Download Algumas definições

January 17, 2018 | Author: Anonymous | Category: , Science, Earth Science, Plate Tectonics
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SOME USEFUL DEFINITIONS AND COMPILATIONS in Introduction to Ore-Forming Processes by Laurence Robb Blackwell Publishing 374 p.

Com base na discussão da aula de 27 de Março define com as tuas palavras os seguintes termos (insere exemplos): Some general definitions This section is not intended to provide a comprehensive glossary of terms used in this book. There are, however, several terms that are used throughout the text where a definition is either useful or necessary in order to avoid ambiguity. The following definitions are consistent with those provided in the Glossary of Geology (Bates and Jackson, 1987) and The Encyclopaedia of the Solid Earth Sciences (Kearey, 1993). Ore (minério; mena): any naturally occurring material from which a mineral or aggregate of value can be extracted at a profit. In this book the concept extends to coal (a combustible rock comprising more than 50% by weight carbonaceous material) and petroleum (naturally occurring hydrocarbon in gaseous, liquid, or solid state).

Syngenetic (singenético): refers to ore deposits that form at the same time as their host rocks. In this book this includes deposits that form during the early stages of sediment diagenesis.

Epigenetic (epigenético): refers to ore deposits that form after their host rocks.

Hypogene (hipogénico): refers to mineralization caused by ascending hydrothermal solutions.

Supergene (Supergénico): refers to mineralization caused by descending solutions. Generally refers to the enrichment processes accompanying the weathering and oxidation of sulfide and oxide ores at or near the surface.

Metallogeny (metalogenia): the study of the genesis of mineral deposits, with emphasis on their relationships in space and time to geological features of the Earth's crust.

Metallotect (metalotecto): any geological, tectonic, lithological, or geochemical feature that has played a role in the concentration of one or more elements in the Earth's crust.

Metallogenic Epoch (época metalogenética): a unit of geologic time favorable for the deposition of ores or characterized by a particular assemblage of deposit types.

Metallogenic Province (provincia metalogenética): a region characterized by a particular assemblage of mineral deposit types.

Epithermal (epitermal): hydrothermal ore deposits formed at shallow depths (less than 1500 meters) and fairly low temperatures (50-200 ºC).

Mesothermal (mesotermal): hydrothermal ore deposits formed at intermediate depths (1500-4500 meters) and temperatures (200-400 ºC).

Hypothermal (hipotermal): hydrothermal ore deposits formed at substantial depths (greater than 4500 meters) and elevated temperatures (400-600 ºC).

Jazigo Mineral – Depósito Mineral – Yacimiento de mineral – parte da crosta onde seproduziu uma concentração/acumulação de uma substância mineral, que pode ser utilizda industrialmente, devido à sua quantidade e condições de jazida.

Ocorrência mineral – apenas regista a presença de uma determinda substância mineral, geralmente interessante, mas sem eventual expressão económica

Clarke – concentração média do elemento químico na crosta

Factor de concentração – Factor multiplicativo que deverá ser multiplicado ao clarke de um elemento químico para que uma determinada substância tenha um teor mínimo explorável económicamente.

AI Fe Cu Ni Zn Sn Au Pt

Average crustal abundance 8.2% 5.6% 55 ppm 75 ppm 70 ppm 2 ppm 4 ppb 5 ppb

Typical exploitable grade 30% 50% 1% 1% 5% 0.5% 5 g t-1 5 g t-1

Approximate concentration factor x4 x9 x180 x130 x700 x2500 x1250 x1000

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