PLANAGEO Geological MappingMain goals, methodology and expected results

1st Angola Mining Conference & ExhibitionCCTA - Luanda, 20 e 21 de Novembro, 2019

Area 3 – Southwest Angola:

• 476.512 Km2 (37,5 % of Angola’s total area)

• 44 sheets (Geological Map of Angola, 1/250 000)

• Deadline – 5 years

Working conditions:

• Very different climates and landscapes – complex logistics

• Explosive remnants of four decades of war

The challenge of Geological Mapping in PLANAGEO

How to make good quality geological maps under these conditions?Let us consider this question from different perpectives:

Definition and representation of geological units

Legend for the continuous Gelogical map of Angola

Expected results: usefulness for Mineral Exploration

Definition and representation of geological units

Former geological maps

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Remote sensing and airborne geophysics (mag/rad)

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Preliminary geological maps

• Compilation of former geological information• Use of Remote Sensing and Airborne Geophysics• Elaboration of preliminary geological maps• Concept of legend architecture

Definition and representation of geological units

Extensive sampling program (1:250 000)18 770 points of observation and data registration

6 787 samples of rocks and sediments253 samples for geochronology: U-Pb, Ar-Ar, Nd(TDM)

174 points for passive seismics data acquisition527 measures of magnetic susceptibility in rocks

55 samples for paleomagnetism determinations

Brownfield & Charpentier (2006)

Legend for the continuous Geological Map of Angola

Level 1 Sedimentary cover

Level 1a Perioceanic basins Intracontinental basins

Level 2 Namibe Kwanza Baixo Congo Congo Kalahari

Legend architecture• Main geotectonic units of Africa (Level 1)• Correlation domains (Level 2)

Hueck et al., 2018

Level 1 Basement

Level 1a Mobile Belts Cratons (Congo craton)

Carvalho et al., 2000

Legend for the continuos Geological Map of Angola

Legend architecture for the Continuous Geological Map of Angola• Complementary studies (Geochronology U-Pb, Ar-Ar, Nd) for definition of geological domains inside Congo Craton (Level 2)

Level 1 Basement

Level 1a Mobile Belts (Pan-African) Cratons (Cratão do Congo)

Level 2(provisional)

Espinheira -Kaoko

Alto Zambeze

Congo Ocidental

Namibe Centro-Oeste

Huambo -Bié

Cassinga

Some previous attempts todefine geological domains insideCongo Craton. PLANAGEO’s workshould improve this previousknowledge. The main objectiveis to give more consistence tothe legend architecture. Thegeochronological results areproving to be truly decisive inthe achievement of this goal.

Level 1(with possible sublevels)

Level 2

(with possible sublevels)

Level 3

Cartographic units grouped with geological significance (sedimentary, magmatic, tectonometamorphic)

This level includes a fundamental procedure in the geological mapping of vast regions: the correlation of geological units

Includes all the units defined during the geological mapping works according to the international codes for definition and nomenclature of lithostratigraphic and lithodemic units

Fixed organization levels of broad consensus among geologists

Dynamic level for permanent replacement of former units and inclusion of new units

Legend architecture for Continuous Geological Map of Angola• Prepares the integration of all preexisting or future geological knowledge • Includes minimal interpreted knowledge• It forms the basis of any GIS data model

This level aims to obtain a broad consensus for the organization of geological units

Legend for the continuos Geological Map of Angola (provisional example)

Legend for the continuos Geological Map of Angola

2nd level of horizontal organization: geological correlation

3rd level of horizontal organization: Geological/cartographic units

1st level of horizontal organization: main geotectonic units 1st

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Geological maps with the usual:• Description of geological units

and type of contacts;• Graphic interpretations of

regional macrostructures; • Representation of polycyclic

geological sets and probably, 1st order epigenic transformations;

(Adapted from Jelsma et al., 2018)

Legend with hierarchical architecture (both vertical and horizontal), showing:• Major geotectonic units;• Domains of basinal

correlation;• Tectonic domains in mobile

belts• Probable domains of cratonic

polycyclic amalgamation• Main regional thermotectonic

and magmatic events

• Existence criteria (geological models of existence)▪ Does geology support the existence of a certain resource?

• Location criteria (geological models of location) – facing the viability of

existence, geology guides the selection of areas most favorable to the occurrence:

• Quality/dimension/concentration criteria (geological models of concentration– in the most favorable locations will be exploration projects for

“value” determination

State

Private promotors

Usefulness in mineral exploration

Geological Map – essential tool in the exploration of mineral resources

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Geological Maps

Exploration projects

Muito obrigado pela vossa atençãoMany thanks for your attention