Geology and Mineral Resources of the Monlevade and Rio Piracicaba Quadrangles, Minas Gerais Brazil
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Geology and Mineral Resources of the Monlevade and Rio Piracicaba Quadrangles, Minas Gerais Brazil GEOLOGICAL SURVEY PROFESSIONAL PAPER 341-E 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 Geology and Mineral Resources of the Monlevade and Rio Piracicaba Quadrangles, Minas Gerais Brazil By ROBERT G. REEVES GEOLOGY AND MINERAL RESOURCES OF PARTS OF MINAS GERAIS, BRAZIL GEOLOGICAL SURVEY PROFESSIONAL PAPER 341-E 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 : 1966 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, 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 Geology Continued Abstract- __--_--_------________-_____________ El Structure Continued Introduction,. _-_---_______--__________-__-__- 2 Minor structures_______-______-------_____ E23 Topographic features----__________________ 3 Planar structures _ 23 Climate and vegetation -_____________-_--_ 4 Lineation_ _______ 23 History, mining, and steel production.______ 4 Drag folds _______ 24 Fieldwork and study______________________ 6 Structural deformation 24 Acknowledgments -____-___-_-_________-__ 7 Mineral resources, _ _______--__ 24 24 Geology _____________________________________ 7 Itabirite_ _ _________--_-__----------_----_- 24 Regional setting-_________________________ 7 Iron ores--. _____--___--------_---_-------- 30 Rio das Velhas Series._____--_______--____ 8 High-grade hematite ore_- _ _____________ 30 Monlevade Gneiss____________________ 10 Canga_. ___-_--_-_-_-_---_-._---------- 36 Pacas Amphibolite Member-_______ 13 Rubble ore_ --------------------------- 37 Quartzite and schist-_. ____________ 14 Manganese. _ _ _____-____-- -________--__----__- 37 Itabirite. - _______________________ 15 Manganiferous itabirite___ _ _________________ 37 Minas Series_-_--_____--_______--___-__-_ 15 Other manganese-rich rocks. _-___-_--_--___. 38 Caraga Group_-_--_-__--___-_________ 16 Manganese ore _____-___-___-__---------_-. 38 Moeda Formation ________________ 17 Gold placer deposits. ____-_--___-___----------_- 39 39 Batatal Formation._______________ 18 Pegmatite deposits. --------------------------- Building stone, clay, and sand and gravel- __ ______ 39 Itabira Group._______________________ 18 Mines, deposits, prospects, and quarries. --------- 40 Cau6 Itabirite.__________________ 18 Iron ore mines and deposits- _________---___. 40 Sitio Largo Amphibolite ___________ 19 Andrade mine area_ ______________--_-_- 40 Piracicaba Group.____________________ 20 Tanque mine area___. ___________------. 43 Elefante Formation_______________ 20 Morro Agudo iron ore deposit..--------- 43 Pan tame Member. ____________ 20 Morro da Agua Limpa iron ore deposit- _. 45 Bicas Gneiss Member.________ 21 P6 de Serra iron ore deposit __-__-_----. 46 Structure ________________________________ 21 Manganese mines and prospects _____________ 46 Major structural features______________ 21 Agua Limpa manganese mine- ____-___-. 46 48 Folds --------__-_--_____--_-_ 21 Manganese prospects. _ _________-_-___-. Other mines and quarries ___._____--_-_-__--. 50 Regional folds____----_-______ 21 P6 de Serra pegmatite mine. ____________ 50 Subsidiary folds. _____________ 22 Talho Aberto pegmatite mine ___________ 52 Cross folds___---__--____-_-_. 22 Jacui quarry _________-____-----------. 52 Folds in the Monlevade Gneiss. 22 Monlevade quarry ___________--------_. 52 Faults- -----____-______.______-__ 22 Rio Piracicaba quarry__ _______-----___. 53 Major faults _________________ 22 Literature cited- _______._-___-____---___---------_. 53 Other faults.--_______________ 23 Index ____________-_--_--------------------------- 55 ILLUSTRATIONS [Plates are in pocket] PLATE 1. Geologic map of the Monlevade quadrangle, Minas Gerais, Brazil. 2. Geologic map of the Rio Piracicaba quadrangle, Minas Gerais, Brazil. 3. Geologic sections of the Monlevade-aad Rio Piracicaba quadrangles. 4-7. Geologic maps and sections of the 4. Andrade mine, Monlevade quadrangle. 5. Morro Agudo iron deposit, Rio Piracicaba quadrangle. 6. Morro da Agua Limpa iron depo3itrRi<>rPiracicaba quadrangle. 7. Agua Limpa manganese mine, Rio Piracicaba quadrangle. in IV CONTENTS Page FIGURE 1. Index map of Brazil showing the Quadrilatero Ferrffero and Minas Gerais_____-_-_-__-_-___-_---_______ E3 2. Aerial view of the Monlevade steel plant__-_________________________________________________________ 5 3. Geologic sketch map of the Quadrilatero Ferrifero.__________________________________________________ 8 4. Precambrian rocks of the Monlevade and Rio Piracicaba quadrangles._________________________________ 9 5. Photograph of Monlevade augen gneiss_--_________------__-------------_---------------___-----_--- 11 6. Photograph of grossly banded Monlevade Gneiss.___________________________________________________ 12 7-9. Photomicrograph of 7. Pacas Amphibolite Member-________________________________________________________________ 14 8. Garnetiferous muscovite-quartz schist____--_--------------------_-------_-_-----------_---_-_- 15 9. Staurolite schist--___-__--__-__________________----_______-___-_-___--____-____________-____ 16 10-13. Photograph of 10. Contact between Caue Itabirite and Batatal Formation.-_______________________________________ 18 11. Cuesta.of canga on Caue Itabirite__--_-___-------------_-------------------------___-__----.._ 19 12. Typical outcrop of weathered itabirite________________________________________________________ 25 13. Itabirite._-_-------------____-_-_---_-_--------------------------------------__---_-_-____ 26 14. Photomicrograph of itabirite- _____________________________________________________________________ 26 15. Photomicrograph of schistose itabirite-._____________________________________________________________ 27 16. Photograph of metamorphosed itabirite_-_-___-_-__-__------------_---------------_----_-___---_-___ 27 17. Photomicrograph of metamorphosed itabirite________________________________________________________ 28 18. Photograph of gneissic itabirite__-_---__--__-_-_--__---__---_---------------_---_-______---________ 28 19. Photomicrograph of gneissic itabirite___________________-__--_---------_---_--__-___________________ 29 20-23. Photograph of 20. Hard hematite ore_..________________________________________________________________________ 30 21. Schistose hematite ore______________________________________________________________________ 31 22. Pencil ore.________________________________________________________________________________ 32 23. "Logs" of itabirite______________________________--___-----_---_-___--__-_-____.___________. 32 24. Aerial view of Andrade mine_________-__________________-____--_-----_-_---_----__________________ 41 25-27. Photograph of 25. Highly deformed itabirite___________________________________________________________________ 42 26. Drag-folded manganiferous itabirite-________--_____--_-_-_-__-_---____--__-_-________________ 47 27. Manganese ore______________________________________________________________________________ 48 28. Geologic map and sections, Pe" de Serra pegmatite mine_________-_-__-_---------------____--______-___ 51 TABLES TABLE 1. Chemical analyses of granitic gneiss and schist from the Monlevade and Rio Piracicaba quadrangles.______ Ell 2. Chemical analyses of amphibolites from the Monlevade and Rio Piracicaba quadrangles.----------------- 13 3. Analyses of itabirite from the Monlevade and Rio Piracicaba quadrangles compared with itabirite from other parts of the Quadrilatero Ferrffero_-_______-___________-_--_-__-_---_--_____---___---_----------- 29 4. Analyses of high-grade hematite ores from the Monlevade and Rio Piracicaba quadrangleS-___--_-_------- 33 5. Production, Andrade and Tanque mines__________________________-_--__-_--__---_________---------- 40 6. Reserves of ore and itabirite in the Andrade ore body.__-_--____________-_-_-_-_--____-__--------__-- 43 7. Analyses of Morro Agudo ore.____________________________________________________________________ 45 8. Ore reserves of the Morro Agudo deposit-____________________-__-_-_--_________-_-___-______------- 45 GEOLOGY AND MINERAL RESOURCES OF PARTS OF MINAS GERAIS, BRAZIL GEOLOGY AND MINERAL RESOURCES OF THE MONLEVADE AND RIO PIRAGIGABA QUADRANGLES, MINAS GERAIS, BRAZIL By ROBERT G. REEVES ABSTRACT in the Monlevade and Rio Piracicaba quadrangles and in the The Monlevade and Rio Piracicaba 7%-minute quadrangles Quadrilatero Ferrifero in general. It is divided into three are along the eastern border of the Quadrilatero Ferrifero of groups: the lower Carac.a Group, of predominantly clastic south-central Minas Gerais, Brazil. The Quadrilatero Ferrifero, sediments now metamorphosed chiefly to quartzite and an area of about 7,000 square kilometers, contains numerous muscovite-quartz schist; the intermediate Itabira Group, of high-grade hematite deposits and many billions of tons of iron- predominantly chemical sediments now metamorphosed to formation of intermediate grade (35-50 percent Fe), much of itabirite and marble; and the upper Piracicaba Group, of which is easily concentratable. mainly clastic sediments now metamorphosed principally to The