Geology and Mineral Resources of Paraguay A Reconnaissance

72 GEOLOGY AND MINERAL RESOURCES OF PARAGUAYRecords of wells drilled by Union Oil Company in the Gran Chaco,western Paraguay, 1944 to 1949, inclusive ContinuedLa Paz well D-l Continued**$§)"'Sand, silty, red and green; with somelime ________ ___381Shale, black to gray, hard, unstratified;with abundant mica __ _ _ __ 275Shale as above, with nodules of pyrite andcalcite-filled fractures144Sandstone, fine, hard, gray, micaceous;with some shaleShale, hard, and sandstone, both micaceous.343682Shale, dark-gray to black, medium-hard,laminated, micaceous; some fine sandstonein lower part _ _ _ _1, 133Sandstone, coarse; interbedded with shale;some fragments of black dolomite _ 10Shale, dolomite, and fine sandstone withpyrite29Shale, dark-gray, interbedded with lightgraysandstone55(Hole ended in hard quartzite.)Pirizal well D-l:Clay, pale- red; with a few layers of finesand; veinlets and crystals of gypsumlocally _ __ ____ _____Clay, same as above, with green clayeysiltstone and some gray sandy mudstone_Siltstone, red; with about 30 percent green,fine sandy siltstone __ _____ _ __Siltstone, green, red, and brown; someamorphous gypsum _____Siltstone, greenish-blue; alternating withbrown siltstone that contains thin sandylavers __ __________ _____Siltstone, clayey, red and green; with partingsof sand __ _ __ _ ___Quartz sand, gray, fine- to medium-grained.Siltstone, sandy, red; with a few greenstreaks and fragments of anhydriteSandstone, dark-gray, fine-grained; upperpart is hard and crossbedded, lower partvery friable _______ ___ ____Sand, dark-gray, silty __ __ _ _ _ _ _ ___Shale, pebbly, conglomeratic sandstone andsilty gray sand; small particles of carbonaceousmaterial. __ ____ ___ ___Sand, fine-grained, chestnut-brownSand, friable, fine- to medium-grained, gray;with carbonaceous material along beddingplanes. __ ______ _ ___Siltstone, sand and gypsum, gray, green, anddark-red _ __ _ ___Sandstone, dark-red, fine-grained, silty; containssome gypsum crystals; friable inpart _ __ __Siltstone, red; with sandy streaksSand, dark- red, fine-grained; with siltystreaks _ __ ______Siltstone and sandstone, dark-red1,7101,400248922200310306405101020303020102943Depth(feet)4, 5814,8565,0005,3436,0257, 1587, 1687, 1977,2521,7103, 1103,3584,2804, 4804,7904,8205,4605,4655,4755,4855, 5055, 5355,6655, 5855, 5955,6245,667Records of wells drilled by Union Oil Company in the Gran Chaco,western Paraguay, 1944 to 1949, inclusive ContinuedT-,. . , n-r-vi /-( j.- iPinzal well D-l ContinuedThickness(feet)Depth(feet)Siltstone, sandy, red to chestnut-brown;with intervals of fine red sand at 5,750,5,770, and 5,800-5,840 ft; clean mediumtocoarse-grained quartz sand at 5,710-5,740 and 5,870-5,910 ft_______ __ 271 5,938Sand and siltstone, fine-grained, silty red_ _ 72 6, 010Siltstone, sandy, red to chestnut-brown;with fine-grained red sand at 6,050-6,090ft and 6,160-6,170 ft and clean mediumtocoarse-grained quartz sand at 6,040-6,050, 6,100-6,120 and 6,180-6,220 ft.. ._ 270 6, 280Sandstone, fine-grained, silty, red; with redsiltstone at 6,300-6,310, 6,350-6,370 and6,470-6,490 ft and abundant quartz sandat 6,370-6,380 and 6,400- 6,410 ft. _ - - - 260 6, 540Siltstone, red to chestnut-brown; with finegrainedred sand in lower 20 ft_ ________ 94 6, 634Conglomerate of fine to coarse sand andwell-rounded quartz pebbles.._______--- 30 6,664Siltstone, sandy, red___.____________ 20 6,684No recovery,__________________-__-_--- 16 6,700Siltstone, sandy, red; with thin layers of finesand. ._.________-_________________ 500 7,200Siltstone, red and chestnut-brown; with afew fragments of anhydrite___________ 1,086 8,286Siltstone, sandy, pale, red______________ 20 8, 306Sandstone and siltstone, fine-giained, red tochestnut-brown; with some fragments ofanhydrite,._________________ 773 9,079Shale, hard, varicolored______-___---_---_ 21 9, 100Siltstone, red to dark-red; with some sand-_ 946 10,046Siltstone and hard shale, red to chestnutbrown;with some gray-green nodules. 285 10, 331Orihuela well B-l:Clay, yellowish- to greenish-blue; with finetomedium-grained sand_______________ 1,100 1,100Quartz sand, medium-grained; with someyellow clay___________________--_--- 150 1,250Sand, muddy, fine- to medium-grained,yellow to dark-red____-___-_--_------- 80 1,330Mud and clay, red to yellow; with a littlequartz sand-_________--__--______- 1,170 2,500Mud, sandy, soft, light-red. -_________-_- 20 2, 520Mud and clay, dark-red; with quartz sand__ 750 3, 270Mud and clay, dark-red; with fine- to medium-grainedquartz sand and streaks ofwhite bentonite or ash__ __________---- 60 3, 330Mud and clay; same as above, with layersof white calcareous sandstone and one2-in layer of sandy conglomerate______ 190 3,520Mud, sandy, dark-red; with laminae of verysoft dark-red clay-____--_------------- 10 3,530Mud; same as above, with one 4-in layer ofsoft pebbly sand__--__----_----------- 20 3,550Sand, light red, muddy, fine-grained-_____ 30 3, 580Sandstone, soft, friable, fine- to mediumgrainedreddish-gray, with pebbles-_____ 300 3, 880