Sample records for intrusion rock
from WorldWideScience.org

Sample records 1 - 2 shown.



1

Kimberlito Canastra-1 (São Roque de Minas, MG): geologia, mineralogia e reservas diamantíferas/ The Canastra-1 kimberlite (Sao Roque de Minas town, MG): geology, mineralogy and diamond reserves

Chaves, Mario Luiz de Sá C.; Brandão, Paulo Roberto Gomes; Girodo, Antonio Carlos; Benitez, Leila
2008-09-01

Resumo em português A pesquisa de fontes diamantíferas primárias no Brasil iniciou-se na década de 1960, culminando com a descoberta da mineralização no kimberlito Canastra-1, que representa a primeira fonte primária com teores economicamente viáveis do país. O kimberlito aflora na região da Serra da Canastra, nas cabeceiras do rio São Francisco. A intrusão é constituída de dois blows alinhados segundo NW-SE, o trend estrutural da região definido em metassedimentos do Grupo Can (mais) astra. O blow menor (NW), quase circular e com ±0,8 ha de área, possui teores desprezíveis em diamantes. O outro (SE), com quase 1 ha, é mineralizado a um teor médio de 12-18 ct/100 t de rocha. Variações significativas também são verificadas em relação às fácies petrográficas do kimberlito, homogênea no blow NW, enquanto a SE é heterogênea, ocorrendo a mistura de várias fácies. A curta distância entre os blows ( Resumo em inglês The research on the primary diamond sources in Brazil started in the 1960 years and had its highest achievement with the discovery of the mineralized Canastra-1 kimberlite which is the first Brazilian primary deposit having economic contents. This pipe surfaces in the Serra da Canastra (Canastra Range) near the sources of the São Francisco River. The intrusion is made up of two blows lined along NE-SE, which is the region's structural trend defined in the metasedimentary (mais) rocks of the Canastra Group. The smaller blow is nearly circular with an area of approximately 0.8 ha and has only negligible diamond content. The SE blow has almost 1.0 ha and is mineralized with an average content of 12 to 18 ct/100 tonnes of rock. There are also significant differences in the petrographic facies of the two bodies, which is homogeneous in the NW blow while the SE blow is heterogeneous, with the occurrence of a mixture of several facies. The short distance between the blows justifies the assumption that they join in depth, therefore being apophyses of the same intrusion. The mineral chemistry of the indicators showed a strong resemblance with some diamondiferous African kimberlites. Data from experimental mining indicated an excellent quality for this kimberlite's diamonds, with US$180-200/ct estimated average value.

Scientific Electronic Library Online (Portuguese)

2

Caracterização hidrogeoquímica de água subterrânea em área de influência de futuras instalações de usinas hidrelétricas: bacia hidrográfica do rio Taquari-Antas/RS, Brasil/ Hydrochemical characterization of groundwaters in projected hydroelectric power plant areas: Taquari-Antas Basin/RS, Brazil

Scopel, Rejane Maria; Teixeira, Elba Calesso; Binotto, Raquel Barros
2005-06-01

Resumo em inglês The identification and characterization of the hydrochemistry of the groundwaters has been done for seven wells. The sampling occurred during three bimonthly campaigns. The results classified the waters as of the calcium bicarbonated type for the majority of the samples, except for one well, whose composition is of the sodium bicarbonated type. The major ions found and how they determine the quality parameters are consistent with the reactions of mineral dissolution of th (mais) e majority of volcanic rocks and the reactions with intrusion of alkaline rock in only one well. Anomalous values of nitrate in some wells alert to the impact of especially polluting sources at the time the reservoirs of the hydroeletric plant were formed.

Scientific Electronic Library Online (Portuguese)