Geology and Mineral Resources of Paraguay A Reconnaissance

70 GEOLOGY AND MINERAL RESOURCES OF PARAGUAYRecords of wells drilled by Union Oil Company in the Gran Chaco,western Paraguay, 1944 to 1949, inclusive ContinuedT>- -i n T> i n j_- i Thickness DepthPicuiba well B-l Continued(feet) (feet)Silt-stone, micaceous, pale bluish-gray togray, with fine- to medium-grainedpebbly sandstone, lime-cemented andmicaceous; some pyrite_ _______________Sandstone, very hard, crossbedded, lightgray,fine- to medium-grained; containssome pebbles, interbedded with micaceousshale and sandy siltstone; some pyrite___Shale, hard, sandy, dark-brown, slightlymicaceous- ___________________________Sandstone, gray, fine- to medium-grained,and brick-red siltstone with gray micaceousSpots__ _ _-__-_-______-___-_____Sandstone, same as above, but containinghard marine shale, becoming more abundantdownward, ______________________Shale, hard, micaceous, gray, with laminae801011273, 5553, 5653, 5693,5803,607of firm, very fine grained sandstone.Sandstone below 3,845 ft yields strongodor of petroleum and gives other positivetests for petroleum________________ 248 3, 855Shale, hard, dark-olive-gray, with a fewlaminae of hard, gray, fine-grained sandstone.No evidence of petroleum_______ 135 3,990Shale, hard, dark, with dark stains oforganic material; some gray very finegrained sandstone; yields slight odor ofpetroleum,-- _ _________________________Shale, same as above but no odor of petroleum;highly micaceous in interval 4,060-4,070 ft______________________________Shale, same as above, with strong odor ofpetroleum in interval 4,168-4,175 ft andslight odor at interval 4,460-4,470 ft;contains one 2-in layer of limestone at5,207 ft______________________________3014813774,0204, 1685,545Shale, dark-gray, hard, very little sandstone______________________________Sandstone, friable, gray, fine- to mediumgrained;yields odor of petroleum.______Shale, micaceous, gray; with fine-grainedsilty light-gray sandstone ______________630409446, 1756,2157, 159Shale, soft micaceous dark-gray; slightodor of petroleum in one 1-ft zone neartop...______________________________ 356 7,515Santa Rosa well 1:Clay, varicolored_______________________ 810Sand, gray, fine-grained, silty, with streaksof waxy-green and red clay near base_ _ 30Clay, varicolored.______________________ 20Sand, gray, fine-grained_________________ 43Clay, red and green_____________________ 55Sand, gray, fine-grained, with sandy claybetween 974 and 980 ft_____________.__ 37Clay, blue and red______________________ 10Sand, bluish-gray, firm; silty and very finegrained, ____________________________ 10Clay, red and blue, firm, sandy; containsinclusions of hard limestone ___________ 108108408609039589951,0051,0151,025Records of wells drilled by Union Oil Company in the Gran Chaco,western Paraguay, 1944 to 1949, inclusive ContinuedThicknessSanta Rosa well 1 Continued(feet)Sand, gray, friable, very fine grained andwell-sorted_-___----_------__-----_--- 30Clay, blue and red, firm, sandy to verySand, gray, fine-grained, well-sorted andwith well-rounded grains. _ ____________Clay, blue and red, mostly firm and sandy,with limy material in places. __ _ ________Sand, blue-gray, firm, with a few smallClay, red and blue, mostly firm and sandy. _Sand, white, fine-grained, firm limy _______Clay, blue and red, sandy in lower 10 ft. __Conglomerate of well-rounded black andred pebbles in matrix of blue and red14010290101203020Depth(feet)1,0551,1951,2051, 4951,5051, 6251, 6551, 675sandy clay-_____---_-----_--_-------- 10 1,685Clay, blue and red; mostly firm and sandy;contains many small concretions of limymaterial and a few pebbles. ____________ 645 2, 330Sand, gray, fine-grained _ ________--_-__-_ 50 2,380Clay, red and blue, mostly firm and sandy;contains limy concretions in places. _____ 175 2,555Sand, gray, fine-grained, soft_____-____-_- 10 2,565Clay, blue and red; firm and very sandy,with medium- to coarse-grained sand;many limy concretions in places ________ 30 2, 595Sand, gray, coarse-grained. ______________ 40 2,635Clay, blue and red; very firm, sandy _ _____ 10 2, 645Sand, bluish-gray, fine- to coarse-grained,friable to firm; clayey in many places;contains abundant small pebbles ofvarious colors almost throughout; limynodules abundant in places. One 1-ftcore of hard sandy blue-green to purplelimestone near bottom, __ _____________ 90 2,735Limestone, firm, sandy, nodular, light-gray _with streaks of red; contains large angularred and light-gray pebbles of quartziteand smaller well-rounded pebbles; top 2 ftappears weathered; grades downward tomassive white to light-gray limestone.Limestone contains 87.5 percent CaCOs,11.5 percent insoluble, and traces of MgOand FejO8 ------------------------ 10 2,745Limestone, white to gray to red, hard, massiveto nodular; sandy in places _ ______ 10 2, 755Sand, friable to firm, white to gray, fine- tomedium-grained; mostly silty; containsnodules of hard massive limestone and afew large pebbles--------------------- 80 2,835Clay, red, firm, sandy; alternates with grayfirm coarse-grained sand; many pebbles ofquartzite in lower 10 ft-__- ------------ 130 2,965Sand, red and blue, firm, fine- to mediumgrained;silty and clayey with small angularpebbles throughout- _______-_____-- 20 2,985Conglomerate, containing pebbles of sandstone,shale, and siliceous material inmatrix of sandy clay, interbedded withreddish-white hard sandstone containingmany small rounded pebbles. __________ 8 2, 993