Iron-Formation: Facts and Problems (eBook)

Front Cover 1
Iron-Formation: Facts and Problems 4
Copyright Page 5
Contents 10
Foreword 6
Contributing Authors 8
CHAPTER 1.INTRODUCTION 16
Origin, purpose, and scope of this volume 16
Classification and nomenclature of iron-formation 17
Acknowledgements 26
References 26
CHAPTER 2. ANIMIKIE BASIN, LAKE SUPERIOR REGION. U.S.A. 28
Introduction 28
Regional geologic setting 29
Geochronology 34
Documentation of the basin 35
Description of the basin 38
The iron-formations and their depositional environments 53
Secondary enrichment deposits 70
References 73
CHAPTER 3. THE HAMERSLEY BASIN 82
Introduction 82
Documentation 83
Location, area, shape, and outcrop limits 85
Stratigraphy 88
The iron-formations 98
Structure 110
Metamorphism 111
Tectonic development of the basin 113
Surface configuration and depositional conditions 130
Mineral deposits 134
Acknowledgements 135
References 136
CHAPTER 4. PALAEOENVIRONMENTAL SETTING OF IRON-FORMATIONS IN THE DEPOSITIONAL BASIN OF THE TRANSVAAL SUPERGROUP, SOUTH AFRICA 144
Introduction 144
Documentation of the depository 146
Structure and metamorphism of the strata 146
Age 153
Nomenclature 153
Tectono-sedimentary and stratigraphic setting of the iron-formations 155
Schmidtsdrif Subgroup 160
Campbellrand–Malmani carbonate sequence 164
Asbesheuwels Subgroup 165
Koegas Subgroup 177
Rooihoogte and Timeball Hill Formations 182
Makganyene Diamictite 183
Voëlwater Subgroup 185
Manganore Iron Formation 192
Vertical distribution of iron and manganese in the Transvaal Supergroup 194
Conclusion 196
Acknowledgements 201
References 201
CHAPTER 5. THE KRIVOY ROG BASIN 214
Introduction 214
History of geological research 214
Geological structure of the basin 215
The iron-formations 227
Metamorphism 236
Genetic model for Precambrian banded iron-formations 242
Iron ore deposits 246
References 250
CHAPTER 6. IRON-FORMATION IN FOLD BELTS MARGINAL TO THE UNGAVA CRATON 254
Introduction 254
History and documentation of geology 259
Description of basins 260
Depositional environments 283
References and selected bibliography 289
CHAPTER 7. THE NABBERU BASIN OF WESTERN AUSTRALIA 296
Introduction 296
Documentation of the basin 297
Description of the basin 299
Depositional environment 317
Depositional facies model 320
Acknowledgements 321
References 322
CHAPTER 8. PART A: A CONTRIBUTION ON THE CHEMICAL COMPOSITION OF PRECAMBRIAN IRON-FORMATIONS 326
Introduction 326
Systematic studies 327
Discussion and conclusions 338
Acknowledgements 342
References 343
PART B: RARE EARTH ELEMENTS IN IRON-FORMATION 346
Introduction 346
REE distribution in iron-formation 350
Evolution of Precambrian oxidation states 351
Mineralogical facies 354
Diagenesis 355
Volcanic input to iron-formations 356
Summary 356
References 358
PART C: OXYGEN ISOTOPE GEOCHEMISTRY OF IRON-FORMATION 360
Introduction 360
Proterozoic iron-formation 362
Archean iron-formation 369
Discussion 370
Acknowledgement 371
References 371
CHAPTER 9. THE PALAEONTOLOGY AND PALAEOECOLOGY OF PRECAMBRIAN IRON-FORMATIONS 374
Introduction 374
Palaeontology 378
Palaeoecology 390
Microbial deposition of iron-formation 393
Conclusions 394
Acknowledgements 395
References 396
CHAPTER 10. BANDED IRON–FORMATION – A GRADUALIST’S DILEMMA 402
Introduction 402
What needs to be explained 403
Assumptions and constraints 404
The seminal sources 405
The original model 406
Subsequent modification of the model 407
Testable corollaries of the model 409
Findings relevant to a test of the model 410
Current status of the model as it relates to BIF 413
References 415
CHAPTER 11. DIAGENESIS AND METAMORPHISM OF PRECAMBRIAN BANDED IRON-FORMATIONS 418
Introduction 418
Major-element geochemistry of banded iron-formations 419
Diagenetic to very low-grade metamorphic assemblages 423
Physical and chemical conditions of iron-formation diagenesis and very low-grade metamorphism 439
Medium-grade metamorphic assemblages 441
Physical and chemical conditions of medium-grade metamorphism 450
High-grade metamorphic assemblages 451
Physical and chemical conditions of high-grade metamorphism 458
Theoretical evaluation of the conditions of metamorphism of iron-formations 462
Acknowledgements 465
References 466
CHAPTER 12. DISTRIBUTION OF BANDED IRON-FORMATION IN SPACE AND TIME 472
Introduction 472
Age and tonnage assessments 472
Temporal and spatial distribution 475
Significance of peaks in the depositional record 484
Acknowledgement 486
References 487
Chapter 13. CHEMICAL FACTORS IN THE DEPOSITION AND DIAGENESIS OF BANDED IRON-FORMATION 492
Introduction 492
The Dales Gorge Member 493
The nature of the source solutions 494
The primary precipitation 499
The primary sediment and its diagenesis 508
Conclusion 511
Acknowledgements 511
References 511
CHAPTER 14. SUPERGENE ALTERATION OF BANDED IRON-FORMATION 514
Introduction 514
Physical weathering 515
Chemical weathering 516
Discussion 529
Conclusion 532
Acknowledgements 533
References 533
Subject Index 536