The tectono-stratigraphic relationships between the upper Precambrian and lower Paleozoic Volta Basin and the Pan-African Dahomeyide orogenic belt (West Africa)

Affaton, Pascal; Sougy, Jean; Trompette, Roland

doi:10.2475/ajs.280.3.224

Cited by 95 publications

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“…This basin appears as a semibasin (i.e., a half-basin), truncated to the East by the thrust front of the Dahomeyide Orogenic Belt [1,9,21]. Three megasequences are recognized.…”

Section: The Stable Zonementioning

confidence: 99%

“…Structurally, the lower and middle megasequences show significant eastward thickening in the Volta Basin where they are folded and partially incorporated into the frontal units of the Pan-African Dahomeyide Orogenic Belt [8][9][10]25]. According to Affaton [7], the associated structural and geophysical characteristics indicate a composite geodynamic evolution.…”

Section: The Stable Zonementioning

confidence: 99%

“…The Stable Zone corresponds to the southeastern margin of the Guinea [14] or Leo-Man Shield and its Neoproterozoic cover represented by the Volta Basin [1,5,9]. In southeast Ghana, the Stable Zone is mainly composed of Archean to Paleoproterozoic rocks involved in the Eburnean thermotectonic events and stabilized at the end of this orogeny (2000 ± 200 Ma).…”

Section: The Stable Zonementioning

confidence: 99%

“…It comprises different lithostructural units in the West (external structural units) or in the East (internal structural units), in relationship with the granulitic and eclogitic massifs representing the suture zone [1,10]. The external structural units are composed of sediments and metasediments, representing the lateral equivalents of the lower and middle megasequences of the Volta Basin [7,9,26], and/or gneissic nappes corresponding to the Eburnean rocks that were highly reworked during the Pan-African orogeny [1,18,[27][28][29].…”

Section: The Pan-african Mobilementioning

confidence: 99%

“…This Mobile Zone overthrusts the Volta Basin in the North and its Eburnean basement in the South. The Mobile Zone is described as a pile of west verging nappes involved in several folding phases [1,[6][7][8][9][10]. This juxtaposition of distinct lithostructural assemblages was resulted from the Pan-African tectogenesis.…”

Section: Introductionmentioning

confidence: 99%

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Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa)

Tairou

Affaton

Anum

et al. 2012

Journal of Geological Research

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This faulting tectonics analysis concerns the southernmost segment of the Dahomeyide Orogen and the West-African craton eastern margin in southeast Ghana. The analysis of strike-slip faults in the frontal units of the Dahomeyide Belt indicates that four distinct compressive events (NE-SW, ENE-WSW to E-W, ESE-WNW to SE-NW and SE-NW to SSE-NNW) originated the juxtaposition of the Pan-African Mobile Zone and the West-African craton. These paleostress systems define a clockwise rotation of the compressional axis during the structuring of the Dahomeyide Orogen (650-550 Ma). The SE-NW and SSE-NNW to N-S compressional axes in the cratonic domain and its cover (Volta Basin) suggest that the reactivation of the eastern edge of the West African craton is coeval with the last stages of the Pan-African tectogenesis in southeast Ghana. An extensional episode expressed as late normal faulting is also recorded in this study. This E-W to SE-NW extension, which is particular to the southernmost part of the Dahomeyide Belt, appears to be post-Pan-African. This extension probably contributed to the formation of a major Jurassic rifting zone that originated the Central Atlantic and the Benue Trough.

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“…This basin appears as a semibasin (i.e., a half-basin), truncated to the East by the thrust front of the Dahomeyide Orogenic Belt [1,9,21]. Three megasequences are recognized.…”

Section: The Stable Zonementioning

confidence: 99%

Section: The Stable Zonementioning

confidence: 99%

Section: The Stable Zonementioning

confidence: 99%

Section: The Pan-african Mobilementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa)

Tairou

Affaton

Anum

et al. 2012

Journal of Geological Research

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Occurrence and geochemistry of metamafic rocks from the Forquilha Eclogite Zone, central Ceará (NE Brazil): geodynamic implications

2011

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In the northern region of the Borborema Province, a 30 km-long mafic/ultramafic belt of high pressure (HP) rocks called the Forquilha Eclogite Zone has been recently discovered in the Central Domain of Ceará State. The belt comprises three groups of rocks: (1) garnet amphibolites, (2) retrograded eclogites and (3) clinopyroxene-garnet amphibolites, all of them being hosted in garnet AE kyanite þ sillimanite schists and orthogneisses which are often migmatized. The geochemical analyses of 30 representative samples confirm differences among the three groups that were initially classified by petrography. The garnet amphibolites are the most depleted rocks, with relatively flat rare earth element (REE) PM pattern and (SPIDER) PM pattern with negative Rb, Th, Nb, Sr and Zr anomalies. It is the most fractionated group, ranging from picrobasalts to andesites. Fractional crystallization and mineral accumulation are indicated by Eu and Sr anomalies. The data show geochemical affinities with island-arc basalts. The retrograded eclogites display flat (REE) PM , but without Eu anomalies. Nb/La ratios are low and variable, as for slightly enriched MORB from ocean floor or intra-oceanic back-arc environments. However, a genetic link with the Group 1 rocks cannot be completely discarded. The clinopyroxene-garnet amphibolites are the most enriched group. (REE) PM and (SPIDER) PM patterns show many features of alkaline basalts. In the Nb/Yb versus Th/Yb diagram the data cluster near the E-MORB standard. Several geochemical aspects of these rocks fit well those from the HP/UHP Pan-African/Brasiliano Suture Zone in the Dahomeyides/Hoggar regions of West Africa. However, differences in their extent and lack of alignment preclude a direct correlation among these zones.

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The Avalon Zone: A Pan‐African terrane in the Appalachian Orogen of Canada

1983

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The Precambrian sequences of the Avalon Zone in Canada (southeastern margin of the Appalachian Orogen) are interpreted as a Pan‐African orogenic belt incorporated into the Appalachian Orogen during Palaeozoic times as its southeastern margin. The Precambrian evolution of the Avalon Zone was genetically unrelated to subsequent Palaeozoic evolution. The Avalon Zone shows marked similarities in age, tectonic history, and facies development to the Pan‐African belts adjacent to the West African Craton. Precambrian evolution of the zone began with circa 800 Ma rifting of a sialic gneissic basement and deposition of a Middle Proterozoic(?) carbonate‐clastic cover sequence. Early crustal rifting was associated with localized partial melting and metamorphism. Limited crustal separation led to the restricted development of circa 760 Ma oceanic volcanics. Continued rifting and subsequent closure of these narrow ocean basins led to the eruption of widespread subaerial volcanic suites, block faulting, granite plutonism, and local, late Proterozoic sedimentary basin formation. Precambrian evolution of the zone terminated with the Avalonian Orogeny (circa 650‐600 Ma), a deformational event, the affects of which are most evident locally along the northwestern margin of the zone. The controlling features of the Proterozoic evolution of the Avalon Zone are a series of linear intracratonic troughs and small ocean basins that formed during thinning and separation of the crust by ductile spreading, rupture, and delamination (cf. Martin and Porada 1977). The variation in degree of crustal separation led to subsequent variation in orogenesis during late Proterozoic compression. The zone marks the original westward limit of Pan‐African activity and displays no apparent genetic link with the Appalachian Orogen in Canada until Devonian times.

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The tectono-stratigraphic relationships between the upper Precambrian and lower Paleozoic Volta Basin and the Pan-African Dahomeyide orogenic belt (West Africa)

Cited by 95 publications

References 0 publications

Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa)

Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa)

Occurrence and geochemistry of metamafic rocks from the Forquilha Eclogite Zone, central Ceará (NE Brazil): geodynamic implications

The Avalon Zone: A Pan‐African terrane in the Appalachian Orogen of Canada

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