Geology and Mineral Resources of Paraguay A Reconnaissance

IGNEOUS AND METAMORPHIC ROCKS 35FIGURE 27. Diabase (specimen P-37) on the road north of Piribebuy showing characteristic holocrystalline aggregate of calcic plagioclase,/, and augite,py, with magnetite-ilmenite, m-i. X 15. Crossed nicols.TABLE 3. Chemical analyses of Serra Geral lava and related rocksof ParaguaySiO 2____A1.03Fe2O3____. _ _ ...FeO _____________MgO_ ...........CaO ____ ... _Na2O_ ....... .K20 _____________H20+ ... ..Ti0 2 __. ............CO 2_. _____________P 2OS .... ...MnO_... ___________Cr2O 3 _ __ .Density, _ _ .NormP-58a i51.2715.728.611.533.725.983.714.15.871.821.64.01.43.17.1899.812.73II-5-2-3P-92150.0512.955.798.204.258.382.50J.501.18.803.56.00.53.2599.942.81III-4-3-41 Spectrographic ai nalyses for trace elements made. Densities by L. N. Tarrant,U. S. Geological Survey.NOTE. See following table for explanation of field numbers.Field No.RockP-58a_____ Basalt, Acahay calderaA48.6312.4911.729.082.378.752.46.64.79.802.20.77100. 70II1.4-3-4B48.3810.4212.114.993.537.984.741.50.961.972.581.04Tr.100. 20m-5-1-4C49.659.2615.254.123.218.824.391.75.332.431.42.43101. 06III-5-1-4AnalystD40.9515.376.364.3810.4611.673.971.26.863.93.25.09Tr..10.1999.842.932III-6-3-4III-7-3-4Lois D. Trumbull, U. S. Geol.Survey.Lois D. Trumbull.Maurice Goldschlag.P-92 __... . B asalt, Foz de Iguacu, Brazil __A_. _______ 0livine diabase, Ce rro Domingo,Sierra Ybytu ruzu.B_________ 0livine diabase, Cerro Alberto, Maurice Goldschlag.Sierra Ybyturuzu.C.. . E iabase porphyrite, Cerro Maurice Goldschlag.Howyf.D_ __ Limburgite, Cerro Tacumbu_ ... Lindner (Milch 1905).465871 5£TABLE 4. Spectrographic analyses of Serra Geral lava and relatedrocks of Paraguay[Analyst: Paul R. Barnett, U. S. Geological Survey. Looked for but not found: As,Ag, Au, B, Bi, Cd, Ge, In, Pb, Pt, Sb, Sn, Ta, Th, Tl, U, W, Zn]BaBeCoCr. ... ...CuLaMo...Nb_PbSc_ -Sr_ ._____ _V ____________-ynZr_ -NOTE.P-58a0.20 .004.0005.005.002.01.0004.004.002.002.002.2.04.009.0002.03P-920.060 .004.003.03.0020.0005.005.005.002.004.09.05.008.0002.02See table below for explanation of field numbers.Field No.P-58a__ __P-92__ .P 54dp-54g;::::Basalt (TertiarBasalt (Serra CNepheline syerShonkinite (an riteRockP-54d0.20 .002.002.005.002.020 .008.001.003.001.3.02.006.0002.07LocalityP-54g0.20 .004.04.005.002.010.005.03.003.002.2.03.005.0001.04Acahay caldera.Foz de Iguacu, Brazil.Mbocayaty.Do.table 4. Analyses of basalt from the Acahay calderaare included in both tables.Five of the six analyses of basalt and related rocksshown in table 3 are obviouslv similar, indicating; that