UNITED STATES THE INTERIOR SURVEY : r v .PROJECT REPORT :v Colombia Investigations : J (IR) CO-lt - Charles M. Tschanz U. S. Geological Survey ; :> Andres Jimeno V. and Jaime Cruz B. Institute Naclonal de Investigaciones Geologico-Mineras ;S:, "Geological "Survey^ ";-.- " - . .-. ,.- -. is preliminary* and has not edited -6ir% reviewed for confor- ty witfi^ Geological Survey tandards or nomenclature Prepared on behalf of the Agency for International Development U. S. Department of State and the Government of Colombia 1970 THE MINERAL RESOURCES OF THE SIERRA NEVADA de SANTA MARIA, COLOMBIA (ZONE I) by Charles M. Tschanz U. S. Geological Survey and Andres Jimeno V. and Jaime Cruz B. Institute Nacional de Investigaciones Geologico-Mineras CONTENTS Page ABSTRACT....................................................... 1 INTRODUCTION................................................... 2 NONMETALLIC MINERAL RESOURCES.................................. 4 Limes tone................................................. 4 Limestone near Durania............................... 6 Geology......................................... 6 Reserves.............'........................... 6 Chemical composition............................ 15 Factors affecting txploitation.................. 18 Limestone near the Rancheria valley.................. 18 Geology......................................... 18 Reserves........................................ 19 Chemical composition................................. 21 < Factors affecting exploitation.................. 22 Other deposits.,..................................... 23 Marble.................................................... 23 Marble near Cienaga.................................. 24 Geology......................................... 24 Exploitation.................................... 26 Economic potential.............................. 27 Reserves of low-magnesian marble................ 27 Dolomite reserves............................... 30 Marble on Cuchilla Piedras Blancas................... 31 CONTENTS (continued) NONMETALLIC MINERAL RESOURCES '(continued) Talc-tremolite............................................ 34 Deposits on Quebrada Rodriguez....................... 35 Geology......................................... 35 Economic potential.............................. 36 Feldspar.................................................. 38 Clay................t..................................... 39 KaoUnite deposits near San Pedro de la Sierra....... 39 KaoUnite deposits near El Platanal.................. 40 KaoUnite deposits near El Secreto (El Congo)........ 42 « Bentonite depos its................................... 43 Graphite.................................................. 43 Mica...................................................... 45 Silica.................................................... 46 Gypsum.................................................... 47 Salt...................................................... 47 Asbes tos.................................................. 48 Magnesite................................................. 48 METALLIC MINERAL RESOURCES..................................... 48 Iron and titanium minerals and apatite.................... 48 Apatite-ilmenite deposits on Quebrada del Hierro..... 49 Geology......................................... 49 Analytical data................................. 50 Economic potential.............................. 51 ii CONTENTS (continued) Page METALLIC MINERAL RESOURCES (continued) Iron and titanium minerals and apatite (continued) Metamorphic rocks rich in ilmenite, magnetite, or apatite............................................... 53 Mocoa (Espiritu Santo) magnetite deposit................ 54 La Reina magnetite deposits............................. 56 La Socola magnetite deposit............................. 57 Black beach sands....................................... 57 Copper....................................................... 59 Deposits in redbeds....4................................ 60 Description........................................ 60 Economic potential................................. 63 El Rincon copper deposit................................ 64 Gold......................................................... 65 Other metallic minerals...................................... 69 Exploration potential for sulfide deposits................... 70 Suggestions for future exploration........................... 72 WATER RESOURCES................................................... 74 Rancheria Valley............................................. 74 Cesar Valley................................................. 75 REFERENCES CITED.................................................. 77 iii ILLUSTRATIONS Plate 1. Reconnaissance geologic map of the Sierra Nevada de Santa Marta, Colombia............................. In pocket Figure 1. Geologic map of the limestone deposits near Durania........................................... In pocket 2. Geologic map and cross section of marble and dolomite near Cienaga............................. In pocket 3. Map showing talc and tremolite deposits derived from serpentine near Quebrada Rodriguez........... In pocket 4. Map of the apatite-ilmenite deposits near Quebrada del Hierro........................................ In pocket TABLES Table 1. Summary of the limestone reserves near Durania...... 7 2. Indicated reserves in Block 1, Durania............... 9 3. Indicated reserves in Block 2, Durania............... 10 4. Indicated reserves in Block 3, Durania............... 11 5. Indicated reserves in Block 4, Durania.....*......... 12 6. Indicated reserves in Block 5, Durania............... 13 7. Indicated reserves in Block 6, Durania............... 14 8. Analyses of limestones east of reserve blocks, Durania............................................ 16 9. Chemical analyses of Cretaceous limestones west of the Rancheria Valley near Chorrera................. 20 10. Chemical analyses of the marbles and do1oraltic marbles near Qienaga............................... 28 11. Average chemical analyses of marbles on Cuchilla Piedras Blancas.................................... 33 iv THE MINERAL RESOURCES OF THE SIERRA NEVADA de SANTA MARTA, COLOMBIA (ZONE I) By Charles M. Tschanz U. S. Geological Survey and Andres Jimeno V. and Jaime Cruz B. Institute Nacional de Investigaciones Geologico-Mineras ABSTRACT The Sierra Nevada de Santa Marta on the north coast of Colombia is an isolated triangular mountain area that reaches altitudes of t> almost 19,000 feet. The exceedingly complex geology is shown on the 1:200,000 geologic map. Despite five major periods of granitic intrusion, three major periods of metamorphism, and extensive volcanic eruptions, metallic i k deposits are small and widely scattered. Sulfide deposits of signifi­ cant economic value appear to be absent. Many small copper deposits of chalcocite, cuprite, malachite, and azurite are found in epidotized rock in Mesozoic redbeds and intercalated volcanic rocks, but their economic potential is very small. Deposits of other common base metals appear to be absent. The most important metallic deposits may prove to be unusual bimineralic,apatite-ilmenite deposits associated with gneissic anorthosite. The known magnetite deposits are too small to be exploited commercially. Primary gold deposits have not been identified and the placer deposits are uneconomic and very small. The largest and most important deposits are nonmetallic. Enormous reserves of limestone are suitable for cement manufacture and some high-purity limestone is suitable for the most exacting chemical uses. Small deposits of talc-tremolite could be exploited locally for ceramic use. The important noncoking bituminous coal deposits in the Cerrejon area are excluded from this study. Other nonmetallic resources include igneous dimension stone in a variety of colors and textures, and agri­ cultural dolomite. There probably are important undeveloped ground water resources on the slopes of the wide Rancheria and Cesar valleys, which separate the Sierrd Nevada from the Serrania de Perija. INTRODUCTION The present study is one of four Colombian areas or zones whose mineral resources were evaluated by the Inventario Minero Nacional, Ministry of Mines and Petroleum, Republic of Colombia, in cooperation with geological consultants of the U. S. Geological Survey. The four- year program was established by the Ministry and was partly financed from a loan granted to the Colombian government by the Agency for Inter­ national Development, U. S. Department of State. The Inventario Minero Nacional was closely affiliated with the Servicio Geologico Nacional through the project, and both are now part of the Institute Nacional de Investigaciones Geologico-Mineras. Nearly all the geological field work was done by Colombian geo­ logists as shown on the index map on plate 1, but this report is the sole responsibility of the authors. Credit to the individual Colombian geologists is given where appropriate in the text and on the illustrations The area covered by this report, which includes the Sierra Nevada de Santa Marta, consists of 22,500 square kilometers on the north coast of Colombia and has been identified as Zone 1 by the Inventario Minero Nacional. The Sierra Nevada is an isolated triangular mountain mass that lies on the projection of the Cordillera Central, but Zone 1 also includes the wide valley drained by the Rios Cesar and Rancheria and a S y small part of the Serrania de Perija east of it, which is the