Popigai Impact Structure and Its Diamond-Bearing Rocks

ISBN-13: 9783030085926 / Angielski / Miękka / 2019 / 204 str.

Victor L. Masaitis

Spis treści

INTRODUCTION

CHAPTER 1. MAIN GEOLOGICAL FEATURES OF IMPACT CRATER AND ITS ENVIRONMENT

1.1. Crystalline basement

1.2. Platform cover

1.3. Topography of the hollow and its surroundings

1.4. Gravity and magnetic fields

1.5. Morphology and inner geological structure

1.6. Subdivision of impact lithological units and impact rocks

1.7. Crater age

CHAPTER 2. CONCENTRIC STRUCTURAL ZONES AND ITS IMPACT BRECCIA AND IMPACTITES

2.1. Outer zone of sin-impact deformations and outer slope of the ring trough

2.1.1. Area of the Sogdoku Upland

2.1.2. Area of the middle course of the Chordy-Daldyn River

2.1.3. Area of the up-stream of the Tongulakh River

2.1.4. Area of the up-stream of the  Arylakh-Yurjage River

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2.2. Ring trough and ring uplift (peak ring)

2.2.1. Area of the up-stream and middle courses of the Balagan-Yurjage River

2.2.2. Area of the Majachica Upland

2.3. Central depression. Area of the lower course of Daldyn River

2.4. Post-impact   deformations

CHAPTER 3.  SHOCK-METAMORPHOSED CRYSTALLINE ROCKS, IMPACT BRECCIAS  AND IMPACTITES

3.1. Crystalline target rocks and their shock metamorphic features

3.1.1. Brief characteristic of gneisses and plagiogneisses

3.1.2. Mineralogical criterions   of the shock metamorphic parameters

3.1.3. Weakly and moderately shock-metamorphosed rocks

3.1.4. Intensely  shock-metamorphosed  rocks

3.1.5. Very intensely  shock-metamorphosed  rocks

3.2. Impact lithic breccias

3.2.1. Autochtonous and paraautochtonous lithic breccia

3.2.3. Allochtonous lithic breccia

3.2.3.1. Mega- and mesobreccia

3.2.3.2. Microbreccia (coptoclastite)

3.3. Tagamites

3.3.1. Composition, texture and principles of subdivision

3.3.2. Low-temperature tagamites (LT)

3.3.3. High-temperature tagamites (HT)

3.4. Suevites

3.4.1. Composition, texture, and principles of subdivision

3.4.2. Suevites, enriched by epiclasts

3.4.3. Suevites, enriched by vitroclasts

3.4.4. Impact glasses from suevites and coptoclastites

3.5. Hydrothermal alterations of impact breccias and impactites

CHAPTER 4. PETROCHEMISTRY AND GEOCHEMISTRY  OF IMPACTITES AND TARGET ROCKS

4.1. Petrochemistry and geochemistry

4.2. Isotopic composition

4.3. Geochemical evidence of impactor’s matter

CHAPTER 5. IMPACT DIAMONDS FROM SHOCKED CRYSTALLINE ROCKS AND IMPACTITES

5.1. Morphology of diamond paramorphs

5.2. Phase composition and microtexture

5.3. Physical properties

5.4. Isotopic composition

CHAPTER 6. GENERAL PATTERNS  OF IMPACT DIAMOND DISTRIBUTION  

6.1. General characteristics on sampling

6.2. Distribution of impact diamonds  over the impact structure

6.3. Impact diamond content and composition of host rocks

6.4. Distribution of impact diamonds in sheet-like tagamite bodies

6.5. Impact diamonds in placers

6.6. Deposits of impact diamonds and their resources

CHAPTER 7. ORIGIN OF DIAMOND-BEARING  IMPACTITES

7.1. Reconstruction of the impact event

7.2. Main features of evolution of impact melt-forming and rock-forming petrological systems

7.2.1. Initial petrological systems

7.2.2. Transitional petrological systems

7.2.3. Final petrological systems

CONCLUSION

REFERENCES

Blurb

This book highlights the most prominent research on the Popigai meteorite crater (Siberia, Russia), the 6th largest known impact structure in the world. Not only does the crater have a diameter of roughly 100 km, it is also an estimated 35.7 million years old.

This monograph is an updated, extended and revised edition of the Russian-language book “Diamond-bearing Impactites of Popigai Astrobleme” and presents the most comprehensive research on the Popigai impact structure. The Popigai crater is unique in that the total amount of impact diamonds it contains exceeds all the other diamond-bearing provinces of the world.

The work presented here is based on the geological mapping, core logging, geophysical survey and petrological studies of the crater, and was written by the team of geologists who first described the Popigai impact structure and its diamonds, and took part in the exploration of their deposits from 1970 to 1985.