Physiographic, Stratigraphic and Structural Development of the Quadrilatero Ferrifero Minas Gerais, Brazil
Total Page：16
File Type：pdf, Size：1020Kb
Physiographic, Stratigraphic and Structural Development of the Quadrilatero Ferrifero Minas Gerais, Brazil GEOLOGICAL SURVEY PROFESSIONAL PAPER 641-A Prepared in cooperation with the Departamento Nacional da Producao Mineral of Brazil under the auspices of the Agency for International Development of the United States Department of State Physiographic, Stratigraphic and Structural Development of the Quadrilatero Ferrifero Minas Gerais, Brazil By JOHN VAN N. DORR 2d REGIONAL GEOLOGY OF THE QUADRILATERO FERRIFERO, MINAS GERAIS, BRAZIL GEOLOGICAL SURVEY PROFESSIONAL PAPER 641-A Prepared in cooperation with the Departamento Nacional da Producao Mineral of Brazil under the auspices of the Agency for International Development of the United States Department of State UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969 UNITED STATES DEPARTMENT OF THE INTERIOR WALTER J. HIGKEL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page Stratigraphy Continued Abstract.. _ ________________________________________ Al Minas Series Continued Page Introduction-______________________________________ 3 Caraga Group Continued Location and importance of area________________ 3 Environment of deposition. A38 Development of project_______._________________ 4 Metamorphism. __________ 39 Acknowledgments. _____________________________ 6 Itabira Group..______________ 39 Transportation__ _ _____________________________ 7 Caue1 Itabirite.___________ 40 Climate._____---_-_---_-__-___._______________ 7 Gandarela Formation _____ 44 Topography and physiography.______________________ 7 Environment of deposition. 47 Drainage systems.______________________________ 7 Metamorphism. __________ 48 Influence of rock types on topography_____________ Piracicaba Group.____________ 48 Granitic rocks______________________________ Cercadinho Formation. _ _ _ _ 49 Argillaceous rocks._________________________ 9 Fe~cho do Funil Formation. 52 Quartzose rocks___________________________ 9 Tabooes Quartzite. _______ 54 Dolomite __________________________________ 10 Barreiro Formation. ______ 54 Iron-formation _ ____________________________ 10 Sabara Formation. _______ 55 Canga_ _-_-_-_--__----_______._____________ 10 Environment of deposition. 58 Hematite __________________________________ 10 Metamorphism_ __________ 59 Physiographic development-_____________________ 10 Itacolomi Series._________________ 59 Stratigraphy, ______________________________________ 14 Rio das Velhas Series__________________________ 15 Type Itacolomi. ____________________________ 59 Nova Lima Group._________________________ 16 Santo Ant6nio f acies. _______________________ 60 Contacts and thickness.__--___-__-______ 16 Relation between the type Itacolomi and the Lithology_ _____________________________ 16 Santo Ant&nio f acies_ ________-__----______ 62 Schists and phyllites________________ 17 Environment of deposition. __________________ 62 Iron-formation, ____________________ 18 History and problems of regional stratigraphic Quartz-dolomite and quartz-ankerite correlation. __________________________________ 63 rock_ __________________________ 19 Unmetamorphosed sedimentary rocks_ ____________ 68 Quartzite __________________________ 19 Fonseca Formation. ________________________ 68 Conglomerate. _____________________ 20 Other Tertiary rocks. _______________________ 68 Graphitic and carbonaceous phyllite. 20 Mudstone_ _________ __ ____________________ 69 Environment of deposition and nature of Weathering products. _______________________ 71 original sediments.____________________ 20 Saprolite_ _____ __ _____________________ 71 Metamorphism. ________________________ 21 Splash rock_ ___________________________ 72 Maquine' Group ____________________________ 21 Laterite_ ________________--____---_---_ 72 Palmital Formation.____________________ 22 73 Casa Forte Formation___________________ 23 Alluvium. __________ 75 Maquine" Group undivided...____________ 24 Talus and colluvium. 76 Environment of deposition_______________ 24 Landslides. _ ________ 76 Metamorphism. ________________________ 25 Igneous and granitic rocks. 76 Interpretation of the Rio das Velhas Series_____ 25 Granitic rocks______ 76 Minas Series.__________________________________ 27 Ultramafic rocks___._. 78 Contact with the Rio das Velhas Series. ______ 27 Distribution, weathering, and metamorphism_ 28 Distribution. __ _____________________ 79 Tamandu& Group..____________t____________ 28 Age____________________________ __ 79 Cambotas Quartzite..___________________ 30 Gabbroic rocks and diabase________________ 79 Unnamed formation___________________ 31 Porphyry dikes.__________________________ 80 Rocks tentatively correlated with the Pegmatite dikes__________________________ 80 Tamandud, Group___________________ 32 Quartz veins.____________________________ 81 Environment of deposition_______________ 33 Quartz associated with steatitic bodies___ 81 Caraga Group._____________________________ 33 Cleavage and fibrous quartz__________ 81 Moeda Formation._____________________ 34 Quartz as metamorphic segregations___ 81. Batatal Formation.,____________________ 37 Gold-bearing hydrothermal quartz veins- 82 HI rv CONTENTS Page Regional structure: Continued Regional structure-_________________________________ A82 Post Itacolomi orogeny Continued Pre-Minas structure___________________________ 83 Major folds Continued! Page Pre-Itacolomi faulting.__________________________ 84 Rio das Velhas uplift._______________ A92 Post-Minas-pre-Itacolomi deformation__ _________ 84 Vargem do Lima syncline. 93 Post-Itacolomi orogeny__________________________ 84 Conceig ao-Caraga uplift- _____ 93 Major folds______________________________ 85 Other uplifts._______________ 94 Santa Rita syncline_______-_____________ 85 Faults______-____________ 95 Dom Bosco syncline___________________ 86 Thrust faults__-_-_------___. 95 Moeda syncline_______________________ 87 Tear faults___-____--____. 97 Serra do Curral_______________________ 88 Cross faults.__-_-__-_-____-- 98 Gandarela syncline-___________________ 90 Geologic evolution of the Quadrilatero Ferrifero. 99 Ouro Fino syncline_-_--__--_--_____---_- 91 Structures in the Itabira and Monlevade Ref erences. _________________________________ 104 districts. ______---____--_________-___ 91 Index._______________--_-_---____--__-____. 107 ILLUSTRATIONS [Plates are in separate volume] PLATE 1. Geologic map and sections of the Quadrilatero Ferrffero, Minas Gerais, Brazil. 2-10. Geologic maps: 2. Santa Luzia quadrangle, by B. P. Alves. 3. Serra da Piedade quadrangle, by B. P. Alves. 4. Caete" quadrangle, by B. P. Alves. 5. Gandarela quadrangle, by J. E. O'Rourke. 6. Rio de Pedras quadrangle, by J. E. O'Rourke. 7. Sao Bartolomeu quadrangle, by A. L. M. Barbosa. 8. Ant6nio Pereira quadrangle, by A. L. M. Barbosa. 9. Ouro Pr£to and Santa Rita do Ouro PrSto quadrangles, by A. L. M. Barbosa. 10. Mariana and Rio das Bandeiras quadrangles, by A. L. M. Barbosa. 11. Geologic sections of the Sao Bartolomeu, Ant6nio Pereira, Ouro Pre'to, Santa Rita do Ouro Pr£to, Mariana, and Rio das Bandeiras quadrangles. 12. Diagram showing development of stratigraphic column of the Quadrilatero Ferrffero, Brazil, 1915-65. Page FIGUBE 1. Index map of the Quadrilatero Ferrffero-___________________-____-__--------_---_----_----_----_--- A3 2. Photograph showing post-Gondwana surface preserved on canga sheet, Serra da Rola Moga -____--____ 12 3. Photograph showing ancient surfaces on the Moeda Plateau____-------------------------------------- 13 4. Photograph showing panoramic view, Macacos quadrangle.______ .__.___-______--____-_-_--_---_-__-- 14 5. Aerial photograph of Minas-Rio das Velhas Series unconformity.____-_-__--_- ________________________ 29 6. Photograph of typical bare outcrops and cliffs of the Cambotas Quartzite in the Serra do Caraga_ _______ 30 7. Photograph of typical cliffy outcrops of the Cambotas Quartzite in the Serra das Cambotas______________ 30 8. Map showing variations in thickness of the Moeda Formation-_______________________________________ 35 9. Photograph of cobbles in basal conglomerate of the Moeda Formation.________-_____-___-_-_-___--___- 36 10. Photograph of puddingstone conglomerate in the Moeda Formation.__________________________________ 37 11. Photograph of the typical topographic expression of the Moeda Formation in the Serra das Gaivotas. Ibirite1 quadrangle..-_ ___________________________________-__-____-___---_------_----------------_-- 37 12. Map showing regional variations in thickness of the Cau§ Itabirite__ _ ___________________ ._______--____ 41 13-25. Photographs: 13. Sill in itabirite-____--_. __._________________________-_______-.__-____----_----_----.---- 43 14. Cau6 Itabirite between Alegria and Conta Historia_-_______________________-____--_-----__-- 44 15. Cercadinho Formation in the Gandarela syncline._________________________________________ ._ 50 16. Basal conglomerate of the Sabard, Formation-______________________________-___---_--__----- 56 17. Boulder of granite in tilloid of the Sabar£ Formation._._-_________________--___---_-----_--_ 57 18. Festoon crossbedding in the Santo Antonio facies of the Itacolomi Series.____-____-___-_-_-_--_ 61 19. Basal conglomerate in "mudstone". ___________________________________________ .___--_-___- 69 20. Outcrop of "mudstone".____________--__-__-----_-_ .________--____--__---_-----_-----_--- 70 21. Laterization profile, Mutuca bauxite mine.. ____________