zone Structural Synthesis 4.6.1 Primary and Secondary Fracture/Thrust/Shear Structural Data Analysis 4.6.2 High Strain Zone (HSZ) Structural Data Synthesis Reference 5 Structural Geology of the Northern and North-Eastern Zone (N–NE Zone), Leh–Ladakh Region 5.1 Introduction, Zonal Structural Styles, and Variations 5.2 Structural Data, Geological Cross Sections, and Structural Analysis of the N–NE Zone 6 Structure and Lithology of the Indus Suture Rocks (Indus Formation) in the Leh–Ladakh Region 6.1 Scope of This Chapter 6.2 Lithological Characteristics of the Indus Suture Rocks in the Leh–Ladakh Region 6.3 Structural Interpretation of the Indus Suture Rocks (ISR) in the Leh–Ladakh Region 7 Deformation Model for the Ladakh Batholith in the Leh–Ladakh Region 7.1 Geotectonics Structure and Deformation 7.2 Crustal Deformation Model: Fractured Basement References