Tesis Doctoral de Jaime - GeologÃa del Paraguay

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XIGeothermometric data from Ymi-1 and Yzu-1 spinel xenocrysts are very similar to those from theSiberian Platform kimberlites, i.e. 30-40 mW/m 2 heat flow (TMg thermometer). A variation ofDoroshev's barometer (Cr# multiplied by the Cr203 content), when applied to the same Ymi-1 andYzu-1 spinel xenocrysts, allowed the formation/provenance <strong>de</strong>pth of the calc-alkaline, picritic,lamprophyric magmas to be estimated as equivalent to 10-50 Kb. These data suggest that Ymi-1 andYzu-1 sampled peridotites from a cratonized, <strong>de</strong>ep lithospheric mantle, which had a 35 mW/m 2geothermal gradient in the Jurassic (~ 130 Ma) .In the cr# vs. Fe 2 +# and MgCr204-MgAI204-MgFe204 diagrams, many Ymi-1 spinel xenocrystsand some Yzu-1 spinel inclusions in olivines plot in the fields of spinels from peridotites of thediamondiferous facies and/or associated with diamond. This fact suggests that that they were pulledaway from the roots of the cratonized peridotitic mantle of the diamondiferous facies and brought bythe magma to the surface.The Fe 3 +/(Fe 3 + +Fe 2 +) vs. cr# diagram indicated for Ymi-1 spinel xenocrysts conditions of formationbelow the OFM buffer, with high concentration of inclusions and some spinels from the concentratesfalling in the 0 -1 buffer, and microphenocrysts from concentrates and some inclusions plotting ineven lower oxygen fugacity fields, i.e. < 1+1 to 1+2. These fugacity values correspond to veryfavorable conditions for the formation of diamond in the cratonic roots. Spinel inclusions in olivinesfrom Ymi-1 and Yzu-1 were formed in a 0-1 to 1+2 buffer environment, which corroborates totransport conditions corresponding to oxygen fugacities favorable to the preservation of diamond.Ymi-1 and Ymi-8 ilmenite grains were also analysed in the MgTi03-FeTi03-Fe203 system, yieldingoxidation/reduction conditions around the 10- 6 buffer (~wustite-magnetite), which corroborated to arelative reducing environment, favorable to the preservation of diamond.The Arroyo Itá region (Ybytyruzú field), where particles of Au were found, crosscut by lamprophyricrocks, is a possible field to study the genetic link between lamprophyric rocks and Au occurrences.
CAPíTULO 1 Introducao ao problemaConvencionalmente sao referidas como rochas potássicas · aquelas que possuem araza o molar K20/Na20 em torno ou algo maior que 1 e com o teor em MgO>3%,sendo que a restri
Page 1 and 2: UNIVERSIDADE DE SAO P AULO INSTITUT
Page 3 and 4: Ag radecim entosA consecu~o deste p
Page 5 and 6: IICAPíTULO 3 - Petrografia e quím
Page 7 and 8: IVo diamante..... .................
Page 9 and 10: VIFotomicrografia 6 "Lamproíto" Yz
Page 12 and 13: IXteor de ao ser aos mesmos xenocri
Page 16 and 17: 2amplo intervalo composicional pode
Page 18 and 19: 4que variam dos 42 aos 63% (i.e., r
Page 20 and 21: 6de monticellita, espinélio magnes
Page 22 and 23: 8clinopyroxenio diopsídico, em mat
Page 24 and 25: 10olivinamacromicrorricamacroJmicro
Page 26 and 27: --rr-----¿:r------~r -K\ 712~·OO
Page 28 and 29: 14Trabalhos de campoForam mapeados
Page 30 and 31: 16Si02, Ti02, A1 20 3, Cr203, FeO,
Page 32 and 33: 18*Micas foram normalizadas para 22
Page 34 and 35: 20 riebekitaarfvedsonita ferri=ferr
Page 36 and 37: 22das ilmenitas, representam soluc;
Page 38 and 39: CAPÍTULO 2GEOLOGIAIntroduçãoCrá
Page 41 and 42: 27do Sul ou bloco Taquarembó, e os
Page 43 and 44: 29Curitiba…..terrenos Arcon e Par
Page 45: Paraguai (Figura 2-5), separando á
Page 51: 37Geologia do Paraguai OrientalNo P
Page 55 and 56: 41baixo das coberturas da Bacia do
Page 58 and 59: 44Ybytyruzú. Os diques estão cort
Page 60 and 61: 46Dentro deste segmento do rift des
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50Este corpo como os outros pipes f
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56Pipe Ymi-8Esta estrutura, destaca
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61Figura 2-8), seguem rumo N-S e as
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65textura muito fina a fina; cortam
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CAPÍTULO 3Petrografia e Química M
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69Espinélios com estrutura normal
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71magnesioferrita ser difícil de a
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7373
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75atenção sobre o acerto ou não
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7777
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7979
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81A composição das olivinas (apê
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83eletrônica, eles forneceram aná
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85borda de opacos (corrosão parcia
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87As inclusões em minerais máfico
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890.29 de ZnO. No sistema ulvoespin
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91comumente observadas nos feldspat
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93escura de aspecto basaltóide. Ao
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95dados modais (Tabela 3-3) permite
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97arronzados, são observados em Ym
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99Os fenocristais (única fase anal
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101Feldspatóides/zeólitasEm Yzu-1
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103ocupando intersticialmente as ri
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105vesiculado, porém identificando
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10714.52-16.49% nas bordas aluminos
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109EspinéliosNestas rochas, os esp
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111111
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113113
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115115
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117117
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119119
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121121
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123123
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125125
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127127
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129mel. Os cristais em geral inclue
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131(bordas/matriz), 8.21 (centro -q
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133empobrecidos em TiO 2 (a-hósped
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135São feldspatos potássicos do t
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137137
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139139
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141141
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143143
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145145
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147147
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149149
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151similares, exceto os piroxênios
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153153
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155Segundo Rock (1991) e Rock et al
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157
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159Conquanto se tenha em mente que
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161picro-“lamprofírico” rumo
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163Os quatro cristais de espinélio
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165Pseudobrooquita (cor preto): pos
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167se apresentam com algumas feiç
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169As análises de dois cristais de
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171Arroyo Itá: este córrego alime
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173Finalmente Finnerty (1989) revis
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175
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177
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179
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181
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183
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185
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187Nos últimos anos foi evidenciad
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189temperatura no manto sub litosf
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191A densidade das rochas é uma fu
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193marcar o topo do astenosfera . A
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195No Sul, o cráton Rio de la Plat
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197Sul, em território brasileiro,
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199Ybytyruzú); Triássico/Jurássi
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201Grupo Independencia. Associados
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203carbonatitos e nefelinitos e mui
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205e Yzu-1 caem no campo dos pirox
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207e FeO com a diminuição do teor
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209Estas considerações e as feiç
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211Em verdade, Ymi-5, Yzu-2 e Yzu-3
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213(Figura 3-23 (a) e (b)). A subst
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215Condições termodinámicas acus
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217“os lamprófiros picríticos Y
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219vs Fe 2+ # e MgCr 2 O 4 -MgAl 2
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221do Au no seu próprio direito. P
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2231992; 1996). Bitchene (1989) ind
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227BARTON, M.,1979. A comparative s
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229 BRIGATTI, M.F.; MEDICI, L.; SAC
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- - ---- - -231COMIN-CHIARAMONTI, P
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- --- ---233DOROSHEV, A.M.; BREY, G
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235FORBES, W.C. & FLOWER, M.J.F. 19
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237HAGGERTY, S. 1973. Spinels of un
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239JAQUES, A.L.; HAGGERTY, S.E.; LU
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241MANSKER, W.L.; EWING, R.C. & KEI
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-N1XO~;-P.- & BOYO, F.R. 1973. Petr
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- --aUARTIERI, s.; ANTONIOLl, G.; A
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,--SH- E~TON, J.W. & CUNOARI, A. 19
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. VELAZQUEZ, V.F., 1992. Província
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242Porto Alegre, Vol 1: 255 p. (Tex
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244PRESSER, J.L.B.; 1994. Leucita e
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246ROCK, N.M.S.; GASKARTH, J.W.; HE
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248STOLZ, A.J.; VARNE, R; WHELLER,
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250Bultfontein mine, South Africa.
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A1 Composi~ao química, em porcenta
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SampleAnalysisLocationMineral1O.012
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SampleAnalysisLocationMineral1O.039
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Sample 10.030 10.032 10.033 10.034
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SampleAnalysig17.003 17.004 17.005
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Sample 15 ,000 15.001 22.000 22 ,00
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Page 287 and 288:
Sample 10.009 10.010 10011 10.012 1
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Sample 10.027 10.028 10.029 10.030
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Sample 10.050 1Oc. 000 IOc.OOI 1Oc.
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Samp1e 14.006a 14.006b 14.007a 14.0
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Sample 14.017a 14017b 14.018a 14.01
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Sample 15.000 15.001 15.002 15.003
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Sample 22.004 22005 22.006 22.007 2
Page 301 and 302:
Sample 23005 23.006 23 .007 23008 2
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Sample 26.010 26.011 26.012 26.013
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Sample 10.000a 10.ooob 10.001a 10.0
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Sample 1O.017a 10.017b 10018a 1O.01
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Sample 10.102 IOc.OOla IOc.OOlb 1()
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Sarnple 10.022 10.023 10.024 10.025
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Sample 10.047 10.048 10.049 10050 1
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Sample 14.004 14.005 14.006 14.007
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Sample 17.004a 17.004b 17.005 17.00
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Sample 21OO8b 21.009AnalysisrnfLoca
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Sample 15.006 15.007 15.008 15.009
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Sample 22000a 22000b 2200la 22.00lb
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SampJe 22015 22.017 22.019 22.020 2
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Sample 23.006 23 .007 23.008 23.009
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Sample 30.006 30.007 30.008 30.009
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A4 Composicao química, em porcenta
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,,,100.072 1-100010 YMI-l -pl sp 0,
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21 ,01221.01321 ,01421.01521 ,016gn
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28.008 YZU-6 .p 0.000 18,230 0 ,250
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Sample 10.000 10.001 10.002 10.003
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Sample 14.001 14.002 14.003 14.004
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Sample 15.000 15.001 15.002 15.005
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Sample 26.008 26.009 26010 26.011An
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SAMPLE ANALYSIS LOCATION \4INERAL S
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Sample 15.002 15.003 15004 15.005 1
Page 351 and 352:
Page 353 and 354:
Sample 10.009 10010 10.011 10.012 1
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Sample IOc.OO7 14.000 14.001 14.002
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Sample 21.01021.01121.01221.01321.0
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Sample 15.009 15.010 15 .011 15.012
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Sample 22.014 22.015 22.016 22.017
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Sample 26.000 26001 26.002 26003 26
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AS Composicao química, em porcenta
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Sample18.00018020 18.021 18028Analy
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Sample 10.009 10.010 10.013 10014 1
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Sample 22.000 22.001 22.002 22.003
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A9 Composicao química, em porcenta
Page 375 and 376:
Sample 10.002 10.013 10024 10.027 1
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Tesis Doctoral de Jaime - GeologÃ­a del Paraguay

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Tesis Doctoral de Jaime - GeologÃa del Paraguay