Two series of Ediacaran collision-related granites in the Guéra Massif, South-Central Chad: Tectonomagmatic constraints on the terminal collision of the eastern Central African Orogenic Belt

Shellnutt, J. Gregory; Pham, Ngoc Ha T.; Yeh, Meng Wan; Lee, Tung Yi

doi:10.1016/j.precamres.2020.105823

Cited by 14 publications

(8 citation statements)

References 72 publications

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“…Lithologically, the Central Massif is composed of Neoproterozoic metavolcanic (amphibolite, metaandesite), metamorphic rocks (schists, marbles, quartzite, paragneiss and orthogneiss; Isseini et al, 2013;Kusnir and Moutaye, 1997) intruded by 595 and 545 Ma granitoids and gabbros (Shellnutt et al, 2020(Shellnutt et al, , 2019(Shellnutt et al, , 2018(Shellnutt et al, , 2017Nkouandou et al, 2017;Couzinié et al, 2020). Petrographically, the granitoids are classified into alkaline granites, monzonites and syenites.…”

Section: Central Massifmentioning

confidence: 99%

“…Hafnium isotopes preserve significant continental crustal influence (εHf(t) = -4.69 and -20.22), interpreted as representing melting of older Saharan Metacraton. Shellnutt et al (2020) dated a series of ferroan and magnesian alkali to calc-alkali rocks between ca. 600-580 Ma from the Central Massif.…”

Section: Timing and Nature Of Magmatism And Sedimentation In Chadmentioning

confidence: 99%

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Age and hafnium isotope evolution of Sudanese Butana and Chad illuminates the Stenian to Ediacaran evolution of the south and east Sahara

Blades

Collins

Foden

et al. 2021

Precambrian Research

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Section: Central Massifmentioning

confidence: 99%

Section: Timing and Nature Of Magmatism And Sedimentation In Chadmentioning

confidence: 99%

Age and hafnium isotope evolution of Sudanese Butana and Chad illuminates the Stenian to Ediacaran evolution of the south and east Sahara

Blades

Collins

Foden

et al. 2021

Precambrian Research

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“…Little is known about the Guéra massif which is primarily composed of granitoids (with minor gabbroic bodies) and metamorphic rocks (Isseini et al, 2013;Kusnir and Moutaye, 1997). A recent U-Pb dating survey of the igneous rocks revealed emplacement ages ranging between 595 and 545 Ma (Shellnutt et al, 2020(Shellnutt et al, , 2019(Shellnutt et al, , 2018(Shellnutt et al, , 2017 while a Neoproterozoic age is inferred for the metamorphic lithologies.…”

Section: Geological Settingmentioning

confidence: 99%

Crystalline inliers near Lake Iro (SE Chad): Post-collisional Ediacaran A2-type granitic magmatism at the southern margin of the Saharan Metacraton

Couzinié

Ménot

Doumnang

et al. 2020

Journal of African Earth Sciences

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The structure and evolution of the continental crust in the southern part of the Saharan Metacraton (central Africa) is poorly known due to extensive laterite and sediment cover as well as geographic isolation. We report on a series of five crystalline inliers newly discovered near Lake Iro (south-eastern Chad) that offered the opportunity to amphibole assemblage from a porphyritic granite melt and (ii) both granite types yield zircon U-Pb emplacement ages consistent within a 575.3 ± 5.6 to 581.3 ± 3.8 Ma time frame. The Lake Iro granites thus represent the oldest of a series of post-collisional igneous associations exposed in southern Chad and nearby countries which, collectively, show that the amalgamation of the constituent blocks of the southern Saharan Metacraton is older than 580 Ma.

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“…All outcropping rocks in the area of Figure 1 belong to the Neoproterozoic orogeny and correspond to granitoids with minor presence of more mafic intrusions as well as metamorphic rocks [7][8][9]. Intrusions are dated in between 545 and 590 Ma.…”

Section: Introductionmentioning

confidence: 99%

Petrographic and Mechanical Study of Aggregates from Central Chad: a case for Natural Selection of hard rocks

Al-hadj,

Rochette,

Allafouza

2024

Preprint

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This study focusses on the geological formations of the Alfallé massif located approximately 75km east of the town of N'Goura, in the Hadjer-Lamis Province of Chad (13°N, 17°E), and their ability to provide good quality aggregates in an area with poor hard rock ressources. We investigated the petrographic and mechanical characteristics of these formations in a resource perspective. The massif is made up of three lithologies: alkali feldspar megacrystalline granite, biotite-rich fine grained quartz monzonite and biotite-rich fine grained gneiss. Alkali feldspar megacrystalline granite is composed of quartz (30%), orthoclase (30%), plagioclase (20%), biotite (15%) and opaque minerals (≈5%). Micro-monzonite is composed of quartz (15-20%), orthoclase (20-25%), plagioclase (18-25%), biotite (20-25%) and opaque minerals (≈4%). The biotite gneiss is composed of quartz (25-30%), alkali feldspars (25-27%), plagioclase (17%), biotite (25-27%) and opaque minerals (≈5%). The mechanical characteristics of the aggregates show that the aggregates studied have specific density values of between 2.58 and 2.75g/cm3 with an average value of 2.66g/cm3, a Los-Angeles coefficient of 11.2% to 28.9% with an average value of 20.1% and a wet Micro-Deval coefficient of 5.2% to 10.8% with an average value of 7.6%. The values obtained indicate that the materials studied have excellent to satisfactory properties, and that Alfallé massif provide the best characteristics among six different quarrying area in Central Chad. We propose that such rare residual reliefs within the mega-Chad paleolake area reach optimal mechanical properties through a natural selection process, specific of the paleolake erosional conditions.

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Two series of Ediacaran collision-related granites in the Guéra Massif, South-Central Chad: Tectonomagmatic constraints on the terminal collision of the eastern Central African Orogenic Belt

Cited by 14 publications

References 72 publications

Age and hafnium isotope evolution of Sudanese Butana and Chad illuminates the Stenian to Ediacaran evolution of the south and east Sahara

Age and hafnium isotope evolution of Sudanese Butana and Chad illuminates the Stenian to Ediacaran evolution of the south and east Sahara

Crystalline inliers near Lake Iro (SE Chad): Post-collisional Ediacaran A2-type granitic magmatism at the southern margin of the Saharan Metacraton

Petrographic and Mechanical Study of Aggregates from Central Chad: a case for Natural Selection of hard rocks

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