Skip to main content
main-content

Über dieses Buch

The book is a thoughtful discussion with scientists studying convergent plate boundaries such as the well-known, active India-Eurasia collision zone. It provides a comprehensive collection of petrographic images of ophiolitic rocks exhumed from oceanic lithosphere and mantle at the India-Asia plate boundary. Ophiolite is exposed in the northwestern Himalayas, eastern Indian plate margin and Andaman-Nicobar Islands. At the eastern margin, it occurs in a narrow strip comprising mantle peridotite tectonite, cummulate peridotite-gabbro-plagiogranite-anorthosite, mafic dyke, volcanics and oceanic sediments. Low temperature/high pressure rocks including blueschists and eclogites were extensively studied recently. Ophiolite derived sediments and podiform chromites will also be discussed to provide complete details. Supplemental maps, geological sections, field sketches and photographs will explain the structure, stratigraphy, ore mineralization, and metamorphic history.

Inhaltsverzeichnis

Frontmatter

Description of Ophiolite Suites and the Naga Hills Ophiolite

Frontmatter

Chapter 1. Introduction

An ophiolite is a section of the oceanic lithosphere emplaced on continental crust or within the accretionary prism sediments of a subduction zone. Much of our knowledge of the vertical structure of the ocean floor comes from the study of ophiolite sequences. From bottom to top, a typical and complete ophiolite sequence comprises depleted mantle peridotite with tectonite at the base, layered ultramafic–mafic cumulates, massive (isotropic) gabbro, sheeted dikes and extrusive volcanic rocks represented by pillow basalts (Anonymous

1972

; Coleman

1977

).

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 2. Ophiolite Around the Indian Plate Margin

Ophiolite and ophiolitic rocks were emplaced along the western, northern and eastern margins of the Indian plate during the northward movement of the Indian plate and the collision of the Indian continental block first with intra-oceanic island arcs within the Neotethys, and then with the Helmand and Kabul continental blocks to the west (Tapponnier et al.

1981

), the Asian continental block to the north (Gansser

1964

) and the Myanmar continental block to the east (Mitchell

1993

)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 3. Geology of the Naga Hills Ophiolite

The NE–SW-oriented Naga Hills, constituting the northern part of the Indo-Myanmar Ranges (IMR) in the northeast Indian states of Manipur, Nagaland, parts of Arunachal Pradesh and the adjoining areas of western Myanmar, is known for the occurrence of ophiolitic rocks within a narrow arcuate zone along the middle of the belt.

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 4. Structure and Tectonics of the Naga Hills

The evolution of the NHO is linked with the fragmentation and dispersion of Gondwana (protocontinent of the southern hemisphere) and its subsequent collision and amalgamation with Eurasia during Meso-Cenozoic time. The post-fragmentation history of Gondwana and its unification with Eurasia is responsible for shaping the present physiographic configuration of southern Europe and Southeast Asia, including larger tracts of the Russian Federation and China.

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 5. Petrography

The textural relations among minerals are shown in optical photomicrographs. Unless specified otherwise, the photomicrographs were collected in the plane-polarised, transmitted light mode. A few backscattered electron images were also collected with the electron microprobe to supplement the optical microscope images.

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 6. Petrogenesis

The average composition of peridotite from the ophiolite belt in Manipur shows high MgO(32.0 wt.%), Al

2

O

3

(1.28–3.30 wt.%),Ni (1966 ppm),Cr (2005 ppm)and Co (130 ppm) and low TiO

2

(0.12 wt.%), CaO (6.56 wt.%), Na

2

O (0.44 wt.%) and K

2

O (0.07 wt.%) (Singh et al.

2010

; Singh

2013

).

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Photomicrographs and Backscattered Electron Images

Frontmatter

Chapter 7. Peridotite Tectonite

Highly fractured olivine showing strain shadow adjacent to Cr-spinel grains in dunite between crossed polars. The fractures are filled with serpentine (384/79-1).

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 8. Spinel Peridotite

Spinel harzburgite consisting of serpentinised olivine, non-pleochroic orthopyroxene and partially resorbed Cr-spinel with inclusions of serpentine (M77/20-2)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 9. Pyroxenite

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 10. Serpentinite

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 11. Rodingite

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 12. Chromitite

Plate Chr-1: Brecciated olivine with euhedral chromite and a vein of serpentine containing granular opaque magnetite in harzburgite tectonite. (380/79-3)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 13. Peridotite Cumulate

Plate Pc-1

Small grains of olivine remnants and opaque in serpentinised dunite. The olivine grains show uniform extinction indicating absence of strain (126/80-2)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 14. Gabbro

Plate G-1: Olivine gabbro between crossed polars showing a large grain of plagioclase surrounded by olivine and clinopyroxene in equilibrium. The plagioclase is saussuritised and the olivine is partly serpentinised. The plagioclase contains an olivine inclusion (158/80-2).

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 15. Plagiogranite

Plate PG-1: Hypidiomorphic granular texture in tonalite between crossed polars consisting of twinned plagioclase, quartz, amphibole, chlorite and epidote. Chlorite is more abundant than amphibole (M-1-3).

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 16. Anorthosite

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 17. Dolerite

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 18. Mafic Volcanics

Pseudomorph of chlorite + epidote after olivine phenocryst in porphyritic olivine basalt. The fine-grained groundmass shows an intersertal to intergranular texture (230/79-2).

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 19. Basaltic Hyaloclastite

Plate Hy-1: Folded carbonate and quartz veins (

white

) in a glassy groundmass of fragmented hyaloclastite dissected by micro-shear. The carbonates are intermixed with chlorite in the

lower left corner

(19/79-1).

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 20. Volcaniclastics

Fine tuff (ash) between crossed polars containing fine particles of quartz, orange glass and amygdule. Late silica veins runs through quartz particles. (86/80-1)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 21. Very-Low Grade Metamorphics

Plate Vlgm-1: Very-low grade, zeolite facies metamorphite between crossed polars containing spherulitic natrolite, twinned albite, epidote, green chlorite and opaque. (K-79-7)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 22. Greenschist

Greenschist consisting of actinolite, chlorite, albite, epidote and quartz. The amphiboles impart lineation(23/80-1)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 23. Glaucophane Schist

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 24. Eclogite

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 25. Oceanic Sediments

Pressure solution fracture in tuffaceous sediment. Slippage and plastic flow developed by ino-silicates under stress such that the strain is limited to a secondary fabric. (507/79-1).

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 26. Cover Sediments (Jopi Formation)

Plate Ptb-1: Fragment of brown lithic clast (rhyolite) in polymictic tuff breccia containing fine clasts of (a) serpentinite, (b) radiolarian chert and (c) foraminifera. The brown lithic clast is bordered by a girdle of rounded ortho- and clino-pyroxenes (d) and chert grains succeeded by a short band of radiolarian chert, a long band of trachyte (e) with particles of shale/argillite, and (f) lapillus. (C21/79-4)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 27. Late Tertiary Granites

Plate Ltg-1

Late felsic intrusive under crossed polars showing post-crystalline deformation with parallel orientation of quartz and feldspar grains. Plagioclase is saussuritised and twinned. K-feldspar, muscovite and epidote are minor constituents of the rock (369/70-2)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Chapter 28. Metamorphics of the Nimi Formation

Plate Nimi-1 Elongated tabular crystals of staurolite and muscovite flakes along foliation in chlorite-biotite-muscovite-garnet-staurolite schist with quartz and feldspar from the Nimi Formation at the eastern tectonic margin of the NHO. Staurolite is strongly pleochroic and possibly formed by reactions involving chlorite, muscovite and garnet (32/80-3)

Naresh Chandra Ghose, Nilanjan Chatterjee, Fareeduddin

Backmatter

Weitere Informationen

BranchenIndex Online

Die B2B-Firmensuche für Industrie und Wirtschaft: Kostenfrei in Firmenprofilen nach Lieferanten, Herstellern, Dienstleistern und Händlern recherchieren.

Whitepaper

- ANZEIGE -

Systemische Notwendigkeit zur Weiterentwicklung von Hybridnetzen

Die Entwicklung des mitteleuropäischen Energiesystems und insbesondere die Weiterentwicklung der Energieinfrastruktur sind konfrontiert mit einer stetig steigenden Diversität an Herausforderungen, aber auch mit einer zunehmenden Komplexität in den Lösungsoptionen. Vor diesem Hintergrund steht die Weiterentwicklung von Hybridnetzen symbolisch für das ganze sich in einer Umbruchsphase befindliche Energiesystem: denn der Notwendigkeit einer Schaffung und Bildung der Hybridnetze aus systemischer und volkswirtschaftlicher Perspektive steht sozusagen eine Komplexitätsfalle gegenüber, mit der die Branche in der Vergangenheit in dieser Intensität nicht konfrontiert war. Jetzt gratis downloaden!

Bildnachweise